Accession Number : ADA307356

Title :   Effects of Speciation In Sediment-Water Exchange of Metals.

Descriptive Note : Annual progress rept. 15 Jun 93-15 Jun 94,

Corporate Author : OLD DOMINION UNIV RESEARCH FOUNDATION NORFOLK VA

Personal Author(s) : Donat, John R. ; Burdige, David J.

PDF Url : ADA307356

Report Date : 31 AUG 1995

Pagination or Media Count : 4

Abstract : Beginning in October 1993, we sampled sediments from two estuarine sites in Chesapeake Bay having contrasting biogeochemical and physical characteristics. Temporal variability at these sites has been examined during fall '93 and spring '94. Our results show that total dissolved copper concentrations in upper pore water intervals (8-11 nM) are similar to bottom water concentrations (5-12 nM). Virtually all of the copper (96.9 to 99.9%) dissolved in the pore waters and bottom waters of these two sites exists in electrochemically non-labile forms, probably as organic or mixed organic-inorganic (e.g., sulfide-containing) complexes. Such forms generally are regarded as being unavailable for biological uptake. The most striking result is that concentrations of copper-binding ligands in the upper intervals of the pore waters are at least 10 times greater than in the bottom waters. Despite similar levels of DOC in the pore waters at the mid-Bay site (site M) and at the lower Bay site (site S), levels of copper-binding ligands are 2 to 3 times greater in the pore waters at site M than at site S. In addition, the concentration gradient of copper-binding ligands across the sediment-water interface is much larger at site M than at site S, suggesting the stronger possibility of a benthic flux of such ligands from site M sediments. These differences may result from the dissimilar physical and chemical characteristics of the two sites. These results will guide our second- and third-year goal of quantifying fluxes of dissolved copper and copper-binding ligands across the sediment-water interface in Chesapeake Bay and the adjacent coastal Atlantic shelf/slope region.

Descriptors :   *METALS, *WATER, *COPPER, *LIGANDS, *EXCHANGE, *SEDIMENTS, CHEMICAL PROPERTIES, INTERFACES, MOLECULES, PHYSICAL PROPERTIES, FLUX(RATE), SITES, ELECTROCHEMISTRY, SAMPLING, CONCENTRATION(COMPOSITION), DISSOLVING, SULFIDES, GRADIENTS, BIOLOGICAL ABSORPTION, BENTHONIC ZONES, INTERVALS, ESTUARIES, CHESAPEAKE BAY, BOTTOM WATERS.

Subject Categories : Geology, Geochemistry and Mineralogy
      Inorganic Chemistry
      Physical and Dynamic Oceanography
      Hydrology, Limnology and Potamology

Distribution Statement : APPROVED FOR PUBLIC RELEASE