[Spatiotemporal Distribution and Source Analysis of Heavy Metals in Surface Sediments in Lake Ulansuhai Based on PCA-APCS-MLR Model].

To explore the spatial and temporal distribution characteristics of heavy metals in the surface sediments of lakes in cold regions during ice-sealing and non-ice-sealing periods, we analyzed the potential ecological risk degree and the pollution sources. A total of 20 sampling sites in Lake Ulansuhai in cold regions were collected from 2020 to 2021, and 120 surface sediment samples were collected during different periods. The contents of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg were determined. Correlation analysis, principal component analysis, and the absolute factor score-multiple linear regression (APCS-MLR) receptor model were used to trace the source of heavy metal pollution. The results showed that:① the distribution of heavy metals in lake surface sediments was different between the ice-sealing period and the non-ice-sealing period. The distribution of heavy metals during the ice-sealing period was higher in the north and lower in the south. Cd and Hg were mainly distributed in the central and southern lakes during the non-glacial period. ② Hg, Cd, and As were moderately polluted, and Ni was mildly polluted in the surface sediments of the lake. The overall performance was at a high risk level, and the pollution level during the non-ice-sealing period was higher than that during the ice-sealing period. The main environmental risk factors were Hg and Cd, which showed high risk and moderate risk, respectively. ③ The sources of heavy metals in lake surface sediments were mainly industrial sources from mining and transportation, agricultural sources, and natural sources. As, Ni, Pb, and Hg were mainly affected by industrial sources, with contribution rates of 62.67%, 75.31%, 77.47%, and 80.11%, respectively. The main sources of Cu and Zn were natural sources, and Cd was greatly affected by agricultural sources. The contribution rate was 81.57%. The source of Cr was mainly affected by natural factors, and the influence of human activities and unknown sources require further attention.