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  • 2020-2024  (47)
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  • 1
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    Constraints on Earth System Functioning at the Paleocene‐Eocene Thermal Maximum From the Marine Silicon Cycle (2020)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2023-02-08
    Description: The Paleocene‐Eocene Thermal Maximum (PETM, ca. 56 Ma) is marked by a negative carbon isotope excursion (CIE) and increased global temperatures. The CIE is thought to result from the release of 13C‐depleted carbon, although the source(s) of carbon and triggers for its release, its rate of release, and the mechanisms by which the Earth system recovered are all debated. Many of the proposed mechanisms for the onset and recovery phases of the PETM make testable predictions about the marine silica cycle, making silicon isotope records a promising tool to address open questions about the PETM. We analyzed silicon isotope ratios (δ30Si) in radiolarian tests and sponge spicules from the Western North Atlantic (ODP Site 1051) across the PETM. Radiolarian δ30Si decreases by 0.6‰ from a background of 1‰ coeval with the CIE, while sponge δ30Si remains consistent at 0.2‰. Using a box model to test the Si cycle response to various scenarios, we find the data are best explained by a weak silicate weathering feedback, implying the recovery was mostly driven by nondiatom organic carbon burial, the other major long‐term carbon sink. We find no resolvable evidence for a volcanic trigger for carbon release, or for a change in regional oceanography. Better understanding of radiolarian Si isotope fractionation and more Si isotope records spanning the PETM are needed to confirm the global validity of these conclusions, but they highlight how the coupling between the silica and carbon cycles can be exploited to yield insight into the functioning of the Earth system.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Silicate content and stable silicon isotopic composition in porewater sampled during James Clark Ross cruise JR15003 in 2015 (2020)
    PANGAEA
    Details
    Publication Date: 2023-05-20
    Description: The West Antarctic Peninsula (WAP) is a highly productive shelf region during austral summer, supporting a rich ecosystem that has a significant impact on carbon sequestration. This ecosystem is heterogeneous, and characterised by biological "hotspots" fuelled largely by diatom production. The specific mechanisms determining the location and extent of these hotspots are not fully understood. Sedimentary enrichment of silicic acid (DSi) relative to other nutrients along the WAP, suggest that nutrient transfer across the sediment-water interface could have an impact on algal community composition. Here we combine reaction-transport modelling with porewater profiles of DSi concentration and stable silicon isotopic composition, biogenic silica content (BSi) and diatom abundances from sediment cores collected along the WAP, to assess the DSi flux and the processes that release this key nutrient from the WAP sediment into the overlying waters. We estimate a DSi diffusive flux of 2.67- 10**10 ± 2.75- 10**9 mol/yr for the WAP continental shelf area, which is lower than that previously estimated for the open Southern Ocean. Porewater isotopic compositions suggest that DSi concentrations are supplied primarily by BSi dissolution and respond to authigenic phase formation. Reaction-transport modelling highlights the highly dynamic environment of core-top sediments and the strong impact of surface productivity on sedimentary processes and the early diagenetic release of DSi. Both observations and modelling suggest a strong pelagic influence on benthic environment with the silicon benthic fluxes highly variable on different temporal and spatial scales, and thus sensitive to sea ice dynamics and climate change.
    Keywords: Benthic flux; Campaign; continental shelf; DATE/TIME; DEPTH, sediment/rock; early diagenesis; Event label; James Clark Ross; JR15003; JR15003_1; JR15003_2; JR15003_3; Latitude of event; Longitude of event; MULT; Multiple investigations; Opal, biogenic silica; Silicate; Silicon cyle; Station label; West Antarctic Peninsula; δ30Si, silicic acid; δ30Si, silicic acid, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 259 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 3
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    Silicate content and stable silicon isotopic composition in seawater sampled during James Clark Ross cruise JR15003 in 2015 (2020)
    PANGAEA
    Details
    Publication Date: 2023-05-20
    Description: The West Antarctic Peninsula (WAP) is a highly productive shelf region during austral summer, supporting a rich ecosystem that has a significant impact on carbon sequestration. This ecosystem is heterogeneous, and characterised by biological "hotspots" fuelled largely by diatom production. The specific mechanisms determining the location and extent of these hotspots are not fully understood. Sedimentary enrichment of silicic acid (DSi) relative to other nutrients along the WAP, suggest that nutrient transfer across the sediment-water interface could have an impact on algal community composition. Here we combine reaction-transport modelling with porewater profiles of DSi concentration and stable silicon isotopic composition, biogenic silica content (BSi) and diatom abundances from sediment cores collected along the WAP, to assess the DSi flux and the processes that release this key nutrient from the WAP sediment into the overlying waters. We estimate a DSi diffusive flux of 2.67- 10**10 ± 2.75- 10**9 mol/yr for the WAP continental shelf area, which is lower than that previously estimated for the open Southern Ocean. Porewater isotopic compositions suggest that DSi concentrations are supplied primarily by BSi dissolution and respond to authigenic phase formation. Reaction-transport modelling highlights the highly dynamic environment of core-top sediments and the strong impact of surface productivity on sedimentary processes and the early diagenetic release of DSi. Both observations and modelling suggest a strong pelagic influence on benthic environment with the silicon benthic fluxes highly variable on different temporal and spatial scales, and thus sensitive to sea ice dynamics and climate change.
    Keywords: Benthic flux; Campaign; continental shelf; DATE/TIME; DEPTH, water; early diagenesis; Event label; James Clark Ross; JR15003; JR15003_1; JR15003_2; JR15003_3; Latitude of event; Longitude of event; MULT; Multiple investigations; Silicate; Silicon cyle; Station label; West Antarctic Peninsula; δ30Si, silicic acid; δ30Si, silicic acid, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 175 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 4
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    Hydrographic and biogeochemical data from Godhäbsfjord and Ameralik Fjord, SW Greenland, 2018-2019 (2023)
    PANGAEA
    Details
    Publication Date: 2023-08-26
    Description: Dataset containing hydrographic and biogeochemical data from two fjords (Godhäbsfjord and Ameralik Fjord) in southwest Greenland. Data was collected during expeditions in July 2018 (KQ2018) and September 2019 (TU2019), as part of ERC funded (678371) project ICY-LAB (Isotope CYcling in the LABrador Sea) and Royal Society funded (RGF\EA\181036) project Biogeochemical Cycling in Greenlandic Fjords. All data derived from sensors are reported as an average related to the sampling period for the laboratory analysed data. For data corresponding with Towfish samples, this is a time-averaged value, corresponding to the time the Towfish was in the water and sampling occurred. For Niskin derived samples, the average for sensor derived data was calculated from a 5m depth window from a depth profiler CTD. Sampling method refers to the method in water samples were collected, prior to filtration, storage and laboratory analysis. FISH = a Towfish that was deployed for surface (up to 5m, average 3m) sampling. All detailed sampling protocols and station descriptions can be found in the associated cruise reports.
    Keywords: Alkaline extraction and Hach Lange spectrophotometer with the Heteropoly Blue Method; Biogeochemical_Cycling; Biogeochemical Cycling; Biogeochemical Cycling in Greenlandic Fjords; Bottle, Niskin; Calcium; Campaign of event; Carbon, organic, dissolved; Chloride; Chlorophyll a; Coastal Cycling; Date/Time of event; Day of the year; DEPTH, water; Event label; EXO3; EXO3 Multiparameter Water Quality Sonde (YSI, Xylem Inc., USA); FISH; Fish undulating, recording system tow; Glacial Export; Grab; GRAB; Greenlandic Fjords; ICY-LAB; Ion chromatograph, Dionex Corporation, ICS-5000; Isotope CYcling in the LABrador Sea; Isotope Ratio Mass Spectrometer, IsoPrime100; KQ18; KQ18/AF1_FISH; KQ18/AF1_GRAB; KQ18/AF1_NISKIN-1; KQ18/AF1_NISKIN-2; KQ18/AF2_FISH; KQ18/AF2_NISKIN-1; KQ18/AF2_NISKIN-2; KQ18/AF2_NISKIN-3; KQ18/AF3_FISH; KQ18/AF3_NISKIN-1; KQ18/AF3_NISKIN-2; KQ18/AF3_NISKIN-3; KQ18/GF1_FISH; KQ18/GF1_NISKIN-1; KQ18/GF1_NISKIN-2; KQ18/GF1_NISKIN-3; KQ18/GF2_FISH; KQ18/GF2_NISKIN-1; KQ18/GF2_NISKIN-2; KQ18/GF3_NISKIN; KQ18/GF4_FISH; KQ18/GF5_FISH; KQ18/GF5_NISKIN-1; KQ18/GF5_NISKIN-2; KQ18/GF5_NISKIN-3; KQ18/GF6_FISH; KQ18/GF6_NISKIN-1; KQ18/GF6_NISKIN-2; Latitude of event; Longitude of event; Magnesium; NIS; Nitrate; Nitrite; Nutrient Export; Phosphate; Potassium; R/V Kisaq; Salinity; Sample method; SEAL AutoAnalyzer 3 HR (AA3 HR); Shimadzu TOC-L total organic carbon analyzer; Silica, amorphous; Silicon, dissolved; Sodium; Station label; Sulfate; Temperature, water; TU19; TU19/AM10_FISH; TU19/AM10_NISKIN-1; TU19/AM10_NISKIN-2; TU19/AM10_TM-NISKIN; TU19/AM12_GRAB; TU19/AM3_FISH; TU19/AM3_NISKIN-1; TU19/AM3_NISKIN-2; TU19/AM3_TM-NISKIN; TU19/AM7_FISH; TU19/AM7_NISKIN-1; TU19/AM7_NISKIN-2; TU19/AM7_TM-NISKIN-1; TU19/AM7_TM-NISKIN-2; TU19/GF10_FISH; TU19/GF10_NISKIN-1; TU19/GF10_NISKIN-2; TU19/GF10_TM-NISKIN-1; TU19/GF10_TM-NISKIN-2; TU19/GF10_TM-NISKIN-3; TU19/GF13_FISH; TU19/GF13_NISKIN-1; TU19/GF13_NISKIN-2; TU19/GF13_TM-NISKIN; TU19/GF2_NISKIN; TU19/GF3_FISH; TU19/GF3_NISKIN-1; TU19/GF3_NISKIN-2; TU19/GF5_FISH; TU19/GF5_NISKIN; TU19/GF7_FISH; TU19/GF7_NISKIN-1; TU19/GF7_NISKIN-2; TU19/GF7_TM-NISKIN-1; TU19/GF7_TM-NISKIN-2; TU19/GF-Inlet_FISH; TU19/GF-Inlet_NISKIN; TU19/GF-Inlet_TM-NISKIN; TU19/GFX_FISH; TU19/GFX_NISKIN-1; TU19/GFX_NISKIN-2; TU19/GFX_TM-NISKIN-1; TU19/GFX_TM-NISKIN-2; TU19/GFX_TM-NISKIN-3; Tulu; Turbidity (Nephelometric turbidity unit); δ18O
    Type: Dataset
    Format: text/tab-separated-values, 1148 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 5
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    Diatom abundances in sediment sampled during James Clark Ross cruise JR15003 in 2015, West Antarctic Peninsula (2020)
    PANGAEA
    Details
    Publication Date: 2023-07-10
    Description: The West Antarctic Peninsula (WAP) is a highly productive shelf region during austral summer, supporting a rich ecosystem that has a significant impact on carbon sequestration. This ecosystem is heterogeneous, and characterised by biological "hotspots" fuelled largely by diatom production. The specific mechanisms determining the location and extent of these hotspots are not fully understood. Sedimentary enrichment of silicic acid (DSi) relative to other nutrients along the WAP, suggest that nutrient transfer across the sediment-water interface could have an impact on algal community composition. Here we combine reaction-transport modelling with porewater profiles of DSi concentration and stable silicon isotopic composition, biogenic silica content (BSi) and diatom abundances from sediment cores collected along the WAP, to assess the DSi flux and the processes that release this key nutrient from the WAP sediment into the overlying waters. We estimate a DSi diffusive flux of 2.67- 10**10 ± 2.75- 10**9 mol/yr for the WAP continental shelf area, which is lower than that previously estimated for the open Southern Ocean. Porewater isotopic compositions suggest that DSi concentrations are supplied primarily by BSi dissolution and respond to authigenic phase formation. Reaction-transport modelling highlights the highly dynamic environment of core-top sediments and the strong impact of surface productivity on sedimentary processes and the early diagenetic release of DSi. Both observations and modelling suggest a strong pelagic influence on benthic environment with the silicon benthic fluxes highly variable on different temporal and spatial scales, and thus sensitive to sea ice dynamics and climate change.
    Keywords: Abundance, marine diatoms; Benthic flux; Campaign; Chaetoceros spp. resting spores; continental shelf; DATE/TIME; DEPTH, sediment/rock; early diagenesis; Event label; Fragilariopsis curta; Fragilariopsis cylindrus; Fragilariopsis kerguelensis; James Clark Ross; JR15003; JR15003_1; JR15003_2; JR15003_3; Latitude of event; Longitude of event; MULT; Multiple investigations; Silicon cyle; Station label; Thalassiosira antarctica; Thalassiosira antarctica, resting spores; Thalassiosira gracilis var. expecta; Thalassiosira lentiginosa; West Antarctic Peninsula
    Type: Dataset
    Format: text/tab-separated-values, 456 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 6
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    Hydrographic and pore water, core incubation, and sediment leachate geochemical data from Ameralik Fjord and Nuup Kangerlua (Godhäbsfjord) in Southwest Greenland, 2019 (2023)
    PANGAEA
    Details
    Publication Date: 2023-10-31
    Description: This data set includes hydrographic and pore water and core incubation silicic acid concentration and isotope measurements, sediment Si-HCl and Si-Alk contents and isotope measurements, and pore water nutrient, major, and trace element concentrations measured in the fjords Ameralik Fjord and Nuup Kangerlua (Godhäbsfjord) in southwest Greenland. Data was collected during a research expedition, R/V Tulu 2019, in September 2019, as part of ERC funded (678371) project ICY-LAB (Isotope CYcling in the LABrador Sea) and Royal Society funded (RGF\EA\181036) project Biogeochemical Cycling in Greenlandic Fjords. Temperature and salinity data derived from CTD rosette casts were recorded at station AM10 in Ameralik Fjord and station GF-inlet in Nuup Kangerlua. Fjord water sampling was carried out at 2 stations (AM10 and AM12) in Ameralik Fjord and station GF-inlet in Nuup Kangerlua using Towfish and Niskin bottles for near surface and sub surface samples, respectively. For bottle samples, temperature and salinity were measured using an EXO3 Multiparameter Water Quality Sonde. Fjord sediments were collected by a large bore sediment corer (Aquatic Research Instruments) at station AM10a in Ameralik Fjord and station GF-inlet in Nuup Kangerlua. Pore waters were extracted from the sediment cores using Rhizon samplers and core incubation experiments were carried out following the methodology of Hammond et al. (2004, doi:10.4319/lom.2004.2.146). Sediment reactive silica was leached using a sequential extraction method from Michalopoulos and Aller (2004, doi:10.1016/j.gca.2003.07.018) and Pickering et al. (2020, doi:10.1029/2020GL087877).
    Keywords: CTD data; isotope; pore water; sediment; silicon
    Type: Dataset
    Format: application/zip, 5 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 7
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    Core incubation geochemical data from southwest Greenland fjords (2023)
    PANGAEA
    Details
    Publication Date: 2023-10-31
    Keywords: Campaign of event; CDRILL; Core drilling; CTD data; Date/Time of event; Event label; Greenland; ICP-MS, Thermo Scientific Neptune; isotope; Latitude of event; Longitude of event; pore water; sediment; silicon; Time Stamp; TU19; TU19_GF-inlet; Tulu; δ30Si; δ30Si, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 39 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 8
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    Hydrology data collected from CTD in southwest Greenland fjrods (2023)
    PANGAEA
    Details
    Publication Date: 2023-10-31
    Keywords: Campaign of event; CTD/Rosette; CTD data; CTD-RO; Date/Time of event; DEPTH, water; Event label; Greenland; isotope; Latitude of event; Longitude of event; Multiparameter Sonde, YSI, Xylem Inc., USA, EXO2 [serial number: 18K105254]; pore water; Salinity; sediment; silicon; Temperature, water; TU19; TU19-AM10; TU19-GF-inlet; Tulu
    Type: Dataset
    Format: text/tab-separated-values, 124 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 9
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    Pore water geochemical data from southwest Greenland fjords (2023)
    PANGAEA
    Details
    Publication Date: 2023-10-31
    Keywords: Aluminium; Campaign of event; CDRILL; Core drilling; CTD data; Date/Time of event; DEPTH, sediment/rock; Event label; Gas chromatography triple quadrupole Mass Spectrometer (ICP-QQQ-MS), Agilent Technologies, Agilent 8800; Greenland; ICP-MS, Thermo Scientific Neptune; Iron; isotope; Latitude of event; Lithium; Longitude of event; Magnesium; Manganese; Nitrate and Nitrite; pore water; Potassium; sediment; Segmented flow colorimetric auto-analyser, SEAL AutoAnalyzer 3; Silica, dissolved; silicon; TU19; TU19_AM10a; TU19_GF-inlet; Tulu; δ30Si; δ30Si, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 336 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 10
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    Hydrology data collected from Grab in southwest Greenland fjrods (2023)
    PANGAEA
    Details
    Publication Date: 2023-10-31
    Keywords: Campaign of event; CTD data; Date/Time of event; DEPTH, water; Event label; EXO3; EXO3 Multiparameter Water Quality Sonde (YSI, Xylem Inc., USA); Grab; GRAB; Greenland; isotope; Latitude of event; Longitude of event; pore water; Salinity; sediment; silicon; TU19; TU19-AM12; Tulu
    Type: Dataset
    Format: text/tab-separated-values, 1 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
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