DDE in sediments of the Palos Verdes shelf, California: In situ transformation rates and geochemical fate
January 1, 2008
From 1947 to 1971 the world's largest manufacturer of DDT discharged process wastes into the sewers of Los Angeles County. Roughly 870-1450 t of DDT were released to the ocean off Palos Verdes, CA, a portion of which (???100 t) resides in sediments on the continental shelf and slope. The most abundant DDT compound in the sediments, p,p???-DDE, is degrading by reductive dechlorination, butthe rate of transformation and factors controlling it are not well understood. In order to estimate in situ transformation rates and predict the long-term fate of p,p???-DDE, box cores were collected in 1992 and 2003 from a single location on the Palos Verdes Shelf and analyzed for 8 DDT compounds and 84 polychlorinated biphenyl (PCB) congeners. The PCBs show no evidence of dechlorination, and inventories did not change between 1992 and 2003. By contrast, the inventory of p,p???-DDE decreased by 43%, whereas that of p,p???-DDMU, the putative reductive dechlorination product increased by 34%. The first-order transformation rate for p,p???-DDE at the study site is 0.051 ?? 0.006 yr-1. A multistep reaction model suggests that inventories of p,p???-DDE and p,p???-DDMU will continue to decline, whereas that of p,p???-DDNU will reach a maximum around 2014.
Citation Information
Publication Year | 2008 |
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Title | DDE in sediments of the Palos Verdes shelf, California: In situ transformation rates and geochemical fate |
DOI | 10.1021/es7029619 |
Authors | R.P. Eganhouse, J. Pontolillo |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Environmental Science & Technology |
Index ID | 70000135 |
Record Source | USGS Publications Warehouse |