Original scientific paper

Porewater Gradients and Diffusive Benthic Fluxes of Co, Ni, Cu, Zn, and Cd in San Francisco Bay

Ignacio Rivera-Duarte ; Earth Science, WIGS, Earth and Marine Sciences Building, University of California, Santa Cruz, CA 95064
A. Russell Flegal ; Earth Science, WIGS, Earth and Marine Sciences Building, University of California, Santa Cruz, CA 95064

Abstract

In order to determine the remobilization of Co, Ni, Cu, Zn, and Cd from the sediments, gradients of their dissolved (< 0.45 pm) and particulate concentrations were measured in both relatively pristine and contaminated sediments of San Francisco Bay, as well as relatively pristine adjacent embayments (Tomales Bay and Drakes Estero). Three mechanisms were determined to regulate the diage- netic release of those elements to porewaters: (i) the degradation of organic matter in oxic and suboxic zones; (ii) the reduction of Mn in suboxic zones; and (iii) the formation of soluble metal-sulfide complexes in anoxic zones. While the estimated diffusive benthic fluxes of Ni, Cu, and Cd were relatively small (< 10%) compared to their riverine fluxes, the estimated diffusive benthic fluxes of Co and Zn were similar (« 100%) to their riverine inputs. These initial estimates also indicate that the total (dissolved and particulate) benthic remobilization of Co, Ni, Cu, and Zn is greater than either riverine or point source inputs of those elements to San Francisco Bay. Moreover, those benthic inputs are projected to become more significant as the anthropogenic inputs of those elements, from both point sources and non-point sources, are reduced.

Keywords

Hrčak ID:

135638

URI

https://hrcak.srce.hr/135638

Publication date:

3.4.1997.

Visits: 1.139 *