A pollution risk assessment and source analysis of heavy metals in sediments: A case study of Lake Gehu, China

This study concerned the sampling and detection of 10 heavy metals, including Hg, Pb, Cu, Zn, Co, As, Cd, Cr, Mn, and Ni, in the sediment of Lake Gehu in Jiangsu Province. A geographic information system (GIS) was used to show the spatial distribution of the heavy metals in the sediments of the lake. Then, the geological accumulation index, enrichment coefficient and potential ecological risk index was used to assess the potential risks brought by the accumulation of these heavy metals. Correlation analysis was used to qualitatively analyze the sources of the heavy metals and determine the correlation between them. The positive definite matrix factorization model (PMF) was also used to quantitatively analyze the source of the heavy metals. The study concluded that the concentration of heavy metals in the southwest of Lake Gehu is relatively low. According to the calculation results of the geological accumulation index and the enrichment coefficient, the sediments of Lake Gehu are most seriously polluted by Cd, especially during the period of normal water levels. The potential ecological risk index shows that the central part of Lake Gehu poses the highest risk of pollution from heavy metals, and nearly reaches the High Risk category. There is a positive correlation between the heavy metals Hg, Cu, Co, and a significant positive correlation between Pb, Zn, As, Cr, Mn, and Ni. These two groups of heavy metals are also highly homologous. Local industries including printing and dyeing textiles, electroplating, chemical making, agriculture, and metal manufacturing are all causes of heavy metal pollution. From all of these, factories that dye and print textiles, and metal manufacturing plants are the main causes of pollution.