Benthic Flux of Dissolved Nickel into the Water Column of South San Francisco Bay.

摘要

Field and laboratory studies were conducted between April, 1998 and May, 1999 to provide the first direct measurements of the benthic flux of dissolved (0.2-micron filtered) nickel between the bottom sediment and water column at three sites in the southern component of San Francisco Bay (South Bay), California. Dissolved nickel and predominant ligands (represented by dissolved organic carbon, and sulfides) were the solutes of primary interest. Benthic flux (sometimes referred to as internal recycling) represents the transport of dissolved chemical species between the water column and the underlying sediment. Water-quality managers are often faced with requests to reconsider criteria for contaminant loads to aquatic systems. This is particularly true in San Francisco Bay where contaminants (e.g., nickel and copper) enter the estuarine water column from a wide range of sources (e.g., municipal and industrial discharge, urban and agricultural runoff, weathering processes, and internal remobilization). There have been frequent demands by managers and the general public to quantify the connections between fluxes of contaminants and the health, abundance, and distribution of biological resources (Kuwabara and others, 1999), motivating three decades of sustained progress by the USGS in better understanding San Francisco Bay. One relatively new field of study in San Francisco Bay focuses on a poorly understood, yet potentially predominant, source of contaminants to the bay: internal recycling or benthic flux of biologically reactive trace metals and ligands. This bioavailability and flux of contaminants and nutrients into the water column of San Francisco Bay is affected by chemical (i.e., oxidation-reduction reactions, complexation and repartitioning) and benthic biological processes.