Selenium Behavior in San Francisco Bay Sediments |
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| Authors: | Shannon Meseck and Gregory Cutter |
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| Institution: | (1) Department of Ocean, Earth, and Atmospheric Sciences, Old Dominion University, Norfolk, VA 23529-0276, USA;(2) Present address: NOAA/NEMFS 212 Rogers Ave., Milford, CT 06460, USA |
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| Abstract: | Sediment and porewater samples (1997–1999) were collected in the Northern Reach of the San Francisco Bay and Sacramento–San
Joaquin Delta for determinations of sedimentary selenium and its chemical speciation. Total sedimentary selenium increased
with depth, with approximately 50% of the sedimentary selenium as elemental selenium and 35% as organic selenide. Porewater
total dissolved selenium increased with depth in the estuary and Delta, and fluxes out of the sediments were calculated at
0.01 and 0.06 nmol cm−2 year−1 for the estuary and Delta, respectively. Present-day sediment–water exchange of dissolved selenium and internal transformations
cannot explain the observed increase in total sedimentary selenium with depth. However, mass balance calculations demonstrate
that the increase in total selenium with depth may be linked to higher dissolved selenium concentrations in the water column
in the 1980s, suggesting that the sediments could be used as historical recorders of selenium in the estuary. |
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