Acid Volatile Sulfides and Simultaneously Extracted Copper, Lead, and Zinc in Sediments of Sinclair Inlet, Washington

Acid volatile sulfides AVS and simultaneously extracted metal SEM concentrations of copper Cu, lead Pb, and zinc Zn were measured in the marine sediments of Sinclair Inlet, Puget Sound, Washington, as part of a project to evaluate the flux of metals between the sediment and bottom water of the Inlet. The AVS samples were collected from the same stations used to measure metal fluxes with a benthic chamber. The stations represented a range of previously measured heavy metal sediment concentrations in the Inlet. Two sediment cores 10 to 30 cm depth were collected from each station one core was selected to determine the AVS profile 2-cm increments, and the other was homogenized to obtain a composite AVS value for the top 10 cm. The AVS measured in composite samples ranged from 0.8 to 98.0 micrometers molg. For nine of the ten stations composite AVS concentrations were 2.2 to 10.3 times higher than the SEM concentrations of Cu, Pb, and Zn, and 1.1 to 6.2 times higher than the sum of divalent metal concentrations Cd, Cu, Hg, Ni, Pb, Ag, and Zn measured in bulk sediment grabs collected from the same stations. One station has a composite AVS concentration lower than the composite SEM concentration, resulting in SEMAVS 2.5. Seven of the ten stations has high AVS concentrations at the surface 20 micrometers molg, which increased at intermediate depths and decreased towards the bottom of the core. Simultaneously extracted Cu profiles were relatively uniform with depth and ranged from 0.1 to 11.2 micrometers molg. There was not a clear relationship between AVS and metal flux measured with the benthic chamber.