Biogenic silica recycling in sea ice inferred from Si-isotopes: constraints from Arctic winter first-year sea ice

• Published in: Biogeochemistry
• Main Authors: Fripiat, François, Tison, Jean-Louis, André, Luc, Notz, Dirk, Delille, Bruno
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science & Business Media B.V. 2013
• Subjects: Sea ice; Nutrients Cycles; Silicon; Biogenic silica production; Biogenic silica dissolution; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Antarc*; Antarctic; greenlandic
• Online Access: https://orbi.uliege.be/handle/2268/156910; https://orbi.uliege.be/bitstream/2268/156910/1/fripiat%20et%20al_%20revised.pdf; https://doi.org/10.1007/s10533-013-9911-8

peer reviewed We report silicon isotopic composition (d30Si vs. NBS28) in Arctic sea ice, based on sampling of silicic acid from both brine and seawater in a small Greenlandic bay in March 2010. Our measurements show that just before the productive period, d30Si of sea-ice brine similar to d30Si of the underlying seawater. Hence, there is no Si isotopic fractionation during sea-ice growth by physical processes such as brine convection. This finding brings credit and support to the conclusions of previous work on the impact of biogenic processes on sea ice d30Si: any d30Si change results from a combination of biogenic silica production and dissolution. We use this insight to interpret data from an earlier study of sea-ice d30Si in Antarctic pack ice that show a large accumulation of biogenic silica. Based on these data, we estimate a significant contribution of biogenic silica dissolution (D) to production (P), with a D:P ratio between 0.4 and 0.9. This finding has significant implications for the understanding and parameterization of the sea ice Sibiogeochemical cycle, i.e. previous studies assumed little or no biogenic silica dissolution in sea ice. BELCANTO