ABSTRACT

Accumulating heavy metal contamination in soils caused by industrial waste, fertilizer, and wastewater irrigation is a matter of grave concern for the environment and food safety. In recent years, remediation agents with the characteristics of economy, high efficiency, and simple operation have become a popular choice for remediation of heavy metal contaminated soil. By far, there are relatively few studies evaluating the effects on remediation agents for their both heavy metal passivation and soil fertility promotion. This study investigated the effects of a remediation agent on Cd passivation, soil pH, and heavy metal uptake by rice crops. Eight treatments were used to evaluate the effect of Cd immobilization in soil. Changes in soil pH and soil Cd fractions were monitored during incubation for 30 days. The field study was conducted during the whole growth stages of rice crops, samples of rice plants and soil at the tillering, booting, and harvesting stages were collected and tested. Cd fractions were extracted from soil at different stages to investigate the effects of various treatments on Cd uptake and bioaccumulation in rice plants. The results show that composite mineral remediation agents composed of mineral fertilizer and synthetic zeolite could effectively improve the pH of soil in incubation experiments and field experiments. Composite mineral remediation agents were effective in stabilizing Cd and increasing rice yield. Mineral fertilizer and Synthetic zeolite played an important role in the tillering stage and harvesting stage of rice growth in field, respectively. Group A4 (mineral fertilizer: synthetic zeolite at mass ration of 10:6) had the best results. Compared with control experiment (CK), HOAc extractable Cd of A4 group decreased by 6%, oxidizable Cd of A4 group increased by 2%, and the residue Cd of A4 group increased by 4%.

摘要

由工业废物、化肥和废水灌溉引起的土壤重金属污染累积是环境和食品安全严重关注的问题。近年来，具有经济、高效、操作简单等特点的修复剂已成为重金属污染土壤修复的热门选择。到目前为止，评估修复剂对重金属钝化和土壤肥力促进作用的研究相对较少。本研究调查了修复剂对水稻作物镉钝化、土壤 pH 值和重金属吸收的影响。八种处理用于评估土壤中 Cd 的固定效果。在孵化 30 天期间监测土壤 pH 值和土壤 Cd 组分的变化。在水稻作物的整个生长阶段进行了田间研究，收集并测试了分蘖、孕穗和收获阶段的水稻植物和土壤样品。从不同阶段的土壤中提取 Cd 组分，研究不同处理对水稻 Cd 吸收和生物积累的影响。结果表明，在孵化试验和田间试验中，矿物肥料和合成沸石组成的复合矿物修复剂能有效改善土壤的pH值。复合矿物修复剂对稳定镉和提高水稻产量有效。矿物肥料和合成沸石分别在水稻田间生长的分蘖期和收获期发挥了重要作用。A4 组（矿物肥料：质量比为 10 的合成沸石：6）取得了最好的成绩。与对照实验（CK）相比，A4组HOAc可萃取Cd降低6%，A4组可氧化Cd增加2%，A4组残留Cd增加4%。