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Calculating the Diffusive Flux of Persistent Organic Pollutants between Sediments and the Water Column on the Palos Verdes Shelf Superfund Site using Polymeric Passive Samplers
Citation:
Fernandez, Loretta A., W. Lao, K. Maruya, AND Robert M. Burgess. Calculating the Diffusive Flux of Persistent Organic Pollutants between Sediments and the Water Column on the Palos Verdes Shelf Superfund Site using Polymeric Passive Samplers. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 48(7):3925-3934, (2014).
Impact/Purpose:
Passive samplers were used to deduce water concentrations of persistent organic pollutants (POPs) in the surface sediments and near-bottom water of a marine Superfund site on the Palos Verdes Shelf, California, USA. Deduced concentrations in the porewaters and water column at four stations were used to calculate the flux of POPs, including DDE, DDD, DDMU, and selected PCB congeners, across the sediment-water interface due to molecular diffusion. This work demonstrates the utility of passive samplers for making in situ flux measurements at contaminated sediment sites.
Description:
Passive samplers were used to determine water concentrations of persistent organic pollutants (POPs) in the surface sediments and near-bottom water of a marine Superfund site on the Palos Verdes Shelf, California, USA. Measured concentrations in the porewater and water column at four stations were used to calculate the flux of POPs, including DDE, DDD, DDMU, and selected PCB congeners, across the sediment-water interface due to molecular diffusion. Three passive sampling materials were compared: PE strips, POM strips, and SPME fibers. Performance reference compounds (PRCs) were used with PE and POM to correct for incomplete equilibration, and the resulting POP concentrations determined by each material agreed within one order of magnitude. SPME fibers, without PRC corrections, produced values that were generally much lower (one to two orders of magnitude) than those measured using PE and POM. In addition, within the Superfund site, diffusive fluxes measured using PE strips at stations outside of a pilot remedial sand cap area were similar to those measured at a station inside the capped area: 240 to 260 ng cm-2 y-1 for p,p’-DDE. Outside of the Superfund site, flux was not detectable at a station in Santa Monica Bay because concentrations in the water column and sediment porewater were too similar. The largest diffusive fluxes of POPs were calculated at station 8C, the site where the highest sediment concentrations have been measured in the past, 1100 ng cm-2 y-1 for p,p’-DDE. This work demonstrates the utility of passive samplers for making in situ flux measurements at contaminated sediment sites.
