Chiral Source Apportionment of Polychlorinated Biphenyls to the Hudson River Estuary Atmosphere and Food Web

Abstract

The New York/New Jersey Harbor Estuary is subject to significant contamination of polychlorinated biphenyls (PCBs) from numerous sources, including the historically contaminated Upper Hudson River, stormwater runoff and sewer overflows, and atmospheric deposition from PCBs originating from the surrounding urban area. However, the relative importance of these sources to the estuary's food web is not fully understood. Sources of PCBs to the estuary were apportioned using chiral signatures of PCBs in air, water, total suspended matter, phytoplankton, and sediment. PCBs 91, 95, 136, and 149 were racemic in the atmosphere of the estuary. However, the other phases contained nonracemic PCB 95 and to a lesser extent PCB 149. Thus, the predominant atmospheric source of these congeners is likely unweathered local pollution and not volatilization from the estuary. The similarity in chiral signatures in the other phases is consistent with dynamic contaminant exchange among them. Chiral signatures in the dissolved phase and total suspended matter were correlated with Upper Hudson discharge, suggesting thatthe delivery of nonracemic contaminated sediment from the Upper Hudson, not the atmosphere, controls phytoplankton uptake of some PCBs. Thus, measures to control PCB contamination in the Upper Hudson should be effective in reducing loadings to the estuary's aquatic ecosystem.

Chirality as an Environmental Forensics Tool

“…Thus, these observations were consistent with bioaccumulation of weathered residues as the process responsible for nonracemic EFs. Likewise, zooplankton in the Hudson River estuary had slightly nonracemic amounts of PCBs 95 (mean EF ¼ 0.48 using Equation (4.4) on Chirasil-Dex) and PCB 149 (mean EF ¼ 0.52), which were very similar to those in the estuary waters and sediments [194]. These EFs were most likely due to runoff of nonracemic PCBs, weathered by reductive dechlorination, from Hudson River sediments [160].…”

“…These assumptions may not necessarily hold. For example, for reductive dechlorination of PCBs in sediments, it is possible for degradation to take place upstream followed by resuspension and redeposition elsewhere [156,194]. The calculated k m is an aggregate of all reactions, enantioselective or otherwise, involving the chemical in question.…”

“…PCB-containing building sealants, leaking transformers with PCB-bearing capacitor oil) would be the most effective means of lowering urban atmospheric PCB concentrations. Asher, Wong, and Rodenburg [194] observed that PCBs in the air overlying the Hudson River Estuary at New York City was racemic, consistent with an unweathered local urban source to the local atmosphere, consistent with observations of racemic chlordanes in the urbanized air of Chicago and Toronto [308]. However, estuary waters had nonracemic PCB 95 (EF range of 0.47 to 0.48 using Equation (4.4) on Chirasil-Dex) [194] similar to that in Hudson River sediment [160] and correlated to the Hudson River's water discharge (Figure 4.17).…”

Chiral Chemicals as Tracers of Atmospheric Sources and Fate Processes in a World of Changing Climate

“…21) Speciation of primary vs. secondary (soil volatilisation) sources of PCBs based on enantiomer profiles was also reviewed 21) and this concept was further applied in a recent study to identify sources near a hazardous waste incinerator. 29) Although PCB residues in soil are frequently nonracemic, [27][28][29][30][31][32] racemic PCBs are found in air [29][30][31]44) except very close to the soil surface and in grass. 45) This suggests that primary emissions still control PCB levels in the bulk atmosphere.…”

Assessing ongoing sources of dissolved‐phase polychlorinated biphenyls in a contaminated stream

“…For instance, congener profiles captured by passive samplers were used to distinguish between atmospheric deposition and in situ sediment remobilization as sources of dissolved PCBs [18][19][20]. Recent studies have also employed chiral analysis to provide insight into the sources of PCB in the water column [21,22]. Because their usage ended in 1977, PCBs detected in the study area are not likely from active discharge.…”