Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Sediments of a Heavily Polluted Maozhou River, Southern China

In this study, eighteen 3.30-m-long sediment profiles were sampled in Maozhou River. In order to investigate the sediment pollution status and potential sources of heavy metals, we performed heavy metal contents, grain size, organic matter concentration, moisture concentration and total phosphorus analysis, and assessed the ecological risk of heavy metal pollution in the study area using enrichment coefficient, geo-accumulation index and potential ecological risk index. The results indicated that the heavy metal concentrations in the Maozhou River sediments were 3.73-417 times higher than the soil background in Guangdong Province and the average concentrations were 0.447-15.1 times higher than Chinese lacustrine sediments. The Cr, Ni, Cu, Zn, Cd and Pb contents were significantly correlated with each other (p < 0.01), indicating similar deposition process. In addition, spatial and vertical distribution of heavy metals showed similar variation patterns and extreme high contents are distributed in the interchange area. The ecological risk of Maozhou River was much higher than other river sediments in Guangdong Province, especially for Cu, Cd and Ni. The variation pattern of potential ecological risk index is similar with that of heavy metals and the assessment results indicated high ecological risk in the Maozhou River sediments, which is in good agreement with the EF and I-geo results. This study would provide some references for the treatment of heavy metals' pollution in Maozhou River.

Automated summary

The study revealed that heavy metal concentrations in Maozhou River sediments were significantly higher than soil backgrounds in Guangdong Province and Chinese lacustrine sediments. The correlations between Cr, Ni, Cu, Zn, Cd, and Pb contents were significant. Maozhou River exhibited higher ecological risk compared to other rivers in Guangdong Province, especially for Cu, Cd, and Ni. The variation pattern of potential ecological risk index was similar to that of heavy metals, indicating high ecological risk in Maozhou River sediments.