园林废弃物堆肥对铅镉污染土壤的修复效果

Pb and Cd-polluted soil remediation effects by green waste compost

为明确园林废弃物堆肥(GWC)对重金属污染土壤的修复效果,通过小白菜盆栽试验,向铅(Pb)、镉(Cd)污染土壤中分别按0(CK)、1%、3%、5%的施用量添加GWC和泥炭,研究不同单一/混合处理对土壤酶活性,Pb、Cd在土壤孔隙水中浓度和在土壤中赋存形态的影响,并探究小白菜地上部和根部Pb、Cd积累转运的关系。结果表明:各处理3%和5%的施用量显著提高了土壤酶活性,5%泥炭对提高脱氢酶和过氧化氢酶活性更显著,5%GWC对提高脲酶和磷酸酶活性更显著。土壤孔隙水Pb浓度在第1~7 d时随不同处理的施用量增多而降低;5%GWC及5%混施处理在第1 d时的Pb浓度与CK相比分别降低了78%和56%。不同处理中孔隙水Cd浓度在第1 d时均高于CK,其中5%GWC相比CK增加了70%;泥炭处理中Cd浓度随时间延长呈现先上升后下降的趋势。3%和5%处理下土壤酸溶态Pb、Cd显著减少,残渣态显著增加,植株地上部和根部Cd含量显著下降,富集系数和转运系数也相应降低,其中5%混合施用效果最显著。Pb含量在3%和5%GWC施用下显著上升。研究表明,单一、混合施用GWC及泥炭对土壤中Pb、Cd有显著的钝化效果,且泥炭对于降低植物体重金属积累的效果好于GWC。

A pot experiment was conducted to clarify the remediation effects of green waste compost(GWC)on soil contaminated with lead(Pb)and cadmium(Cd).Treatment of 0(control,CK),1%,3%,and 5%application rates of single and mixed GWC and peat were applied to study the effects of Pb and Cd contamination on the activity of soil dehydrogenase,urease,catalase,and phosphatase;Pb and Cd concentration in the soil pore water,as well as the accumulation and translocation of Pb and Cd in shoots and roots of Brassica chinensis L.was also investigated.At application rates of 3%and 5%the soil enzyme activity was significantly increased;5%peat demonstrated the most significant increase in dehydrogenase and catalase activity,while 5%GWC significantly increased the activity of urease and phosphatase.Pb concentration in the soil pore water decreased over 7 days,following the increase in the application rate of the different treatments;On Day 1,the Pb concentration of the 5%GWC and mixed treatment soils decreased by 78%and 56%,respectively,as compared to CK.On Day 1,the Cd concentration in the soil pore water for the different treatments was higher than that of CK;5%GWC increased by 70%,as compared to CK.The Cd concentration in the peat treatment initially increased,after which it decreased.Under the treatments of 3%and 5%,acid-soluble Pb,Cd in the soil was significantly reduced,while its residual form significantly increased.The Cd content in the plant′s shoots and roots significantly reduced,and the bioconcentration factor and translocation factor also reduced correspondingly;5%mixed treatment application had a significantly better effect.Overall,both single and mixed applications of GWC and peat are capable of remediating Pb-Cd polluted soil,but the effect of peat in declining accumulation is better than that of GWC.