Ecological Risk Assessment and Contamination History of Heavy Metals in the Sediments of Chagan Lake, Northeast China

Panfeng Liu,Meilan Wen,Sheli Chai,Liangliang Huang,Yinghong Liu,Xianrong Luo,Chaojie Zheng,Zhiqiang Wu

doi:10.3390/w13070894

Abstract

The study deals with the spatio-temporal distribution of heavy metals in the sediments of Chagan lake, Northeast China. The pollution history of heavy metals is studied simultaneously through the 210Pb dating method by analyzing the characteristic of As, Hg, Cd, Cr, Ni, Cu, Pb, and Zn concentration-depth profiles. The potential ecological risk index (RI) and geo-accumulation index (Igeo) were used to evaluate the contamination degree. Principal component analysis (PCA), based on the logarithmic transformation and isometric log-ratio (ilr) transformed data, was applied with the aim of identifying the sources of heavy metals. The element concentrations show that the heavy metals are enriched in the surface sediment and sediment core with a varying degree, which is higher in the surficial residue. The results of Igeo indicate that the Cd and Hg in the surface sediment have reached a slightly contaminated level while other elements, uncontaminated. The results of RI show that the study area can be classified as an area with moderate ecological risk in which Cd and Hg mostly contribute to the overall risk. For the sediment core, the 210Pb dating results accurately reflect the sedimentary history over 153 years. From two evaluation indices (RI and Igeo) calculated by element concentration, there is no contamination, and the potential ecological risk is low during this period. The comparative study between raw and ilr transformed data shows that the closure effect of the raw data can be eliminated by ilr transformation. After that, the components obtained by robust principal component analysis (RPCA) are more representative than those obtained by PCA, both based on ilr transformed dataset, after eliminating the influence of outliers. Based on ilr transformed data with RPCA, three primary sources could be inferred: Cr, Ni, As, Zn, and Cu are mainly derived from natural sources; the main source of Cd and Hg are associated with agricultural activities and energy development; as for Pb, it originated from traffic and coal-burning activities, which is consistent with the fact that the development of tourism, fishery, and agriculture industries has led to the continuous increasing levels of anthropogenic Pb in Chagan Lake. The summarized results and conclusions will undoubtedly enhance the governmental awareness of heavy metal pollution and facilitate appropriate pollution control measures in Chagan Lake.

Highlights

IntroductionLake sediments are the terminal point of material accumulation in the River Basin and the reservoir of potential pollution sources (such as heavy metals, organic matter, etc.) entering the lake [1–4]
Lake sediments are the terminal point of material accumulation in the River Basin and the reservoir of potential pollution sources entering the lake [1–4]
The comparison of heavy metals concentrations between the Chagan and other lakes showed that the content of heavy metal in the present study was lower than those in the major lakes (Table 2) [47,48], while higher than those in the Nen River, which is the largest tributary of the Songhua River [49]

Summary

Introduction

Lake sediments are the terminal point of material accumulation in the River Basin and the reservoir of potential pollution sources (such as heavy metals, organic matter, etc.) entering the lake [1–4]. The changes in the lake environmental conditions will potentially lead to the transfer of heavy metals from sediments to lake water, which will become the secondary water pollution sources, potentially affecting water quality and aquatic organisms in the lake [8–11]. Chagan Lake is an important ecological barrier, a vital fishery base, and a famous tourist area in the west of Jilin Province. It plays an essential role in regulating climate, protecting regional biodiversity, developing ecological industry, and maintaining regional ecological balance [12,13].

Methods

Results

Conclusion