贝壳粉对农田土壤镉污染钝化修复效应

Effect of shell powder on immobilization remediation of cadmium contaminated farmland soil

通过静态培养试验和盆栽试验,研究了贝壳粉对Cd污染农田土壤的修复效应及其对土壤质量的影响。结果表明:静态培养试验中,随贝壳粉施加量的增加,土壤pH上升,而土壤有机质、速效氮、速效磷和速效钾含量则降低。贝壳粉对土壤中TCLP-Cd的钝化率最高达64.13%,各处理较对照差异显著(P<0.05)。施加贝壳粉后土壤过氧化氢酶、过氧化物酶、脲酶活性增幅最高分别达到64.31%、30.26%、17.08%。盆栽试验中,施用贝壳粉可以使土壤中重金属Cd由水溶态和还原态向氧化态和残渣态转化。贝壳粉处理使油菜叶片叶绿素含量提高,但对植物鲜质量没有显著影响(P>0.05),油菜地上部Cd含量较对照下降了3.13%~26.71%,地下部Cd含量较对照下降了12.22%~31.49%。当贝壳粉投加量达到1%时,油菜可食部分Cd含量符合国家食品中污染物限量标准(GB 2762-2017)。施用贝壳粉钝化修复Cd污染土壤切实可行,可进一步开展大田试验验证效果。

The effects of shell powder on the remediation effect and soil quality of Cd contaminated farmland soil were studied using a static culture test and pot experiment. In the static culture experiment, with the increase of the shell powder applied, the soil pH increased, while the contents of soil organic matter, available nitrogen, available phosphorus and available potassium were decreased. The immobilization rate of TCLP-Cd in soil was up to 64.13%, and each treatment was significantly higher than the control(P<0.05). The maximal increase of the activities of catalase, peroxidase, and urease in soil were up to 64.31%, 30.26% and 17.08%, respectively. In the pot experiment, the application of the shell powder could convert the heavy metal Cd in the soil from the water-soluble state and the reduced state to the oxidation state and the residual state. Shell powder treatment increased the chlorophyll content of rape leaves and had no significant effect on the fresh weight(P>0.05)of plants. The Cd content in the upper part of the rape decreased by 3.13%~26.71% compared with the control. The Cd content in the roots decreased by 12.22%~31.49% compared with the control. When the shell powder dosage reached 1%, Cd content in edible part of rape met with the national food contaminant limit standard(GB 2762-2017). It is more feasible to immobilize remediation of Cd contaminated soil using shell powder, and the further field experiment should be carried out to verify the effect.