Silicate content and stable silicon isotopic composition in porewater sampled during James Clark Ross cruise JR15003 in 2015

DOI

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- 1010 ± 2.75- 109 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.

Identifier
DOI https://doi.org/10.1594/PANGAEA.920054
Related Identifier https://doi.org/10.1029/2019GB006486
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.920054
Provenance
Creator Cassarino, Lucie ORCID logo; Hendry, Katharine R ORCID logo; Henley, Sian Frances ORCID logo; MacDonald, Ellen ORCID logo; Arndt, Sandra ORCID logo; de Freitas, Felipe Sales ORCID logo; Pike, Jennifer ORCID logo; Firing, Yvonne L ORCID logo
Publisher PANGAEA
Publication Year 2020
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Dataset
Format text/tab-separated-values
Size 259 data points
Discipline Earth System Research
Spatial Coverage (-70.171W, -67.582S, -64.848E, -64.509N); West Antarctic Peninsula
Temporal Coverage Begin 2015-12-25T00:00:00Z
Temporal Coverage End 2015-12-28T00:00:00Z