Risk assessment of organochlorine pesticides in drinking water source of the Yangtze River

https://doi.org/10.1016/j.ecoenv.2019.109390Get rights and content

Highlights

  • The predominant organochlorine pesticides in water, SPM, and sediment were β-HCH and p,p'-DDE.

  • The history use of technical HCH and technical DDT were main sources.

  • Fugacity fractions indicated the transmission of HCHs, DDTs and PeCB from water to sediment.

  • Low ecotoxicological risk and no carcinogenic risk were observed.

Abstract

Organochlorine pesticides have been banned for many years, but the residual trace amount of organochlorine in water may still pose ecotoxicological risk. Meanwhile, the potential risk of organochlorine pesticides released from sediments, especially into drinking water sources, is receiving increasing attention. The present study assessed the pollution and potential risk of drinking water sources along the midstream and downstream Yangtze River. Residues of organochlorine pesticides (OCPs) in water, suspended particle matter (SPM), and sediment were evaluated with isotope dilution HRGC/HRMS. The results indicated that OCPs in water, SPM, and sediment ranged in 0.52–92.97 ng/L, 0.10–4.10 ng/L, and 0.038–11.36 ng/g, respectively. The predominant OCPs in water, SPM, and sediment were β-HCH, p,p'-DDE and PeCB. At site Y1, 8, 13, 18, β-HCH has a higher proportion in sediment samples, while, α-HCH has a higher proportion in SPM samples. The industrial use of HCHs in the history was the main HCHs source for most water and sediment samples, which indicated an absence of fresh inputs of industrial HCHs. Meanwhile, the abundance of p,p'-DDE in water, sediment and SPM samples could be attributed to long-term aerobic degradation of DDTs. The values of ffsw of HCHs, DDTs and PeCB indicate the transfer from water to sediment. Risk assessment showed that HCHs and DDTs posed low ecotoxicological risk to the Yangtze River.

Introduction

Organochlorine pesticides (OCPs) have been extensively studied in the last 30 years because of their long-range transmission, high lipophilicity, chronic and acute toxicities, as well as persistence and bioaccumulation in the environment (Wang et al., 2018a; Da et al., 2014; He et al., 2012; Fang et al., 2017; Li et al., 2014; Rainer et al., 2014). Two typical representatives of OCPs, hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), were widely used in China from 1950 to 1983 (Lin et al., 2016). Dichlorodiphenyltrichloroethanes (DDTs, including o,p′-DDT, p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE and p,p′-DDE) have been proven potentially toxic and their health risk to human has been demonstrated (Zhang et al., 2017). Among the four isomers of hexachlorocyclohexanes (HCHs, including α-HCH, β-HCH, γ-HCH, and δ-HCH), β-HCH is the most persistent isomer in the environment, and its bioaccumulation and chronic toxicity have been shown to incur serious consequences (Yang et al., 2005b; Balázs et al., 2018). As of today, lindane (γ-HCH) is still widely used in some countries, probably because of its easy degradation, slow-acting toxic effects, and low carcinogenic risk, although it has been shown to possess some neurotoxicity (Zhu et al., 2017). Although DDTs and HCHs have been banned for nearly 30 years, their residues can still be found in the environment, including in some drinking water sources (Da et al., 2014; Liu et al., 2016; Zhao et al., 2018).

Pathways of transporting OCPs into the aquatic environment include deposition, industrial discharge, run-off from farmland, etc. The soil organic carbon–water partitioning coefficient (Koc*) is an important parameter that evaluates the equilibrium of the contaminants between sediment and water (Huang et al., 2019; Donald and Anderson, 2017). In addition, the sediment–water transmission of OCPs is also very important in controlling water quality and assessing the exposure of aquatic organism and human to environmental contamination (Tang et al., 2013; Yang et al., 2013). While many studies have focused on the soil–air and water–air exchange of persistent organic pollutants (PAHs, PCBs, OCPs, etc.), few examined the sediment–water transmission to compare the transmission trends of different media (Pokhrel et al., 2018; Juhasz et al., 2014). Various multimedia models can be used to quantitatively explore the fate and transmission of OCPs in the environment (Liu et al., 2016; Wang et al., 2011; Ali et al., 2016; Yadav et al., 2019). The process of sediment–water transmission can be quantified with the fugacity fraction (ff) approach to understand the sediment–water transmission of OCPs and assess the sediment–water equilibrium.

The safety of drinking water has received increasing attention in recent years (Ding et al., 2019; Zhang et al., 2019). Unfortunately, OCPs are detected in many drinking water sources, such as the Yellow River and the Taihu Lake (Wang et al., 2018a; Li et al., 2018a). Since trace organochlorine in water may pose ecotoxicological risk and seriously threaten human health (Li et al., 2018b; Müllera et al., 2017; Emmaluel et al., 2015)., it is necessary carry out health risk assessment by evaluating the safety of drinking water.

The Yangtze River Delta is an area with intensive economic development as a result of globalization, and it is the largest comprehensive industrial base in China. It mainly receives the supply of drinking water from the Yangtze River. In this study, to evaluate the pollution and potential risks of drinking water sources along midstream and downstream Yangtze River, residues of organochlorine pesticides (OCPs) in water, suspended particle matter (SPM), and sediment were investigated by isotope dilution using HRGC/HRMS. This study may provide useful information with regard to the sediment–water transmission of OCPs and serve as a benchmark for policy makers to reduce the associated health risks.

Section snippets

Study area and sampling

Samples of overlying water, SPM, and sediment were collected in November 2016 from drinking water sources along the Yangtze River at the locations specified in Fig. 1, among which the midstream sites included Y1–Y14 and the downstream sites included Y17–Y35. Surface water samples were filled into a 1 L brown glass bottle and passed through 0.45 μm filter membrane, and samples of SPM were then retained on the filter membrane. All samples were stored in an ice box. Sediments were collected at

Occurrence of OCPs in drinking water sources from the Yangtze River

Tables S1–S3 list the concentration of HCHs, DDTs and PeCB in the water, SPM, and sediment samples. The standard of ES-5349-L includes 22 OCP compounds (Table S4), among which with only HCHs, DDTs and PeCB are discussed in the current study because the other compounds were not readily found in the samples. Analyses showed that all water and sediment samples contained PeCB, α-HCH, β-HCH, γ-HCH, and δ-HCH. The ΣOCPs concentration ranged in 0.31–5.39 ng/L, 0.23–11.36 ng/L, and 0.52–92.97 ng/g for

Conclusions

The ΣHCHs and ΣDDTs concentrations were at a low level in the drinking water sources of the Yangtze River. The dominant OCPs included PeCB, β-HCH and p,p′-DDE in the water and sediment samples collected along the midstream and downstream Yangtze River. Both water and sediment samples had a much higher concentration of α-HCH and β-HCH than γ-HCH and δ-HCH. The medium value concentration of DDTs from sediment samples fell in the order of p,p'-DDE > o,p'-DDT > o,p'-DDD > p,p'-DDT > p,p'-DDD. The

Acknowledgments

This research was funded by special program for the Basic Work of Science and Technology (2015FY110900-6).

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