USAP-DC

{"dp_type": "Project", "free_text": "SEDIMENT CHEMISTRY"}

[{"awards": null, "bounds_geometry": null, "dataset_titles": null, "datasets": null, "date_created": "Thu, 13 Jun 2024 00:00:00 GMT", "description": "The Amundsen Sea, near the fastest melting Antarctic glaciers, hosts one of the most productive polar ecosystems in the world. Phytoplankton serve as the base of the food chain, and their growth also removes carbon dioxide from the atmosphere. Phytoplankton growth is fertilized in this area by nutrient iron, which is only present at low concentrations in seawater. Prior studies have shown the seabed sediments may provide iron to the Amundsen Sea ecosystem. However, sediment sources of iron have never been studied here directly. This project fills this gap by analyzing sediments from the Amundsen Sea and investigating whether sediment iron fertilizes plankton growth. The results will help scientists understand the basic ecosystem drivers and predict the effects of climate change on this vibrant, vulnerable region. This project also emphasizes inclusivity and openness to the public. The researchers will establish a mentoring network for diverse polar scientists through the Polar Impact Network and communicate their results to the public through the website CryoConnect.org. \u003cbr/\u003e\u003cbr/\u003eThis project leverages samples already collected from the Amundsen Sea (NBP22-02) to investigate sediment iron (Fe) cycling and fluxes. The broad questions driving this research are 1) does benthic Fe fertilize Antarctic coastal primary productivity, and 2) what are the feedbacks between benthic Fe release and carbon cycling in the coastal Antarctic? To answer these questions, the researchers will analyze pore water Fe content and speciation and calculate fluxes of Fe across the sediment-water interface. These results will be compared to sediment characteristics (e.g., organic carbon content, reactive Fe content, proximity to glacial sources) to identify controls on benthic Fe release. This research dovetails with and expands on the science goals of the ?Accelerating Thwaites Ecosystem Impacts for the Southern Ocean? (ARTEMIS) project through which the field samples were collected. In turn, the findings of ARTEMIS regarding modeled and observed trace metal dynamics, surface water productivity, and carbon cycling will inform the conclusions of this project, allowing insight into the impact of benthic Fe in the whole system. This project represents a unique opportunity for combined study of the water column and sediment biogeochemistry which will be of great value to the marine biogeochemistry community and will inform future sediment-ocean studies in polar oceanography and beyond.\u003cbr/\u003e\u003cbr/\u003eThis award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "SEDIMENT CHEMISTRY; TRACE ELEMENTS", "locations": null, "north": null, "nsf_funding_programs": null, "paleo_time": null, "persons": null, "platforms": null, "repositories": null, "science_programs": null, "south": null, "title": "Benthic Iron Fluxes and Cycling in the Amundsen Sea", "uid": "p0010463", "west": null}, {"awards": "2147045 Learman, Deric", "bounds_geometry": "POLYGON((-180 -60,-168 -60,-156 -60,-144 -60,-132 -60,-120 -60,-108 -60,-96 -60,-84 -60,-72 -60,-60 -60,-60 -62,-60 -64,-60 -66,-60 -68,-60 -70,-60 -72,-60 -74,-60 -76,-60 -78,-60 -80,-72 -80,-84 -80,-96 -80,-108 -80,-120 -80,-132 -80,-144 -80,-156 -80,-168 -80,180 -80,171 -80,162 -80,153 -80,144 -80,135 -80,126 -80,117 -80,108 -80,99 -80,90 -80,90 -78,90 -76,90 -74,90 -72,90 -70,90 -68,90 -66,90 -64,90 -62,90 -60,99 -60,108 -60,117 -60,126 -60,135 -60,144 -60,153 -60,162 -60,171 -60,-180 -60))", "dataset_titles": "Physical and geochemical data from shelf sediments eastern Antarctica", "datasets": [{"dataset_uid": "601876", "doi": "10.15784/601876", "keywords": "Antarctica; Cryosphere", "people": "Learman, Deric", "repository": "USAP-DC", "science_program": null, "title": "Physical and geochemical data from shelf sediments eastern Antarctica", "url": "https://www.usap-dc.org/view/dataset/601876"}], "date_created": "Tue, 30 Aug 2022 00:00:00 GMT", "description": "Microbes in Antarctic surface marine sediments have an important role in degrading organic matter and releasing nutrients to the ocean. Organic matter degradation is at the center of the carbon cycle in the ocean, providing valuable information on nutrient recycling, food availability to animals and carbon dioxide release to the atmosphere. The functionality of these microbes has been inferred by their genomics, however these methods only address the possible function, not their actual rates. In this project the PIs plan to combine genomics methods with cellular estimates of enzyme abundance and activity as a way to determine the rates of carbon degradation. This project aims to sample in several regions of Antarctica to provide a large-scale picture of the processes under study and understand the importance of microbial community composition and environmental factors, such as primary productivity, have on microbial activity. The proposed work will combine research tools such as metagenomics, meta-transcriptomics, and metabolomics coupled with chemical data and enzyme assays to establish degradation of organic matter in Antarctic sediments. This project benefits NSFs goals of understanding the adaptation of Antarctic organisms to the cold and isolated environment, critical to predict effects of climate change to polar organisms, as well as contribute to our knowledge of how Antarctic organisms have adapted to this environment. Society will benefit from this project by education of 2 graduate students, undergraduates and K-12 students as well as increase public literacy through short videos production shared in YouTube. The PIs propose to advance understanding of polar microbial community function, by measuring enzyme and gene function of complex organic matter degradation in several ocean regions, providing a circum-Antarctic description of sediment processes. Two hypotheses are proposed. The first hypothesis states that many genes for the degradation of complex organic matter will be shared in sediments throughout a sampling transect and that where variations in gene content occur, it will reflect differences in the quantity and quality of organic matter, not regional variability. The second hypothesis states that a fraction of gene transcripts for organic matter degradation will not result in measurable enzyme activity due to post-translational modification or rapid degradation of the enzymes. The PIs will analyze sediment cores already collected in a 2020 cruise to the western Antarctic Peninsula with the additional request of participating in a cruise in 2023 to East Antarctica. The PIs will analyze sediments for metagenomics, meta-transcriptomics, and metabolomics coupled with geochemical data and enzyme assays to establish microbial degradation of complex organic matter in Antarctic sediments. Organic carbon concentrations and content in sediments will be measured with \u03b413C, \u03b415N, TOC porewater fluorescence in bulk organic carbon. Combined with determination of geographical variability as well as dependence on carbon sources, results from this study could provide the basis for new hypotheses on how climate variability, with increased water temperature, affects geochemistry in the Southern Ocean. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 90.0, "geometry": "POINT(-165 -70)", "instruments": null, "is_usap_dc": true, "keywords": "BENTHIC; ECOSYSTEM FUNCTIONS; Weddell Sea; Antarctic Peninsula; SEDIMENT CHEMISTRY; R/V NBP", "locations": "Antarctic Peninsula; Weddell Sea", "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Learman, Deric", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -80.0, "title": "Collaborative Research: ANT LIA: Connecting Metagenome Potential to Microbial Function: Investigating Microbial Degradation of Complex Organic Matter Antarctic Benthic Sediments", "uid": "p0010373", "west": -60.0}, {"awards": "2212904 Herbert, Lisa; 2407093 Herbert, Lisa", "bounds_geometry": "POLYGON((-120 -71,-118 -71,-116 -71,-114 -71,-112 -71,-110 -71,-108 -71,-106 -71,-104 -71,-102 -71,-100 -71,-100 -71.4,-100 -71.8,-100 -72.2,-100 -72.6,-100 -73,-100 -73.4,-100 -73.8,-100 -74.2,-100 -74.6,-100 -75,-102 -75,-104 -75,-106 -75,-108 -75,-110 -75,-112 -75,-114 -75,-116 -75,-118 -75,-120 -75,-120 -74.6,-120 -74.2,-120 -73.8,-120 -73.4,-120 -73,-120 -72.6,-120 -72.2,-120 -71.8,-120 -71.4,-120 -71))", "dataset_titles": null, "datasets": null, "date_created": "Sun, 07 Aug 2022 00:00:00 GMT", "description": "The Amundsen Sea, near the fastest melting Antarctic glaciers, hosts one of the most productive polar ecosystems in the world. Phytoplankton serve as the base of the food chain, and their growth also removes carbon dioxide from the atmosphere. Phytoplankton growth is fertilized in this area by nutrient iron, which is only present at low concentrations in seawater. Prior studies have shown the seabed sediments may provide iron to the Amundsen Sea ecosystem. However, sediment sources of iron have never been studied here directly. This project fills this gap by analyzing sediments from the Amundsen Sea and investigating whether sediment iron fertilizes plankton growth. The results will help scientists understand the basic ecosystem drivers and predict the effects of climate change on this vibrant, vulnerable region. This project also emphasizes inclusivity and openness to the public. The researchers will establish a mentoring network for diverse polar scientists through the Polar Impact Network and communicate their results to the public through the website CryoConnect.org. This project leverages samples already collected from the Amundsen Sea (NBP22-02) to investigate sediment iron (Fe) cycling and fluxes. The broad questions driving this research are 1) does benthic Fe fertilize Antarctic coastal primary productivity, and 2) what are the feedbacks between benthic Fe release and carbon cycling in the coastal Antarctic? To answer these questions, the researchers will analyze pore water Fe content and speciation and calculate fluxes of Fe across the sediment-water interface. These results will be compared to sediment characteristics (e.g., organic carbon content, reactive Fe content, proximity to glacial sources) to identify controls on benthic Fe release. This research dovetails with and expands on the science goals of the \u201cAccelerating Thwaites Ecosystem Impacts for the Southern Ocean\u201d (ARTEMIS) project through which the field samples were collected. In turn, the findings of ARTEMIS regarding modeled and observed trace metal dynamics, surface water productivity, and carbon cycling will inform the conclusions of this project, allowing insight into the impact of benthic Fe in the whole system. This project represents a unique opportunity for combined study of the water column and sediment biogeochemistry which will be of great value to the marine biogeochemistry community and will inform future sediment-ocean studies in polar oceanography and beyond. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": -100.0, "geometry": "POINT(-110 -73)", "instruments": null, "is_usap_dc": true, "keywords": "TRACE ELEMENTS; SEDIMENT CHEMISTRY; Amundsen Sea", "locations": "Amundsen Sea", "north": -71.0, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences; Post Doc/Travel", "paleo_time": null, "persons": "Herbert, Lisa", "platforms": null, "repositories": null, "science_programs": null, "south": -75.0, "title": "OPP-PRF: Benthic Iron Fluxes and Cycling in the Amundsen Sea", "uid": "p0010362", "west": -120.0}, {"awards": "1744871 Robinson, Rebecca", "bounds_geometry": "POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))", "dataset_titles": "Diatom assemblage from IODP Site U1357; Diatom-bound and bulk sedimentary N isotopes from ODP Site 1098, Western Antarctic Peninsula; Diatom-bound and bulk sedimentary nitrogen isotopes from IODP Site U1357; Dissolved nutrients, cell counts, and nitrogen isotope measurements from Chaetoceros socialis culture experiments; ODP Site 1098 deglacial diatom assemblage; Sediment chemistry of ODP Site 1098", "datasets": [{"dataset_uid": "601818", "doi": "10.15784/601818", "keywords": "Antarctica; Cryosphere; Geochemistry; Sediment; Wilkes Land", "people": "Dove, Isabel", "repository": "USAP-DC", "science_program": null, "title": "Diatom assemblage from IODP Site U1357", "url": "https://www.usap-dc.org/view/dataset/601818"}, {"dataset_uid": "601727", "doi": "10.15784/601727", "keywords": "Antarctica", "people": "Dove, Isabel", "repository": "USAP-DC", "science_program": null, "title": "Dissolved nutrients, cell counts, and nitrogen isotope measurements from Chaetoceros socialis culture experiments", "url": "https://www.usap-dc.org/view/dataset/601727"}, {"dataset_uid": "601816", "doi": "10.15784/601816", "keywords": "Antarctica; Antarctic Peninsula; Cryosphere; Geochemistry; Sediment", "people": "Dove, Isabel; Jones, Colin; Kelly, Roger; Robinson, Rebecca", "repository": "USAP-DC", "science_program": null, "title": "Diatom-bound and bulk sedimentary N isotopes from ODP Site 1098, Western Antarctic Peninsula", "url": "https://www.usap-dc.org/view/dataset/601816"}, {"dataset_uid": "601778", "doi": "10.15784/601778", "keywords": "Antarctica; Antarctic Peninsula; Cryosphere", "people": "Dove, Isabel", "repository": "USAP-DC", "science_program": null, "title": "Sediment chemistry of ODP Site 1098", "url": "https://www.usap-dc.org/view/dataset/601778"}, {"dataset_uid": "601817", "doi": "10.15784/601817", "keywords": "Antarctica; Cryosphere; Wilkes Land", "people": "Dove, Isabel; Kelly, Roger; Robinson, Rebecca", "repository": "USAP-DC", "science_program": null, "title": "Diatom-bound and bulk sedimentary nitrogen isotopes from IODP Site U1357", "url": "https://www.usap-dc.org/view/dataset/601817"}, {"dataset_uid": "601777", "doi": "10.15784/601777", "keywords": "Antarctica; Antarctic Peninsula; Cryosphere; Sediment Core Data", "people": "Dove, Isabel", "repository": "USAP-DC", "science_program": null, "title": "ODP Site 1098 deglacial diatom assemblage", "url": "https://www.usap-dc.org/view/dataset/601777"}], "date_created": "Wed, 28 Jul 2021 00:00:00 GMT", "description": "The chemical composition of diatom fossils in the Southern Ocean provides information about the environmental history of Antarctica, including sea ice extent, biological production, and ocean nutrient distribution. The sea ice zone is an important habitat for a group of diatoms, largely from the genus Chaetoceros, that have a unique life cycle stage under environmental stress, when they produce a structure called a resting spore. Resting spores are meant to reseed the surface ocean when conditions are more favorable. The production of these heavy resting spores tends to remove significant amounts of carbon and silicon, essential nutrients, out of the surface ocean. As a result, this group has the potential to remove carbon from the surface ocean and can impact the sedimentary record scientists use to reconstruct environmental change. This project explores the role of resting spores in the sedimentary record using the nitrogen isotopic signature of these fossils and how those measurements are used to estimate carbon cycle changes. The work will include laboratory incubations of these organisms to answer if and how the chemistry of the resting spores differs from that of a typical diatom cell. The incubation results will be used to evaluate nutrient drawdown in sea ice environments during two contrasting intervals in earth history, the last ice age and the warm Pliocene. This work should have significant impact on how the scientific community considers the impact of seasonal sea ice cover in the Southern Ocean in terms of how it responds to and regulates global climate. The project provides training and research opportunities for undergraduate and graduate students. Ongoing research efforts in Antarctic earth sciences will be disseminated through an interactive display at the home institution. The work proposed here will address uncertainties in how Chaetoceros resting spores record surface nutrient conditions in their nitrogen stable isotopic composition, the relative impact of their specific signal with respect to the full sedimentary assemblage, and their potential to bias or enhance environmental reconstructions in the sea ice zone. Measurements of nitrogen stable isotopes of nitrate, biomass, and diatom-bound nitrogen and silicon-to-nitrogen ratios of individual species grown in the laboratory will be used to quantify how resting spores record nutrient drawdown in the water column and to what degree their signature is biased toward low nutrient conditions. These relationships will be used to inform diatom-bound nitrogen isotope reconstructions of nutrient drawdown from a Pliocene coastal polyna and an open ocean core that spans the last glacial maximum. This proposal capitalizes on the availability of Southern Ocean isolates of Chaetoceros spp. collected in 2017 for the proposed culture work and archived sediment cores and/or existing data. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 180.0, "geometry": "POINT(0 -89.999)", "instruments": null, "is_usap_dc": true, "keywords": "Amd/Us; USAP-DC; Antarctica; ISOTOPES; MARINE SEDIMENTS; LABORATORY; USA/NSF; NITROGEN; AMD", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Robinson, Rebecca", "platforms": "OTHER \u003e PHYSICAL MODELS \u003e LABORATORY", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "The nitrogen isotopic composition of diatom resting spores in Southern Ocean sediments: A source of bias and/or paleoenvironmental information?", "uid": "p0010234", "west": -180.0}, {"awards": "2031442 Learman, Deric", "bounds_geometry": "POLYGON((-180 -60,-167.5 -60,-155 -60,-142.5 -60,-130 -60,-117.5 -60,-105 -60,-92.5 -60,-80 -60,-67.5 -60,-55 -60,-55 -62,-55 -64,-55 -66,-55 -68,-55 -70,-55 -72,-55 -74,-55 -76,-55 -78,-55 -80,-67.5 -80,-80 -80,-92.5 -80,-105 -80,-117.5 -80,-130 -80,-142.5 -80,-155 -80,-167.5 -80,180 -80,178 -80,176 -80,174 -80,172 -80,170 -80,168 -80,166 -80,164 -80,162 -80,160 -80,160 -78,160 -76,160 -74,160 -72,160 -70,160 -68,160 -66,160 -64,160 -62,160 -60,162 -60,164 -60,166 -60,168 -60,170 -60,172 -60,174 -60,176 -60,178 -60,-180 -60))", "dataset_titles": "Physical and geochemical data from shelf sediments near the Antartic Pennisula", "datasets": [{"dataset_uid": "601607", "doi": "10.15784/601607", "keywords": "Antarctica; Antarctic Peninsula; Grain Size; Grain Size Analysis; Marine Geoscience; Marine Sediments; Organic Matter Geochemistry; Sediment Core Data; Shelf Sediments; Weddell Sea", "people": "Learman, Deric", "repository": "USAP-DC", "science_program": null, "title": "Physical and geochemical data from shelf sediments near the Antartic Pennisula", "url": "https://www.usap-dc.org/view/dataset/601607"}], "date_created": "Wed, 28 Jul 2021 00:00:00 GMT", "description": "Western Antarctica is one of the fastest warming locations on Earth. Its changing climate will lead to an increase in sea-level and will also alter regional water temperature and chemistry. These changes will directly alter the microbes that inhabit the ecosystem. Microbes are the smallest forms of life on Earth, but they are also the most abundant. They drive cycling of essential nutrients, such as carbon and nitrogen that are found in ocean sediments. In this way they form the foundation of the food chain that supports larger and more complex life. However, we do not know much about how different communities of microbes break down sediments in Antarctica and this will influence the chemistry of those waters. This research will determine how communities of microbes on the coastal shelf of Antarctica degrade complex organic sediments using genetic and chemical data. This data will identify the species in the community, what enzymes they are producing and what chemical reactions they are driving. This research will create broader impacts as the data will be used to create in-class activities that improve a student\u2019s data analysis and critical thinking skills. The data will be used in graduate, undergraduate and K-12 classrooms. This research will provide genetic and enzymatic insight into how microbial communities in benthic sediments on the coastal shelf of Antarctica degrade complex organic matter. The current understanding of how benthic microbial communities respond to and then degrade complex organic matter in Antarctica is fragmented. Recent work suggests benthic microbial communities are shaped by organic matter availability. However, those studies were observational and did not directly examine community function. A preliminary study of metagenomic data from western Antarctic marine sediments, indicates a genetic potential for organic matter degradation but functional data was not been collected. Other studies have examined either enzyme activity or metagenomic potential, but few have been able to directly connect the two. To address this gap in knowledge, this study will utilize metagenomics and metatranscriptomics, coupled with microcosm experiments, enzyme assays, and geochemical data. It will examine Antarctic microbial communities from the Ross Sea, the Bransfield Strait and Weddell Sea to document how the relationship between a communities\u2019 enzymatic activity and the genes used to degrade complex organic matter is related to sediment breakdown. The data will expand our current knowledge of microbial genetic potential and provide a solid understanding of enzyme function as it relates to degradation of complex organic matter in those marine sediments. It will thereby improve our understanding of temperature change on the chemistry of Antarctic seawater. This award reflects NSF\u0027s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u0027s intellectual merit and broader impacts review criteria.", "east": 160.0, "geometry": "POINT(-127.5 -70)", "instruments": null, "is_usap_dc": true, "keywords": "ECOSYSTEM FUNCTIONS; USAP-DC; Antarctic Peninsula; BENTHIC; SHIPS; SEDIMENT CHEMISTRY; Amd/Us; AMD; USA/NSF; Weddell Sea", "locations": "Antarctic Peninsula; Weddell Sea", "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "paleo_time": null, "persons": "Learman, Deric", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e SHIPS", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -80.0, "title": "RAPID: Meta-genomic and Transcriptomic Investigation of Complex Organic Matter Degradation in Antarctic Benthic Sediments", "uid": "p0010235", "west": -55.0}, {"awards": "1543344 Soreghan, Gerilyn", "bounds_geometry": null, "dataset_titles": "Data and metadata for \"Quantifying surface area in muds from the Antarctic Dry Valleys: Implications for weathering in glacial systems\"", "datasets": [{"dataset_uid": "601599", "doi": "10.15784/601599", "keywords": "Antarctica; Anza Borrego; Iceland; McMurdo Dry Valleys; Norway; Peru; Puerto Rico; Taylor Valley; Washington; Wright Valley", "people": "Demirel-Floyd, Cansu", "repository": "USAP-DC", "science_program": null, "title": "Data and metadata for \"Quantifying surface area in muds from the Antarctic Dry Valleys: Implications for weathering in glacial systems\"", "url": "https://www.usap-dc.org/view/dataset/601599"}], "date_created": "Tue, 18 May 2021 00:00:00 GMT", "description": "As glaciers creep across the landscape, they can act as earthmovers, plucking up rocks and grinding them into fine sediments. Glaciers have moved across the Antarctic landscape over thousands to millions of years, leaving these ground-up sediments in their wake. This study builds on pilot discoveries by the investigators that revealed remarkably large and variable measurements of surface area in glacially-derived fine-grained sediments found in the McMurdo Dry Valleys (MDV), one of the few landscapes on the Antarctic continent not currently covered by ice. Surface area is key to chemical weathering, the process by which rock is converted to soils as ions are carried away in streams and groundwater. These chemical weathering processes are also one of the primary means by which the Earth system naturally removes carbon dioxide from the atmosphere. Hence, high surface areas observed in sediments implies high \"weatherability\" which in turn translates to more potential carbon dioxide removed from the atmosphere. Therefore, chemical weathering in high surface area glacial sediments may have significant impacts on Earth\u0027s carbon cycle. The researchers will measure the chemical and physical properties of sediments previously collected from the Dry Valleys to understand what factors lead to production of sediment with high-surface area and potential \"weather ability\" and investigate how sediment produced in these glacial systems could ultimately impact Earth\u0027s carbon budget. Results from this research will help scientists (including modelers) refine predictions of the effects of melting glaciers- and attendant exposure of glacial sediment? on atmospheric carbon levels. These results may also contribute to applied research efforts on development of carbon-dioxide removal technologies utilizing principles of rock weathering. In addition to the scientific benefits, this research will involve several students at the undergraduate, graduate, and post-doctoral levels, including science education undergraduates, thus contributing to training of the next-generation STEM workforce. Physical weathering produces fresh surfaces, greatly enhancing specific surface area (SSA) and reactive surface area (RSA) of primary minerals. Quantifying SSA and RSA of sediments is key to determining dissolution and leaching rates during natural weathering, but few data exist on distribution of sediment SA, particularly in glacial and fluvial systems. Pilot data from glacial stream systems in Taylor Valley and Wright Valley (located in the MDV) exhibit remarkably high and variable values in both SSA and RSA, values that in some cases greatly exceed values from muds in temperate glacial systems. This discovery motivates the current research, which aims to investigate the hypothesis that high and variable SAs of muds within Wright and Taylor Valleys reflect textural and/or compositional inheritance from the differing depositional settings within the MDV, biologic controls, dust additions, and/or pedogenic processes. These hypotheses will be tested by sedimentologically, mineralogically, and geochemically characterizing muds from glacially derived sediment deposited in various environments (cold vs. wet based glaciation; fluvial, lacustrine, dust, and drift deposits) and of varying age (Miocene to Modern) from the MDV and quantifying variation of SA and reactivity. Comparisons with analyzed muds from temperate glacial systems will enable polar-temperate comparisons. Analyses will focus on muds of previously collected sediment from the MDVs. Grain size and SSA will be measured by Laser Analysis and N2 adsorption BET, respectively. After carbonate removal, samples will be re-analyzed for SSA, and muds characterized geochemically. Mineralogy and bulk chemistry will also be assessed on co-occurring sand fractions, and textural attributes documented. SSA-normalized dissolution experiments will be used to compare solutes released from sediments to determine RSAs. Results will be integrated with the various sedimentologic and geochemical analyses to test the posed hypotheses. Ultimately, this research should shed light on how weathering in Antarctic systems contributes to global carbon cycling.", "east": null, "geometry": null, "instruments": null, "is_usap_dc": true, "keywords": "USAP-DC; AMD; FIELD INVESTIGATION; USA/NSF; Dry Valleys; SEDIMENT CHEMISTRY; Amd/Us; Antarctica; Weathering", "locations": "Antarctica; Dry Valleys", "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Soreghan, Gerilyn; Elwood Madden, Megan", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Quantifying surface area in muds from the Antarctic Dry Valleys: Implications for weathering in glacial systems", "uid": "p0010181", "west": null}, {"awards": "1542962 Anderson, Robert", "bounds_geometry": "POLYGON((-171 -57,-170.8 -57,-170.6 -57,-170.4 -57,-170.2 -57,-170 -57,-169.8 -57,-169.6 -57,-169.4 -57,-169.2 -57,-169 -57,-169 -57.72,-169 -58.44,-169 -59.16,-169 -59.88,-169 -60.6,-169 -61.32,-169 -62.04,-169 -62.76,-169 -63.48,-169 -64.2,-169.2 -64.2,-169.4 -64.2,-169.6 -64.2,-169.8 -64.2,-170 -64.2,-170.2 -64.2,-170.4 -64.2,-170.6 -64.2,-170.8 -64.2,-171 -64.2,-171 -63.48,-171 -62.76,-171 -62.04,-171 -61.32,-171 -60.6,-171 -59.88,-171 -59.16,-171 -58.44,-171 -57.72,-171 -57))", "dataset_titles": "Expedition Data of NBP1702; Water Mass Structure and Bottom Water Formation in the Ice-age Southern Ocean ; Water Mass Structure and Bottom Water Formation in the Ice-age Southern Ocean (SNOWBIRDS)", "datasets": [{"dataset_uid": "200126", "doi": "10.7284/907211", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data of NBP1702", "url": "https://www.rvdata.us/search/cruise/NBP1702"}, {"dataset_uid": "200166", "doi": "", "keywords": null, "people": null, "repository": "NCEI", "science_program": null, "title": "Water Mass Structure and Bottom Water Formation in the Ice-age Southern Ocean ", "url": "https://www.ncdc.noaa.gov/paleo/study/31312"}, {"dataset_uid": "200165", "doi": "", "keywords": null, "people": null, "repository": "BCO-DMO", "science_program": null, "title": "Water Mass Structure and Bottom Water Formation in the Ice-age Southern Ocean (SNOWBIRDS)", "url": "https://www.bco-dmo.org/dataset/813379/data"}], "date_created": "Fri, 25 Sep 2020 00:00:00 GMT", "description": "Scientists established more than 30 years ago that the climate-related variability of carbon dioxide levels in the atmosphere over Earth\u0027s ice-age cycles was regulated by the ocean. Hypotheses to explain how the ocean regulates atmospheric carbon dioxide have long been debated, but they have proven to be difficult to test. Work proposed here will test one leading hypothesis, specifically that the ocean experienced greater density stratification during the ice ages. That is, with greater stratification during the ice ages and slower replacement of deep water by cold dense water formed near the poles, the deep ocean would have held more carbon dioxide, which is produced by biological respiration of the organic carbon that constantly rains to the abyss in the form of dead organisms and organic debris that sink from the sunlit surface ocean. To test this hypothesis, the degree of ocean stratification during the last ice age and the rate of deep-water replacement will be constrained by comparing the radiocarbon ages of organisms that grew in the surface ocean and at the sea floor within a critical region around Antarctica, where most of the replacement of deep waters occurs. Completing this work will contribute toward improved models of future climate change. Climate scientists rely on models to estimate the amount of fossil fuel carbon dioxide that will be absorbed by the ocean in the future. Currently the ocean absorbs about 25% of the carbon dioxide produced by burning fossil fuels. Most of this carbon is absorbed in the Southern Ocean (the region around Antarctica). How this will change in the future is poorly known. Models have difficulty representing physical conditions in the Southern Ocean accurately, thereby adding substantial uncertainty to projections of future ocean uptake of carbon dioxide. Results of the proposed study will provide a benchmark to test the ability of models to simulate ocean processes under climate conditions distinctly different from those that occur today, ultimately leading to improvement of the models and to more reliable projections of future absorption of carbon dioxide by the ocean. The proposed work will add a research component to an existing scientific expedition to the Southern Ocean, in the region between the Ross Sea and New Zealand, that will collect sediment cores at three to five locations down the northern flank of the Pacific-Antarctic Ridge at approximately 170\u00b0W. The goal is to collect sediments at each location deposited since early in the peak of the last ice age. This region is unusual in the Southern Ocean in that sediments deposited during the last ice age contain foraminifera, tiny organisms with calcium carbonate shells, in much greater abundance than in other regions of the Southern Ocean. Foraminifera are widely used as an archive of several geochemical tracers of past ocean conditions. In the proposed work the radiocarbon age of foraminifera that inhabited the surface ocean will be compared with the age of contemporary specimens that grew on the seabed. The difference in age between surface and deep-swelling organisms will be used to discriminate between two proposed mechanisms of deep water renewal during the ice age: formation in coastal polynyas around the edge of Antarctica, much as occurs today, versus formation by open-ocean convection in deep-water regions far from the continent. If the latter mechanism prevails, then it is expected that surface and deep-dwelling foraminifera will exhibit similar radiocarbon ages. In the case of dominance of deep-water formation in coastal polynyas, one expects to find very different radiocarbon ages in the two populations of foraminifera. In the extreme case of greater ocean stratification during the last ice age, one even expects the surface dwellers to appear to be older than contemporary bottom dwellers because the targeted core sites lie directly under the region where the oldest deep waters return to the surface following their long circuitous transit through the deep ocean. The primary objective of the proposed work is to reconstruct the water mass age structure of the Southern Ocean during the last ice age, which, in turn, is a primary factor that controls the amount of carbon dioxide stored in the deep sea. In addition, the presence of foraminifera in the cores to be recovered provides a valuable resource for many other paleoceanographic applications, such as: 1) the application of nitrogen isotopes to constrain the level of nutrient utilization in the Southern Ocean and, thus, the efficiency of the ocean?s biological pump, 2) the application of neodymium isotopes to constrain the transport history of deep water masses, 3) the application of boron isotopes and boron/calcium ratios to constrain the pH and inorganic carbon system parameters of ice-age seawater, and 4) the exploitation of metal/calcium ratios in foraminifera to reconstruct the temperature (Mg/Ca) and nutrient content (Cd/Ca) of deep waters during the last ice age at a location near their source near Antarcitca.", "east": -169.0, "geometry": "POINT(-170 -60.6)", "instruments": null, "is_usap_dc": true, "keywords": "BIOGEOCHEMICAL CYCLES; SEDIMENT CHEMISTRY; South Pacific Ocean; SHIPS", "locations": "South Pacific Ocean", "north": -57.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Anderson, Robert; Fleisher, Martin; Pavia, Frank", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e SHIPS", "repo": "R2R", "repositories": "BCO-DMO; NCEI; R2R", "science_programs": null, "south": -64.2, "title": "Water Mass Structure and Bottom Water Formation in the Ice-age Southern Ocean", "uid": "p0010130", "west": -171.0}, {"awards": "1724670 Williams, Trevor", "bounds_geometry": "POLYGON((-70 -60,-65 -60,-60 -60,-55 -60,-50 -60,-45 -60,-40 -60,-35 -60,-30 -60,-25 -60,-20 -60,-20 -62.5,-20 -65,-20 -67.5,-20 -70,-20 -72.5,-20 -75,-20 -77.5,-20 -80,-20 -82.5,-20 -85,-25 -85,-30 -85,-35 -85,-40 -85,-45 -85,-50 -85,-55 -85,-60 -85,-65 -85,-70 -85,-70 -82.5,-70 -80,-70 -77.5,-70 -75,-70 -72.5,-70 -70,-70 -67.5,-70 -65,-70 -62.5,-70 -60))", "dataset_titles": "Argon thermochronological data on detrital mineral grains from the Weddell Sea embayment", "datasets": [{"dataset_uid": "601378", "doi": "10.15784/601378", "keywords": "40Ar/39Ar Thermochronology; Antarctica; Argon; Chemistry:sediment; Chemistry:Sediment; Detrital Minerals; Glaciers/ice Sheet; Glaciers/Ice Sheet; Marine Sediments; Mass Spectrometer; Provenance; R/v Polarstern; Sediment Core Data; Subglacial Till; Till; Weddell Sea", "people": "Williams, Trevor", "repository": "USAP-DC", "science_program": null, "title": "Argon thermochronological data on detrital mineral grains from the Weddell Sea embayment", "url": "https://www.usap-dc.org/view/dataset/601378"}, {"dataset_uid": "601379", "doi": "10.15784/601379", "keywords": "40Ar/39Ar Thermochronology; Antarctica; Argon; Chemistry:sediment; Chemistry:Sediment; Detrital Minerals; Glaciers/ice Sheet; Glaciers/Ice Sheet; Marine Geoscience; Mass Spectrometer; Provenance; R/v Polarstern; Sediment Core Data; Subglacial Till; Till; Weddell Sea", "people": "Williams, Trevor", "repository": "USAP-DC", "science_program": null, "title": "Argon thermochronological data on detrital mineral grains from the Weddell Sea embayment", "url": "https://www.usap-dc.org/view/dataset/601379"}, {"dataset_uid": "601377", "doi": "10.15784/601377", "keywords": "40Ar/39Ar Thermochronology; Antarctica; Argon; Chemistry:sediment; Chemistry:Sediment; Detrital Minerals; Glaciers/ice Sheet; Glaciers/Ice Sheet; Marine Sediments; Mass Spectrometer; Provenance; R/v Polarstern; Sediment Core Data; Subglacial Till; Till; Weddell Sea", "people": "Williams, Trevor", "repository": "USAP-DC", "science_program": null, "title": "Argon thermochronological data on detrital mineral grains from the Weddell Sea embayment", "url": "https://www.usap-dc.org/view/dataset/601377"}], "date_created": "Thu, 10 Sep 2020 00:00:00 GMT", "description": "Abstract for the general public: The margins of the Antarctic ice sheet have advanced and retreated repeatedly over the past few million years. Melting ice from the last retreat, from 19,000 to 9,000 years ago, raised sea levels by 8 meters or more, but the extents of previous retreats are less well known. The main goal of this project is to understand how Antarctic ice retreats: fast or slow, stepped or steady, and which parts of the ice sheet are most prone to retreat. Antarctica loses ice by two main processes: melting of the underside of floating ice shelves and calving of icebergs. Icebergs themselves are ephemeral, but they carry mineral grains and rock fragments that have been scoured from Antarctic bedrock. As the icebergs drift and melt, this \u0027iceberg-rafted debris\u0027 falls to the sea-bed and is steadily buried in marine sediments to form a record of iceberg activity and ice sheet retreat. The investigators will read this record of iceberg-rafted debris to find when and where Antarctic ice destabilized in the past. This information can help to predict how Antarctic ice will behave in a warming climate. The study area is the Weddell Sea embayment, in the Atlantic sector of Antarctica. Principal sources of icebergs are the nearby Antarctic Peninsula and Weddell Sea embayment, where ice streams drain about a quarter of Antarctic ice. The provenance of the iceberg-rafted debris (IRD), and the icebergs that carried it, will be found by matching the geochemical fingerprint (such as characteristic argon isotope ages) of individual mineral grains in the IRD to that of the corresponding source area. In more detail, the project will: 1. Define the geochemical fingerprints of the source areas of the glacially-eroded material using samples from each major ice stream entering the Weddell Sea. Existing data indicates that the hinterland of the Weddell embayment is made up of geochemically distinguishable source areas, making it possible to apply geochemical provenance techniques to determine the origin of Antarctica icebergs. Few samples of onshore tills are available from this area, so this project includes fieldwork to collect till samples to characterize detritus supplied by the Recovery and Foundation ice streams. 2. Document the stratigraphic changes in provenance of iceberg-rafted debris (IRD) and glacially-eroded material in two deep water sediment cores in the NW Weddell Sea. Icebergs calved from ice streams in the embayment are carried by the Weddell Gyre and deposit IRD as they pass over the core sites. The provenance information identifies which groups of ice streams were actively eroding and exporting detritus to the ocean (via iceberg rafting and bottom currents), and the stratigraphy of the cores shows the relative sequence of ice stream activity through time. A further dimension is added by determining the time lag between fine sediment erosion and deposition, using a new method of uranium-series isotope measurements in fine grained material. Technical abstract: The behavior of the Antarctic ice sheets and ice streams is a critical topic for climate change and future sea level rise. The goal of this proposal is to constrain ice sheet response to changing climate in the Weddell Sea during the three most recent glacial terminations, as analogues for potential future warming. The project will also examine possible contributions to Meltwater Pulse 1A, and test the relative stability of the ice streams draining East and West Antarctica. Much of the West Antarctic ice may have melted during the Eemian (130 to 114 Ka), so it may be an analogue for predicting future ice drawdown over the coming centuries. Geochemical provenance fingerprinting of glacially eroded detritus provides a novel way to reconstruct the location and relative timing of glacial retreat during these terminations in the Weddell Sea embayment. The two major objectives of the project are to: 1. Define the provenance source areas by characterizing Ar, U-Pb, and Nd isotopic signatures, and heavy mineral and Fe-Ti oxide compositions of detrital minerals from each major ice stream entering the Weddell Sea, using onshore tills and existing sediment cores from the Ronne and Filchner Ice Shelves. Pilot data demonstrate that detritus originating from the east and west sides of the Weddell Sea embayment can be clearly distinguished, and published data indicates that the hinterland of the embayment is made up of geochemically distinguishable source areas. Few samples of onshore tills are available from this area, so this project includes fieldwork to collect till to characterize detritus supplied by the Recovery and Foundation ice streams. 2. Document the stratigraphic changes in provenance of iceberg-rafted debris (IRD) and glacially-eroded material in two deep water sediment cores in the NW Weddell Sea. Icebergs calved from ice streams in the embayment are carried by the Weddell Gyre and deposit IRD as they pass over the core sites. The provenance information will identify which ice streams were actively eroding and exporting detritus to the ocean (via iceberg rafting and bottom currents). The stratigraphy of the cores will show the relative sequence of ice stream activity through time. A further time dimension is added by determining the time lag between fine sediment erosion and deposition, using U-series comminution ages.", "east": -20.0, "geometry": "POINT(-45 -72.5)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e CORERS \u003e SEDIMENT CORERS; IN SITU/LABORATORY INSTRUMENTS \u003e SPECTROMETERS/RADIOMETERS \u003e MASS SPECTROMETERS", "is_usap_dc": true, "keywords": "TERRIGENOUS SEDIMENTS; Subglacial Till; USAP-DC; ICEBERGS; AMD; USA/NSF; ISOTOPES; AGE DETERMINATIONS; Argon; Provenance; Till; Amd/Us; R/V POLARSTERN; FIELD INVESTIGATION; SEDIMENT CHEMISTRY; Weddell Sea; Antarctica; LABORATORY", "locations": "Weddell Sea; Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Williams, Trevor; Hemming, Sidney R.", "platforms": "LAND-BASED PLATFORMS \u003e FIELD SITES \u003e FIELD INVESTIGATION; OTHER \u003e PHYSICAL MODELS \u003e LABORATORY; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V POLARSTERN", "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -85.0, "title": "Collaborative Research: Deglacial Ice Dynamics in the Weddell Sea Embayment using Sediment Provenance", "uid": "p0010128", "west": -70.0}, {"awards": "1551195 Burdige, David", "bounds_geometry": "POLYGON((-71 -64,-70.1 -64,-69.2 -64,-68.3 -64,-67.4 -64,-66.5 -64,-65.6 -64,-64.7 -64,-63.8 -64,-62.9 -64,-62 -64,-62 -64.4,-62 -64.8,-62 -65.2,-62 -65.6,-62 -66,-62 -66.4,-62 -66.8,-62 -67.2,-62 -67.6,-62 -68,-62.9 -68,-63.8 -68,-64.7 -68,-65.6 -68,-66.5 -68,-67.4 -68,-68.3 -68,-69.2 -68,-70.1 -68,-71 -68,-71 -67.6,-71 -67.2,-71 -66.8,-71 -66.4,-71 -66,-71 -65.6,-71 -65.2,-71 -64.8,-71 -64.4,-71 -64))", "dataset_titles": "Expedition data of NBP1601; Project: Organic Carbon Oxidation and Iron Remobilization by West Antarctic Shelf Sediments", "datasets": [{"dataset_uid": "200148", "doi": "", "keywords": null, "people": null, "repository": "BCO-DMO", "science_program": null, "title": "Project: Organic Carbon Oxidation and Iron Remobilization by West Antarctic Shelf Sediments", "url": "https://www.bco-dmo.org/project/806864"}, {"dataset_uid": "002665", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP1601", "url": "https://www.rvdata.us/search/cruise/NBP1601"}], "date_created": "Tue, 16 Jun 2020 00:00:00 GMT", "description": "General Statement: The continental shelf region west of the Antarctic Peninsula has recently undergone dramatic changes and ecosystem shifts, and the community of organisms that live in, or feed off, the sea floor sediments is being impacted by species invasions from the north. Previous studies of these sediments indicate that this community may consume much more of the regional productivity than previously estimated, suggesting that sediments are a rich and important component of this ecosystem and one that may be ripe for dramatic change. Furthermore, under richer sediment conditions, iron is mobilized and released back to the water column. Since productivity in this ecosystem is thought to be limited by the availability of iron, increased rates of iron release from these sediments could stimulate productivity and promote greater overall ecosystem change. In this research, a variety of sites across the shelf region will be sampled to accurately evaluate the role of sediments in consuming ecosystem productivity and to estimate the current level of iron release from the sediments. This project will provide a baseline set of sediment results that will present a more complete picture of the west Antarctic shelf ecosystem, will allow for comparison with water column measurements and for evaluation of the fundamental workings of this important ecosystem. This is particularly important since high latitude systems may be vulnerable to the effects of climate fluctuations. Both graduate and undergraduate students will be trained. Presentations will be made at scientific meetings, at other universities, and at outreach events. A project web site will present key results to the public and explain how this new information improves understanding of Antarctic ecosystems. Technical Description of Project: In order to determine the role of sediments within the west Antarctic shelf ecosystem, this project will determine the rates of sediment organic matter oxidation at a variety of sites across the Palmer Long Term Ecosystem Research (LTER) study region. To estimate the rates of release of iron and manganese from the sediments, these same sites will be sampled for detailed vertical distributions of the concentrations of these metals both in the porewaters and in important mineral phases. Since sediment sampling will be done at LTER sites, the sediment data can be correlated with the rich productivity data set from the LTER. In detail, the project: a) will determine the rates of oxygen consumption, organic carbon oxidation, nutrient release, and iron mobilization by shelf sediments west of the Antarctic Peninsula; b) will investigate the vertical distribution of diagenetic reactions within the sediments; and c) will assess the regional importance of these sediment rates. Sediment cores will be used to determine sediment-water fluxes of dissolved oxygen, total carbon dioxide, nutrients, and the vertical distributions of these dissolved compounds, as well as iron and manganese in the pore waters. Bulk sediment properties of porosity, organic carbon and nitrogen content, carbonate content, biogenic silica content, and multiple species of solid-phase iron, manganese, and sulfur species will also be determined. These measurements will allow determination of total organic carbon oxidation and denitrification rates, and the proportion of aerobic versus anaerobic respiration at each site. Sediment diagenetic modeling will link the processes of organic matter oxidation to metal mobilization. Pore water and solid phase iron and manganese distributions will be used to model iron diagenesis in these sediments and to estimate the iron flux from the sediments to the overlying waters. Finally, the overall regional average and distribution of the sediment processes will be compared with the distributions of seasonally averaged chlorophyll biomass and productivity.", "east": -62.0, "geometry": "POINT(-66.5 -66)", "instruments": null, "is_usap_dc": true, "keywords": "BIOGEOCHEMICAL CYCLES; Iron Remobilization; R/V NBP; NBP1601; SEDIMENT CHEMISTRY; USAP-DC; West Antarctic Shelf", "locations": "West Antarctic Shelf", "north": -64.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Burdige, David; Christensen, John", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "BCO-DMO", "repositories": "BCO-DMO; R2R", "science_programs": null, "south": -68.0, "title": "Organic carbon oxidation and iron remobilization by West Antarctic shelf sediments ", "uid": "p0010108", "west": -71.0}]

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