Trace Metal Cycling in South San Francisco Bay

The non-point source sediment fluxes of Cd, Cu, and
Ni from the sediment-water interface in South San
Francisco Bay are described and compared to known
point sources of both anthropogenic and watershed
origins. Fluxes of these metals were determined by
benthic flux chambers and by the mathematical
modeling of gradients in metal concentrations in
pore water taken from sediment cores. Experiments
were also performed to assess benthic macrofaunal
contributions of sediment fluxes using the invasive
Asian clam Potamocorbula amurensis. Because of major
clean-up efforts conducted since the 1970 s fluxes of
contaminants from point sources have decreased
significantly yet metal contamination remain high.
Fluxes from non-point sources must comprise a
significant source to the South Bay waters. The
addition of clams reversed the direction and
increased the magnitude of the fluxes of these
metals. These data suggest 1) non-point sources such
as sedimentary flux is important and 2) that invasive
species such as P. amurensis, can have profound
affects on benthic bioirrigation in the sediments due
to burrowing and feeding generating exchange of
pore waters with the overlying water column.

Autorentext

John Haskins grew up in the Bay Area and after attending USF hewent on to complete his Masters in marine science at Moss LandingMarine Laboratories. John is currently working at the ElkhornSlough National Estuarine Research Reserve conducting waterquality studies around the Elkhorn Slough watershed.

Klappentext

The non-point source sediment fluxes of Cd, Cu, andNi from the sediment-water interface in South SanFrancisco Bay are described and compared to knownpoint sources of both anthropogenic and watershedorigins. Fluxes of these metals were determined bybenthic flux chambers and by the mathematicalmodeling of gradients in metal concentrations inpore water taken from sediment cores. Experimentswere also performed to assess benthic macrofaunalcontributions of sediment fluxes using the invasiveAsian clam Potamocorbula amurensis. Because of majorclean-up efforts conducted since the 1970's fluxes ofcontaminants from point sources have decreasedsignificantly yet metal contamination remain high.Fluxes from non-point sources must comprise asignificant source to the South Bay waters. Theaddition of clams reversed the direction andincreased the magnitude of the fluxes of thesemetals. These data suggest 1) non-point sources suchas sedimentary flux is important and 2) that invasivespecies such as P. amurensis, can have profoundaffects on benthic bioirrigation in the sediments dueto burrowing and feeding generating exchange ofpore waters with the overlying water column.