Trace-metal pollution of soils in northern England

Data from a regional geochemical survey of topsoils (n=818) in rural and pert-urban areas over a single parent material (Coal Measures) Are used to identify two types of trace-metal pollution severe local contamination at 20 sites and widespread; diffuse pollution in more densely populated areas. Median concentrations of several trace metals in topsoils were significantly higher in areas of high, compared to low; population density (percentage increases in parenthesis): As (31), Cu (39), Fe, (7), Mo (26-36); Ni (29), Pb (20), Sri (40), and Zn (11). Four potential pathways of diffuse trace-metal pollution are postulated: coal-ash dispersal, atmospheric aerosols derived from coal combustion, the historical spreading of sewage waste, and those related to road vehicles. The statistical analysis of geochemical data classified by local, human population density can be an effective means of identifying the magnitude and extent of diffuse pollution, and could help to establish natural background levels.