Targeting Remediation Dredging by Ecological Risk Assessment of Heavy Metals in Lake Sediment: A Case Study of Shitang Lake, China

Zhongya Fan,Yiping Li,Shu Lin,Chunyan Tang,Wencai Wang,Fantang Zeng,Zhong Wang

doi:10.3390/su11247251

Zhongya Fan, Yiping Li + Show 5 more

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https://doi.org/10.3390/su11247251

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Abstract

Understanding the spatial distribution and pollution characteristics of heavy metals in lake sediment is crucial for studying deposition and migration processes, assessing lake conditions, and determining the extent of remediation dredging. The present work is a case study of heavy metal pollution in Shitang Lake in Anhui province, China. Heavy metal concentrations were determined in sediment at locations across the lake to a depth of 100 cm, and pollution levels were assessed on the basis of the Geoaccumulation Index (Igeo) and Potential Ecological Risk Index (RI). Hg and Cd were the predominant heavy metals in the sediment, and the Igeo and RI indicated high pollution levels in the northern and southern zones of the lake. These findings can be used to guide the prioritization of dredging operations.

Highlights

Shallow lakes are a significant part of wetland ecosystems
The formula is as follows: Igeo = log2(ωi/kωni) where Igeo denotes the Igeo, ωi denotes the mass fraction of heavy metal i in sediment, mg/kg, ωni denotes geochemical background values of heavy metal i in sedimentary rocks, mg/kg, and k is a constant that accounts for the variation in background values that may be caused by digenesis, and its value is usually 1.5
The results suggest that the severe ecological risk level component of the sediment is mostly within the top 40 cm and is the most important to dredge

Summary

Introduction

Shallow lakes are a significant part of wetland ecosystems They provide a habitat for birds and serve important functions in flood control, water supply, aquaculture, fishing, and recreation. The anthropogenic impact on the lake waters include a significant heavy metal load which accumulates in lake sediment and are sources of sustained pollution. These potentially hazardous elements can represent a threat for the safety of water supply since they can be remobilized by changes in environmental conditions (redox potential, pH, dissolved oxygen, and water temperature) [5,6]. The results include some uncertainty due to limitations in the assessment method

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