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AMINO ACID COMPOSITION OF SUSPENDED PARTICLES, SEDIMENT-TRAP MATERIAL, AND BENTHIC SEDIMENT IN THE POTOMAC ESTUARY
Citation:
Sigleo, A. AND D. Shultz. AMINO ACID COMPOSITION OF SUSPENDED PARTICLES, SEDIMENT-TRAP MATERIAL, AND BENTHIC SEDIMENT IN THE POTOMAC ESTUARY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/221 (NTIS PB94169968), 1993.
Description:
Sediment trap deployments in estuaries provide a method for estimating the amount of organic material transported to the sediments from the euphotic zone. he amino acid composition of suspended particles, benthic sediment, and sediment-trap material collected at 2.4 m, 5.8 m, and 7.9 m depths in the Potomac Estuary was determined in stratified summer waters, and in well-mixed oxygenated waters (DO) in late fall. he total vertical flow, or flux. of material into the top traps ranged from 3 g m-2 d-1 in August to 4.9 g m-2 d-1 in October. he carbon and nitrogen fluxes increased in the deepest traps relative to the surface traps during both sampling periods, along with that of the total material flux (up to 47.3 g m-2 d-1 in the deepest trap), although the actual weight percent of organic carbon and organic nitrogen decreased with depth. mino acid concentrations ranged from 129 mg g-1 in surface water particulate material to 22 mg g-1 in particulate material in 9-m-deep waters and in the benthic sediment. mino acid concentrations from 2.4-m-depth sediment traps averaged 104 + 29 mg g-1 in stratified waters and 164 +/- 81 mg g-1 in well-mixed waters. he deep trap samples averaged 77.3 +/- 4.8 mg g-1 amino acids in summer waters and 37 +/- 16 mg g-1 in oxygenated fall waters. mino acids comprised 13% to 39% of the organic carbon and 12% to 89% of the organic nitrogen in these samples. nalysis of the flux results suggest that resuspension combined with lateral advection from adjacent slopes can account for up to 27% of the material in the deep traps when the very was well-mixed and unstratified. hen the estuary was stratified in late summer, the amino acid carbon prod by primary productivity in the euphotic zone decreased by 85% (86% for total organic carbon) at the pycnocline at 6 m depth, leaving up to 15% of the vertical organic flux available for benthic sediment deposition.