The current status of heavy metal in lake sediments from China: Pollution and ecological risk assessment.

Yongfeng Xu,Yi Wu,Jiangang Han,Pingping Li

doi:10.1002/ece3.3124

Abstract

Heavy metal contamination in lake sediments is a serious problem, particularly in developing countries such as China. To evaluate heavy metal pollution and risk of contamination in lake sediments on a national scale in China, we collated available data in the literature of the last 10 years on lake sediments polluted with heavy metals from 24 provinces in China. Based on these data, we used sediment quality guidelines, geoaccumulation index, and potential ecological risk index to assess potential ecological risk levels. The results showed that approximately 20.6% of the lakes studied exceeded grade II level in Chinese soil quality standards for As, 31.3% for Cd, 4.6% for Cu, 20.8% for Ni, 2.8% for Zn, and 11.1% for Hg, respectively. Besides, the mean concentrations for As in 10.3% of lakes, Hg in 11.9% of lakes, and Ni in 31.3% of lakes surpassed the probable effect level. The potential ecological risk for toxic metals decreased in the order of Cd > Hg > As > Cu > Pb > Ni > Cr > Zn, and there were 21.8% of the lakes studied in the state of moderate risk, 10.9% in high risk, and 12.7% in very high risk. It can be concluded that Chinese lake sediments are polluted by heavy metals to varying degrees. In order to provide key management targets for relevant administrative agencies, based on the results of the pollution and ecological risk assessments, Cd, Hg, As, Cu, and Ni were selected as the priority control heavy metals, and the eastern coastal provinces and Hunan province were selected as the priority control provinces. This article, therefore, provides a comprehensive assessment of heavy metal pollution in lake sediments in China, while providing a reference for the development of lake sediment quality standards.

Highlights

There are a great number of lakes in China, with a total area of 81,415 km2, accounting for 0.9% of the country’s land
The results indicate that the risk of pollution in lake sediments increases with the development of economy, but decreases when a turning point is reached
Through a systematic assessment using sediment quality guidelines (SQGs), Igeo and potential ecological risk index methods, this study analyzes data from 110 Chinese lakes in 24 provinces and gives the first description of the overall pollution status of heavy metals in Chinese lake sediments and risks posed to the ecological environment

Summary

Introduction

There are a great number of lakes in China, with a total area of 81,415 km, accounting for 0.9% of the country’s land. The contamination of lake sediments by heavy metals has become one of the hot topics in the field of environmental science because of their potential biological toxicity, environmental durability, 5454 | www.ecolevol.org . Sediments can adsorb heavy metals in water and in turn reduce the level of pollution of the water. The pollutants can be released from the sediments when environmental conditions such as electrical conductivity (EC), pH, temperature, sediment particle size, oxidation–reduction potential change in the water or in the sediments and can cause secondary pollution to the water environment (Dong et al, 2014; Eggleton & Thomas, 2004; Fu et al, 2014; Ndimele, 2012; Zhang, Juying, Mamat, & Qing, 2016). It is necessary to investigate heavy metal pollution in lake sediments and assess ecological risks caused by heavy metals in order to protect the corresponding aquatic ecological environment and human health

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Discussion

Conclusion