应用ICP-MS分析猪污物中铅砷镉的形态分布

为有效控制资源化过程中畜禽污物所含重金属对环境和人类健康的危害，需要监测污物中重金属的赋存形态和浓度。采集北京昌平种猪场的猪污物样品(鲜样和干清样)，用BCR提取法、硝酸-高氯酸消化法和ICP-MS仪器检测铅砷镉(Pb，As，Cd)总量及各形态含量。结果表明，猪污物中Pb，As，Cd的总量分别为29.0，28.2和0.288 mg·kg-1 DW(鲜样)以及19.7，28.2 和0.134 mg·kg-1 DW(干清样)，均没有超过我国的城镇垃圾农用控制标准(As接近标准值)。两类样品中重金属的形态分布规律明显不同：鲜样中三种金属可交换态及碳酸盐结合态均超过50%，有机物及硫化物结合态则低于20%;而干清样中高生态毒性的可交换态及碳酸盐结合态和Fe/Mn氧化物结合态的比例较鲜样中都明显降低(降幅可达20%以上)，表明干清样用于堆肥对农田更安全。该研究结果将为北京地区养猪场污物的资源开发和生态安全评价提供重要基础数据。

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·kg-1 dry weight (DW) in the fresh hoggery wastes respectively, and 19.7, 28.2 and 0.134 mg·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.