Patterns of Accumulation of Airborne Organochlorine Contaminants in Lichens from the Upper Great Lakes Region of Ontario

Abstract

Spatial trends and patterns of accumulation of organochlorine (OC) contaminants were determined in lichen samples from 35 locations across Ontario, Canada, between 1985 and 1987. Concentrations of total DDT isomers [0.34–2.6 ng (g of dry wt)−1], total chlordane (0.36–1.7 ng g−1), and dieldrin (0.17–1.1 ng g−1) in 1987 were significantly higher in lichen from south-central Ontario locations than samples from northern and northwestern locations, while several of the latter sites had higher levels of hexachlo-rocyclohexane (HCH) isomers and pentachloroanisole (P5-CA). Similar levels and relative proportions of these compounds were observed in 1986 samples. Total PCB congener (ΣPCB) concentrations [2.0–7.7 ng (g of dry wt)−1] were elevated at south-central Ontario sites and, unexpectedly, at several other locations remote from obvious sources. Principal components analysis indicated that, in 1987, northwestern Ontario samples were distinguished from most southern locations by higher proportions of more volatile OCs (HCH isomers, P5CA, chlo-robenzenes). Air-plant bioconcentration factors (BCFV) ranged from 8.8 × 106 for hexachlorobenzene to 2.3 × 107 for ΣPCB at southern Ontario locations and were significantly correlated with octanol-air partition coefficients. BCFv's may have broad application for predicting air concentrations of semivolatile organic contaminants. © 1993, American Chemical Society. All rights reserved.