我国规模化养猪场粪便重金属污染特征与农用风险评价

系统收集了我国21省市规模化养猪场粪便和11省市猪饲料重金属浓度数据,分析了其污染特征,同时对各省市猪粪总量及其重金属总含量、猪粪安全农用年限进行了估算。结果表明:在21省市中,猪粪中Cu、Zn、As、Cd、Cr平均含量超标省市分别占到95.2%、85.7%、33.3%、20%和5.26%。在其中有猪饲料数据的11省市中,猪饲料Cu含量超标的样品数量占到100%(四川除外,为75%),超标倍数在13.2~49.0之间;猪饲料Zn含量超标的样品数量占到60.0%~100%,超标倍数在1.3~9.5之间。猪粪和饲料间Cu、Zn达到极显著相关水平(p0.01)。猪粪安全农用估算结果表明,限制我国规模化养殖场猪粪农用的主要因素是Cu、Zn和Cd。吉林省、辽宁省和山东省分别连续施用猪粪16、23、91 a,土壤中Cd含量超过国家土壤质量二级标准(GB 15618—2008)。北京连续施用猪粪65、51 a而天津连续施用猪粪53、91 a,土壤Cu和Zn含量分别超过国家土壤环境质量二级标准。建议在生猪养殖及其粪便农用过程中,不仅要从源头严格控制饲料中Cu、Zn等微量元素添加量,还应按照标准严格控制猪粪农田施用量。

Characteristics of Heavy Metals Pollution in Pig Manures and Environmental Risks Evaluation in Intensive Pig Farming Areas in China

Information about the concentrations of heavy metals in pig manure from large-scale pig farms was collected from 21 provinces and cities in China, and information about the concentrations of heavy metals in pig feeds was collected from 11 provinces and cities. The data were analyzed systematically to evaluate the total amount of pig manure and heavy metals produced in each province. The period over which the pig manure could safely be applied to agricultural land was assessed by calculating the total amount of heavy metals found in the manure produced and the total land available for application in each province and city. The results indicated that in the 21 provinces and cities, 20 of them had pig manure samples that were over the recommended concentration limit for Cu, 18 of them were over the limit for Zn, six of them were over the limit for As, four of them were over the limit for Cd and one of them was over the limit for Cr. Moreover, in 10 provinces 100% of the pig feed samples were over the national standard for Cu (13.2~49.0 times of the standard) and in one province 75% were over the standard. On average, for Zn concentrations the pig feeds were 1.3~9.5 times of the national standard. There were significant positive correlations for Cu and Zn between pig manures and feeds (p<0.01). The main limitations to the land application of the pig manure were due to the amounts of Cu, Zn and Cd. For example, in Jilin, Liaoning and Shandong Provinces, the concentrations of Cd in soils would exceed the environmental quality standards for soils after 16, 23 and 91 years, respectively, if the manure was applied to land in these provinces at the current rate. Additionally, the concentrations of Cu and Zn in soils in Beijing would exceed the standards in 65 and 51 years, respectively, while in Tianjin the soil standards for Cu and Zn would be exceeded in 53 and 91 years, respectively. This analysis suggested that it was important to control the rates of pig manure application in agriculture and reduce the amounts of Cu and Zn in pig feeds.