Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in urban soils of Glasgow, UK

Concentrations of total organic carbon (TOC), total petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined in 84 near-surface soils (5–20 cm depth) taken from a 255 km2 area of Glasgow in the Clyde Basin, UK, during July 2011. Total petroleum hydrocarbon range was 79–2,505 mg kg–1 (mean 388 mg kg–1; median 272 mg kg–1) of which the aromatic fraction was 13–74 % (mean 44 %, median 43 %) and saturates were 28–87 % (mean 56 %, median 57 %). P16 PAH varied from 2–653 mg kg–1 (mean 32.4 mg kg–1; median 12.5mg kg–1) and P31 PAH range was 2.47–852 mg kg–1 (mean 45.4 mg kg–1; median 19.0 mg kg–1). PPCBtri-hepta range was 2.2–1052 mg kg–1 (mean 32.4 mg kg–1; median 12.7 mg kg–1) and the PPCB7 range was 0.3–344 mg kg–1 (mean 9.8 mg kg–1; median 2.7 mg kg–1). The concentration, distribution and source of the persistent organic pollutants were compared with those found in urban soils from other cities and to human health assessment criteria for chronic exposure to chemicals in soil. Total concentrations encountered were generally similar to other urban areas that had a similar industrial history. Benzo[a]pyrene concentrations were assessed against four different land use scenarios (irrespective of current land use) using generic assessment criteria resulting in six of 84 samples exceeding the residential criteria. Isomeric PAH ratios and relative abundance of perylene suggest multiple and environmentally modified pyrogenic PAH sources, inferred to be representative of diffuse pollution. PPCB7 concentrations were exceeded in 10 % of sites using the Dutch target value of 20 mg kg–1. PCB congener profiles were environmentally attenuated and generally dominated by penta-, hexa- and hepta-chlorinated congeners.