不同改良剂施用对污染土壤养分转化及砷和铅生物有效性的影响

Effects of Different Soil Amendments on Soil Nutrient Transformation and Bioavailability of Arsenic and Lead in Contaminated Soil

为比较不同小龙虾壳基土壤改良剂对砷、铅复合污染土壤的修复效果,通过盆栽试验,探究施用1%(w/w)小龙虾壳粉(CSP)、甲壳素(CT)、小龙虾壳炭(CSB)及甲壳素-小龙虾壳炭配施(CT-CSB,CT∶CSB为1∶1)对土壤养分、酶活性、重金属生物有效性及青菜生长的影响。结果表明,不同改良剂施用均可显著提高土壤pH和阳离子交换量,降低土壤中有效态铅的含量,施用CSB对降低土壤中有效态铅含量的效果最显著,较对照降低了35.3%;添加CT、CSB和CT-CSB均可降低土壤中有效态砷的含量,其中,CT-CSB处理较对照降低77.2%。CT、CSB、CT-CSB处理显著提高土壤中ɑ-葡萄糖苷酶、纤维二糖水解酶、β-木糖苷酶、β-N-乙酰基氨基葡萄糖苷酶和酸性磷酸酶的活性。土壤酶活性与重金属有效态含量的相关性分析表明,施加改良剂可降低重金属胁迫,提高土壤酶活性。添加不同土壤改良剂均可降低青菜可食部分对砷和铅的积累,提高青菜对氮、磷和钾的吸收量,从而促进植物生长,CT-CSB处理的青菜可食部分生物量较对照提高190.9%。综上,CT、CSB、CT-CSB在砷铅复合污染土壤修复方面均有较大应用潜力,CSB综合效果最为明显,可以作为土壤砷、铅原位钝化修复的一种新材料。

A pot experiment was conducted to compare the remediation effects of different soil amendments derived from crawfish shell on an arsenic(As)and lead(Pb)contaminated soil.Soil amendments,including crawfish shell powder(CSP),chitin(CT),crawfish shell biochar(CSB)and CT-CSB combination(CT-CSB,CT∶CSB is 1∶1),were employed to assess the influence of their applications(1%)on the availability of nutrients,activities of enzymes,bioavailability of As and Pb,as well as growth of pak choi(Brassica chinensis).The results indicated that all treatments significantly increased the pH and cation exchange capacity(CEC)of the soil.Concentrations of available Pb decreased in all treatments,and the maximum reduction was found in the CSB treatment,which was 35.3%lower than control.Application of CT,CSB and CT-CSB decreased the concentrations of available As,and the maximum reduction was found in the CT-CSB treatment,which was 77.2%lower than control.The activities of soil enzymes includingα-glucosidase,cellobiohydrolase,xylosidase,acetyl glucosaminidase and acid phosphatase were enhanced after the addition of CT,CSB and CT-CSB.Correlations analysis between soil enzyme activity and the concentrations of available Pb and As indicated that the application of different amendments could alleviate the stress of As and Pb in the soil,and thus enhance soil enzyme activities.Application of all amendments decreased the uptake of As and Pb in the edible part of pak choi,and increased the phytoavailability of nitrogen,phosphorus and potassium,thus promoting plant growth.The biomass of the edible part of pak choi increased by 190.9%in the CT-CSB treatment,compared with the control.In conclusion,application of CT,CSB and CT-CSB,in particular CSB,had superior potential for promoting plant growth and remediating soil polluted by As and Pb,offering a new approach for the in-situ remediation of soil co-contaminated with As and Pb.