Polychlorinated biphenyls (PCBs) continue to be contaminants of concern across the Great Lakes. It is unclear whether current concentrations are driven by on-going primary emissions from their original uses, or whether ambient PCBs are dominated by their environmental cycling. Freely dissolved PCBs in air and water were measured using polyethylene passive samplers across Lakes Erie and Ontario during summer and fall, 2011 to investigate their spatial distribution, determine and apportion their sources and to asses their air-water exchange. Average gaseous and freely dissolved ∑29 PCB concentrations ranged from 5.0 to 160 pg/m3 and 2.0 – 55 pg/L respectively (Figure 1). Gaseous concentrations were significantly correlated (R2 = 0.80) with urban area within 20 km radius. Flux calculations indicated net volatilization (0.30 – 18 ng/m2/day) from the water in 92 % of the samples. Dissolved PCBs were often far above equilibrium with the gas-phase, probably linked to direct PCB emissions from areas of concern. Positive Matrix Factorization indicated that although weathered Aroclors (gaseous PCBs) and original Aroclors (dissolved PCBs) dominate in some samples, on-going non-Aroclor sources such as paints/dyes (PCB 11) and coal/wood combustion showed significant contributions across the lower Great Lakes (Figure 2). Accordingly, control strategies should give further attention to PCBs emitted from current use sources.

Spatial distribution, air-water exchange and source apportionment of polychlorinated biphenyls in the lower Great Lakes Basin

250th National Meeting (2015)

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