模拟酸雨对施用猪粪的菜园土壤重金属有效性的影响

采用室内培养方法，研究了酸雨对施用富含重金属的猪粪后菜园土壤重金属有效态含量的影响。结果表明，酸雨可显著降低菜园土壤pH值，但有机肥处理对酸雨有一定的缓冲作用。土壤Cu，Zn，Cd和Pb的有效态含量均随酸雨处理H⁺浓度的提高而有不同程度的增加，有效态As含量则随H⁺浓度的提高而降低，添加猪粪处理（M）与无机重金属处理（HM）的重金属有效态含量没有明显的差异，但含量均高于对照（CK）。可见，除了As外，源于有机肥的重金属与无机重金属的有效性同样受到酸雨的促进作用，具有一定的环境风险。因此，在酸沉降频繁的南方地区，长期大量施用富含重金属的猪粪在改善菜园土壤养分状况的同时也增加了土壤环境和蔬菜的重金属污染的风险。

Effect of simulated acid rain on the bioavailability of heavy metals from the vegetable soil amended with swine manure

Incubation experiment was employed to study the effects of simulated acid rain on availability concentrations of heavy metals from the vegetable soils amended with metal-rich swine manure. The results indicated that the acid rain affected the availability concentrations of heavy metals by decreasing the pH of soil. The available concentrations of Zn,Cd, Pb increased with the increasing of H~+ concentration,whereas the opposite trend was observed for As. Furthermore, vegetable soil amended with metal-enriched swine manure as well as the inorganic heavy metals,would result in significantly higher available concentrations of Cu ,Zn, and As. Therefore, the bioavailability of heavy metals from vegetable soil amended with either the manure or the inorganic heavy metal,would be affected by acid rain and exhibit potential risks to environment. As a result,long-term heavy application of metal-rich swine manures to vegetable soils in the southern areas subjected to frequent acid rain deposition would not only improve the nutrient conditions of vegetable soil,but also increase a potential risk of heavy metal contamination to soil environment and vegetables.