Distance—Decline patterns in heavy metal contamination of soils and plants in Birmingham, England

A field experiment was undertaken in and near Birmingham, England to investigate heavy metal contamination in relation to distance from the city centre. It was postulated that contamination processes known to affect city soils and vegetables would extent beyond the city limit to affect rural soils. To test the hypothesis radish plants were grown in 31 sites along a 22 km transect extending from the centre of Birmingham to the rural area to the southeast. Concentrations of Cd, Cu, Pb and Zn in soils and plants revealed a general order of contamination urban > suburban > rural. The distance—decline relationships were modelled using polynomial regression analysis and quadratic regressions yielded satisfactory fits. The initial hypothesis was confirmed and soils and plants lying outside the city can be contaminated by pollutants presumably arising from man's urban and industrial activities. Soil—plant relationships and the origin of lead in radish leaves are discussed.