title: Measuring and Modeling Organochlorine Pesticide Response to Activated Carbon Amendment in Tidal Sediment Mesocosms.
abstract: Activated carbon (AC) sediment amendment for hydrophobic organic contaminants (HOCs) is attracting increasing regulatory and industrial interest. However, mechanistic and well-vetted models are needed. Here, we conduct an 18 month field mesocosm trial at a site containing dichlorodiphenyltrichloroethane (DDT) and chlordane. Different AC applications were applied and, for the first time, a recently published mass transfer model was field tested under varying experimental conditions. AC treatment was effective in reducing DDT and chlordane concentration in polyethylene (PE) samplers, and contaminant extractability by Arenicola brasiliensis digestive fluids. A substantial AC particle size effect was observed. For example, chlordane concentration in PE was reduced by 93% 6 months post-treatment in the powdered AC (PAC) mesocosm, compared with 71% in the granular AC (GAC) mesocosm. Extractability of sediment-associated DDT and chlordane by A. brasiliensis digestive fluids was reduced by at least a factor of 10 in all AC treatments. The model reproduced the relative effects of varying experimental conditions (particle size, dose, mixing time) on concentrations in polyethylene passive samplers well, in most cases within 25% of experimental observations. Although uncertainties such as the effect of long-term AC fouling by organic matter remain, the study findings support the use of the model to assess long-term implications of AC amendment.
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305-5080, United States.
authors.forename: Jay M
authors.initials: JM
authors.lastname: Thompson
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305-5080, United States.
authors.forename: Ching-Hong
authors.initials: CH
authors.lastname: Hsieh
authors.affiliation: Chevron Energy Technology Company , Richmond, California 94801, United States.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Hoelen
authors.affiliation: Department of Integrative Biology, University of California , Berkeley, California 94720-3140, United States.
authors.forename: Donald P
authors.initials: DP
authors.lastname: Weston
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305-5080, United States.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Luthy
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry; D003634:DDT / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D010575:Pesticides
chemical_list: D010575:Pesticides; D002606:Charcoal; D002244:Carbon; D003634:DDT