Isotope analysis of lead pollution sources in wheat kernel

To identify and apportion the contributions of lead pollution sources in wheat kernel, the surrounding area of a lead-zinc smelter in northwestern China was taken as the study area, local atmospheric deposits, tilled soils (0-20 cm), and the corresponding wheat samples were collected and then lead concentrations and isotope ratios was analyzed by ICP-MS . The spatial distribution of atmospheric lead settlement fluxes as well as lead concentrations in soil and wheat kernel were predicted by Ordinary Krigging methods. The contributions of lead pollution sources to wheat kernel were calculated with a linear mixing model. The results showed that lead concentrations in tilled soil ranged from 21.8 to 40.0 mg/kg, and the average level (27.1 mg/kg) was higher than background value (21.4 mg/kg) of local soil samples, which indicated that the soil in local area was polluted slightly. The lead concentrations of wheat kernel in the canyon ranged 0.269-0.768 mg/kg, of which the average level was 0.430 mg/kg, and 100% of the wheat samples exceeded the maximum level in GB2762-2005. The contributions of atmospheric deposits and tilled soil to lead concentrations in wheat kernel were 90%-99% and 1%-10%, respectively. The paper provided scientific basis for making policy on heavy metal contamination control and food safety production system.