工矿企业产生的铬渣、含铬废水由于管理不善导致土壤铬污染严重，迫切需要寻求低成本铬污染土壤修复技术。提出腐解稻草中溶解性有机质（Dissolved Organic Matter， DOM）提取液洗脱铬污染土壤的技术，通过实验室模拟试验，以2种铬污染土壤（总铬含量为分别为121.54、941.90 mg/kg，六价铬含量分别为119.90、856.90 mg/kg）为研究目标，采用振荡淋洗法考察了固液比、淋洗时间、淋洗次数等因素对土壤中总铬、六价铬洗脱效果的影响，并探讨了淋洗前后铬形态变化及淋洗后土壤残留六价铬的持续钝化能力。研究结果表明：稻草经35 d腐解后的DOM提取液洗脱土壤中铬效果最佳，确定为最佳淋洗剂；固液比1：15、淋洗4h/次、淋洗2次为最佳淋洗工艺条件，该条件下，2种铬污染土壤总铬分别洗脱了47.79%、85.92%，六价铬含量分别削减了51.76%、95.09%；DOM提取液呈弱碱性，包含大量羧基、羟基及酚类物质，对水溶态、弱酸提取态和残渣态铬有较好的洗脱效果，有效降低了土壤环境风险，且能持续钝化淋洗后土壤中残余的六价铬。

Chromium slag and chromium-containing wastewater produced by some industrial and mining enterprises in our country often cause serious chromium pollution in soil due to poor management. It is urgent to seek low-cost remediation technology for chromium-contaminated soil. A technology for eluting chromium-contaminated soil with an extract of Dissolved Organic Matter (DOM) in decomposing rice straw was proposed. Through laboratory simulation tests, two types of chromium contaminated soil (the total chromium content is 121.54 mg/kg and 941.90 mg/kg respectively, and the hexavalent chromium is 119.90 mg/kg and 856.90 mg/kg respectively) as the research goals. The effect of solid-liquid ratio, leaching time, leaching times and other factors on the elution effect of total chromium and hexavalent chromium in the soil was investigated by the oscillation leaching method. The chromium form changes before and after leaching and the continuous passivation ability of hexavalent chromium remaining in the soil after leaching were also discussed. The results showed that DOM extract from rice straw decomposed for 35 days had the best effect of eluting chromium in soil and was determined as the best eluent. The solid-liquid ratio is 1:15, leaching for 4 h/ time, and leaching for 2 times is the best leaching process condition. Under this condition, the total chromium content in soil is eluted by 47.79% and 85.92%, and the hexavalent chromium content is reduced by 51.76% and 95.09%, respectively. DOM extract is weakly alkaline and contains a large number of carboxyl, hydroxyl and phenolic substances. It has good elution effect on chromium in water soluble, weak acid extracted and residue state, effectively reduces the environmental risk of soil, and can continuously passivate the residual hexavalent chromium in the leached soil.

中国石油化工股份有限公司科技计划项目（319005-7）；江苏省科技支撑计划项目（BE2016653）