生物炭和石灰石对大冶市农田土壤镉的原位钝化修复

发布时间：2019-03-27 12:31

【摘要】：重金属污染问题已经引起了社会的广泛关注,农田重金属污染与粮食安全、人类健康密切相关。本实验选取湖北大冶市王祠村某镉污染农田进行重金属原位钝化修复实验,该地区由于地处矿区,土壤中镉浓度为2.84 mg kg-1,已达到重度污染标准。实验采用小区实验,向土壤中施加不同配比的生物炭及石灰石,以生菜为供试植株,进行两年实验。通过对施加修复材料后土壤pH值,土壤有机质,植物镉含量,土壤各形态镉分布变化的测定及分析,评价生物炭和石灰石配合施用的修复效果及效果的持续性。研究结果主要如下:1.土壤pH值增加0.42~1.40个单位,土壤离子交换态镉降低4.64%~36.81%。土壤残渣态镉升高了27.88%~58.02%,升高的大小顺序为对照㩳生物炭㩳石灰石㩳生物炭+石灰石,生物炭石灰石混施处理中土壤有机质含量增加了3.75%~10.66%。生菜叶片中的镉含量降低了25.30%~53.46%,最低下降到0.35 mg kg-1,生菜根系中镉含量下降了20.86%~61.00%,降低的大小顺序为对照㩳生物炭㩳石灰石㩳生物炭+石灰石。2.单施生物炭和石灰石的处理提高土壤pH值的效果能持续一年时间,生物炭石灰石混施处理提高土壤pH值的效果能维持两年时间。单施生物炭和石灰石的处理降低土壤有效态Cd含量的效果能维持一年时间,混施处理降低土壤有效态镉含量的效果能维持两年时间。综上所述,单施生物炭、石灰石以及生物炭石灰石的混合施用均能改善土壤的理化性质,降低土壤中Cd的生物有效性,减少生菜根部和叶片中的Cd含量,其中生物炭和石灰石混施修复效果最好,且修复效果能持续1~2年。本研究为农田土壤重金属Cd的修复提供了相应依据。
[Abstract]:Heavy metal pollution has caused widespread concern in society. Heavy metal pollution in farmland is closely related to food security and human health. In this experiment, a cadmium-contaminated farmland in Wangci village, Daye City, Hubei Province, was selected for in-situ passivation remediation of heavy metals. Due to its location in the mining area, the concentration of cadmium in the soil was 2.84 mg kg-1, which had reached the standard of severe pollution. The plot experiment was carried out by applying different proportion of biochar and limestone to the soil. Lettuce was used as the test plant for two years. Through the determination and analysis of soil pH value, soil organic matter, plant cadmium content and the distribution of cadmium in various forms of soil after the application of remediation materials, the remediation effect and sustainability of combined application of biochar and limestone were evaluated. The main findings of the study are as follows: 1. The pH value of soil increased by 0.42 ~ 1.40 units, and the cadmium ion exchange state decreased by 4.64% and 36.81%, respectively. Soil residual cadmium increased by 27.88% ~ 58.02%, and the order of increase was in the order of control. Biochar? limestone? The content of soil organic matter increased by 3.75% ~ 10.66% in the treatment of biocarbon limestone and biocarbon limestone mixed application. The cadmium content in lettuce leaves decreased by 25.30% and 53.46%, the lowest decreased to 0.35 mg kg-1, the cadmium content in lettuce root decreased by 20.86% and 61.00%, and the order of the decrease was in the order of control. Biochar? limestone? Biochar limestone. 2. The effect of increasing soil pH value by biochar and limestone alone could last for one year, and the effect of biocarbon limestone mixed application could last two years. The effect of using biochar and limestone alone to reduce the available Cd content in soil could be maintained for one year, and the effect of mixed application on reducing available cadmium content in soil could be maintained for two years. In conclusion, the combined application of biochar, limestone and biocharcoal limestone can improve the physical and chemical properties of soil, decrease the bioavailability of Cd in soil, and reduce the content of Cd in roots and leaves of lettuce. The combined application of biochar and limestone was the best, and the repair effect lasted for 1 ~ 2 years. This study provided the basis for the remediation of heavy metal Cd in farmland soil.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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