物炭配施微肥对菜园土壤有效态重金属含量的影响

汪亚会 , 覃雨虹 , 马彦蓉 , 尚怡静 , 黎华寿 , 陈桂葵     

摘要：【目的】 研究生物炭配施微肥对土壤有效态重金属含量的影响。【方法】 采用室内模拟试验，向重金属污染的菜园土壤中添加皇竹草生物炭、咖啡渣生物炭、花生壳生物炭和微肥(铁肥、锰肥和硅肥)，分别在处理14和28 d时测定土壤中5种重金属(Cu、Pb、Zn、Cd和Ni)的有效态含量。【结果】 添加了生物炭或微肥土壤中的有效态重金属含量均比对照组低。其中单一钝化剂处理中，皇竹草生物炭和硅肥的钝化效果较好。在复配试验中，皇竹草生物炭+铁肥对土壤重金属Cu、Pb和Cd的钝化效果较好，处理14 d后其有效态含量的降幅分别达32.94%、31.26%和21.21%，对土壤有效态Zn含量的降幅为6.82%，但对土壤Ni的钝化效果不明显；处理14 d后咖啡渣生物炭+铁肥对土壤重金属Ni和Zn有效态含量的降幅也分别达22.64%和10.35%，钝化效果显著；处理28 d后，花生壳生物炭+铁肥对土壤重金属Cu钝化效果最好，有效态Cu含量降幅达49.06%；咖啡渣生物炭+硅肥对土壤Ni和Zn钝化效果最好，有效态含量降幅分别达23.73%和9.72%。【结论】 生物炭配施微肥对土壤有效态重金属含量降低的效果优于单施生物炭或单施微肥，其中，皇竹草生物炭配施铁肥可用于土壤重金属Cu、Pb、Zn和Cd复合污染的钝化。

关键词：生物炭    微肥    菜园土壤    有效态重金属    钝化    

Influence of biochar combining with micro-fertilizer on available heavy metal content in vegetable garden soil

WANG Yahui , QIN Yuhong , MA Yanrong , SHANG Yijing , LI Huashou , CHEN Guikui     

Abstract: 【Objective】 To examine the effect of biochar combining with micro-fertilizer on soil available heavy metal content.【Method】 Indoor simulation experiment was conducted. Pennisetum hydridum biochar, coffee grounds biochar, peanut shell biochar and micro-fertilizer (iron fertilizer, manganese fertilizer and silicon fertilizer) were added to the vegetable garden soils polluted by heavy metals, and the contents of available Cu, Pb, Zn, Cd and Ni were determined on the 14th and 28th days. 【Result】 The available heavy metal contents in soils added with biochar or micro-fertilizer were lower than that of the control group. In single passivator treatments, P. hydridum biochar and silicon fertilizer had better heavy metal immobilization effects. In the blended passivator treatments, P. hydridum biochar combining with iron fertilizer had better Cu, Pb and Cd immobilization effects, the contents of available Cu, Pb, and Cd decreased by 32.94%, 31.26% and 21.21% respectively on the 14th day. The content of available Zn decreased by 6.82%, and the immobilization effect on Ni was not obvious. When coffee grounds biochar was added with iron fertilizer, the contents of available Ni and Zn decreased by 22.64% and 10.35% respectively on the 14th day. The immobilization effects were remarkable. On the 28th day, peanut shell biochar combining with iron fertilizer showed the best immobilization effect on Cu, the content of available Cu decreased by 49.06%. Coffee grounds biochar combining with silicon fertilizer had the best immobilization effect on Ni and Zn, the contents of available Ni and Zn decreased by 23.73% and 9.72% respectively. 【Conclusion】 The reduction effects of biochar combining with micro-fertilizer on available heavy metal content in soil are better than that of single biochar or micro-fertilizer. P. hydridum biochar combining with iron fertilizer can be used to immobilize combined heavy metal pollution of Cu, Pb, Zn and Cd in soil.

Key words: biochar    micro-fertilizer    vegetable soil    available heavy metal    deactivation    

农药、化肥的不合理施用和长期污灌等已造成菜地土壤重金属污染。根据资料显示，我国接近 2 000万hm² 的耕地面积已惨遭重金属污染^[1]，其中珠江三角洲附近的菜地土壤重金属污染尤为严重^[2-3]。调查数据显示，目前广东省近40%的菜地土壤已受不同重金属的污染，主要是Cd和Pb污染，10%属严重超标^[4]。因此，加强广东省菜地土壤重金属污染的防控已迫在眉睫。

大量研究表明，蔬菜体内的重金属含量与土壤中的重金属有效态含量成正相关^[5-7]，降低土壤中重金属有效态含量则可减少植物吸收重金属，因此，降低菜地土壤重金属的有效态含量是缓解当前菜地土壤重金属污染的最直接途径之一。有研究表明，向污染的土壤中添加生物炭，可降低土壤重金属的有效态含量，从而降低重金属的生物有效性