人口聚集程度和产业类型会影响重金属元素在山地河流沉积物中的空间分布。在2019年12月采集位于重庆市长寿区典型山地河流——桃花溪城市段和农村段河底沉积物,并监测各点位沉积物样品中的重金属含量。结果表明,桃花溪城市段沉积物所监测8种重金属均值含量均高于农村段,其中Cd和Cu含量在两者间存在显著差异,人类聚集会影响重金属在河流沉积物中的空间分布。在改进的地累积指数(Im)评价体系中,流域内有20.59%的点位处于偏中度或中度污染,说明桃花溪沉积物重金属含量仅在部分点位存在富集。在潜在生态风险指数(RI)评价体系中,流域内有67.65%的点位具有中等或较高的潜在生态风险；在沉积物质量基准法(SQGs)评价体系中,所有监测点位沉积物重金属含量对生物的毒害性均处于中等风险,表明桃花溪沉积物重金属对地表水环境所带来的生态风险不容忽视。通过PMF模型解析表明,桃花溪沉积物中重金属的主要来源依次为：水产养殖源(38.79%)＞自然源(20.40%)＞人类活动复合源(20.35%)＞工业源Ⅱ型(16.69%)＞工业源Ⅰ型(3.78%)。

The spatial distribution of heavy metals in the sediments of mountainous rivers is influenced by population density and industry type. In December 2019, sediment samples were collected in a typical mountainous river (Taohuaxi River) which covered both urban and rural sections in Changshou District, Chongqing. The contents of heavy metals in the sediment samples at each point were measured. The results showed that the average heavy metal contents in the sediments of the urban section of Taohuaxi River were higher than those in the rural section for all the eight heavy metals monitored, with significant differences observed in Cd and Cu contents. Human population density was found to affect the spatial distribution of heavy metals in river sediments. A proportion of 20.59% in the monitored sites in the basin was found to be Near Moderate or Moderate Pollution according to the improved Geoaccumulation Index (I_m), indicating that heavy metals were only enriched at certain sites in Taohuaxi River. According to the Potential Ecological Risk Index (RI), 67.65% in the monitored sites in the basin were at Medium or High potential ecological risk. In the Sediment Quality Guideline method (SQGs), the toxicity of heavy metals in the sediments at all monitoring points was found to be of moderate risk to organisms. The ecological risks of heavy metals in the sediments of Taohuaxi River should not be ignored. The results of the Positive Matrix Factorization (PMF) model analysis showed that five main sources of heavy metals in the sediments of Taohuaxi River were identified. The contribution of these sources was in the order of aquaculture sources (38.79%) > natural sources (20.40%) > anthropogenic mixed sources (20.35%) > industrial sources Type II (16.69%) > industrial sources Type I (3.78%).

长江生态环保集团有限公司科研项目资助(合同编号：HBZB2022095)