大理河流域微塑料空间分布及其来源

Spatial distribution and source of microplastics in the Dali River Basin

微塑料(直径<5 mm的塑料颗粒)作为一种新型环境污染物,对土壤及水生生态系统构成了严重威胁.本研究基于黄河中游大理河流域采集的21个沉积泥沙和12个农田土壤样品,分析了大理河流域不同介质中微塑料赋存特征和组成差异,揭示了不同介质中微塑料来源及沉积泥沙中微塑料丰度的影响因素.结果表明,大理河流域沉积泥沙和农田土壤中都受到微塑料的严重污染,其丰度分别为440~1190个·kg^(-1)和1180~2930个·kg^(-1),其中,小粒径微塑料(粒径<500μm)为主要组成,分别占泥沙和土壤中微塑料颗粒总数的50.12%和72.5%.纤维是泥沙和土壤中微塑料最常见的形状,分别为66.95%和48.3%;薄膜和小球微塑料在农田土壤中较多,比沉积泥沙中高6.51%和13.83%.通过拉曼光谱仪测试,沉积泥沙中微塑料聚合物组成主要为聚对苯二甲酸乙二醇酯(PET)和聚丙烯(PP),农田土壤中主要微塑料聚合物组成为聚乙烯(PE).农用地膜是农田土壤中主要微塑料来源,生活污水和固体废物是泥沙中微塑料的主要来源.此外,沉积泥沙中微塑料丰度的主要影响因素为速效磷含量和径流流速.本研究结果可为深入了解黄河中游流域微塑料污染状况提供参考.

As a new type of environmental pollutant,microplastics(plastic particles with a diameter of<5 mm)pose a serious threat to soil and aquatic ecosystems.Based on 21 sediment samples and 12 farmland soil samples collected in the Dali River Basin in the middle reaches of the Yellow River,the characteristics and composition differences of microplastics in different media in the Dali River Basin were analyzed,and the source of microplastics in different media and the influencing factors of the abundance of microplastics in sediments were revealed.The results showed that the sediments and farmland soils in Dali River Basin were seriously polluted by microplastics,and their abundances were 440~1190 items·kg^(-1) and 1180~2930 items·kg^(-1),respectively.Small-sized microplastic(particle diameter<500μm)is the main components,accounting for 50.12%and 72.5%of the total number of microplastic particles in sediment and soil,respectively.Fibers is the most common shape in sediment and soil,accounting for 66.95%and 48.3%,respectively.In contrast,the amount of films and spheres microplastics in farmland soil was 6.51%and 13.83%higher than that in sediments,respectively.Raman spectrometer test showed that the microplastic polymers in sediments were mainly composed of polyethylene terephthalate(PET)and polypropylene(PP),while the microplastic polymers in farmland soils were mainly composed of polyethylene(PE).Agricultural mulch is the main source of microplastics in farmland soil,and domestic sewage and solid waste are the main sources of microplastics in sediment.In addition,the abundance of microplastics in sediment is mainly affected by the content of available phosphorus and runoff velocity.The results can provide a reference for in-depth understanding of microplastic pollution in the middle Reaches of the Yellow River basin.