固原市农田土壤微塑料的分布特征及风险评估

Distribution Characteristics and Risk Assessment of Microplastics in Farmland Soil in Guyuan

为探明固原市农田土壤中微塑料分布特征,通过现场采集调查、显微镜观察和傅里叶变换红外光谱等方法分析了固原市农田土壤中微塑料的丰度、类型、颜色、大小和外形等特征,用污染负荷指数法(PLI)评估了微塑料污染风险.结果表明,固原市农田土壤(耕作层)微塑料丰度为186.32~1 286.24 n·kg^(-1),设施农业土壤微塑料丰度分别较非设施农业有膜和无膜种植土壤显著增加35.56%和228.91%,耕作层微塑料丰度是犁底层的0.31倍.PE(26.42%~62.83%)和PP(27.64%~42.62%)为主要的微塑料类型,设施农业土壤微塑料种类数显著大于非设施农业.<100μm微塑料占32.21%~42.52%,而>1 000μm只占0.28%~12.31%,耕作层微塑料粒径比犁底层高47.39%,设施农业土壤微塑料粒径最大,非设施无膜种植最小.微塑料形状主要为薄膜、纤维、碎片和微珠,其中纤维状丰度最大,薄膜状次之.共检测出7种颜色的微塑料,以白色和黑色为主.研究区污染风险总体为低风险,设施农业土壤微塑料污染风险最高.研究结果将为我国农田土壤微塑料污染评估及微塑料土壤环境行为提供数据参考.

The farmland ecosystem faces the emerging risk of microplastic pollution.To investigate the distribution characteristics of microplastics in agricultural soils in Guyuan City,the abundance,type,color,size,and shape of microplastics in Guyuan City agricultural soils were analyzed using field survey,microscopic observation,and Fourier transform infrared spectroscopy.In addition,the risk of microplastic pollution was assessed using the pollution load index method(PLI).The results showed that the microplastic abundance of agricultural soils(0⁃20 cm)in Guyuan City ranged from186.32 to 1286.24 n·kg^(-1),and the microplastic abundance of soils in facility agriculture increased significantly by 35.56%and 228.91%compared with those in non⁃facility agriculture with and without film,respectively,and the microplastic abundance in the arable layer was 0.31 times higher than that in the plough pan layer.PE(26.42%to 62.83%)and PP(27.64%to 42.62%)were the main microplastic polymer types,and the number of soil polymer species was significantly greater in facility agriculture than that in non⁃facility agriculture.Microplastics<100μm accounted for 32.21%⁃42.52%,whereas>1000μm accounted for only 0.28%⁃12.31%.The particle size of microplastics in the arable layer was 47.39%higher than that in the plough pan layer,and the particle size of microplastics was the largest in facility agriculture and the smallest in non⁃facility film⁃free planting.Microplastics were mostly in the form of films,fibers,fragments,and microbeads,with the greatest abundance in the form of fibers and the second largest in the form of films.A total of seven colors of microplastics were monitored,mainly white and black.The overall risk of contamination in the study area was low,and the highest risk of microplastic contamination was found in the soil of facility agriculture.The results of the study will provide data reference for the assessment of microplastic contamination in agricultural soils and microplastic soil environmental behavior in China.