| 复合淋洗条件下农用地耕作层土壤去镉效率及其功能调节 |
| 摘要点击 1958 全文点击 596 投稿时间：2021-06-10 修订日期：2021-07-10 |
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| 中文关键词 复合淋洗 重金属 土壤健康 迁移转化 生物质炭 |
| 英文关键词 composite leaching heavy metals health of soil migration and transformation biochar |
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| 中文摘要 |
| 为探究中（重）度重金属元素镉（Cd）污染农用地土壤淋洗修复的可行性，采用土柱模拟原位淋洗的方法，选择柠檬酸（CA）+氯化铁（FeCl3）复合淋洗剂，在最佳浓度组合及淋洗剂添加量下，探究Cd在耕作层及其以下剖面层的分布特征，同时考察淋洗过程对土壤健康质量的影响及生物质炭的调节效果.结果表明：①0.1 mol·L-1 CA与0.01mol·L-1 FeCl3是最佳浓度组合，此浓度组合下，当淋洗剂添加量为9孔隙体积时，淋洗后20 cm土柱中Cd含量低于供试土壤相应pH值的风险筛选值0.4 mg·kg-1（GB 15618-2018）.②最佳淋洗条件下，60 cm土柱中Cd的纵向分布结果表明，淋洗后随土层深度增加总Cd含量依次递增，且土柱淋出液中含有一定量Cd，淋洗过程促进了Cd向下迁移.复合淋洗后土壤有效态Cd含量也随土层深度的增加而增加，这部分归因于不同土层可交换态及碳酸盐结合态Cd含量的变化.③CA+FeCl3复合淋洗可导致土壤部分健康指标及酶活性降低.生物质炭添加可改善淋洗后土壤的健康状况，使土壤健康指标及酶活性显著性恢复，亦可降低Cd二次活化的风险.结果表明，CA+FeCl3复合淋洗能够将土壤中部分Cd淋洗到耕作层以下，但淋洗过程可能对土壤健康产生一定的影响，生物质炭对淋洗后土壤恢复性调节效果显著. |
| 英文摘要 |
| In order to explore the feasibility of soil leaching and the remediation of agricultural land polluted by medium (heavy) cadmium (Cd), the soil column was used to simulate in-situ leaching, and the citric acid (CA)+ferric chloride (FeCl3) composite leaching agent was selected. Under the optimal concentration combination and the addition amount of the composite leaching agent, the distribution characteristics of Cd in the plow-layer soil and below were investigated. The influence of the leaching process on soil health and the regulation effect of biochar were also investigated. The results showed that:① 0.1 mol·L-1 CA and 0.01 mol·L-1 FeCl3 were the best concentration combinations; under this concentration combination, when the eluent reached 9 pore volume, the content of Cd in the 20 cm soil column was lower than the risk screening value of 0.4 mg·kg-1 (GB 15618-2018) in the corresponding pH value of the tested soil after leaching. ② Under the optimal leaching conditions, the longitudinal distribution of Cd in the 60 cm soil column showed that the content of total Cd increased with the increase in soil depth after leaching, and the leachate of the soil column contained a certain amount of Cd, indicating that the leaching process promoted the downward migration of Cd. The content of available Cd in the soil after composite leaching also increased with the increase in soil depth, which was partly due to the change in exchangeable and carbonate-bound Cd in different soil layers. ③ A portion of the soil health indexes and enzyme activities decreased after CA+FeCl3 composite leaching. The addition of biochar can improve the health status of the soil after leaching; the soil health indexes and enzyme activities were restored significantly, and the risk of Cd reactivation also decreased after the addition of biochar. The results showed that part of Cd in the soil can be leached below the plow layer by CA+FeCl3 composite leaching; however, the leaching process may have a certain impact on soil health, and biochar has a significant effect on the recovery of soil after leaching. |
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