Distribution and phytoavailability of lead in a soil contaminated with lead shot

This paper presents a study of Pb contamination of soil at a clay target shooting facility in Canterbury, New Zealand. The spatial distribution of Pb concentrations in the topsoil at the gun club site was investigated and Pb in the soil profile was determined to a depth of 200 mm. The greatest EDTA-extractable soil Pb concentrations (4000 to 8300 mg Pb kg(-1) soil) were found approximately 120 m down the range from the point of shooting. At least 30% of the shot fall area sampled exceeded the Australian and New Zealand guideline limit of 300 mg Pb kg(-1) soil. Lead concentrations in the soil profile were fairly uniform to a depth of 200 mm due to regular incorporation of Pb shot by ploughing. A greenhouse study was conducted to assess plant uptake of Pb from soils sampled at the target shooting site. Lead concentrations in the roots of all five species grown were several magnitudes higher than those present in the leaves. However, sufficient plant translocation of Pb occurred for the leaves to exceed the maximum allowable limit for foodstuffs.