[Application of ICP-MS to species determination of Pb, As and Cd in hoggery waste]

Distribution of heavy metal species in animal wastes needs to be monitored to control the heavy metal pollution during the utilization of wastes. Here, ICP-MS was applied to determine the speciation of Pb, As and Cd in the wastes from two hoggeries in the suburb of Beijing. The air-dried and finely ground samples were digested by HNO3-HClO4, or, sequentially extracted with BCR procedure before content determination of heavy metals. The total concentrations of Pb, As and Cd were 29.0, 28.2 and 0.288 mg x kg(-1) dry weight (DW) in the fresh hoggery wastes respectively, and 19.7, 28.2 and 0.134 mg x kg(-1) DW in the dry-cleaning waste, respectively. The concentrations of the three metals in both fresh and dry-cleaning wastes were all lower than the control standards for urban wastes for agricultural use promulgated by the national government, although As was close to the control value. Over 50% of Pb, As and Cd in the fresh waste were exchangeable/carbonate species, and less than 20% were organic/sulphide. However, species distributions of the heavy metals changed markedly after the process of dry-cleaning. The fraction of highly ecotoxic species (exchangeable/carbonate bound and Fe/Mn oxide bound) in the dry-cleaning waste decreases by 5%-25% for the three metals, indicating reduced risks of heavy metal pollutions when dry-cleaning wastes are applied to farmlands. This study contributes basic data for the resource utilization and ecological security assessment of hoggery wastes from Beijing.