摘要
为了研究蚯蚓堆肥过程中重金属的迁移转化特征,利用不同质量的牛粪(350～400g)、秸秆(150～200g)和过磷酸钙(25～75g)混合配比成6组基质,探索分析添加蚯蚓(50～150g)堆肥过程中基质重金属(Cu、V、Mn、As、Zn和Cr)总量和形态的变化特征及其影响因素.结果表明:与添加蚯蚓质量为50g与100g相比,添加蚯蚓质量为150g时,Cu(总量27.00mg/kg,可氧化态22.03mg/kg)、Zn(总量288.89mg/kg,可还原态22.03mg/kg)、V(总量15.22mg/kg,残渣态8.87mg/kg)和Cr(总量26.79mg/kg)是显著较低的(P＜0.05);4周的蚯蚓堆肥降低了 Mn、As的总量和Cu、V的生物有效性,但增加了 Cu、V、Zn的总量和Mn、Zn的生物有效性;基质pH值和有机质含量是影响堆肥过程中重金属总量及其形态明显变化的关键因素;基于潜在风险指数和风险评价编码法发现基质还田对土壤重金属污染的潜在风险较小.
Abstract
In order to study the transport and transformation characteristics of heavy metals(HMs)during the process of earthworm composting,six groups of composting substrates were prepared by combining different proportions of cow manure(350～400g),straw(150～200g),and calcium superphosphate(25～75g),followed by addition of earthworms with different masses(50～150g).Changes in the total contents and occurrence forms of HMs(Cu,V,Mn,As,Zn,and Cr)in the substrate were investigated.In comparison to the treatment groups with addition of 50g and 100g earthworm,significantly lower contents(P＜0.05)were observed for the group with 150g earthworm addition in terms of total Cu(27.00mg/kg),oxidizable Cu(22.03mg/kg),total Zn(288.89mg/kg),reducible Zn(22.03mg/kg),total V(5.22mg/kg),residual V(8.87mg/kg)and total Cr(26.79mg/kg),respectively.Four weeks of earthworm composting increased the contents of total Cu,total V,total Zn,and the bioavailability of Mn and Zn,but decreased the contents of total Mn,total As and the bioavailability of Cu and V.Both the pH and organic matter content in the substrate were identified to be the key factors influencing the observed changes in the total amount and occurrence forms of HMs during the composting process.Based on the assessment of potential risk index and risk assessment coding,it is suggested that the risk of soil contamination by HMs induced by compost amendment is relatively small.
维普
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