B049-0010
Mechanisms of Silica Availability in a New England Salt Marsh

Thursday, 10 December 2020
Poster
Olivia Williams1, Joanna C Carey2, Andrew C Kurtz3, Meagan Eagle Eagle4 and Kevin D Kroeger4, (1)Oregon State University, College of Earth Ocean and Atmospheric Sciences, Corvallis, OR, United States, (2)Babson College, Mathematics and Science Division, Babson Park, MA, United States, (3)Boston University, Earth & Environment Department, Boston, MA, United States, (4)U.S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA, United States
Abstract:
Salt marshes are important sites of silica cycling and export to adjacent coastal systems. However, it is not known whether the dissolved silica (DSi) in marshes primarily originates from mineral weathering or from the dissolution of biogenic silica. We analyzed porewater and groundwater samples from Sage Lot Pond, MA, USA for DSi concentrations and Ge/Si ratios, which can be used as a tracer of DSi origin. Ge/Si ratios in the porewater averaged 6.2 ± 0.34 µmol/mol, which is consistent with the signal of silicate weathering, rather than biogenic silica dissolution. Our findings reinforce the importance of sediment retention as a priority for marsh stewardship in order to preserve critical silica availability in coastal systems.
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