长江流域微塑料污染特征及生态风险评价

长江作为我国第一大河流，其流域微塑料污染状况尚未得到全面研究.为此，针对流域尺度建立微塑料综合调查评价体系，以探明长江流域微塑料空间分布与组成特征，解析其影响因素，评价其生态风险.结果表明，研究区域微塑料丰度范围为21~44 080 n·m^-3，平均丰度为4 483 n·m^-3.在其空间分布上，支流高于干流（赣江除外），其中岷江流域成都段是微塑料检出丰度最高的支流地区.流域微塑料尺寸集中在0~1 mm，形状以纤维和碎片为主，颜色以彩色（有色）和透明为主.进一步引入微塑料多样性指数，发现辛普森指数和香农-维纳指数均能量化流域微塑料特征组成的多样性，但二者变化趋势存在一定差别.回归分析显示，人类活动与微塑料丰度呈显著正相关（P<0.05），8种人类活动因子中民用汽车保有量和旅游收入与微塑料丰度相关性最强，说明交通运输业和旅游业是影响微塑料分布的主要因素.从微塑料的潜在生态风险指数来看，长江流域微塑料具有一定的生态风险，68.97%的区域属于Ⅲ级和Ⅳ级风险区，其中太湖微塑料生态风险应受到更为广泛地关注.

Pollution Characteristics and Ecological Risk Assessment of Microplastics in the Yangtze River Basin

The Yangtze River, the largest river in China, has not been comprehensively studied for its basin''s microplastic pollution status. Therefore, a comprehensive investigation and assessment system of microplastics was developed at the river basin scale to characterize the spatial distribution and composition of microplastics in the Yangtze River Basin in order to analyze their influencing factors and assess their ecological risks. The results showed that the microplastic abundance in the study area ranged from 21 to 44 080 n·m^-3, with an average abundance of 4 483 n·m^-3. The spatial distribution of microplastic abundance was higher in the tributaries than in the main streams (except the Ganjiang Basin), with the Chengdu of the Minjiang Basin being the tributary area with the highest abundance of microplastics detected. The size of microplastics in the river basin was concentrated in the 0-1 mm range; the shapes were mainly fiber and fragment; and the colors were mainly colored and transparent. Further, introducing the diversity index of microplastics, it was found that both the Simpson index and the Shannon-Wiener index could quantify the diversity of microplastic characteristic composition in the river basin, but there were certain differences in the changing trends between the two. Regression analysis showed that anthropogenic activities were significantly and positively correlated with microplastic abundance (P<0.05), and among the eight anthropogenic activity factors, civilian vehicle ownership and tourism income were the most strongly correlated with microplastic abundance, indicating that transportation and tourism were the main factors influencing microplastic distribution. From the perspective of the potential ecological risk index of microplastics, microplastics in the Yangtze River Basin posed a certain ecological risk, with 68.97% of the area falling within risk zones III and IV, with the ecological risk of microplastics in Taihu Lake warranting more widespread attention.