钝化材料对猪粪堆肥过程中重金属（Cu、Zn）形态转化的影响及其植物毒性分析

采用三级四步连续提取法（BCR）研究生物质炭、VT-1000菌剂2种钝化材料对猪粪堆肥过程中重金属Cu、Zn含量和形态的影响,并探讨其对植物种子的毒性。结果表明：堆肥处理后,猪粪中的重金属Cu、Zn总量会出现“相对浓缩效应”,致使其浓度升高;堆肥处理能促使重金属Zn的形态向活性降低的方向转化,从而降低其生物有效性;生物质炭对猪粪堆肥处理后重金属Cu、Zn的钝化效果较好,对弱酸提取态Cu、Zn的钝化效果分别为27.23%、73.46%;经2种钝化材料处理后的猪粪堆肥对种子的发芽率、根长、发芽指数均无显著影响（P>0.05）,说明经过堆肥处理的猪粪已充分腐熟且对种子的萌发无抑制作用。研究结果提示,生物质炭是理想的降低猪粪中Cu、Zn生物有效性的钝化材料,且有利于降低猪粪堆肥土地利用中重金属污染风险。

Effect of Passivation Materials on Form Transformation of Heavy Metals (Cu,Zn) During Pig Manure Composting and Assessment of Their Phytotoxicity

The effect of two heavy metal passivators （biochar and VT-1000 microorganisms agent） on concentrations and forms of heavy metals （Cu and Zn） during pig manure composting was studied by BCR sequential extraction method. Furthermore, the phytotoxicity of the compost treated with the two heavy metal passivators was evaluated. The results showed that after composting, the total concentrations of Cu and Zn in pig manure exhibited a ′relative concentration effect′, resulting in an increase in their concentrations. Composting treatment promoted the transformation of Zn from high-activity form to low one, thereby reducing its bioavailability. Biochar had better passivation effect on Cu and Zn after composting, and its passivation rate on acid extractable fraction of Cu and Zn was 27.23% and 73.46%, respectively. The composted pig manure treated with the two passivation materials had no significant （P>0.05） effect on germination rate, root length and germination index of the seeds. It was indicated that the pig manure treated by composting was fully decomposed and had no inhibitory effect on seed germination. The combined data suggest that biochar is an ideal passivation material for reducing the bioavailability of Cu and Zn in pig manure, and it is conductive to reduce the risk of heavy metal pollution in land fertilized with pig manure compost.