title: Importance of black carbon to sorption of native PAHs, PCBs, and PCDDs in Boston and New York harbor sediments.
abstract: The solid-water distribution ratios (Kd values) of "native" PAHs, PCBs, and PCDDs in Boston and New York Harbor sediments were determined using small passive polyethylene samplers incubated for extended times in sediment-water suspensions. Observed solid-water distribution coefficients exceeded the corresponding f(oc)Koc products by 1-2 orders of magnitude. It was hypothesized that black carbon (fBC), measured in the Boston harbor sediment at about 0.6% and in the New York harbor sediment at about 0.3%, was responsible for the additional sorption. The overall partitioning was then attributed to absorption into the organic carbon and to adsorption onto the black carbon via Kd = f(oc)Koc + f(BC)K(BC)C(w)n-1 with Cw in microg/L. Predictions based on published Koc, K(BC), and n values for phenanthrene and pyrene showed good agreement with observed Kd,obs values. Thus, assuming this dual sorption model applied to the other native PAHs, PCBs, and PCDDs, black carbon-normalized adsorption coefficients, K(BC)S, were deduced forthese contaminants. Log K(BC) values correlated with sorbate hydrophobicity for PAHs in Boston harbor (log K(BC) approximately 0.83 log gamma w(sat) - 1.6; R2 = 0.99, N= 8). The inferred sorption to the sedimentary BC phase dominated the solid-water partitioning of these compound classes, and its inclusion in these sediments is necessary to make accurate estimates of the mobility and bioavailability of PAHs, PCBs, and PCDDs.
authors.affiliation: Ralph M Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. lohmann@alum.mit.edu
authors.forename: R
authors.initials: R
authors.lastname: Lohmann
authors.forename: J K
authors.initials: JK
authors.lastname: Macfarlane
authors.forename: P M
authors.initials: PM
authors.lastname: Gschwend
mesh_terms: D000327:Adsorption; D001682:Biological Availability; D001900:Boston; D002244:Carbon / Q000737:chemistry*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry; D009518:New York; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis* / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants; D002244:Carbon; D011078:Polychlorinated Biphenyls