SS2.02 Biogeochemical Process at the Sediment-Water Interfaces
Date: Tuesday, June 11, 2002
Time: 4:45:00 PM
Location: Carson B
 
WestonNB, Dept. Marine Sciences, University of Georgia, Athens, GA, USA, nweston@arches.uga.edu
Porubsky, W, P, Dept. Marine Sciences, University of Georgia, Athens, GA, USA, newcastl@arches.uga.edu
Joye, S, B, Dept. Marine Sciences, University of Georgia, Athens, GA, USA, mjoye@arches.uga.edu
 
SEASONAL PATTERNS OF POREWATER NUTRIENTS, DISSOLVED ORGANICS, REDOX SPECIES AND GASES IN ESTUARINE SEDIMENTS
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Porewater equilibration meters were deployed to obtain seasonal (4x/yr) steady-state high depth resolution profiles of shallow estuarine porewater nutrients (NH4, NO3, PO4), dissolved organics (DOC, DON, DOP), redox species (Fe, Mn, H2S), dissolved gases (O2, N2, CH4), DIC, chloride, sulfate and pH. High sediment pools of DOC in winter were consumed during spring and summer, with a concurrent increase in remineralization products (NH4, PO4, DIC, H2S). DON and DOP, however, did not exhibit seasonal patterns of net consumption, which may reflect a recalcitrant pool of organic N and P in the sediments unavailable to the anaerobic microbial community. C:N:P ratios of organic matter, when rates of consumption were high during summer, were indicative of organic matter sources. Dissolved N2 gas exceeded equilibrium at depth on most dates and was negatively correlated with sediment inventories of sulfide, indicating sulfide inhibition of denitrification or nitrification. Other constituents (Fe, CH4, SO4) exhibited clear seasonal trends, and these results provide a comprehensive analysis of seasonal patterns of sediment organic matter and nutrient cycling and metabolic processes at three estuarine sites.