ZHENG Peijia1, SHI Zeming1,2,*,WANG Jianming1, WANG Xinyu1, ZHU Yinghai1, WANG Yu1,ZHU Yonggui3,LIU Dingyong3

（1. School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;
2. Sichuan Province Key Laboratory of Nuclear Techniques in Geosciences , Chengdu University of Technology, Chengdu 610059, China;
3. Sichuan Provincial Coalfield Geology Bureau 135 Team, Luzhou646000, China）

Abstract： Sancha Lake is the second largest lake in Chengdu city. In order to study the geochemistry characteristics, spatial distribution, and the relationship between city evolution and human activities, and potential ecological risk of heavy metal in sediments of Sancha lake, sediment and soil samples of the lake were collected. The spatial distribution and enrichment characteristics of heavy metals in sediments, the speciation of heavy metals that determined by the BCR method, and the ecological risk were investigated. The results showed that the average contents of Cd, Pb, Zn, Cu, Hg, As, Ni and Cr in surface sediments were 9.61, 1.26, 87.2, 37.8, 0.0700, 42.7, 33.9 and 116(mg/kg), respectively, and the average content of heavy metals in soils were lower than that of sediments. In terms of spatial distribution of heavy metals in sediment, Cd, Pb, Zn, Cu and Hg is higher at the main tourist areas and the historical high-density cage fish area than that of the historical medium and low density cage fish area, while As, Ni and Cr is slightly higher at the historical medium and low density cage fish area than that of the high-density cage fish area. As, Cu, Ni and Pb are mainly exist in residual form, indicating a good stability; Cd is mainly in acid-extractable with poor stability. The assessment of potential ecological risk and the assessment of secondary phase enrichment coefficient method show that sediments of Sancha Lake is relatively clean, and only Cd in the sediment was affected by human activities, the average and range of is 40.4 and 7.07-288, respectively. There are individual points reached the extreme hazard level. Correlation analysis, the distribution of heavy metals in sediments and human activities shows that Cu, Pb, Zn, Cd and Hg are mainly related to cage fish farming, transportation and urban construction, while, Ni, Cr and As are mainly derived from agricultural activities and geotechnical weathering.

Key words：Urban lake；Surface sediments；Heavy metal；Chemical speciation；Pollution assessment

EARTH AND ENVIRONMENT Vol.51, No.3, Tot No.353, 2023, Page 318