黄河流域许多地区由于规划不科学、环保措施不足、监管不严等原因，工业场地往往与农田直接镶嵌，极易造成周边土壤重金属污染。为高效快速低成本修复工业场地周边大范围农田土壤镉污染，选择河南省新乡市凤泉区大块镇工业聚集区周边受污染农田开展大田修复实验，利用2种速生植物3连茬种植(即小白菜-黑麦菜-小白菜)联合2种生物炭(即杨树皮生物炭(PBC)和硫脲改性杨树皮生物炭(TPBC))原位修复土壤镉污染，测定连茬种植下土壤镉的浸出特性及其化学赋存形态，评估2茬小白菜食用健康风险，并揭示生物炭+速生植物联合修复土壤镉污染的潜力。结果表明:① 添加2%杨树皮生物炭(PBC)和2%硫脲改性杨树皮生物炭(TPBC)在60 d后土壤镉浸出量低于《地表水环境质量标准》(GB3838—2002)规定的III级标准，添加1%TPBC在90 d后土壤镉浸出量低于III级标准。② 连茬第3季修复实验后，与CK比，施用1%和2%TPBC的土壤残渣态镉分别增加了71.73%和75.75%;弱酸溶态镉分别下降了130.86%和160.62%。添加1%和2%PBC的土壤残渣态镉分别增加了45.82%和50.07%。弱酸溶态镉分别下降了56.34%和109.27%。联合修复可使弱酸溶态镉和可还原态镉向可氧化态镉和残渣态镉转化，有效降低镉的生物可利用性。③ 联合修复可在90 d内将小白菜的食用健康风险降至人体可接受的阈值。由此认为，生物炭+速生植物联合可减少土壤镉浸出量，有效降低镉的生物可利用性，减少镉在小白菜中的转运。“生物炭+速生植物”修复技术克服了原位修复土壤镉污染低效耗时难题，为大范围高效快速低成本原位修复工业场地土壤污染提供了技术支撑。

Due to unscientific planning,insufficient environmental protection,lax supervision and other reasons,some farmland might be easily polluted with heavy metals in most parts of the Yellow River Basin,where the farmland is always directly embedded with industrial sites.In order to explore an efficiently,and cost-effectively remedy for large-scale Cd-contaminated farmland soil around the industrial site,some in-situ remediation experiments were carried out in the Cd contaminated farmland around the industrial agglomeration area of Dakuai Town,Fengquan District,Xinxiang City,Henan Province.Two fast-growing plants,which were planted continuously (Chinese cabbage-rye vegetable-Chinese cabbage),and 2 kinds of biochar (poplar bark Biochar (PBC),and thiourea-modified poplar bark biochar (TPBC)) were used in the field experiment.The leaching characteristics of soil Cd and the chemical occurrence form under continuous planting were measured.Moreover,the health risks of Chinese cabbage were assessed,the potential capacity of repairing Cd polluted soil,with the remediation mode of biochar plus fast-growing plants,was also revealed.The results showed that:① after 60 days,the leaching concentration of soil Cd when adding 2% PBC and 2% TPBC was lower than the level III standard specified in “Environmental Quality Standard for Surface Water”(GB3838—2002).The soil Cd leaching content with the addition of 1% TPBC after 90 days was lower than the level III standard.② Compared with CK,the 1% and 2% TPBC increased the residual cadmium by 71.73% and 75.75%,and decreased the acid-soluble cadmium by 130.86% and 160.62%,respectively.The 1% and 2% PBC increased the residual cadmium by 45.82% and 50.07%,respectively.The content of acid-soluble cadmium decreased by 56.34% and 109.27%,respectively.The combined remediation could effectively reduce the bioavailability of Cd,through transforming weakly acid-soluble cadmium and reducible cadmium,to oxidizable cadmium and residual cadmium.③ Joint remediation can also reduce the edible health risk of pakchoi to the threshold within 90 days,which was acceptable to the human body.In a word,the combination of biochar and fast-growing plants can reduce the leaching concentration of cadmium in soil,effectively reduce the bioavailability of cadmium,and reduce the transport of cadmium in Chinese cabbage.The remediation technology using “biochar+fast-growing plant” successfully overcomes the difficulties of inefficient and time-consuming in-situ remediation of soil Cd pollution.This technology also provides technical support for the efficient,and low-cost in-situ remediation of large-scale contaminated soil in industrial sites.

1 材料与方法

   1.1 研究区概况

   1.2 生物炭制备

   1.3 实验设计与样品分析

   1.4 镉生物富集系数估算

   1.5 健康风险评价估算

   1.6 数据统计与分析

2 结果与分析

   2.1 不同处理对土壤镉浸出量的影响

   2.2 不同处理对土壤镉化学组成的影响

   2.3 植物的重金属积累和转移系数

   2.4 健康风险评价

   2.5 土壤-植物中镉浓度之间的相关关系

3 讨论

4 结论