Trace metal contamination of soils and vegetables in Shipham, Somerset

Abstract

Copper, lead and zinc ores have been mined in past years in many western counties of Great Britain leaving a legacy of extensive soil contamination. A survey of north-east Clwyd (Davies & Roberts, 1978) revealed that in the Halkyn Mountain area some 171 km2 of land are contaminated by lead and 69 km2 by cadmium (including 13 km2 containing from 10 to 540 mg Cd/kg soil). The Mendip Hills of Somerset are an ancient leadzinc mining area similar in many ways to Halkyn Mountain and, after some reconnaissance sampling in 1972 and 1974, a trace element survey was initiated in 1977. Topsoil samples (174) were collected on an approximately regular 2×2 km grid from a 600 km8 area of north Somerset including the Mendips (B. E. Davies and R. C. Ginnever, unpublished results). This survey revealed that the Mendips were generally contaminated by cadmium, lead and zinc. Highest soil lead values were found near Wells (11 g/kg) and Charterhouse (73 and 80 g/kg) but in the case of cadmium the survey revealed that some 2 km2 of land around the village of Shipham contained values exceeding 10 mg Cd/kg. Preparatory to detailed investigations planned for 1979 a reconnaissance survey of soils and vegetables from the village was made. Meanwhile, the Department of the Environment announced the results of another (independent) survey which also demonstrated that Shipham possessed a considerable cadmium problem (e.g. McGinty, 1979). A full account of our survey of north Somerset will be published and this paper presents the results from the reconnaissance of Shipham.