Lead contamination of an agricultural soil in the vicinity of a shooting range

In this study, coupled Pb concentration/Pb isotope data were used to evaluate the effect of a shooting range (operational for over 30 years) on Pb contamination of adjacent agricultural soils and the associated environmental risks. Lead was mainly concentrated in the arable layer of the contaminated agricultural soils at total concentrations ranging from 573 to 694 mg kg (-aEuro parts per thousand 1). Isotopic analyses (Pb-206/Pb-207) proved that Pb originated predominantly from the currently used pellets. Chemical fractionation analyses showed that Pb was mainly associated with the reducible fraction of the contaminated soil, which is in accordance with its predominant soil phases (PbO, PbCO3). The 0.05 M EDTA extraction showed that up to 62% of total Pb from the contaminated site is potentially mobilizable. Furthermore, Pb concentrations obtained from the synthetic precipitation leaching procedure extraction exceeded the regulatory limit set by the United States Environmental Protection Agency for drinking water. Ion exchange resin bags showed to be inefficient for determining the vertical distribution of free Pb2 + throughout the soil profile. Increased Pb concentrations were found in the biomass of spring barley (Hordeum vulgare L.) sampled at the studied site and two possible pathways of Pb uptake have been identified: (1) through passive diffusion-driven uptake by roots and (2) especially through atmospheric deposition, which was also proved by analyses of a bioindicator species (bryophyte Hypnum cupressiforme Hedw.). This study showed that shooting ranges can present an important source of Pb contamination of agricultural soils located in their close vicinity.