Abstract:
In order to understand the pollution characteristics of heavy metals in surface sediments of the coastal waters of southwest Fujian, the distributions and potential sources of seven major heavy metals (Cu、Zn、Pb、Cd、Cr、Hg and As) in the surface sediments were investigated in 2020. Furthermore, the Hakanson's potential ecological risk index, geo-accumulation index and enrichment factor were used to evaluate the potential ecological risk of these heavy metals. The results showed that the content of Cd, Cr, Hg and As in the surface sediments were less than those documented by the China's national first-class benchmark (CFCB) of marine sediment quality standards.However, it was found that in some monitored stations, the heavy metal content was higher than those of CFCB quality standard, accounting for 11.8% (Pb), 23.5% (Cu) and 17.6% (Zn), respectively, but less than those documented by the China’s national second-class benchmark (CSCB). All these results indicated that the environmental quality of sediments in the coastal waters of southwest Fujian is good. The contents of the selected metals were significantly correlated with TOC content and particle size, but had not correlationwith sulfide content. The sources of Cu, Zn, Pb and As in the surface sediments of the sea area were similar, and they exhibited the characteristics of compound pollution from agriculture, transportation and soil erosion, while Hg and Cd mainly came from industrial pollution. Based on three methods of ecological risk assessment, which was the Hakanson's potential ecological risk index, geo-accumulation index and enrichment factor, their results were consistent. The single-factor potential ecological risk of these heavy metals in sediments followed the order: Hg>Pb>As>Cd>Cu>Cr>Zn. In conclusion, the potential ecological risk of the study area is at a low level on the whole, but it is still recommended to focus on the control of Hg and Pb pollution.