钝化剂对镉污染土壤修复效果及青菜生理效应影响

Effects of amendments on remediation of cadmium-contaminated soil and physiological characteristics of pakchoi

采用盆栽试验方法,研究海泡石、骨炭粉及二者配合施用对镉污染农田土壤的钝化修复效果以及青菜镉积累和生理生化性质的变化.结果表明,两种钝化剂单施及配施均可以显著提高土壤pH,促进土壤Cd由酸溶态向残渣态转化,降低CaCl2-Cd和TCLP-Cd的含量.与对照相比,海泡石和骨炭粉1∶1配施处理,酸溶态Cd含量降低41.03%,残渣态Cd含量升高1.22倍;且CaCl2-Cd和TCLP-Cd含量分别降低59.65%和58.73%.海泡石和骨炭粉施用不同程度的提高土壤养分含量,增加土壤酶活性和微生物数量.与单施海泡石相比,单施骨炭粉及海泡石与骨炭粉1∶1配施处理土壤有机碳、速效氮和速效磷含量均显著提高(P<0.05);且单施骨炭粉更能有效地促进土壤脲酶和蔗糖酶活性,增幅分别为91.50%和46.52%,但过氧化氢酶活性及细菌、真菌和放线菌数量无明显差异.添加海泡石和骨炭粉显著降低青菜对Cd的积累,缓解Cd胁迫对青菜的毒害作用,有效促进青菜生长.尤其是海泡石和骨炭粉1∶1配施处理,青菜可食部位Cd含量降低53.19%,叶片SOD、POD和CAT活性分别增加65.30%、40.61%和43.35%.

A pot experiment was conducted to examine the immobilization remediation effects of sepiolite and bone char on soil physical and chemical properties, soil enzyme activity and microbial quantity, Cd accumulation in soil and pakchoi(Brassica chinensis L.). The results indicated that application of sepiolite, bone char and sepiolite combined with bone char all could effectively increase the soil pH, promote the transformation of Cd from acid soluble to residual and decrease the contents of CaCl2-Cd and TCLP-Cd in the tested soil. Compared to the control treatment, the content of acid-soluble Cd was decreased by 41.03% and the residual Cd content increased by 1.22 times. The largest drop for CaCl2-Cd and TCLP-Cd was 59.65% and 58.73%, respectively, in the treatment of sepiolite combined with bone char(1∶1). The application of sepiolite and bone char could increase soil nutrients contents, soil enzyme activity and microbial quantity, which contributed to improve the soil environmental quality. Compared to the single sepiolite treatment, the contents of organic carbon, available nitrogen and available phosphorus were significantly increased by single application of bone char and 1∶1 combination of bone char and sepiolite. Moreover, bone char could effectively promote soil urease and invertase activities compared to the application of sepiolite, with increases of 91.50% and 46.52%, respectively. However, there was no significant difference in catalase activity and the number of bacteria, fungi and actinomycetes. The application of sepiolite and bone char could effectively reduce the accumulation of Cd in pakchoi, alleviate the toxic effect of Cd stress and promote the growth of pakchoi. In particular, the concentration of Cd in edible parts of pakchoi decreased by 53.19% in the treatment of 1∶1 combination of bone char and sepiolite. The activities of SOD, POD and CAT in leaves were increased by 65.30%, 40.61% and 43.35%.