Sediments on the Palos Verdes Shelf (PVS), CA are contaminated due to the discharge of DDT-bearing wastes through a submarine outfall system (1947-71).  Pursuant to a decade-long environmental lawsuit in the 1990s, part of the shelf was designated a Superfund site and is now being remediated by the USEPA.  Microbially mediated reductive dechlorination occurs within the sediments resulting in conversion of the major DDT metabolite, DDE, to DDMU and DDMU to DDNU.  Dechlorination rates in shelf sediments vary spatially (0.013-0.085 yr-1), but the factors controlling dechlorination rates remain obscure.  As part of natural recovery studies currently underway, concentrations of ten DDT compounds were measured in porewater of PVS sediments using solid-phase microextraction.  Concentrations and compositions of the DDT compounds vary within the sediment column and across the shelf.  Preliminary examination of the data indicates that poreater concentrations are likely controlled by rates of supply (via desorption) and removal (via dechlorination).

Porewater chemistry of DDT compounds in sediments of the Palos Verdes Shelf, CA and its relevance to natural attenuation processes

243rd National Meeting (2012)

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