Heavy metals in surface sediments of lakes in Guangzhou public parks in China and their relations with anthropogenic activities and urbanization

This study aimed to investigate the pollution of heavy metals in the sediments of park lakes in Guangzhou, which is a large city with rapid urbanization, industrialization, and dense population in South China. Thirty-two surface sediment samples were collected from seven lakes in different districts of this city. The concentrations and distributions of Cr, Ni, Cu, Zn, Cd, and Pb were measured to assess the level of enrichment and toxicity in the sediments. The enrichment factor showed that Pb and Zn showed severe enrichment in all lakes except for the Dafu Shan Forest Park (DFS), and the geo-accumulation index (I_geo) showed that all lakes were polluted with Cu, Pb, Cd, Ni, and Zn in different levels. The results of risk assessment indicated that the DFS located in the suburbs represented moderate risks; however, other lakes in the city central represented high or very high risks. Moreover, Cd had the primary contribution to the risk of the sediments' environment in urban lakes. Multivariate statistical analyses are carried out to explore the correlativity between heavy metals and human development indices. This study indicated that the levels of heavy metals' contamination and ecological risk of urban lakes in Guangzhou have a close relationship with anthropogenic activities.