Assessment on the pollution and risk of heavy metals in surface sediments of Guangxi offshore from 2005 to 2020

The monitoring data of heavy metals in surface sediments from 2005 to 2020 were analyzed in order to discriminate the quality of sediments environmental in Guangxi offshore. In this study, statistical methods, correlation analysis, factor analysis and risk assessment were introduced to analyze the characteristics, trends and ecological risks of heavy metals in surface sediments in Guangxi offshore. The results indicate that approximately 99.0% As, 98.1% Cu, 99.0% Pb, 99.6% Cd, 100% Hg, 97.9% Zn and 100% Cr of monitoring data met the first grade sediment quality of China between 2005 and 2020, and the sediment heavy metal indicators of 58% of the stations have no statistically significant inter-annual changes in the past 15 years. The evaluation results of geo-accumulation index show that about 37.5% of monitoring station in the Guangxi offshore have mild to moderate pollution, and Hg, As and Cd were the main pollution factors. The evaluation results of the potential ecological risk index show that the surface sediments in Guangxi offshore are generally in a low-risk state.