ENVR 40 |
| From 1953 to 1971 the world's largest producer of DDT discharged wastes into the sewers of Los Angeles County. Roughly 900 metric tons of DDT were eventually released to the ocean off Palos Verdes, CA, USA, a portion of which (10-15%) resides in sediments of the continental shelf and slope (now a Superfund site). The fate of this material has been the subject of study for more than 35 years. Yet, questions remain about the best approach for remediation of the site. At issue is whether the most highly contaminated layers of sediment, at sub-bottom depths of 20-40 cm, will be re-exposed or if this can be prevented by continued burial and biotransformation. Cores collected from the Palos Verdes Shelf in 1992 and 2003 were used to estimate first-order transformation rates of p,p'-DDE, the predominant degradation product of DDT. A model for the degradation of three DDT metabolites at this location suggests that the inventory of p,p'-DDE and p,p'-DDMU will continue to decline, whereas that of p,p'-DDNU will reach a maximum around 2014. |
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Symposium Honoring Dr. Walter Giger
8:30 AM-12:15 PM, Monday, August 20, 2007 Boston Park Plaza -- Stanbro Rm, Oral
Division of Environmental Chemistry |