PATTERNS OF ACCUMULATION OF AIRBORNE ORGANOCHLORINE CONTAMINANTS IN LICHENS FROM THE UPPER GREAT-LAKES REGION OF ONTARIO

Spatial trends and patterns of accumulation of organochlorine (OC) con taminants were determined in lichen samples from 35 locations across O ntario, Canada, between 1985 and 1987. Concentrations of total DDT iso mers [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 l ichen from south-central Ontario locations than samples from northern and northwestern locations, while several of the latter sites had high er levels of hexachlorocyclohexane (HCH) isomers and pentachloroanisol e (P5-CA). Similar levels and relative proportions of these compounds were observed in 1986 samples. Total PCB congener (SIGMAPCB) concentra tions [2.0-7.7 ng (g of dry wt)-1] were elevated at south-central Onta rio sites and, unexpectedly, at several other locations remote from ob vious sources. Principal components analysis indicated that, in 1987, northwestern Ontario samples were distinguished from most southern loc ations by higher proportions of more volatile OCs (HCH isomers, P5CA, chlorobenzenes). Air-plant bioconcentration factors (BCF(v)) ranged fr om 8.8 X 10(6) for hexachlorobenzene to 2.3 X 10(7) for SIGMAPCB at so uthern Ontario locations and were significantly correlated with octano l-air partition coefficients. BCF(v)'s may have broad application for predicting air concentrations of semivolatile organic contaminants.