两种钝化剂对污染土壤上生菜吸收重金属和养分的影响

Effects of Two Amendments on Heavy Metal and Nutrient Absorption of Lettuce Grown on Contaminated Soil

为明确分子筛、硅灰石作为钝化剂修复粤北Cd污染农田土壤的效果,采用盆栽生菜(Lactuca sativa)试验,评估钝化剂应用潜力和对作物营养元素吸收可能的负面效应。结果表明,高剂量(≥660 mg Si/kg)分子筛和硅灰石分别降低了土壤Cd和Pb的有效性,而低剂量(220 mg Si/kg)反而使土壤Cd和Pb有效性上升,添加≥660 mg Si/kg的钝化剂使生菜对Cd和Pb积累具有显著抑制效应。硅灰石通过显著提高土壤有效Ca,增强Ca-Cd竞争吸收来抑制生菜Cd累积,而非通过降低土壤Cd有效性起作用。施用分子筛会降低生菜的Ca、Mg、Mn和Zn含量,小幅增加Cu含量。施用硅灰石则降低生菜的Mn、Zn含量,小幅增加Ca、Cu含量。高剂量(880 mg Si/kg)的分子筛会使生菜产量降低29%,而添加≥660 mg Si/kg硅灰石可使产量提高10%~12%。因此,硅灰石具增产抑Cd效能,在大面积Cd污染土壤的修复中有应用前景,但需适度补充Zn、Mn养分。

In order to understand remediation effect of wollastonite(WS)and 4A molecular sieve(MS)on Cd-contaminated soils collected from northern Guangdong Province,the absorption of heavy metal and nutrient of lettuce(Lactuca sativa)was studied by using pot experiment.The results showed that the available Cd and Pb contents of soil significantly reduced with≥660 mg Si/kg MS and WS,on the contrary,those increased with low dose(220 mg Si/kg).Therefore,it indicated that≥660 mg Si/kg MS and WS had significant inhibitory effect on the accumulation of Cd and Pb of lettuce.WS inhibited lettuce Cd uptake through enhancing Ca-Cd competition rather than reducing Cd availability in soil.MS reduced Ca,Mg,Mn and Zn contents and slightly increased Cu content in lettuce.WS decreased Mn and Zn contents and slightly increased Ca and Cu contents in lettuce.The lettuce yield reduced by 29%with high dose of MS(880 mg Si/kg),and increased by 10%-12%with high dose of WS(≥660 mg Si/kg).In conclusion,WS had better performance in boosting crop yield and decreasing crop Cd,showing a potential for remediation of Cd-contaminated soils.Besides,the decreases of Zn and Mn contents in crops should be addressed by the proper addition of Zn and Mn nutrients into soils.