Dynamic Air−Water Exchange of Polychlorinated Biphenyls in the New York−New Jersey Harbor Estuary

Abstract

Simultaneous measurements of polychlorinated biphenyls (PCBs) in the air and water over Raritan Bay and New York Harbor were taken in July 1998, allowing the first determinations of air-water exchange fluxes for this heavily impacted system. Average gas-phase concentrations of sigmaPCBs were 1.0 ng m(-3) above Raritan Bay and 3.1 ng m(-3) above New York Harbor. A similar gradient was observed for dissolved water concentrations (1.6 and 3.8 ng L(-1), respectively). Shallow slopes of log K(oc) vs log K(ow) plots indicated a colloidal contribution to the dissolved concentrations, and a three-phase partitioning model was therefore applied. PCBs associated with colloids ranged from 6% to 93% for trichloro- to nonachlorobiphenyls, respectively. Air-water gas exchange fluxes of sigmaPCBs exhibited net volatilization for both Raritan Bay at +400 ng m(-2) day(-1) and New York Harbor at +2100 ng m(-2) day(-1). The correction for the colloidal interactions decreased the volatilization flux of sigmaPCBs by about 15%. Net air-water exchange fluxes of PCBs are expected to remain positive throughout the year due to the large water-air fugacity gradient and relatively constant seasonal water concentrations. The volatilization fluxes are approximately 40 times greater than atmospheric deposition of PCBs via both wet and dry particle deposition, suggesting that the estuary acts as a net source of PCBs to the atmosphere year-round.

The factors controlling the partitioning of polybrominated diphenyl ethers and polychlorinated biphenyls in the water-column of the Pearl River Estuary in South China

“…These results are consistent with those of Butcher et al (1998), which suggests that less than 10% of PCBs containing three or more chlorines are sorbed to colloids in the Hudson River (USA) under normal conditions (4.79 mg/L DOC and 1.40 mg/L POC). These values conflict with the findings of Baker et al (2002) and Totten et al (2001), who have suggested that at commonly encountered DOC and SPM concentrations, substantial fractions of moderately hydrophobic compounds were sorbed to the colloidal phase. It should be noted that the PCB congeners detected in the present study were di-to tetra-chlorobiphenyls, which are less hydrophobic compounds compared to higher chlorinated congeners.…”

“…It should be noted that the PCB congeners detected in the present study were di-to tetra-chlorobiphenyls, which are less hydrophobic compounds compared to higher chlorinated congeners. In the study by Totten et al (2001), the fractions of tri-and tetra-PCBs sorbed to colloids in the New York/New Jersey Harbor were 6% and 14%, respectively, which was similar to the results in this study. The K OC(obs) values of PCBs were one to two orders of magnitude higher than the values predicted from the empirical organic matter partitioning model for the two yearly campaigns (Fig.…”

“…The slope of the plot of log K OW and log K OC(obs) should be one when partitioning is at equilibrium (Karickhoff et al, 1979). A slope that significantly deviates from one suggests that partitioning is not equilibrated and the deviation is frequently interpreted to mean that the sorption to colloids was significant (Totten et al, 2001). The shallower slope for PBDEs may indicate that more PBDEs are partitioned into colloids than PCBs.…”

“…The colloidal-associated contaminants may be the dominant species in some surface waters. Therefore, colloidal associations significantly impact the geochemistry of HOCs (Totten et al, 2001;Baker et al, 2002). In the particulate phase, carbonaceous materials, such as black carbon (BC), have been shown to be the principal particulate component responsible for the adsorption of HOCs such as pesticides and PAHs (Zhou et al, 1996;Orecchio, 2010).…”

The exchange of SVOCs across the air-sea interface in Singapore's coastal environment

“…SVOCs in the water column partition into three phases: the truly dissolved phase, the particulate phase and the colloidal organic material (Totten et al, 2001). The truly dissolved and colloidal phases can be categorized as apparent dissolved phase, which refers to the non-filter retained fraction.…”