南水北调丹江口库区土壤中微塑料分布特征及风险评估

Distribution Characteristics and Risk Assessment of Microplastics in Soil in Danjiangkou Reservoir Area of South-to-North Water Diversion Project

为探究丹江口库区土壤中微塑料赋存特征及影响因素,通过对果园、旱地、水田和湿地进行土壤样品采集,利用密度分选、显微镜观察和拉曼光谱仪测定等方法对土壤中微塑料进行鉴定.结果表明,研究区采集的64个样本均有微塑料检出,丰度范围为645~15161 n·kg^(-1).空间分布上,库尾高于库中和库首,且表层土壤(0~20 cm)中微塑料的丰度明显低于下层土壤(20~40 cm).微塑料主要类型为聚丙烯(26.4%)和聚酰胺(20.2%),粒径主要集中在50~500μm之间(75%),常见形状为碎片状(66.2%).相关性分析显示,土壤微塑料丰度与土地利用、距水面和住宅的距离、人口密度和土壤性状密切相关.从微塑料污染风险来看,72.1%区域微塑料聚合物污染指数处于Ⅲ级和Ⅳ级,丹江口库区存在一定的微塑料污染风险.研究结果可为微塑料风险评估提供支撑.

To explore the occurrence characteristics and influencing factors of microplastics in soil in the Danjiangkou Reservoir area,this study collected soil samples from orchards,dryland,paddy fields,and wetland and identified microplastics in soil via density sorting,microscope observation,and Raman spectrometry.The results showed that microplastics were detected in 64 samples collected in the study area,and the abundance ranged from 645 to 15161 n·kg^(-1).The spatial distribution of microplastics in the bottom of the reservoir was higher than those in the middle and head of the reservoir,and the abundance of microplastics in the surface soil(0-20 cm)was significantly lower than that in the bottom soil(20-40 cm).The main types of microplastics were polypropylene(26.4%)and polyamide(20.2%),the particle size was mainly concentrated between 50-500μm(75%),and the common shape was fragments(66.2%).Correlation analysis showed that soil microplastic abundance was closely related to land use,distance from water and housing,population density,and soil properties.From the perspective of microplastic pollution risk,72.1%of the region's microplastic polymer risk index was at levelⅢand levelⅣ,and there was a certain risk of microplastic pollution in the Danjiangkou Reservoir area.The results of this study can provide support for risk assessment of microplastics.