PAH-POOLS IN SOILS ALONG A PAH-DEPOSITION GRADIENT

The objectives of this study are to characterize different PAH-pools ( soil horizons, microsites influenced by stem flow, aggregate core and surface fractions, particle size fractions) in soils affected by depos itions. Three forest soils affected by the emissions of an aluminium p lant near Ziar/Central Slovakia were sampled to analyze 20 PAHs. The o rganic layers have high concentrations of PAHs (40-200 mg kg(-1)), dec reasing as soil depth and distance from the aluminium plant increases. At the two sites nearest to the plant PAH-concentrations are higher i n microsites affected by stem flow than in microsites not influenced b y stemflow. They are also higher in aggregate surface fractions than i n aggregate core fractions and in bulk soil samples than in aggregates . Sand- and silt-size particles contain decreasing percentages of the sum PAH-concentrations as distance from the plant increases. This micr oscale heterogeneity affects PAH-availability and has to be considered when assessing environmental risks. Copyright (C) 1996 Elsevier Scien ce Ltd