Superfund dredging restoration results in widespread regional reduction in cadmium in blue crabs

A nickel-cadmium battery factory released about 53 tons of mostly cadmium and nickel hydroxide suspended solid waste between 1953 and 1979 into Foundry Cove, which is tidally connected to the Hudson River estuary. A major Superfund dredging cleanup in 1994-1995 removed most of the cadmium from the sediment from within Foundry Cove. Here, we demonstrate that the cleanup reduced cadmium tissue concentrations (hepatopancreas and leg muscle) in an important fishery species, the blue crab Callinectes sapidus near Foundry Cove, but also across a broad reach of the Hudson River. Before the cleanup, cadmium concentrations in crabs were 4-5 times higher on average than after the cleanup and geographic variation in crab cadmium concentration along the Hudson River estuary was strongly reduced after the cleanup. The factor of reduction in crab tissue concentrations was far less than the factor of reduction of export of cadmium from Foundry Cove into the Hudson or the factor of reduction of cadmium sediment concentrations within the cove following the cleanup. This unique study demonstrates the efficacy of a major dredging cleanup and quantifies the spatial and temporal impact of the cleanup. It demonstrates that cleanup of a point source can have dramatic effects over large spatial scales.