Air-Water Exchange of Polychlorinated Biphenyls in the Delaware River
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- 作者：Amy A. Rowe ; Lisa A. Totten ; Minge Xie ; Thomas J. Fikslin ; Stephen J. Eisenreich
- 刊名：Environmental Science & Technology
- 出版年：2007
- 出版时间：February 15, 2007
- 年：2007
- 卷：41
- 期：4
- 页码：1152 - 1158
- 全文大小：302K
- 年卷期：v.41,no.4(February 15, 2007)
- ISSN：1520-5851
文摘
The air-water exchange of polychlorinated biphenyls(PCBs) often results in net volatilization, which is thoughtto be the most important loss process for PCBs inmany systems. Previous investigations of the air-waterexchange of PCBs have been hampered by difficulties intreatment of the uncertainty in the calculation of air/waterfugacity ratios. This work presents a new framework forthe treatment of uncertainty, where uncertainty in physicalconstants is handled differently from random measurementuncertainty associated with random samples, and itfurther investigates the sorption of PCBs to colloids(dissolved organic carbon). Simultaneous measurementsof PCBs in the air and water of five water quality managementzones of the Delaware River were taken in 2002 insupport of the total maximum daily load (TMDL) process. Gas-phase concentrations of 
chars/Sigma.gif" BORDER=0 >PCBs ranged from 110 to 1350pg m-3, while dissolved water concentrations were between420 and 1650 pg L-1. Shallow slopes of log KOC vs logKOW plots indicated a colloidal contribution to the apparentdissolved-phase concentrations, such that a three-phasepartitioning model was applied. Fugacity ratios for individualcongeners were calculated under the most conservativeassumptions, and their values (log-transformed) wereexamined via a single-sample T-test to determine whetherthey were significantly less than 1 at the 95% confidencelevel. This method demonstrated that air-water exchangeresulted in net volatilization in all zones over all cruisesfor all but seven high molecular weight congeners. Calculatednet fluxes ranged from +360 to +3000 ng m-2 d-1 forchars/Sigma.gif" BORDER=0 >PCBs. The colloidal correction decreased the volatilizationflux of chars/Sigma.gif" BORDER=0 >PCBs by ~30%. The decachlorinated congener(PCB 209), exhibited unusually high concentrations in thesuspended solids, especially in the southern portions of theriver, indicating that there is a distinct source of PCB209 in the Delaware River.
chars/Sigma.gif" BORDER=0 >PCBs ranged from 110 to 1350pg m-3, while dissolved water concentrations were between420 and 1650 pg L-1. Shallow slopes of log KOC vs logKOW plots indicated a colloidal contribution to the apparentdissolved-phase concentrations, such that a three-phasepartitioning model was applied. Fugacity ratios for individualcongeners were calculated under the most conservativeassumptions, and their values (log-transformed) wereexamined via a single-sample T-test to determine whetherthey were significantly less than 1 at the 95% confidencelevel. This method demonstrated that air-water exchangeresulted in net volatilization in all zones over all cruisesfor all but seven high molecular weight congeners. Calculatednet fluxes ranged from +360 to +3000 ng m-2 d-1 forchars/Sigma.gif" BORDER=0 >PCBs. The colloidal correction decreased the volatilizationflux of chars/Sigma.gif" BORDER=0 >PCBs by ~30%. The decachlorinated congener(PCB 209), exhibited unusually high concentrations in thesuspended solids, especially in the southern portions of theriver, indicating that there is a distinct source of PCB209 in the Delaware River.