Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China.
Int J Environ Res Public Health. 2019 Feb 11;16(3):498. doi: 10.3390/ijerph16030498.
Cadmium (Cd) in paddy soil is one of the most harmful potentially toxic elements threatening human health. In order to study the effect of lime combined with intermittent and flooding conditions on the soil pH, Cd availability and its accumulation in tissues at the tillering, filling and maturity stages of rice, as well as enzyme activity and the microbial community in contaminated soil, a field experiment was conducted. The results showed that liming under flooding conditions is a more suitable strategy for in situ remediation of Cd-contaminated paddy soil than intermittent conditions. The availability of Cd in soils was closely related to the duration of flooding. Liming was an effective way at reducing available Cd in flooding soil because it promotes the transformation of Cd in soil from acid-extractable to reducible fraction or residual fraction during the reproductive growth period of rice. Compared with control, after liming, the concentration of Cd in brown rice was reduced by 34.9% under intermittent condition while reduced by 55.8% under flooding condition. Meanwhile, phosphatase, urease, and invertase activities in soil increased by 116.7%, 61.4% and 28.8%, and 41.3%, 46.5% and 20.8%, respectively. The high urease activity in tested soils could be used to assess soil recovery with liming for the remediation of contaminated soil. Soil microbial diversity was determined by the activities of soil acid phosphatase, urease and available Cd by redundancy analysis (RDA). The results indicated that the problem of Cd-contaminated paddy soil could achieve risk control of agricultural planting by chemical treatment such as lime, combined with various water regimes.
镉（Cd）是威胁人类健康的最有害的潜在有毒元素之一，存在于稻田土壤中。为了研究石灰与间歇性淹水条件相结合对土壤 pH 值、Cd 有效性及其在水稻分蘖、灌浆和成熟阶段组织中的积累、污染土壤中酶活性和微生物群落的影响，进行了田间试验。结果表明，淹水条件下的石灰处理比间歇性条件更适合原位修复 Cd 污染稻田。土壤中 Cd 的有效性与淹水时间密切相关。石灰处理是减少淹水土壤中有效 Cd 的有效方法，因为它在水稻生殖生长期促进土壤中 Cd 从酸可提取态向可还原态或残渣态转化。与对照相比，石灰处理后，在间歇性淹水条件下，糙米中 Cd 浓度降低了 34.9%，而在淹水条件下降低了 55.8%。同时，土壤中磷酸酶、脲酶和转化酶的活性分别增加了 116.7%、61.4%和 28.8%，41.3%、46.5%和 20.8%。土壤中高脲酶活性可用于评估石灰处理污染土壤修复后的土壤恢复情况。冗余分析（RDA）表明，通过化学处理（如石灰）与各种水管理相结合，可以控制 Cd 污染稻田的风险。
