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Title: Relative Sorption Coefficient: Key To Tracing Petroleum Migration And Other Subsurface Fluids.
Creator: Zhang, L., Wang, Y., Li, M.-W., Yin, Q.-Z., Zhang, W.
Abstract/Description: The accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we...
Show moreThe accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we present a new approach based on a novel concept of relative sorption coefficient for quantitatively assessing sorption capacities of polar molecules during natural petroleum migration. Using this approach, we discovered previously unrecognized "stripping" and "impeding" effects that significantly reduce the sorption capacities of polar compounds. These discoveries provide new insights into the behaviors of polar compounds and can easily explain why traditional molecular indices yield incorrect information about petroleum migration. In light of these new findings, we established new molecular indices for tracing petroleum migration. We demonstrate via case studies that the newly established indices, unlike traditional molecular indices, are reliable and effective in tracing petroleum migration. Our approach can be applied to diverse basins around the world to reveal distribution patterns of petroleum, which would decrease environmental risks of exploration by reducing unsuccessful wells.
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Date Issued: 2019-11-14
Identifier: FSU_libsubv1_wos_000496416000055, 10.1038/s41598-019-52259-6
Format: Citation

Title: Growth pattern and oxygen isotopic systematics of modern freshwater mollusks along an elevation transect: implications for paleoclimate reconstruction.
Creator: Roy, Rupsa, Wang, Yang, Jiang, Shijun
Abstract/Description: Fossil mollusk shells are widely distributed in the geologic records and their oxygen isotopic compositions have been used to reconstruct seasonality, local climatic and elevation conditions. However, interpretation of isotope data from fossil shells to estimate paleoclimate and elevation is often ambiguous. This study examines the oxygen isotopic systematics of modern freshwater gastropods (Bellamya and Radix) shells along an elevation/climate transect in the Asian monsoon region of China to...
Show moreFossil mollusk shells are widely distributed in the geologic records and their oxygen isotopic compositions have been used to reconstruct seasonality, local climatic and elevation conditions. However, interpretation of isotope data from fossil shells to estimate paleoclimate and elevation is often ambiguous. This study examines the oxygen isotopic systematics of modern freshwater gastropods (Bellamya and Radix) shells along an elevation/climate transect in the Asian monsoon region of China to improve the accuracy of paleoclimate and paleoelevation reconstruction using stable isotopes in fossil shells. The results from sclerochronological analyses of the shells show that the intra-shell oxygen isotopic pattern is determined by seasonal variations in lake water temperature and water isotopic composition as well as the life cycle of the organism. Both Bellamya and Radix appear to grow throughout the year in lakes where water temperature does not fall below 13° C. Radix in the high elevation cold habitat, although prefers to grow in the warmer months, can survive through the freezing temperature. The δ18O patterns in the shells are similar across the elevation/climate transect, showing high δ18O values in the winter months and low δ18O values in the summer months, consistent with the expected pattern in Asian monsoon region. The average growth rates of the shells were highest at the lowest elevation site (warm and humid climate) but were similar at the mid to high elevation sites. For large shells (> 2.2 cm for Bellamya and > 1.4 cm for Radix), average growth temperatures, calculated using the aragonite oxygen isotope thermometer, closely approximate the annual mean water temperature while their intra-shell variability is a good proxy for the amplitude of seasonal variations in monthly air temperature. This suggests that large shells of both Bellamya and Radix are excellent archives of lake environmental conditions and most suitable for paleoenvironmental studies.
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Date Issued: 2019
Identifier: FSU_libsubv1_scholarship_submission_1583274299_840e6efc, 10.1016/j.palaeo.2019.109243
Format: Citation

Title: Relative sorption coefficient: Key to tracing oil migration and other subsurface fluids.
Creator: Zhang, Liuping, Wang, Yang, Li, Maowen, Yin, Qing-Zhu, Zhang, Wenzheng
Abstract/Description: The accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we...
Show moreThe accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we present a new approach based on a novel concept of relative sorption coefficient for quantitatively assessing sorption capacities of polar molecules during natural petroleum migration. Using this approach, we discovered previously unrecognized “stripping” and “impeding” effects that significantly reduce the sorption capacities of polar compounds. These discoveries provide new insights into the behaviors of polar compounds and can easily explain why traditional molecular indices yield incorrect information about petroleum migration. In light of these new findings, we established new molecular indices for tracing petroleum migration. We demonstrate via case studies that the newly established indices, unlike traditional molecular indices, are reliable and effective in tracing petroleum migration. Our approach can be applied to diverse basins around the world to reveal distribution patterns of petroleum, which would decrease environmental risks of exploration by reducing unsuccessful wells.
Show less
Date Issued: 2019
Identifier: FSU_libsubv1_scholarship_submission_1583294878_b92a68b1, 10.1038/s41598-019-52259-6
Format: Citation

Title: Paleoecology of Pleistocene Mammals and Paleoclimatic Change in South China: Evidence from stable carbon and oxygen isotopes.
Creator: Sun, Fajun, Wang, Yang, Wang, Yuan, Jin, Chang-zhu, Deng, Tao, Wolff, Burt
Abstract/Description: The role of climate change in the evolution and diversification of hominoids remains a hotly debated issue. Stable isotope analyses of fossil mammals that coexisted with the hominoids can provide insights into the environments of the hominoids and shed light on this debate. Here, we report results of stable carbon and oxygen isotope analyses of tooth enamel samples from a variety of Pleistocene mammals including pandas, deer, elephants, pigs, rhinos, and bovids from two hominoid fossil...
Show moreThe role of climate change in the evolution and diversification of hominoids remains a hotly debated issue. Stable isotope analyses of fossil mammals that coexisted with the hominoids can provide insights into the environments of the hominoids and shed light on this debate. Here, we report results of stable carbon and oxygen isotope analyses of tooth enamel samples from a variety of Pleistocene mammals including pandas, deer, elephants, pigs, rhinos, and bovids from two hominoid fossil localities (Yuweng Cave and Baxian Cave) in South China. The enamel δ13C values indicate that most of the mammals living in the study area during the late Middle Pleistocene had C3-based diets but a small number of individuals consumed some C4 grasses. This indicates the presence of C4 plants in the region during the late Middle Pleistocene, most likely in patches of open areas in a predominantly forested environment. However, during the early Late Pleistocene, all of the mammals examined had C3-based diets, except one bovid and one panda that may have ingested small amounts of C4 plants. This indicates a dense forested environment with little C4 grasses during the early Late Pleistocene. Like the Early Pleistocene pygmy panda (Ailuropoda microta) from Yanliang Cave, the late Middle Pleistocene Ailuropoda baconi from Yuweng Cave and the early Late Pleistocene Ailuropoda melanoleuca from Baxian Cave had higher mean diet-δ13C values than the other co-occurring herbivores, indicating they preferred relatively open forest habitats and had more restricted diets compared to other mammals. The reconstructed mean paleo-meteoric water δ18Ow values are lower than the annual average δ18Ow value of modern precipitation in the region, suggesting that the climatic conditions during the times when these Pleistocene mammals were alive were colder and/or wetter than today. In addition, δ18O values of the obligate drinkers (pig, rhino, bovid) display an overall decreasing trend, accompanied by increased range of δ18O variations, from the Early Pleistocene to the early Late Pleistocene. This suggests that the regional climate became colder and/or wetter, with increased seasonality, from the Early Pleistocene to the early Late Pleistocene, likely related to intensified glaciation. The change in climate to colder conditions may be responsible for the extinction of the Gigantopithecus in this region.
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Date Issued: 2019
Identifier: FSU_libsubv1_scholarship_submission_1590721871_742fe319, 10.1016/j.palaeo.2019.03.021
Format: Citation

Title: The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics.
Creator: Stukel, Michael R., Kelly, Thomas B., Aluwihare, Lihini I., Barbeau, Katherine A., Georicke, Ralf, Krause, Jeffrey W., Laudry, Michael R., Ohman, Mark D.
Abstract/Description: We investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:234Th ratios of sinking particles collected by a surface-tethered sediment trap (C:234ThST) varied from 2.3 to 20.5 μmol C dpm−1 over a depth range of 47–150 m. C:234ThST was...
Show moreWe investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:234Th ratios of sinking particles collected by a surface-tethered sediment trap (C:234ThST) varied from 2.3 to 20.5 μmol C dpm−1 over a depth range of 47–150 m. C:234ThST was significantly greater (by a factor of 1.8) than C:234Th ratios of suspended >51-μm particles collected in the same water parcels with in situ pumps. C:234Th ratios of large (>200-μm) sinking particles also exceeded those of smaller sinking particles. C:234ThST decreased with depth from the base of the euphotic zone through the upper twilight zone. C:234ThST was positively correlated with several indices of ecosystem productivity including particulate organic carbon (POC) and chlorophyll (Chl) concentrations, mesozooplankton biomass, and the fraction of Chl >20-μm. Principal component analysis and multiple linear regression suggested that decaying phytoplankton blooms exhibited higher C:234ThST than actively growing blooms at similar biomass levels. C:234ThST was positively correlated with indices of the fractional contribution of fecal pellets in sediment traps when the proportion of fecal pellets was low in the traps, likely because of a correlation between mesozooplankton biomass and other indices of ecosystem productivity. However, when fecal pellets were a more important component of sinking material, C:234ThST decreased with increasing fecal pellet content. C:234ThST was also positively correlated with the Si:C ratio of sinking particles. Across the dataset (and across depths) a strong correlation was found between C:234ThST and the ratio of vertically-integrated POC to vertically-integrated total water column 234Th (vC:234Thtot). A mechanistic one-layer, two-box model of thorium sorption and desorption was invoked to explain this correlation. Two empirical models (one using vC:234Thtot; one using depth and vertically-integrated Chl) were developed to predict C:234Th ratios in this coastal upwelling biome. The former regression (log10(C:234ThST) = 0.43 × log10(vC:234Thtot) + 0.53) was found to also be a reasonable predictor for C:234ThST from diverse regions including the Southern Ocean, Sargasso Sea, Subarctic North Pacific, and Eastern Tropical North Pacific.
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Date Issued: 2019
Identifier: FSU_libsubv1_scholarship_submission_1548688180_32dbfc1e, 10.1016/j.marchem.2019.01.003
Format: Citation

Title: Methanotrophy across a natural permafrost thaw environment.
Creator: Singleton, Caitlin M, McCalley, Carmody K, Woodcroft, Ben J, Boyd, Joel A, Evans, Paul N, Hodgkins, Suzanne B, Chanton, Jeffrey P, Frolking, Steve, Crill, Patrick M, Saleska,...
Show moreSingleton, Caitlin M, McCalley, Carmody K, Woodcroft, Ben J, Boyd, Joel A, Evans, Paul N, Hodgkins, Suzanne B, Chanton, Jeffrey P, Frolking, Steve, Crill, Patrick M, Saleska, Scott R, Rich, Virginia I, Tyson, Gene W
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Abstract/Description: The fate of carbon sequestered in permafrost is a key concern for future global warming as this large carbon stock is rapidly becoming a net methane source due to widespread thaw. Methane release from permafrost is moderated by methanotrophs, which oxidise 20-60% of this methane before emission to the atmosphere. Despite the importance of methanotrophs to carbon cycling, these microorganisms are under-characterised and have not been studied across a natural permafrost thaw gradient. Here, we...
Show moreThe fate of carbon sequestered in permafrost is a key concern for future global warming as this large carbon stock is rapidly becoming a net methane source due to widespread thaw. Methane release from permafrost is moderated by methanotrophs, which oxidise 20-60% of this methane before emission to the atmosphere. Despite the importance of methanotrophs to carbon cycling, these microorganisms are under-characterised and have not been studied across a natural permafrost thaw gradient. Here, we examine methanotroph communities from the active layer of a permafrost thaw gradient in Stordalen Mire (Abisko, Sweden) spanning three years, analysing 188 metagenomes and 24 metatranscriptomes paired with in situ biogeochemical data. Methanotroph community composition and activity varied significantly as thaw progressed from intact permafrost palsa, to partially thawed bog and fully thawed fen. Thirteen methanotroph population genomes were recovered, including two novel genomes belonging to the uncultivated upland soil cluster alpha (USCα) group and a novel potentially methanotrophic Hyphomicrobiaceae. Combined analysis of porewater δC-CH isotopes and methanotroph abundances showed methane oxidation was greatest below the oxic-anoxic interface in the bog. These results detail the direct effect of thaw on autochthonous methanotroph communities, and their consequent changes in population structure, activity and methane moderation potential.
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Date Issued: 2018-10-01
Identifier: FSU_pmch_29955139, 10.1038/s41396-018-0065-5, PMC6155033, 29955139, 29955139, 10.1038/s41396-018-0065-5
Format: Citation

Title: Spatiotemporal Variability Of No2 And Pm2.5 Over Eastern China: Observational And Model Analyses With A Novel Statistical Method.
Creator: Liu, Mengyao, Lin, Jintai, Wang, Yuchen, Sun, Yang, Zheng, Bo, Shao, Jingyuan, Chen, Lulu, Zheng, Yixuan, Chen, Jinxuan, Fu, Tzung-May, Yan, Yingying, Zhang, Qiang, Wu, Zhaohua
Abstract/Description: Eastern China (27-41 degrees N, 110-123 degrees E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 mu m (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF-EEMD analysis visualization package to evaluate the spatiotemporal...
Show moreEastern China (27-41 degrees N, 110-123 degrees E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 mu m (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF-EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2, PM2.5, and their associations with meteorological processes over Eastern China in fall-winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north-south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another. We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 mu g m(-3) and PM2.5 by 35 mu g m(-3 )on average over fall-winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north-south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 mu g m(-3) and PM2.5 by 60 mu g m(-3). For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north-south opposing mode of NO2. Both models capture the day-to-day variability of PM2.5 better than that of NO2. These results shed light on model improvement. The EOF-EEMD package is freely available for noncommercial uses.
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Date Issued: 2018-09-07
Identifier: FSU_libsubv1_wos_000444030500003, 10.5194/acp-18-12933-2018
Format: Citation

Title: Tropical Peatland Carbon Storage Linked To Global Latitudinal Trends In Peat Recalcitrance.
Creator: Hodgkins, Suzanne B., Richardson, Curtis J., Dommain, Rene, Wang, Hongjun, Glaser, Paul H., Verbeke, Brittany, Winkler, B. Rose, Cobb, Alexander R., Rich, Virginia I.,...
Show moreHodgkins, Suzanne B., Richardson, Curtis J., Dommain, Rene, Wang, Hongjun, Glaser, Paul H., Verbeke, Brittany, Winkler, B. Rose, Cobb, Alexander R., Rich, Virginia I., Missilmani, Malak, Flanagan, Neal, Ho, Mengchi, Hoyt, Alison M., Harvey, Charles F., Vining, S. Rose, Hough, Moira A., Moore, Tim R., Richard, Pierre J. H., De la Cruz, Florentino B., Toufaily, Joumana, Hamdan, Rasha, Cooper, William T., Chanton, Jeffrey P.
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Abstract/Description: Peatlands represent large terrestrial carbon banks. Given that most peat accumulates in boreal regions, where low temperatures and water saturation preserve organic matter, the existence of peat in (sub)tropical regions remains enigmatic. Here we examined peat and plant chemistry across a latitudinal transect from the Arctic to the tropics. Near-surface low-latitude peat has lower carbohydrate and greater aromatic content than near-surface high-latitude peat, creating a reduced oxidation...
Show morePeatlands represent large terrestrial carbon banks. Given that most peat accumulates in boreal regions, where low temperatures and water saturation preserve organic matter, the existence of peat in (sub)tropical regions remains enigmatic. Here we examined peat and plant chemistry across a latitudinal transect from the Arctic to the tropics. Near-surface low-latitude peat has lower carbohydrate and greater aromatic content than near-surface high-latitude peat, creating a reduced oxidation state and resulting recalcitrance. This recalcitrance allows peat to persist in the (sub)tropics despite warm temperatures. Because we observed similar declines in carbohydrate content with depth in high-latitude peat, our data explain recent field-scale deep peat warming experiments in which catotelm (deeper) peat remained stable despite temperature increases up to 9 degrees C. We suggest that high-latitude deep peat reservoirs may be stabilized in the face of climate change by their ultimately lower carbohydrate and higher aromatic composition, similar to tropical peats.
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Date Issued: 2018-09-07
Identifier: FSU_libsubv1_wos_000444014100015, 10.1038/s41467-018-06050-2
Format: Citation

Title: Tropical peatland carbon storage linked to global latitudinal trends in peat recalcitrance.
Creator: Hodgkins, Suzanne B, Richardson, Curtis J, Dommain, René, Wang, Hongjun, Glaser, Paul H, Verbeke, Brittany, Winkler, B Rose, Cobb, Alexander R, Rich, Virginia I, Missilmani,...
Show moreHodgkins, Suzanne B, Richardson, Curtis J, Dommain, René, Wang, Hongjun, Glaser, Paul H, Verbeke, Brittany, Winkler, B Rose, Cobb, Alexander R, Rich, Virginia I, Missilmani, Malak, Flanagan, Neal, Ho, Mengchi, Hoyt, Alison M, Harvey, Charles F, Vining, S Rose, Hough, Moira A, Moore, Tim R, Richard, Pierre J H, De La Cruz, Florentino B, Toufaily, Joumana, Hamdan, Rasha, Cooper, William T, Chanton, Jeffrey P
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Abstract/Description: Peatlands represent large terrestrial carbon banks. Given that most peat accumulates in boreal regions, where low temperatures and water saturation preserve organic matter, the existence of peat in (sub)tropical regions remains enigmatic. Here we examined peat and plant chemistry across a latitudinal transect from the Arctic to the tropics. Near-surface low-latitude peat has lower carbohydrate and greater aromatic content than near-surface high-latitude peat, creating a reduced oxidation...
Show morePeatlands represent large terrestrial carbon banks. Given that most peat accumulates in boreal regions, where low temperatures and water saturation preserve organic matter, the existence of peat in (sub)tropical regions remains enigmatic. Here we examined peat and plant chemistry across a latitudinal transect from the Arctic to the tropics. Near-surface low-latitude peat has lower carbohydrate and greater aromatic content than near-surface high-latitude peat, creating a reduced oxidation state and resulting recalcitrance. This recalcitrance allows peat to persist in the (sub)tropics despite warm temperatures. Because we observed similar declines in carbohydrate content with depth in high-latitude peat, our data explain recent field-scale deep peat warming experiments in which catotelm (deeper) peat remained stable despite temperature increases up to 9 °C. We suggest that high-latitude deep peat reservoirs may be stabilized in the face of climate change by their ultimately lower carbohydrate and higher aromatic composition, similar to tropical peats.
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Date Issued: 2018-09-07
Identifier: FSU_pmch_30194308, 10.1038/s41467-018-06050-2, PMC6128871, 30194308, 30194308, 10.1038/s41467-018-06050-2
Format: Citation

Title: Synthetic Ozone Deposition And Stomatal Uptake At Flux Tower Sites.
Creator: Ducker, Jason A., Holmes, Christopher D., Keenan, Trevor F., Fares, Silvano, Goldstein, Allen H., Mammarella, Ivan, Munger, J. William, Schnell, Jordan
Abstract/Description: We develop and evaluate a method to estimate O-3 deposition and stomatal O-3 uptake across networks of eddy covariance flux tower sites where O-3 concentrations and O-3 fluxes have not been measured. The method combines standard micrometeorological flux measurements, which constrain O-3 deposition velocity and stomatal conductance, with a gridded dataset of observed surface O-3 concentrations. Measurement errors are propagated through all calculations to quantify O-3 flux uncertainties. We...
Show moreWe develop and evaluate a method to estimate O-3 deposition and stomatal O-3 uptake across networks of eddy covariance flux tower sites where O-3 concentrations and O-3 fluxes have not been measured. The method combines standard micrometeorological flux measurements, which constrain O-3 deposition velocity and stomatal conductance, with a gridded dataset of observed surface O-3 concentrations. Measurement errors are propagated through all calculations to quantify O-3 flux uncertainties. We evaluate the method at three sites with O(3 )flux measurements: Harvard Forest, Blodgett Forest, and Hyytiala Forest. The method reproduces 83 % or more of the variability in daily stomatal uptake at these sites with modest mean bias (21 % or less). At least 95 % of daily average values agree with measurements within a factor of 2 and, according to the error analysis, the residual differences from measured O-3 fluxes are consistent with the uncertainty in the underlying measurements. The product, called synthetic O-3 flux or SynFlux, includes 43 FLUXNET sites in the United States and 60 sites in Europe, totaling 926 site years of data. This dataset, which is now public, dramatically expands the number and types of sites where O-3 fluxes can be used for ecosystem impact studies and evaluation of air quality and climate models. Across these sites, the mean stomatal conductance and O-3 deposition velocity is 0.03-1.0 cm s(-1). The stomatal O-3 flux during the growing season (typically April-September) is 0.5-11.0 nmol O-3 m(-2) s(-1) with a mean of 4.5 nmol O(3 )m(-2) s(-1) and the largest fluxes generally occur where stomatal conductance is high, rather than where O-3 concentrations are high. The conductance differences across sites can be explained by atmospheric humidity, soil moisture, vegetation type, irrigation, and land management. These stomatal fluxes suggest that ambient O-3 degrades biomass production and CO2 sequestration by 20 %-24 % at crop sites, 6 %-29 % at deciduous broadleaf forests, and 4 %-20 % at evergreen needleleaf forests in the United States and Europe.
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Date Issued: 2018-09-06
Identifier: FSU_libsubv1_wos_000443863200002, 10.5194/bg-15-5395-2018
Format: Citation

Title: Adapting open-source drone autopilots for real-time iceberg observations.
Creator: Carlson, Daniel F, Rysgaard, Søren
Abstract/Description: Drone autopilots are naturally suited for real-time iceberg tracking as they measure position and orientation (pitch, roll, and heading) and they transmit these data to a ground station. We powered an ArduPilot Mega (APM) 2.6 with a 5V 11 Ah lithium ion battery (a smartphone power bank), placed the APM and battery in a waterproof sportsman's box, and tossed the box and its contents by hand onto an 80 m-long iceberg from an 8 m boat. The data stream could be viewed on a laptop, which greatly...
Show moreDrone autopilots are naturally suited for real-time iceberg tracking as they measure position and orientation (pitch, roll, and heading) and they transmit these data to a ground station. We powered an ArduPilot Mega (APM) 2.6 with a 5V 11 Ah lithium ion battery (a smartphone power bank), placed the APM and battery in a waterproof sportsman's box, and tossed the box and its contents by hand onto an 80 m-long iceberg from an 8 m boat. The data stream could be viewed on a laptop, which greatly enhanced safety while collecting conductivity/temperature/depth (CTD) profiles from the small boat in the iceberg's vicinity. The 10 s position data allowed us to compute the distance of each CTD profile to the iceberg, which is necessary to determine if a given CTD profile was collected within the iceberg's meltwater plume. The APM position data greatly reduced position uncertainty when compared to 5 min position data obtained from a Spot Trace unit. The APM functioned for over 10 h without depleting the battery. We describe the specific hardware used and the software settings necessary to use the APM as a real-time iceberg tracker. Furthermore, the methods described here apply to all Ardupilot-compatible autopilots. Given the low cost ($90) and ease of use, drone autopilots like the APM should be included as another tool for studying iceberg motion and for enhancing safety of marine operations. •Commercial off-the-shelf iceberg trackers are typically configured to record positions over relatively long intervals (months to years) and are not well-suited for short-term (hours to few days), high-frequency monitoring•Drone autopilots are cheap and provide high-frequency (>1 Hz) and real-time information about iceberg drift and orientation•Drone autopilots and ground control software can be easily adapted to studies of iceberg-ocean interactions and operational iceberg management.
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Date Issued: 2018-09-06
Identifier: FSU_pmch_30225206, 10.1016/j.mex.2018.09.003, PMC6139390, 30225206, 30225206, S2215-0161(18)30145-6
Format: Citation

Title: Aluminium In The North Atlantic Ocean And The Labrador Sea (geotraces Ga01 Section): Roles Of Continental Inputs And Biogenic Particle Removal.
Creator: Barraqueta, Jan-Lukas Menzel, Schlosser, Christian, Planquette, Helene, Gourain, Arthur, Cheize, Marie, Boutorh, Julia, Shelley, Rachel, Pereira, Leonardo Contreira, Gledhill,...
Show moreBarraqueta, Jan-Lukas Menzel, Schlosser, Christian, Planquette, Helene, Gourain, Arthur, Cheize, Marie, Boutorh, Julia, Shelley, Rachel, Pereira, Leonardo Contreira, Gledhill, Martha, Hopwood, Mark J., Lacan, Francois, Lherminier, Pascale, Sarthou, Geraldine, Achterberg, Eric P.
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Abstract/Description: The distribution of dissolved aluminium (dAl) in the water column of the North Atlantic and Labrador Sea was studied along GEOTRACES section GA01 to unravel the sources and sinks of this element. Surface water dAl concentrations were low (median of 2.5 nM) due to low aerosol deposition and removal by biogenic particles (i.e. phytoplankton cells). However, surface water dAl concentrations were enhanced on the Iberian and Greenland shelves (up to 30.9 nM) due to continental inputs (rivers,...
Show moreThe distribution of dissolved aluminium (dAl) in the water column of the North Atlantic and Labrador Sea was studied along GEOTRACES section GA01 to unravel the sources and sinks of this element. Surface water dAl concentrations were low (median of 2.5 nM) due to low aerosol deposition and removal by biogenic particles (i.e. phytoplankton cells). However, surface water dAl concentrations were enhanced on the Iberian and Greenland shelves (up to 30.9 nM) due to continental inputs (rivers, glacial flour, and ice melt). Dissolved Al in surface waters scaled negatively with chlorophyll a and biogenic silica (opal) concentrations. The abundance of diatoms exerted a significant (p < 0.01) control on the surface particulate Al (pAl) to dAl ratios by decreasing dAl levels and increasing pAl levels. Dissolved Al concentrations generally increased with depth and correlated strongly with silicic acid (R-2 > 0.76) west of the Iberian Basin, suggesting net release of dAl at depth during remineralization of sinking opal-containing particles. Enrichment of dAl at near-bottom depths was observed due to the resuspension of sediments. The highest dAl concentrations (up to 38.7 nM) were observed in Mediterranean Outflow Waters, which act as a major source of dAl to mid-depth waters of the eastern North Atlantic. This study clearly shows that the vertical and lateral distributions of dAl in the North Atlantic differ when compared to other regions of the Atlantic and global oceans. Responsible for these large inter- and intra-basin differences are the large spatial variabilities in the main Al source, atmospheric deposition, and the main Al sink, particle scavenging by biogenic particles.
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Date Issued: 2018-08-30
Identifier: FSU_libsubv1_wos_000443197700003, 10.5194/bg-15-5271-2018
Format: Citation

Title: Dissolved Pb And Pb Isotopes In The North Atlantic From The Geovide Transect (geotraces Ga-01) And Their Decadal Evolution.
Creator: Zurbrick, Cheryl M., Boyle, Edward A., Kayser, Richard J., Reuer, Matthew K., Wu, Jinfeng, Planquette, Helene, Shelley, Rachel, Boutorh, Julia, Cheize, Marie, Contreira,...
Show moreZurbrick, Cheryl M., Boyle, Edward A., Kayser, Richard J., Reuer, Matthew K., Wu, Jinfeng, Planquette, Helene, Shelley, Rachel, Boutorh, Julia, Cheize, Marie, Contreira, Leonardo, Barraqueta, Jan-Lukas Menzel, Lacan, Francois, Sarthou, Geraldine
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Abstract/Description: During the 2014 GEOVIDE transect, seawater samples were collected for dissolved Pb and Pb isotope analysis. These samples provide a high-resolution "snapshot" of the source regions for the present Pb distribution in the North Atlantic Ocean. Some of these stations were previously occupied for Pb from as early as 1981, and we compare the 2014 data with these older data, some of which are reported here for the first time. Lead concentrations were highest in subsurface Mediterranean Water (MW)...
Show moreDuring the 2014 GEOVIDE transect, seawater samples were collected for dissolved Pb and Pb isotope analysis. These samples provide a high-resolution "snapshot" of the source regions for the present Pb distribution in the North Atlantic Ocean. Some of these stations were previously occupied for Pb from as early as 1981, and we compare the 2014 data with these older data, some of which are reported here for the first time. Lead concentrations were highest in subsurface Mediterranean Water (MW) near the coast of Portugal, which agrees well with other recent observations by the US GEOTRACES program (Noble et al., 2015). The recently formed Labrador Sea Water (LSW) between Greenland and Nova Scotia is much lower in Pb concentration than the older LSW found in the West European Basin due to decreases in Pb emissions into the atmosphere during the past 20 years. Comparison of North Atlantic data from 1989 to 2014 shows decreasing Pb concentrations consistent with decreased anthropogenic inputs, active scavenging, and advection/convection. Although the isotopic composition of northern North Atlantic seawater appears more homogenous compared to previous decades, a clear spatiotemporal trend in isotope ratios is evident over the past 15 years and implies that small changes to atmospheric Pb emissions continue. Emissions data indicate that the relative proportions of US and European Pb sources to the ocean have been relatively uniform during the past 2 decades, while aerosol data may suggest a greater relative proportion of natural mineral Pb. Using our measurements in conjunction with emissions inventories, we support the findings of previous atmospheric analyses that a significant portion of the Pb deposited to the ocean in 2014 was natural, although it is obscured by the much greater solubility of anthropogenic aerosols over natural ones.
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Date Issued: 2018-08-22
Identifier: FSU_libsubv1_wos_000442399400004, 10.5194/bg-15-4995-2018
Format: Citation

Title: Arbitrary Shaped Beam Scattering From A Chiral-coated Conducting Object With Arbitrary Monochromatic Illumination.
Creator: Wang, Mingjun, Zhang, Huayong, Ke, Xizheng, Liu, Guosheng, Ouyang, Xiaoping
Abstract/Description: An exact semi-analytical method of calculating the scattered fields from a chiral-coated conducting object under arbitrary shaped beam illumination is developed. The scattered fields and the fields within the chiral coating are expanded in terms of appropriate spherical vector wave functions. The unknown expansion coefficients are determined by solving an infinite system of linear equations derived using the method of moments technique and the boundary conditions. For incidence of a Gaussian...
Show moreAn exact semi-analytical method of calculating the scattered fields from a chiral-coated conducting object under arbitrary shaped beam illumination is developed. The scattered fields and the fields within the chiral coating are expanded in terms of appropriate spherical vector wave functions. The unknown expansion coefficients are determined by solving an infinite system of linear equations derived using the method of moments technique and the boundary conditions. For incidence of a Gaussian beam, circularly polarized wave, zero-order Bessel beam and Hertzian electric dipole radiation on a chiral-coated conducting spheroid and a chiral-coated conducting circular cylinder of finite length, the normalized differential scattering cross sections are evaluated and discussed briefly.
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Date Issued: 2018-08-17
Identifier: FSU_libsubv1_wos_000441876700053, 10.1038/s41598-018-30596-2
Format: Citation

Title: Arbitrary shaped beam scattering from a chiral-coated conducting object with arbitrary monochromatic illumination.
Creator: Wang, Mingjun, Zhang, Huayong, Ke, Xizheng, Liu, Guosheng, Ouyang, Xiaoping
Abstract/Description: An exact semi-analytical method of calculating the scattered fields from a chiral-coated conducting object under arbitrary shaped beam illumination is developed. The scattered fields and the fields within the chiral coating are expanded in terms of appropriate spherical vector wave functions. The unknown expansion coefficients are determined by solving an infinite system of linear equations derived using the method of moments technique and the boundary conditions. For incidence of a Gaussian...
Show moreAn exact semi-analytical method of calculating the scattered fields from a chiral-coated conducting object under arbitrary shaped beam illumination is developed. The scattered fields and the fields within the chiral coating are expanded in terms of appropriate spherical vector wave functions. The unknown expansion coefficients are determined by solving an infinite system of linear equations derived using the method of moments technique and the boundary conditions. For incidence of a Gaussian beam, circularly polarized wave, zero-order Bessel beam and Hertzian electric dipole radiation on a chiral-coated conducting spheroid and a chiral-coated conducting circular cylinder of finite length, the normalized differential scattering cross sections are evaluated and discussed briefly.
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Date Issued: 2018-08-17
Identifier: FSU_pmch_30120306, 10.1038/s41598-018-30596-2, PMC6098078, 30120306, 30120306, 10.1038/s41598-018-30596-2
Format: Citation

Title: Statistical Evidence For The Role Of Southwestern Indian Ocean Heat Content In The Indian Summer Monsoon Rainfall.
Creator: Venugopal, T., Ali, M. M., Bourassa, M. A., Zheng, Y., Goni, G. J., Foltz, G. R., Rajeevan, M.
Abstract/Description: This study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 degrees...
Show moreThis study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 degrees C isotherm during January-March is a better qualitative predictor of the ISMR than SST. The success rate in predicting above-or below-average ISMR is 80% for OMT compared to 60% for SST. Other January-March mean climate indices (e.g., NINO3.4, Indian Ocean Dipole Mode Index, El Nino Southern Oscillation Modoki Index) have less predictability (52%, 48%, and 56%, respectively) than OMT percentage deviation (PD) (80%). Thus, OMT PD in the southwestern Indian Ocean provides a better qualitative prediction of ISMR by the end of March and indicates whether the ISMR will be above or below the climatological mean value.
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Date Issued: 2018-08-14
Identifier: FSU_libsubv1_wos_000441536700011, 10.1038/s41598-018-30552-0
Format: Citation

Title: Statistical Evidence for the Role of Southwestern Indian Ocean Heat Content in the Indian Summer Monsoon Rainfall.
Creator: Venugopal, T, Ali, M M, Bourassa, M A, Zheng, Y, Goni, G J, Foltz, G R, Rajeevan, M
Abstract/Description: This study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 °C...
Show moreThis study examines the benefit of using Ocean Mean Temperature (OMT) to aid in the prediction of the sign of Indian Summer Monsoon Rainfall (ISMR) anomalies. This is a statistical examination, rather than a process study. The thermal energy needed for maintaining and intensifying hurricanes and monsoons comes from the upper ocean, not just from the thin layer represented by sea surface temperature (SST) alone. Here, we show that the southwestern Indian OMT down to the depth of the 26 °C isotherm during January-March is a better qualitative predictor of the ISMR than SST. The success rate in predicting above- or below-average ISMR is 80% for OMT compared to 60% for SST. Other January-March mean climate indices (e.g., NINO3.4, Indian Ocean Dipole Mode Index, El Niño Southern Oscillation Modoki Index) have less predictability (52%, 48%, and 56%, respectively) than OMT percentage deviation (PD) (80%). Thus, OMT PD in the southwestern Indian Ocean provides a better qualitative prediction of ISMR by the end of March and indicates whether the ISMR will be above or below the climatological mean value.
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Date Issued: 2018-08-14
Identifier: FSU_pmch_30108244, 10.1038/s41598-018-30552-0, PMC6092415, 30108244, 30108244, 10.1038/s41598-018-30552-0
Format: Citation

Title: The Multi-assumption Architecture And Testbed (maat V1.0): R Code For Generating Ensembles With Dynamic Model Structure And Analysis Of Epistemic Uncertainty From Multiple Sources.
Creator: Walker, Anthony P., Ye, Ming, Lu, Dan, De Kauwe, Martin G., Gu, Lianhong, Medlyn, Belinda E., Rogers, Alistair, Serbin, Shawn P.
Abstract/Description: Computer models are ubiquitous tools used to represent systems across many scientific and engineering domains. For any given system, many computer models exist, each built on different assumptions and demonstrating variability in the ways in which these systems can be represented. This variability is known as epistemic uncertainty, i.e. uncertainty in our knowledge of how these systems operate. Two primary sources of epistemic uncertainty are (1) uncertain parameter values and (2) uncertain...
Show moreComputer models are ubiquitous tools used to represent systems across many scientific and engineering domains. For any given system, many computer models exist, each built on different assumptions and demonstrating variability in the ways in which these systems can be represented. This variability is known as epistemic uncertainty, i.e. uncertainty in our knowledge of how these systems operate. Two primary sources of epistemic uncertainty are (1) uncertain parameter values and (2) uncertain mathematical representations of the processes that comprise the system. Many formal methods exist to analyse parameter-based epistemic uncertainty, while process-representation-based epistemic uncertainty is often analysed post hoc, incompletely, informally, or is ignored. In this model description paper we present the multi-assumption architecture and testbed (MAAT v1.0) designed to formally and completely analyse process-representation-based epistemic uncertainty. MAAT is a modular modelling code that can simply and efficiently vary model structure (process representation), allowing for the generation and running of large model ensembles that vary in process representation, parameters, parameter values, and environmental conditions during a single execution of the code. MAAT v1.0 approaches epistemic uncertainty through sensitivity analysis, assigning variability in model output to processes (process representation and parameters) or to individual parameters. In this model description paper we describe MAAT and, by using a simple groundwater model example, verify that the sensitivity analysis algorithms have been correctly implemented. The main system model currently coded in MAAT is a unified, leaf-scale enzyme kinetic model of C-3 photosynthesis. In the Appendix we describe the photosynthesis model and the unification of multiple representations of photosynthetic processes. The numerical solution to leaf-scale photosynthesis is verified and examples of process variability in temperature response functions are provided. For rapid application to new systems, the MAAT algorithms for efficient variation of model structure and sensitivity analysis are agnostic of the specific system model employed. Therefore MAAT provides a tool for the development of novel or "toy" models in many domains, i.e. not only photosynthesis, facilitating rapid informal and formal comparison of alternative modelling approaches. [GRAPHICS] .
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Date Issued: 2018-08-10
Identifier: FSU_libsubv1_wos_000441298000001, 10.5194/gmd-11-3159-2018
Format: Citation

Title: Allogenic And Autogenic Signals In The Stratigraphic Record Of The Deep-sea Bengal Fan (vol 8, 7973, 2018).
Creator: Blum, Mike, Rogers, Kimberly, Gleason, James, Najman, Yani, Cruz, Jarrett, Fox, Lyndsey
Date Issued: 2018-08-10
Identifier: FSU_libsubv1_wos_000441302400001, 10.1038/s41598-018-30160-y
Format: Citation

Title: Author Correction: Allogenic and Autogenic Signals in the Stratigraphic Record of the Deep-Sea Bengal Fan..
Creator: Blum, Mike, Rogers, Kimberly, Gleason, James, Najman, Yani, Cruz, Jarrett, Fox, Lyndsey
Abstract/Description: A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Date Issued: 2018-08-10
Identifier: FSU_pmch_30097596, 10.1038/s41598-018-30160-y, PMC6086899, 30097596, 30097596, 10.1038/s41598-018-30160-y
Format: Citation

Title: Decadal Variability Of The Meridional Geostrophic Transport In The Upper Tropical North Pacific Ocean.
Creator: Zhou, Hui, Yuan, Dongliang, Yang, Lina, Li, Xiang, Dewar, William
Abstract/Description: The meridional geostrophic transport (MGT) in the interior tropical North Pacific Ocean is estimated based on global ocean heat and salt content data. The decadal variations of the zonally and vertically integrated MGT in the tropical North Pacific Ocean are found to precede the Pacific decadal oscillation (PDO) by 1-3 years. The dynamics of the MGT are analyzed based on Sverdrup theory. It is found that the total meridional transport variability (MGT plus Ekman) is dominated by the MGT...
Show moreThe meridional geostrophic transport (MGT) in the interior tropical North Pacific Ocean is estimated based on global ocean heat and salt content data. The decadal variations of the zonally and vertically integrated MGT in the tropical North Pacific Ocean are found to precede the Pacific decadal oscillation (PDO) by 1-3 years. The dynamics of the MGT are analyzed based on Sverdrup theory. It is found that the total meridional transport variability (MGT plus Ekman) is dominated by the MGT variability having positive correlations with the PDO index. The Sverdrup transports differ from the total meridional transport significantly and have insignificant correlations with PDO index, suggesting that the MGT variability is not controlled by the Sverdrup dynamics. In comparison, the simulated meridional transport variability in the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) and the Ocean General Circulation Model for the Earth Simulator are dominated by the Sverdrup transports, having insignificant correlations with the simulated PDO indices. The comparison suggests that the non-Sverdrup component in the MGT is important for the predictability of PDO and that significant deficiencies exist in these models in simulating a realistic structure of the tropical ocean gyre variability and predicting the decadal climate variations associated with it.
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Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000438848800007, 10.1175/JCLI-D-17-0639.1
Format: Citation

Title: Foraging Ecology And Diet Selection Of Juvenile Green Turtles In The Bahamas: Insights From Stable Isotope Analysis And Prey Mapping.
Creator: Gillis, Anthony J., Ceriani, Simona A., Seminoff, Jeffrey A., Fuentes, Mariana M. P. B.
Abstract/Description: Species' foraging choices influence their somatic growth rates, age at maturity, and time spent in vulnerable early life stages. Thus, differences in population demographics are often attributed to variability either in diet type, quality, and/or quantity ingested. Knowledge of diet selection, though currently limited, can enhance our understanding of the roles of marine turtles in marine ecosystems and, at a finer scale, elucidate how nutrition and diet influence their growth and...
Show moreSpecies' foraging choices influence their somatic growth rates, age at maturity, and time spent in vulnerable early life stages. Thus, differences in population demographics are often attributed to variability either in diet type, quality, and/or quantity ingested. Knowledge of diet selection, though currently limited, can enhance our understanding of the roles of marine turtles in marine ecosystems and, at a finer scale, elucidate how nutrition and diet influence their growth and productivity. To investigate this relationship, we coupled stable isotope analysis with a diet preference index to provide insights into the selection and plasticity of juvenile green turtle Chelonia mydas diet. The study was conducted at 2 sites (Bonefish Hole and South Bimini) in Bimini, Bahamas, in 2016. Habitat surveys were conducted to gather habitat data and determine resource availability. A dichotomy in diet was found between the sites: at Bonefish Hole, turtles exhibited a more generalist omnivorous diet, selecting for sessile filter feeders and green algae, whereas turtles in South Bimini had a more specialist herbivorous diet, primarily consuming seagrasses and selecting for red algae, when available. The foraging dichotomy found in this study expands our understanding of the spatial differences in green turtle biology in the Bahamas and provides novel information for turtle foraging in Bimini. Knowledge about differences in intra-specific diet, with a focus on diet selection and potential drivers, can shed light on the factors that influence critical life history traits and ultimately inform species management.
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Date Issued: 2018-07-12
Identifier: FSU_libsubv1_wos_000440371600015, 10.3354/meps12635
Format: Citation

Title: Global Observations Of Horizontal Mixing From Argo Float And Surface Drifter Trajectories.
Creator: Roach, Christopher J., Balwada, Dhruv, Speer, Kevin
Abstract/Description: Mixing by mesoscale eddies in the ocean plays a major role in setting the distribution of oceanic tracers, with important implications for physical and biochemical systems at local to global scales. Roach et al. (2016; https://doi.org/10.1002/2015JC011440) demonstrated that a two-particle analysis of Argo trajectories produces robust estimates of horizontal mixing in the Southern Ocean. Here we extend this analysis to produce global 1 degrees x1 degrees maps of eddy diffusivity at the nominal...
Show moreMixing by mesoscale eddies in the ocean plays a major role in setting the distribution of oceanic tracers, with important implications for physical and biochemical systems at local to global scales. Roach et al. (2016; https://doi.org/10.1002/2015JC011440) demonstrated that a two-particle analysis of Argo trajectories produces robust estimates of horizontal mixing in the Southern Ocean. Here we extend this analysis to produce global 1 degrees x1 degrees maps of eddy diffusivity at the nominal Argo parking depth of 1,000 m. We also applied this methodology to estimate surface eddy diffusivities from Global Drifter Program (GDP) surface drifters. The global mean eddy diffusivity was 543 +/- 155 m(2)/s at 1,000m and 2637 +/- 311 m(2)/s at the surface, with elevated diffusivities in regions of enhanced eddy kinetic energy, such as western boundary currents and along the Antarctic Circumpolar Current. The eddy kinetic energy at the equator is high at both the surface and depth, but the eddy diffusivity is only enhanced near the surface. At depth the eddy diffusivity is strongly suppressed due to the presence of mean flow. We used our observational estimates to test the validity of an eddy diffusivity parameterization that accounts for mixing suppression in the presence of zonal mean flows. Our results indicated that this parameterization generally agrees with the directly observed eddy diffusivities in the midlatitude and high-latitude oceans.
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Date Issued: 2018-07-01
Identifier: FSU_libsubv1_wos_000441888200008, 10.1029/2018JC013750
Format: Citation

Title: The Relationship Of Near-surface Flow, Stokes Drift And The Wind Stress.
Creator: Clarke, Allan J., Van Gorder, Stephen
Abstract/Description: Many years of simultaneous hourly buoy wind and directional wave spectra data in the Gulf of Mexico and the Pacific were used to estimate Stokes drift and u* e(w) where u* = (magnitude of the local windstress/water density)(1/2) and e(w) is a unit vector in the direction of the local wind. Stokes drift and u* e(w) were strongly vectorally correlated, the two vectors on average being within a few degrees of one another. This result remained valid even when there was evidence of remotely forced...
Show moreMany years of simultaneous hourly buoy wind and directional wave spectra data in the Gulf of Mexico and the Pacific were used to estimate Stokes drift and u* e(w) where u* = (magnitude of the local windstress/water density)(1/2) and e(w) is a unit vector in the direction of the local wind. Stokes drift and u* e(w) were strongly vectorally correlated, the two vectors on average being within a few degrees of one another. This result remained valid even when there was evidence of remotely forced swell. Extension of the observed wave spectra above 0.35 Hz to the u(*)-dependent wave breaking frequency shows that typically the e-folding scale of the Stokes drift with depth is less than 1.8 m, much smaller than the Ekman layer e-folding scale. Therefore, there is negligible induced Eulerian cancellation of the Stokes drift, and the surface particle movement is governed by the Eulerian velocity + vertical bar u(Stokes)vertical bar e(w). Taking into account wave spreading, vertical bar u(Stokes)vertical bar typically ranges from about 3 to 13 cm/s. Thus, the Stokes drift, which can be estimated directly from the wind stress, is an order one contributor to the surface transport of particles. Plain Language Summary Although crucial for the movement of oil spills, red tide, fish eggs and larvae, and floating garbage, much still has to be learned about net particle movement in the top 1 or 2 m of the ocean. George Gabriel Stokes showed mathematically in 1847 that ocean surface waves may affect the net movement of particles at the ocean surface, but later it was shown that because we live on a rotating Earth, the net particle movement in the direction of the waves (the "Stokes drift") might be canceled by another opposite flow. In this paper we demonstrate that because of the ocean turbulence generated by the wind, the main part of the Stokes drift in the top 2 m of the ocean is not canceled by an opposing flow. Furthermore, analysis of simultaneous hourly wind and wave measurements for many years at Christmas Island in the equatorial Pacific, ocean station Papa in the north Pacific, and 10 stations in the Gulf of Mexico shows that Stokes drift is strongly related to the local wind and is in the direction of the wind. Stokes drift is therefore not primarily due to remotely driven swell; rather, it is mainly due to the much shorter waves that the local wind generates. By taking into account when the short waves break, it is shown how Stokes drift can be approximately estimated directly from the local wind.
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Date Issued: 2018-07-01
Identifier: FSU_libsubv1_wos_000441888200015, 10.1029/2018JC014102
Format: Citation

Title: Thallium Isotopes Reveal Protracted Anoxia During The Toarcian (early Jurassic) Associated With Volcanism, Carbon Burial, And Mass Extinction.
Creator: Them, Theodore R., Gill, Benjamin C., Caruthers, Andrew H., Gerhardt, Angela M., Grocke, Darren R., Lyons, Timothy W., Marroquin, Selva M., Nielsen, Sune G., Alexandre, Joao P....
Show moreThem, Theodore R., Gill, Benjamin C., Caruthers, Andrew H., Gerhardt, Angela M., Grocke, Darren R., Lyons, Timothy W., Marroquin, Selva M., Nielsen, Sune G., Alexandre, Joao P. Trabucho, Owens, Jeremy D.
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Abstract/Description: For this study, we generated thallium (TI) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; similar to 183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our TI isotope data, however, reveal explicit...
Show moreFor this study, we generated thallium (TI) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; similar to 183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our TI isotope data, however, reveal explicit evidence for earlier global marine deoxygenation of ocean water, some 600 ka before the classically defined T-OAE. This antecedent deoxygenation occurs at the Pliensbachian/Toarcian boundary and is coeval with the onset of initial large igneous province (LIP) volcanism and the initiation of a marine mass extinction. Thallium isotopes are also perturbed during the T-OAE interval, as defined by carbon isotopes, reflecting a second deoxygenation event that coincides with the acme of elevated marine mass extinctions and the main phase of LIP volcanism. This suggests that the duration of widespread anoxic bottom waters was at least 1 million years in duration and spanned early to middle Toarcian time. Thus, the TI data reveal a more nuanced record of marine oxygen depletion and its links to biological change during a period of climatic warming in Earth's past and highlight the role of oxygen depletion on past biological evolution.
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Date Issued: 2018-06-26
Identifier: FSU_libsubv1_wos_000436245000051, 10.1073/pnas.1803478115
Format: Citation

Title: A New Approach For Incorporating N-15 Isotopic Data Into Linear Inverse Ecosystem Models With Markov Chain Monte Carlo Sampling.
Creator: Stukel, Michael R., Decima, Moira, Kelly, Thomas B.
Abstract/Description: Oceanographic field programs often use delta N-15 biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta N-15 isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this...
Show moreOceanographic field programs often use delta N-15 biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating delta N-15 isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with delta N-15 approach typically does a better job of recovering ecosystem structure than the standard MCMC or L-2 minimum norm (L2MN) approaches, and also outperforms an L2MN with delta N-15 approach. Furthermore, we find that the MCMC with delta N-15 approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with delta C-13 isotopic measurements or variable carbon:nitrogen stoichiometry.
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Date Issued: 2018-06-18
Identifier: FSU_libsubv1_wos_000435528600077, 10.1371/journal.pone.0199123
Format: Citation

Title: A new approach for incorporating 15N isotopic data into linear inverse ecosystem models with Markov Chain Monte Carlo sampling.
Creator: Stukel, Michael R, Décima, Moira, Kelly, Thomas B
Abstract/Description: Oceanographic field programs often use δ15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating δ15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to...
Show moreOceanographic field programs often use δ15N biogeochemical measurements and in situ rate measurements to investigate nitrogen cycling and planktonic ecosystem structure. However, integrative modeling approaches capable of synthesizing these distinct measurement types are lacking. We develop a novel approach for incorporating δ15N isotopic data into existing Markov Chain Monte Carlo (MCMC) random walk methods for solving linear inverse ecosystem models. We test the ability of this approach to recover food web indices (nitrate uptake, nitrogen fixation, zooplankton trophic level, and secondary production) derived from forward models simulating the planktonic ecosystems of the California Current and Amazon River Plume. We show that the MCMC with δ15N approach typically does a better job of recovering ecosystem structure than the standard MCMC or L2 minimum norm (L2MN) approaches, and also outperforms an L2MN with δ15N approach. Furthermore, we find that the MCMC with δ15N approach is robust to the removal of input equations and hence is well suited to typical pelagic ecosystem studies for which the system is usually vastly under-constrained. Our approach is easily extendable for use with δ13C isotopic measurements or variable carbon:nitrogen stoichiometry.
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Date Issued: 2018-06-18
Identifier: FSU_pmch_29912928, 10.1371/journal.pone.0199123, PMC6005467, 29912928, 29912928, PONE-D-18-03219
Format: Citation

Title: The Significance Of Giant Phaeodarians (rhizaria) To Biogenic Silica Export In The California Current Ecosystem.
Creator: Biard, Tristan, Krause, Jeffrey W., Stukel, Michael R., Ohman, Mark D.
Abstract/Description: In marine ecosystems, many planktonic organisms precipitate biogenic silica (bSiO(2)) to build silicified skeletons. Among them, giant siliceous rhizarians (>500 mu m), including Radiolaria and Phaeodaria, are important contributors to oceanic carbon pools but little is known about their contribution to the marine silica cycle. We report the first analyses of giant phaeodarians to bSiO(2) export in the California Current Ecosystem. We measured the silica content of single rhizarian cells...
Show moreIn marine ecosystems, many planktonic organisms precipitate biogenic silica (bSiO(2)) to build silicified skeletons. Among them, giant siliceous rhizarians (>500 mu m), including Radiolaria and Phaeodaria, are important contributors to oceanic carbon pools but little is known about their contribution to the marine silica cycle. We report the first analyses of giant phaeodarians to bSiO(2) export in the California Current Ecosystem. We measured the silica content of single rhizarian cells ranging in size from 470 to 3,920 mu m and developed allometric equations to predict silica content (0.37-43.42 mu g Si/cell) from morphometric measurements. Using sediment traps to measure phaeodarian fluxes from the euphotic zone on four cruises, we calculated bSiO(2) export produced by two families, the Aulosphaeridae and Castanellidae. Biogenic silica export ranged from <0.01 to 0.63 mmol Si.m(-2).day(-1). These two families alone contributed on average 10% (range 0-80%) of total bSiO(2) export from the euphotic zone. Their proportional contributions increased substantially in more oligotrophic regions with lower bSiO(2) fluxes. Using the in situ Underwater Vision Profiler 5, we characterized vertical distributions of the giant phaeodarian family Aulosphaeridae to a depth of 500 m and inferred their contribution to bSiO(2) export in deeper waters. We found a significant increase of Aulosphaeridae export (<0.01 to 2.82 mmol Si.m(-2).day(-1)) when extended to mesopelagic depths. Using a global data set of in situ profiles, we estimated the significance of Aulosphaeridae to bSiO(2) export and revealed that they can act as major exporters of bSiO(2) to the mesopelagic zone in various regions.
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Date Issued: 2018-06-01
Identifier: FSU_libsubv1_wos_000438026200006, 10.1029/2018GB005877
Format: Citation

Title: Advanced Molecular Techniques Provide New Rigorous Tools For Characterizing Organic Matter Quality In Complex Systems.
Creator: Wilson, Rachel M., Tfaily, Malak M.
Abstract/Description: Carbon flux rates are widely understood to be substrate controlled; however, characterizing substrate quality continues to be a challenge. We suggest that, while optical measurements have their place, they are not the only, or the best, tool for characterizing organic matter quality. Nominal oxidation state of the carbon provides a thermodynamically relevant measure, which could be used as a metric of organic matter quality. Calculating nominal oxidation state of the carbon requires a suite...
Show moreCarbon flux rates are widely understood to be substrate controlled; however, characterizing substrate quality continues to be a challenge. We suggest that, while optical measurements have their place, they are not the only, or the best, tool for characterizing organic matter quality. Nominal oxidation state of the carbon provides a thermodynamically relevant measure, which could be used as a metric of organic matter quality. Calculating nominal oxidation state of the carbon requires a suite of advanced complementary analysis but is then trivial to calculate from the resulting data sets.
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Date Issued: 2018-06-01
Identifier: FSU_libsubv1_wos_000438667200001, 10.1029/2018JG004525
Format: Citation

Title: Improvements In Hurricane Intensity Forecasts From A Multimodel Superensemble Utilizing A Generalized Neural Network Technique.
Creator: Ghosh, T., Krishnamurti, T. N.
Abstract/Description: Forecasting tropical storm intensities is a very challenging issue. In recent years, dynamical models have improved considerably. However, for intensity forecasts more improvement is necessary. Dynamical models have different kinds of biases. Considering a multimodel consensus could eliminate some of the biases resulting in improved intensity forecasts as compared to the individual models. Apart from the ensemble mean, the construction of multimodel consensuses has always contributed to...
Show moreForecasting tropical storm intensities is a very challenging issue. In recent years, dynamical models have improved considerably. However, for intensity forecasts more improvement is necessary. Dynamical models have different kinds of biases. Considering a multimodel consensus could eliminate some of the biases resulting in improved intensity forecasts as compared to the individual models. Apart from the ensemble mean, the construction of multimodel consensuses has always contributed to somewhat improved forecasts. The Florida State University (FSU) multimodel superensemble is one that, over the years, has systematically provided improved forecasts for hurricanes, numerical weather prediction, and seasonal climate forecasts. The present study considers an artificial neural network (ANN), based on biological principles, for the construction of a multimodel ensemble. ANN has been used for constructing multimodel consensus forecasts for tropical cyclone intensities. This study uses the generalized regression neural network (GRNN) method for the construction of consensus intensity forecasts for the Atlantic basin. Hurricane seasons 2012-16 are considered. Results show that with only five input models improved guidance for tropical storm intensities may be obtained. The consensus using GRNN mostly outperforms all the models included in the study and the ensemble mean. Forecast errors at the longer forecast leads are considerably less for this multimodel superensemble based on the generalized regression neural network. The skill and correlations of different models along with the developed consensus are provided in our analysis. Results suggest that this consensus forecast may be used for operational guidance and for planning and emergency evacuation management. Possibilities for future improvements of the consensus based on new advances in statistical algorithms are also indicated.
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Date Issued: 2018-06-01
Identifier: FSU_libsubv1_wos_000437098000004, 10.1175/WAF-D-17-0006.1
Format: Citation

Title: Rapid recovery of life at ground zero of the end-Cretaceous mass extinction.
Creator: Lowery, Christopher M, Bralower, Timothy J, Owens, Jeremy D, Rodríguez-Tovar, Francisco J, Jones, Heather, Smit, Jan, Whalen, Michael T, Claeys, Phillipe, Farley, Kenneth,...
Show moreLowery, Christopher M, Bralower, Timothy J, Owens, Jeremy D, Rodríguez-Tovar, Francisco J, Jones, Heather, Smit, Jan, Whalen, Michael T, Claeys, Phillipe, Farley, Kenneth, Gulick, Sean P S, Morgan, Joanna V, Green, Sophie, Chenot, Elise, Christeson, Gail L, Cockell, Charles S, Coolen, Marco J L, Ferrière, Ludovic, Gebhardt, Catalina, Goto, Kazuhisa, Kring, David A, Lofi, Johanna, Ocampo-Torres, Rubén, Perez-Cruz, Ligia, Pickersgill, Annemarie E, Poelchau, Michael H, Rae, Auriol S P, Rasmussen, Cornelia, Rebolledo-Vieyra, Mario, Riller, Ulrich, Sato, Honami, Tikoo, Sonia M, Tomioka, Naotaka, Urrutia-Fucugauchi, Jaime, Vellekoop, Johan, Wittmann, Axel, Xiao, Long, Yamaguchi, Kosei E, Zylberman, William
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Abstract/Description: The Cretaceous/Palaeogene mass extinction eradicated 76% of species on Earth. It was caused by the impact of an asteroid on the Yucatán carbonate platform in the southern Gulf of Mexico 66 million years ago , forming the Chicxulub impact crater. After the mass extinction, the recovery of the global marine ecosystem-measured as primary productivity-was geographically heterogeneous ; export production in the Gulf of Mexico and North Atlantic-western Tethys was slower than in most other regions,...
Show moreThe Cretaceous/Palaeogene mass extinction eradicated 76% of species on Earth. It was caused by the impact of an asteroid on the Yucatán carbonate platform in the southern Gulf of Mexico 66 million years ago , forming the Chicxulub impact crater. After the mass extinction, the recovery of the global marine ecosystem-measured as primary productivity-was geographically heterogeneous ; export production in the Gulf of Mexico and North Atlantic-western Tethys was slower than in most other regions, taking 300 thousand years (kyr) to return to levels similar to those of the Late Cretaceous period. Delayed recovery of marine productivity closer to the crater implies an impact-related environmental control, such as toxic metal poisoning , on recovery times. If no such geographic pattern exists, the best explanation for the observed heterogeneity is a combination of ecological factors-trophic interactions , species incumbency and competitive exclusion by opportunists -and 'chance'. The question of whether the post-impact recovery of marine productivity was delayed closer to the crater has a bearing on the predictability of future patterns of recovery in anthropogenically perturbed ecosystems. If there is a relationship between the distance from the impact and the recovery of marine productivity, we would expect recovery rates to be slowest in the crater itself. Here we present a record of foraminifera, calcareous nannoplankton, trace fossils and elemental abundance data from within the Chicxulub crater, dated to approximately the first 200 kyr of the Palaeocene. We show that life reappeared in the basin just years after the impact and a high-productivity ecosystem was established within 30 kyr, which indicates that proximity to the impact did not delay recovery and that there was therefore no impact-related environmental control on recovery. Ecological processes probably controlled the recovery of productivity after the Cretaceous/Palaeogene mass extinction and are therefore likely to be important for the response of the ocean ecosystem to other rapid extinction events.
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Date Issued: 2018-06-01
Identifier: FSU_pmch_29849143, 10.1038/s41586-018-0163-6, PMC6058194, 29849143, 29849143, 10.1038/s41586-018-0163-6
Format: Citation

Title: Isotopic Composition Of Sinking Particles: Oil Effects, Recovery And Baselines In The Gulf Of Mexico, 2010-2015.
Creator: Chanton, Jeffrey P., Giering, Sarah L. C., Bosman, Samantha H., Rogers, Kelsey L., Sweet, Julia, Asper, Vernon L., Diercks, Arne R., Passow, Uta
Abstract/Description: The extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material. To gauge the recovery and post-spill baseline sources, we measured Delta C-14, delta C-13 and delta S-34 of sinking particles near the spill site and at a reference site and natural seep site. Particulates were collected August 2010-April 2016 in sediment traps moored at sites with depths of 1160-1660 m. Near the spill site,...
Show moreThe extensive release of oil during the 2010 Deepwater Horizon spill in the northern Gulf of Mexico perturbed the pelagic ecosystem and associated sinking material. To gauge the recovery and post-spill baseline sources, we measured Delta C-14, delta C-13 and delta S-34 of sinking particles near the spill site and at a reference site and natural seep site. Particulates were collected August 2010-April 2016 in sediment traps moored at sites with depths of 1160-1660 m. Near the spill site, changes in Delta C-14 indicated a 3-year recovery period, while delta S-34 indicated 1-2 years, which agreed with estimates of 1-2 years based on hydrocarbon composition. Under post-spill baseline conditions, carbon inputs to sinking particulates in the northern Gulf were dominated by surface marine production (80-85%) and riverine inputs (15-20%). Near the spill site, Delta C-14 values were depleted in October 2010 (-140 to -80 parts per thousand), increasing systematically by 0.07 +/- 0.02 parts per thousand day(-1) until July 2013 when values reached -3.2 +/- 31.0 parts per thousand. This Delta C-14 baseline was similar to particulates at the reference site (3.8 +/- 31.1 parts per thousand). At both sites, delta C-13 values stayed constant throughout the study period (-21.9 +/- 0.5 parts per thousand and -21.9 +/- 0.9 parts per thousand, respectively). delta S-34 near the spill site was depleted (7.4 +/- 3.1 parts per thousand) during October 2010-September 2011, but enriched (16.9 +/- 2.0 parts per thousand) and similar to the reference site (16.2 +/- 3.1 parts per thousand) during November 2012-April 2015. At the seep site,Delta C-14 values were -21.7 +/- 45.7 parts per thousand except during August 2012-January 2013 when a significant Delta C-14 depletion of -109.0 +/- 29.1 parts per thousand was observed. We interpret this depletion period, also observed in delta C-13 data, as caused by the incorporation of naturally seeped oil into sinking particles. Determination of post-spill baselines for these isotopic signatures allows for evaluation of anthropogenic inputs in future.
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Date Issued: 2018-05-30
Identifier: FSU_libsubv1_wos_000434243800001, 10.1525/elementa.298
Format: Citation

Title: Allogenic And Autogenic Signals In The Stratigraphic Record Of The Deep-sea Bengal Fan.
Creator: Blum, Mike, Rogers, Kimberly, Gleason, James, Najman, Yani, Cruz, Jarrett, Fox, Lyndsey
Abstract/Description: The Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. Here we present detrital zircon U-Pb provenance data from Miocene to middle Pleistocene Bengal Fan turbidites, and evaluate the influence of allogenic forcing vs. autogenic processes on signal propagation from the Himalaya to the deep sea. Our data record the strong tectonic and climatic forcing characteristic of the Himalayan system: after up to 2500 km of...
Show moreThe Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. Here we present detrital zircon U-Pb provenance data from Miocene to middle Pleistocene Bengal Fan turbidites, and evaluate the influence of allogenic forcing vs. autogenic processes on signal propagation from the Himalaya to the deep sea. Our data record the strong tectonic and climatic forcing characteristic of the Himalayan system: after up to 2500 km of river transport, and >1400 km of transport by turbidity currents, the U-Pb record faithfully represents Himalayan sources. Moreover, specific U-Pb populations record Miocene integration of the Brahmaputra drainage with the Asian plate, as well as the rapid Plio-Pleistocene incision through, and exhumation of, the eastern Himalayan syntaxis. The record is, however, biased towards glacial periods when rivers were extended across the shelf in response to climate-forced sea-level fall, and discharged directly to slope canyons. Finally, only part of the record represents a Ganges or Brahmaputra provenance end-member, and most samples represent mixing from the two systems. Mixing or the lack thereof likely represents the fingerprint of autogenic delta-plain avulsions, which result in the two rivers delivering sediment separately to a shelf-margin canyon or merging together as they do today.
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Date Issued: 2018-05-22
Identifier: FSU_libsubv1_wos_000432655200008, 10.1038/s41598-018-25819-5
Format: Citation

Title: Allogenic and Autogenic Signals in the Stratigraphic Record of the Deep-Sea Bengal Fan.
Creator: Blum, Mike, Rogers, Kimberly, Gleason, James, Najman, Yani, Cruz, Jarrett, Fox, Lyndsey
Abstract/Description: The Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. Here we present detrital zircon U-Pb provenance data from Miocene to middle Pleistocene Bengal Fan turbidites, and evaluate the influence of allogenic forcing vs. autogenic processes on signal propagation from the Himalaya to the deep sea. Our data record the strong tectonic and climatic forcing characteristic of the Himalayan system: after up to 2500 km of...
Show moreThe Himalayan-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth's largest sediment-dispersal system. Here we present detrital zircon U-Pb provenance data from Miocene to middle Pleistocene Bengal Fan turbidites, and evaluate the influence of allogenic forcing vs. autogenic processes on signal propagation from the Himalaya to the deep sea. Our data record the strong tectonic and climatic forcing characteristic of the Himalayan system: after up to 2500 km of river transport, and >1400 km of transport by turbidity currents, the U-Pb record faithfully represents Himalayan sources. Moreover, specific U-Pb populations record Miocene integration of the Brahmaputra drainage with the Asian plate, as well as the rapid Plio-Pleistocene incision through, and exhumation of, the eastern Himalayan syntaxis. The record is, however, biased towards glacial periods when rivers were extended across the shelf in response to climate-forced sea-level fall, and discharged directly to slope canyons. Finally, only part of the record represents a Ganges or Brahmaputra provenance end-member, and most samples represent mixing from the two systems. Mixing or the lack thereof likely represents the fingerprint of autogenic delta-plain avulsions, which result in the two rivers delivering sediment separately to a shelf-margin canyon or merging together as they do today.
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Date Issued: 2018-05-22
Identifier: FSU_pmch_29789592, 10.1038/s41598-018-25819-5, PMC5964172, 29789592, 29789592, 10.1038/s41598-018-25819-5
Format: Citation

Title: Isotope Niche Dimension And Trophic Overlap Between Bigheaded Carps And Native Filter Feeding Fish In The Lower Missouri River, Usa.
Creator: Wang, Jianzhu, Chapman, Duane, Xu, Jun, Wang, Yang, Gu, Binhe
Abstract/Description: Stable carbon and nitrogen isotope values (delta C-13 and delta N-15) were used to evaluate trophic niche overlap between two filter-feeding fishes (known together as bigheaded carp) native to China, silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), and three native filter-feeding fish including bigmouth buffalo (Ictiobus cyprinellus), gizzard shad (Dorosoma cepedianum) and paddlefish (Polyodon spathula) in the lower Missouri River, USA, using the...
Show moreStable carbon and nitrogen isotope values (delta C-13 and delta N-15) were used to evaluate trophic niche overlap between two filter-feeding fishes (known together as bigheaded carp) native to China, silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), and three native filter-feeding fish including bigmouth buffalo (Ictiobus cyprinellus), gizzard shad (Dorosoma cepedianum) and paddlefish (Polyodon spathula) in the lower Missouri River, USA, using the Bayesian Stable Isotope in R statistics. Results indicate that except for bigmouth buffalo, all species displayed similar trophic niche size and trophic diversity. Bigmouth buffalo occupied a small trophic niche and had the greatest trophic overlap with silver carp (93.6%) and bighead carp (94.1%) followed by gizzard shad (91.0%). Paddlefish had a trophic niche which relied on some resources different from those used by other species, and therefore had the lowest trophic overlap with bigheaded carp and other two native fish. The trophic overlap by bigheaded carp onto native fish was typically stronger than the reverse effects from native fish. Average niche overlap between silver carp and native species was as high as 71%, greater than niche overlap between bighead carp and native fish (64%). Our findings indicate that bigheaded carps are a potential threat to a diverse and stable native fish community.
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Date Issued: 2018-05-21
Identifier: FSU_libsubv1_wos_000432537100033, 10.1371/journal.pone.0197584
Format: Citation

Title: Crevasse Splays Versus Avulsions: A Recipe For Land Building With Levee Breaches.
Creator: Nienhuis, Jaap H., Tornqvist, Torbjorn E., Esposito, Christopher R.
Abstract/Description: Natural-levee breaches can not only initiate an avulsion but also, under the right circumstances, lead to crevasse splay formation and overbank sedimentation. The formative conditions for crevasse splays are not well understood, yet such river sediment diversions form an integral part of billion-dollar coastal restoration projects. Here we use Delft3D to investigate the influence of vegetation and soil consolidation on the evolution of a natural-levee breach. Model simulations show that...
Show moreNatural-levee breaches can not only initiate an avulsion but also, under the right circumstances, lead to crevasse splay formation and overbank sedimentation. The formative conditions for crevasse splays are not well understood, yet such river sediment diversions form an integral part of billion-dollar coastal restoration projects. Here we use Delft3D to investigate the influence of vegetation and soil consolidation on the evolution of a natural-levee breach. Model simulations show that crevasse splays heal because floodplain aggradation reduces the water surface slope, decreasing water discharge into the flood basin. Easily erodible and unvegetated floodplains increase the likelihood for channel avulsions. Denser vegetation and less potential for soil consolidation result in small crevasse splays that are not only efficient sediment traps but also short-lived. Successful crevasse splays that generate the largest land area gain for the imported sediment require a delicate balance between water and sediment discharge, vegetation root strength, and soil consolidation.
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Date Issued: 2018-05-16
Identifier: FSU_libsubv1_wos_000434111700035, 10.1029/2018GL077933
Format: Citation

Title: Warming And Inhibition Of Salinization At The Ocean's Surface By Cyanobacteria.
Creator: Wurl, O., Bird, K., Cunliffe, M., Landing, W. M., Miller, U., Mustaffa, N. I. H., Ribas-Ribas, M., Witte, C., Zappa, C. J.
Abstract/Description: This paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95 degrees C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22 degrees C) and saltier skin layer (0.19 practical salinity unit) was found...
Show moreThis paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95 degrees C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22 degrees C) and saltier skin layer (0.19 practical salinity unit) was found in the absence of surface blooms. The results suggest that biologically controlled warming and inhibition of salinization of the ocean's surface occur. Less saline skin layers form during precipitation, but our observations also show that surface blooms of Trichodesmium sp. inhibit evaporation decreasing the salinity at the ocean's surface. This study has important implications in the assessment of precipitation over the ocean using remotely sensed salinity, but also for a better understanding of heat exchange and the hydrologic cycle on a regional scale. Plain Language Summary We provide high-resolution in situ observations of large cyanobacterial blooms floating in a biofilm-like microlayer on the ocean's surface. Our observations show biologically controlled warming and freshening of the surface by the surface blooms that are essential in understanding global heat exchange and the hydrologic cycle. Our study describes a new phenomenon to force "apparent" freshening of the sea surfacein the literature assumed to occur only by precipitation. It further challenges the development of algorithms and validation of remotely sensed temperature and salinity from space. Our finding of active microbial communities in the sea surface microlayer highlights the sea surface as another environment for extreme habitats and microbial adaptation. Our discovery of their influence on satellite observations of sea surface temperature and salinity is fundamental for future research in remote sensing, marine microbiology, air-sea interaction, and climate regulation.
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Date Issued: 2018-05-16
Identifier: FSU_libsubv1_wos_000434111700053, 10.1029/2018GL077946
Format: Citation

Title: Warming and Inhibition of Salinization at the Ocean's Surface by Cyanobacteria.
Creator: Wurl, O, Bird, K, Cunliffe, M, Landing, W M, Miller, U, Mustaffa, N I H, Ribas-Ribas, M, Witte, C, Zappa, C J
Abstract/Description: This paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95°C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22°C) and saltier skin layer (0.19 practical salinity unit) was found in the absence of...
Show moreThis paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95°C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22°C) and saltier skin layer (0.19 practical salinity unit) was found in the absence of surface blooms. The results suggest that biologically controlled warming and inhibition of salinization of the ocean's surface occur. Less saline skin layers form during precipitation, but our observations also show that surface blooms of sp. inhibit evaporation decreasing the salinity at the ocean's surface. This study has important implications in the assessment of precipitation over the ocean using remotely sensed salinity, but also for a better understanding of heat exchange and the hydrologic cycle on a regional scale.
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Date Issued: 2018-05-16
Identifier: FSU_pmch_29937608, 10.1029/2018GL077946, PMC6001423, 29937608, 29937608, GRL57403
Format: Citation

Title: Decadal Surface Temperature Trends In India Based On A New High-resolution Data Set.
Creator: Ross, Robert S., Krishnamurti, T. N., Pattnaik, Sandeep, Pai, D. S.
Abstract/Description: A new comprehensive surface temperature data set for India is used to document changes in Indian temperature over seven decades, in order to examine the patterns and possible effects of global warming. The data set is subdivided into pre-monsoon, monsoon, and post-monsoon categories in order to study the temperature patterns in each of these periods. When the decade means in maximum, minimum and daily mean temperature for the 2000s are compared to those of the 1950s, a consistent pattern of...
Show moreA new comprehensive surface temperature data set for India is used to document changes in Indian temperature over seven decades, in order to examine the patterns and possible effects of global warming. The data set is subdivided into pre-monsoon, monsoon, and post-monsoon categories in order to study the temperature patterns in each of these periods. When the decade means in maximum, minimum and daily mean temperature for the 2000s are compared to those of the 1950s, a consistent pattern of warming is found over northwestern and southern India, and a pattern of cooling is seen in a broad zone anchored over northeastern India and extending southwestward across central India. These patterns are explained by the presence of a large region of anthropogenic brown haze over India and adjacent ocean regions. These aerosols absorb solar radiation, leading to warming of the haze layer over northeastern and central India and to cooling of the surface air beneath. The heated air rises and then sinks to the north and south of the haze region over northwestern and southern India, warming the air by compression as it sinks in those regions. The possible impact of these temperature patterns on Indian agriculture is considered.
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Date Issued: 2018-05-10
Identifier: FSU_libsubv1_wos_000431763100004, 10.1038/s41598-018-25347-2
Format: Citation

Title: Decadal surface temperature trends in India based on a new high-resolution data set.
Creator: Ross, Robert S, Krishnamurti, T N, Pattnaik, Sandeep, Pai, D S
Abstract/Description: A new comprehensive surface temperature data set for India is used to document changes in Indian temperature over seven decades, in order to examine the patterns and possible effects of global warming. The data set is subdivided into pre-monsoon, monsoon, and post-monsoon categories in order to study the temperature patterns in each of these periods. When the decade means in maximum, minimum and daily mean temperature for the 2000s are compared to those of the 1950s, a consistent pattern of...
Show moreA new comprehensive surface temperature data set for India is used to document changes in Indian temperature over seven decades, in order to examine the patterns and possible effects of global warming. The data set is subdivided into pre-monsoon, monsoon, and post-monsoon categories in order to study the temperature patterns in each of these periods. When the decade means in maximum, minimum and daily mean temperature for the 2000s are compared to those of the 1950s, a consistent pattern of warming is found over northwestern and southern India, and a pattern of cooling is seen in a broad zone anchored over northeastern India and extending southwestward across central India. These patterns are explained by the presence of a large region of anthropogenic brown haze over India and adjacent ocean regions. These aerosols absorb solar radiation, leading to warming of the haze layer over northeastern and central India and to cooling of the surface air beneath. The heated air rises and then sinks to the north and south of the haze region over northwestern and southern India, warming the air by compression as it sinks in those regions. The possible impact of these temperature patterns on Indian agriculture is considered.
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Date Issued: 2018-05-10
Identifier: FSU_pmch_29748548, 10.1038/s41598-018-25347-2, PMC5945614, 29748548, 29748548, 10.1038/s41598-018-25347-2
Format: Citation

Title: Distribution And Rates Of Nitrogen Fixation In The Western Tropical South Pacific Ocean Constrained By Nitrogen Isotope Budgets.
Creator: Knapp, Angela N., McCabe, Kelly M., Grosso, Olivier, Leblond, Nathalie, Moutin, Thierry, Bonnet, Sophie
Abstract/Description: Constraining the rates and spatial distribution of dinitrogen (N-2) fixation fluxes to the ocean informs our understanding of the environmental sensitivities of N-2 fixation as well as the timescale over which the fluxes of nitrogen (N) to and from the ocean may respond to each other. Here we quantify rates of N-2 fixation as well as its contribution to export production along a zonal transect in the western tropical South Pacific (WTSP) Ocean using N isotope ("delta N-15") budgets. Comparing...
Show moreConstraining the rates and spatial distribution of dinitrogen (N-2) fixation fluxes to the ocean informs our understanding of the environmental sensitivities of N-2 fixation as well as the timescale over which the fluxes of nitrogen (N) to and from the ocean may respond to each other. Here we quantify rates of N-2 fixation as well as its contribution to export production along a zonal transect in the western tropical South Pacific (WTSP) Ocean using N isotope ("delta N-15") budgets. Comparing measurements of water column nitrate + nitrite delta N-15 with the delta N-15 of sinking particulate N at a western, central, and eastern station, these delta N-15 budgets indicate high, modest, and low rates of N-2 fixation at the respective stations. The results also imply that N-2 fixation supports exceptionally high, i.e. >= 50 %, of export production at the western and central stations, which are also proximal to the largest iron sources. These geochemically based rates of N-2 fixation are equal to or greater than those previously reported in the tropical North Atlantic, indicating that the WTSP Ocean has the capacity to support globally significant rates of N-2 fixation, which may compensate for N removal in the oxygen-deficient zones of the eastern tropical Pacific.
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Date Issued: 2018-05-04
Identifier: FSU_libsubv1_wos_000431435900003, 10.5194/bg-15-2619-2018
Format: Citation

Title: Dissolved Organic Nitrogen Production And Consumption In Eastern Tropical South Pacific Surface Waters.
Creator: Knapp, A. N., Casciotti, K. L., Prokopenko, M. G.
Abstract/Description: Models of dissolved organic nitrogen (DON) production and consumption indicate that marine DON is produced in the euphotic zone, especially in upwelling environments, and is consumed as it transits into more oligotrophic regions where it may support export production. However, evaluation of such models is data limited, and in particular, few measurements of DON concentration and/or nitrogen isotopic composition (N-15) exist from the South Pacific. Here we present measurements of the...
Show moreModels of dissolved organic nitrogen (DON) production and consumption indicate that marine DON is produced in the euphotic zone, especially in upwelling environments, and is consumed as it transits into more oligotrophic regions where it may support export production. However, evaluation of such models is data limited, and in particular, few measurements of DON concentration and/or nitrogen isotopic composition (N-15) exist from the South Pacific. Here we present measurements of the concentration and N-15 of DON collected in the eastern tropical South Pacific during the austral summers of 2010 (El Nino) and 2011 (La Nina). The concentration and N-15 of DON from the eastern tropical South Pacific are broadly consistent with prior measurements elsewhere, that is, DON concentrations of 51M and DON N-15 of 51, but variations were associated with DON production and consumption. Specifically, surface ocean chlorophyll a concentrations were highly correlated with upper 50-m DON stocks (r=0.96), consistent with a photosynthetic source for DON. Additionally, upper 50-m DON stocks and their N-15 were significantly negatively correlated (r=-0.84, p=0.0006), indicating that DON was consumed in surface waters with an isotope effect of 5.51.2 parts per thousand. These results inform our understanding of the controls of DON distributions in the surface ocean and indicate that DON may support export production in nitrate-poor surface waters, which may decouple new from gross production.
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Date Issued: 2018-05-01
Identifier: FSU_libsubv1_wos_000434413500003, 10.1029/2017GB005875
Format: Citation

Title: The Ephemeral Signature Of Permafrost Carbon In An Arctic Fluvial Network.
Creator: Drake, Travis W., Guillemette, Francois, Hemingway, Jordon D., Chanton, Jeffery P., Podgorski, David C., Zimov, Nikita S., Spencer, Robert G. M.
Abstract/Description: Arctic fluvial networks process, outgas, and transport significant quantities of terrestrial organic carbon (C), particularly dissolved organic carbon (DOC). The proportion of permafrost C in these fluxes, however, is poorly constrained. A primary obstacle to the quantification of permafrost-derived DOC is that it is rapidly respired without leaving a unique tracer of its presence. In this study, we investigated the production of bacterial respiratory carbon dioxide (CO2; measured as...
Show moreArctic fluvial networks process, outgas, and transport significant quantities of terrestrial organic carbon (C), particularly dissolved organic carbon (DOC). The proportion of permafrost C in these fluxes, however, is poorly constrained. A primary obstacle to the quantification of permafrost-derived DOC is that it is rapidly respired without leaving a unique tracer of its presence. In this study, we investigated the production of bacterial respiratory carbon dioxide (CO2; measured as dissolved inorganic carbon; DIC) during maximum late-summer thaw in sites spanning a fluvial network (Kolyma Basin, Siberia) to assess whether the biodegradation of permafrost DOC could be detected by the presence of a persistent aged (C-14-depleted) signature on the DIC pool. Using Keeling plot interpretation of DIC produced in bioincubations of river water, we show that bacteria respire varying sources of DOC moving downstream through the fluvial network. Respiration of permafrost (production of aged CO2) was only detected in heavily permafrost thaw influenced sites. In nonpermafrost thaw impacted sites, ambient DIC was modern (C-14-enriched), but rather than precluding the respiration of permafrost OC upstream, we suggest that C-14-depleted DIC is overwhelmed by modern DIC. Investigation of dissolved organic matter composition via Fourier transform ion cyclotron resonance mass spectrometry highlighted that elevated levels of aliphatic and nitrogen-containing compounds were associated with the production of aged DIC, providing molecular-level insight as to why permafrost-derived dissolved organic matter is rapidly respired. Overall, results from this study demonstrate the difficulty of tracing inputs of a highly reactive substrate to systems with diverse organic matter sources.
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Date Issued: 2018-05-01
Identifier: FSU_libsubv1_wos_000435264200003, 10.1029/2017JG004311
Format: Citation

Title: Enhanced Iron Solubility At Low Ph In Global Aerosols.
Creator: Ingall, Ellery D., Feng, Yan, Longo, Amelia F., Lai, Barry, Shelley, Rachel U., Landing, William M., Morton, Peter L., Nenes, Athanasios, Mihalopoulos, Nikolaos, Violaki,...
Show moreIngall, Ellery D., Feng, Yan, Longo, Amelia F., Lai, Barry, Shelley, Rachel U., Landing, William M., Morton, Peter L., Nenes, Athanasios, Mihalopoulos, Nikolaos, Violaki, Kalliopi, Gao, Yuan, Sahai, Shivraj, Castorina, Erin
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Abstract/Description: The composition and oxidation state of aerosol iron were examined using synchrotron-based iron near-edge X-ray absorption spectroscopy. By combining synchrotron-based techniques with water leachate analysis, impacts of oxidation state and mineralogy on aerosol iron solubility were assessed for samples taken from multiple locations in the Southern and the Atlantic Oceans; and also from Noida (India), Bermuda, and the Eastern Mediterranean (Crete). These sampling locations capture iron...
Show moreThe composition and oxidation state of aerosol iron were examined using synchrotron-based iron near-edge X-ray absorption spectroscopy. By combining synchrotron-based techniques with water leachate analysis, impacts of oxidation state and mineralogy on aerosol iron solubility were assessed for samples taken from multiple locations in the Southern and the Atlantic Oceans; and also from Noida (India), Bermuda, and the Eastern Mediterranean (Crete). These sampling locations capture iron-containing aerosols from different source regions with varying marine, mineral dust, and anthropogenic influences. Across all locations, pH had the dominating influence on aerosol iron solubility. When aerosol samples were approximately neutral pH, iron solubility was on average 3.4%; when samples were below pH 4, the iron solubility increased to 35%. This observed aerosol iron solubility profile is consistent with thermodynamic predictions for the solubility of Fe(III) oxides, the major iron containing phase in the aerosol samples. Source regions and transport paths were also important factors affecting iron solubility, as samples originating from or passing over populated regions tended to contain more soluble iron. Although the acidity appears to affect aerosol iron solubility globally, a direct relationship for all samples is confounded by factors such as anthropogenic influence, aerosol buffer capacity, mineralogy and physical processes.
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Date Issued: 2018-05-01
Identifier: FSU_libsubv1_wos_000435190300044, 10.3390/atmos9050201
Format: Citation

Title: Remote Sensing Estimation Of Surface Oil Volume During The 2010 Deepwater Horizon Oil Blowout In The Gulf Of Mexico: Scaling Up Aviris Observations With Modis Measurements.
Creator: Hu, Chuanmin, Feng, Lian, Holmes, Jamie, Swayze, Gregg A., Leifer, Ira, Melton, Christopher, Garcia, Oscar, MacDonald, Ian, Hess, Mark, Muller-Karger, Frank, Graettinger, George...
Show moreHu, Chuanmin, Feng, Lian, Holmes, Jamie, Swayze, Gregg A., Leifer, Ira, Melton, Christopher, Garcia, Oscar, MacDonald, Ian, Hess, Mark, Muller-Karger, Frank, Graettinger, George, Green, Rebecca
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Abstract/Description: The Deepwater Horizon (DWH) oil blowout in the Gulf of Mexico (GoM) led to the largest offshore oil spill in U.S. history. The accident resulted in oil slicks that covered between 10,000 and upward of 40,000 km 2 of the Gulf between April and July 2010. Quantifying the actual spatial extent of oil over such synoptic scales on an operational basis and, in particular, estimating the oil volume (or slick thickness) of large oil slicks on the ocean surface has proven to be a challenge to...
Show moreThe Deepwater Horizon (DWH) oil blowout in the Gulf of Mexico (GoM) led to the largest offshore oil spill in U.S. history. The accident resulted in oil slicks that covered between 10,000 and upward of 40,000 km 2 of the Gulf between April and July 2010. Quantifying the actual spatial extent of oil over such synoptic scales on an operational basis and, in particular, estimating the oil volume (or slick thickness) of large oil slicks on the ocean surface has proven to be a challenge to researchers and responders alike. This challenge must be addressed to assess and understand impacts on marine and coastal resources and to prepare a response to future spills. We estimated surface oil volume and probability of occurrence of different oil thicknesses during the DWH blowout in the GoM by combining synoptic measurements (2330-km swath) from the satellite-borne NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and near-concurrent, much narrower swath (similar to 5 km) hyperspectral observations from the NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). A histogram-matching approach was used to transfer AVIRIS-derived oil volume to MODIS pixel-scale dimensions, after masking clouds under both sun glint and nonglint conditions. Probability functions were used to apply the transformation to 19 MODIS images collected during the DWH event. This generated three types of MODIS oil maps: maps of surface oil volume, maps of relative oil thickness with four different classes (i.e., 0 pm, <0.08 mu m, 0.08 to 8 mu m, and >8 mu m), and maps of probability distributions of different thicknesses. The results were compared with satellite-based synthetic aperture radar measurements and evaluated with concurrent aerial photographs. Although the methods may not be ideal and the results may contain large uncertainties, the current attempt suggests that coarse-resolution optical remote sensing observations can provide estimates of relative oil thickness/volume for large oil slicks captured by satellites. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.
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Date Issued: 2018-04-27
Identifier: FSU_libsubv1_wos_000431592100002, 10.1117/1.JRS.12.026008
Format: Citation

Title: Scales Of Seafloor Sediment Resuspension In The Northern Gulf Of Mexico.
Creator: Diercks, Arne-R., Dike, Clayton, Asper, Vernon L., DiMarco, Steven F., Chanton, Jeffrey P., Passow, Uta
Abstract/Description: Seafloor sediment resuspension events of different scales and magnitudes and the resulting deep (>1,000 m) benthic nepheloid layers were investigated in the northern Gulf of Mexico during Fall 2012 to Summer 2013. Time-series data of size-specific in-situ settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras), particle size distributions (profiling camera), currents (various current meters) and stacked time-series flux data (sediment traps) were combined to...
Show moreSeafloor sediment resuspension events of different scales and magnitudes and the resulting deep (>1,000 m) benthic nepheloid layers were investigated in the northern Gulf of Mexico during Fall 2012 to Summer 2013. Time-series data of size-specific in-situ settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras), particle size distributions (profiling camera), currents (various current meters) and stacked time-series flux data (sediment traps) were combined to recognize resuspension events ranging from small-scale local, to small-scale far-field to hurricane-scale. One small-scale local resuspension event caused by inertial currents was identified based on local high current speeds (>10 cm s(-1)) and trap data. Low POC content combined with high lithogenic silica flux at 30 m above bottom (mab) compared to the flux at 120 mab, suggested local resuspension reaching 30 mab, but not 120 mab. Another similar event was detected by the changes in particle size distribution and settling speeds of particles in the benthic nepheloid layer. Flux data indicated two other small-scale events, which occurred at some distance, rather than locally. Inertia-driven resuspension of material in shallower areas surrounding the traps presumably transported this material downslope leaving a resuspension signal at 120 mab, but not at 30 mab. The passage of hurricane Isaac left a larger scale resuspension event that lasted a few days and was recorded in both traps. Although hurricanes cause large-scale events readily observable in sediment trap samples, resuspension events small in temporal and spatial scale are not easily recognizable in trapped material as they tend to provide less material and become part of the background signal in the long-term averaged trap samples. We suggest that these small-scale resuspension events, mostly unnoticed in conventional time-series sampling, play an important role in the redistribution and ultimate fate of sediment distribution on the seafloor.
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Date Issued: 2018-04-18
Identifier: FSU_libsubv1_wos_000430649900001, 10.1525/elementa.285
Format: Citation

Title: Regional Trends In The Fractional Solubility Of Fe And Other Metals From North Atlantic Aerosols (geotraces Cruises Ga01 And Ga03) Following A Two-stage Leach.
Creator: Shelley, Rachel U., Landing, William M., Ussher, Simon J., Planquette, Helene, Sarthou, Geraldine
Abstract/Description: The fractional solubility of aerosol-derived trace elements deposited to the ocean surface is a key parameter of many marine biogeochemical models. Despite this, it is currently poorly constrained, in part due to the complex interplay between the various processes that govern the solubilisation of aerosol trace elements. In this study, we used a sequential two-stage leach to investigate the regional variability in fractional solubility of a suite of aerosol trace elements (Al, Ti, Fe, Mn, Co,...
Show moreThe fractional solubility of aerosol-derived trace elements deposited to the ocean surface is a key parameter of many marine biogeochemical models. Despite this, it is currently poorly constrained, in part due to the complex interplay between the various processes that govern the solubilisation of aerosol trace elements. In this study, we used a sequential two-stage leach to investigate the regional variability in fractional solubility of a suite of aerosol trace elements (Al, Ti, Fe, Mn, Co, Ni, Cu, Zn, Cd, and Pb) from samples collected during three GEOTRACES cruises to the North Atlantic Ocean (GA01, GA03-2010, and GA03-2011). We present aerosol trace element solubility data from two sequential leaches that provide a "solubility window", covering a conservative lower limit to an upper limit, the maximum potentially soluble fraction, and discuss why this upper limit of solubility could be used as a proxy for the bioavailable fraction in some regions. Regardless of the leaching solution used in this study (mild versus strong leach), the most heavily loaded samples generally had the lowest solubility. However, there were exceptions. Manganese fractional solubility was relatively uniform across the full range of atmospheric loading (32 +/- 13 and 49 +/- 13% for ultra high-purity water and 25% acetic acid leaches, respectively). This is consistent with other marine aerosol studies. Zinc and Cd fractional solubility also appeared to be independent of atmospheric loading. Although the average fractional solubilities of Zn and Cd (37 +/- 28 and 55 +/- 30% for Zn and 39 +/- 23 and 58 +/- 26% for Cd, for ultra high-purity water and 25% acetic acid leaches, respectively) were similar to Mn, the range was greater, with several samples being 100% soluble after the second leach. Finally, as the objective of this study was to investigate the regional variability in TE solubility, the samples were grouped according to air mass back trajectories (AMBTs). However, we conclude that AMBTs are not sufficiently discriminating to identify the aerosol sources or the potential effects of atmospheric processing on the physicochemical composition and solubility of the aerosols.
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Date Issued: 2018-04-18
Identifier: FSU_libsubv1_wos_000430365200001, 10.5194/bg-15-2271-2018
Format: Citation

Title: Methanogens Are Major Contributors To Nitrogen Fixation In Soils Of The Florida Everglades.
Creator: Bae, Hee-Sung, Morrison, Elise, Chanton, Jeffrey P., Ogram, Andrew
Abstract/Description: The objective of this study was to investigate the interaction of the nitrogen (N) cycle with methane production in the Florida Everglades, a large freshwater wetland. This study provides an initial analysis of the distribution and expression of N-cycling genes in Water Conservation Area 2A (WCA-2A), a section of the marsh that underwent phosphorus (P) loading for many years due to runoff from upstream agricultural activities. The elevated P resulted in increased primary productivity and an N...
Show moreThe objective of this study was to investigate the interaction of the nitrogen (N) cycle with methane production in the Florida Everglades, a large freshwater wetland. This study provides an initial analysis of the distribution and expression of N-cycling genes in Water Conservation Area 2A (WCA-2A), a section of the marsh that underwent phosphorus (P) loading for many years due to runoff from upstream agricultural activities. The elevated P resulted in increased primary productivity and an N limitation in P-enriched areas. Results from quantitative real-time PCR (qPCR) analyses indicated that the N cycle in WCA-2A was dominated by nifH and nirK/S, with an increasing trend in copy numbers in P-impacted sites. Many nifH sequences (6 to 44% of the total) and nifH transcript sequences (2 to 49%) clustered with the methanogenic Euryarchaeota, in stark contrast to the proportion of core gene sequences representing Archaea (<= 0.27% of SSU rRNA genes) for the WCA-2A microbiota. Notably, archaeal nifH gene transcripts were detected at all sites and comprised a significant proportion of total nifH transcripts obtained from the unimpacted site, indicating that methanogens are actively fixing N-2. Laboratory incubations with soils taken from WCA-2A produced nifH transcripts with the production of methane from H-2 plus CO2 and acetate as electron donors and carbon sources. Methanogenic N-2 fixation is likely to be an important, although largely unrecognized, route through which fixed nitrogen enters the anoxic soils of the Everglades and may have significant relevance regarding methane production in wetlands. IMPORTANCE Wetlands are the most important natural sources of the greenhouse gas methane, and much of that methane emanates from (sub) tropical peatlands. Primary productivity in these peatlands is frequently limited by the availability of nitrogen or phosphorus; however, the response to nutrient limitations of microbial communities that control biogeochemical cycling critical to ecosystem function may be complex and may be associated with a range of processes, including methane production. We show that many, if not most, of the methanogens in the peatlands of the Florida Everglades possess the nifH gene and actively express it for N-2 fixation coupled with methanogenesis. These findings indicate that archaeal N-2 fixation would play crucial role in methane emissions and overall N cycle in subtropical wetlands suffering N limitation.
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Date Issued: 2018-04
Identifier: FSU_libsubv1_wos_000427697900001, 10.1128/AEM.02222-17
Format: Citation

Title: Sea Surface Temperatures And Seagrass Mortality In Florida Bay: Spatial And Temporal Patterns Discerned From Modis And Avhrr Data.
Creator: Carlson, Daniel F., Yarbro, Laura A., Scolaro, Sheila, Poniatowski, Michael, McGee-Absten, Vicki, Carlson, Paul R.
Abstract/Description: Two major episodes of seagrass mortality have occurred in Florida Bay in the past 30 years: The first occurred between 1987 and 1991 and the second began in 2015. In both episodes, dense beds of turtle grass (Thalassia testudinum) were decimated. Elevated water temperature and hypersalinity have been implicated as contributing factors in both mortality events. During both die-off events seagrass beds on shallow (Z approximate to 0.3 m) mudbanks in western Florida Bay were disproportionately...
Show moreTwo major episodes of seagrass mortality have occurred in Florida Bay in the past 30 years: The first occurred between 1987 and 1991 and the second began in 2015. In both episodes, dense beds of turtle grass (Thalassia testudinum) were decimated. Elevated water temperature and hypersalinity have been implicated as contributing factors in both mortality events. During both die-off events seagrass beds on shallow (Z approximate to 0.3 m) mudbanks in western Florida Bay were disproportionately affected when compared to neighboring seagrass in deeper basins (Z approximate to 1.5 m). A network of in situ monitoring stations has measured sea surface temperature and salinity at hourly intervals in 16 basins in Florida Bay from August 2009 to the present day and these data aided in diagnosing the 2015-2016 die-off event. However, very few in situ observations of sea surface temperature have been collected on Florida Bay's shallow mudbanks as most are inaccessible by boat. As a result, our understanding of the role of elevated SST in shaping the spatial patterns of seagrass mortality is hindered by the spatial distribution of the in situ monitoring data and its record length. Therefore, we turn to remotely sensed SST data to expand our spatial coverage to include the entire Florida Bay ecosystem and to extend the record length to include the 1987-1991 die-off event. 1 km MODIS SST shows that shallow mudbanks were consistently warmer (by up to 6 degrees C) than nearby deeper basins. While water depth is likely the primary driver of spatial variability in SST, Landsat-8 surface reflectance data suggest that shallow seagrass beds could have suffered from the added influence of low surface reflectance, which might have further contributed to their thermal stress. Daily 0.25 degrees AVHRR SST shows that the August maximum SST has increased by 1 degrees C from 1981 to 2016, which is a cause for concern for the future of seagrass in Florida Bay. Correlation of monthly AVHRR SST anomalies with the multivariate ENSO index shows that ENSO can only partially explain the anomalous temperatures. When viewed together, the in situ and remotely sensed SST suggests that both extended exposure to anomalously warm temperatures and large, rapid changes in temperature could have contributed to seagrass mortality during both events.
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Date Issued: 2018-04
Identifier: FSU_libsubv1_wos_000428498400013, 10.1016/j.rse.2018.02.014
Format: Citation

Title: The Role of External Inputs and Internal Cycling in Shaping the Global Ocean Cobalt Distribution: Insights From the First Cobalt Biogeochemical Model..
Creator: Tagliabue, Alessandro, Hawco, Nicholas J, Bundy, Randelle M, Landing, William M, Milne, Angela, Morton, Peter L, Saito, Mak A
Abstract/Description: Cobalt is an important micronutrient for ocean microbes as it is present in vitamin B and is a co-factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is compared to biological demands, cobalt emerges as being depleted in seawater, pointing to a potentially important limiting role. To properly account for the potential biological role for cobalt, there is therefore a need to understand the processes driving the biogeochemical...
Show moreCobalt is an important micronutrient for ocean microbes as it is present in vitamin B and is a co-factor in various metalloenzymes that catalyze cellular processes. Moreover, when seawater availability of cobalt is compared to biological demands, cobalt emerges as being depleted in seawater, pointing to a potentially important limiting role. To properly account for the potential biological role for cobalt, there is therefore a need to understand the processes driving the biogeochemical cycling of cobalt and, in particular, the balance between external inputs and internal cycling. To do so, we developed the first cobalt model within a state-of-the-art three-dimensional global ocean biogeochemical model. Overall, our model does a good job in reproducing measurements with a correlation coefficient of >0.7 in the surface and >0.5 at depth. We find that continental margins are the dominant source of cobalt, with a crucial role played by supply under low bottom-water oxygen conditions. The basin-scale distribution of cobalt supplied from margins is facilitated by the activity of manganese-oxidizing bacteria being suppressed under low oxygen and low temperatures, which extends the residence time of cobalt. Overall, we find a residence time of 7 and 250 years in the upper 250 m and global ocean, respectively. Importantly, we find that the dominant internal resupply process switches from regeneration and recycling of particulate cobalt to dissolution of scavenged cobalt between the upper ocean and the ocean interior. Our model highlights key regions of the ocean where biological activity may be most sensitive to cobalt availability.
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Date Issued: 2018-04-01
Identifier: FSU_pmch_29937626, 10.1002/2017GB005830, PMC5993222, 29937626, 29937626, GBC20642
Format: Citation

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