大塑料和微塑料影响土壤性质与镉生物有效性

Macroplastics and microplastics affect soil properties and cadmium bioavailability

为探究大塑料(>5mm)和微塑料对土壤重金属形态转化的影响,以镉(Cd)污染农田土壤为对象,模拟不同剂量(0.1%、1%和7%)的大塑料和微塑料污染,开展土壤培养试验,研究其对土壤性质、Cd生物有效性和形态的影响.结果表明,培养120d后,与对照组相比,大塑料和0.1%的微塑料对土壤pH值影响较小,1%和7%的微塑料使土壤pH值分别降低0.13和0.36单位;大塑料使土壤溶解性有机碳(DOC)含量增加6.45%~14.38%,7%的微塑料则使DOC含量减少17.10%.大塑料对Cd生物有效性影响较小;微塑料提高了土壤Cd的生物有效性,且与剂量呈正相关,其中7%的微塑料使土壤Cd的可交换态和碳酸盐结合态总占比增加12.77%,DTPA可提取Cd含量占比增加7.91%.研究结果可为塑料与Cd复合污染的农田土壤污染防治提供理论依据.

In order to investigate the effects of macroplastics(>5mm)and microplastics on the transformation of heavy metal speciation in soil,macroplastics and microplastics with different doses(0.1%,1%,and 7%)were mixed in cadmium(Cd)contaminated farmland soil for incubation to evaluate their impacts on soil properties,bioavailability and chemical speciation of Cd.Results showed that after 120 days of incubation,compared with the control treatment,macroplastics and 0.1%microplastics had less impact on soil pH,while 1%and 7%microplastics addition reduced soil pH by 0.13 and 0.36 units,respectively.Besides,the content of soil dissolved organic carbon(DOC)was increased by 6.45%~14.38%in the presence of macroplastics,but decreased by 17.10%in the presence of 7%microplastics.In addition,macroplastics showed little effect on Cd bioavailability,while microplastics increased the exchangeable fractionation and bioavailability of Cd in soil,and the effect was positively correlated with the dose.Among them,7%microplastics increased the proportion of the exchangeable and carbonate-bound Cd by 12.77%,and the proportion of the Diethylene triamine pentaacetate acid(DTPA)extractable Cd was increased by 7.91%.The results of this study will provide a theoretical basis for preventing and controlling the combined pollution of plastic and heavy metals in agricultural soils.