Elsevier

Environmental Pollution

Volume 250, July 2019, Pages 695-707
Environmental Pollution

Spatiotemporal distribution, source apportionment and ecological risk assessment of PBDEs and PAHs in the Guanlan River from rapidly urbanizing areas of Shenzhen, China

https://doi.org/10.1016/j.envpol.2019.04.107Get rights and content

Highlights

  • The concentrations of PBDEs and PAHs in the DS were higher than those in the WS.

  • The sources of PAHs were mainly comprised of fossil fuels and biomass burning.

  • Octa-BDE commercial products were major sources of PBDEs in the study area.

  • PBDEs posed high ecological risks, while PAHs posed low risks in the Guanlan River.

  • PBDEs and PAHs levels were affected by the content of TN, NH4-N, COD, BOD5 and DO.

Abstract

In this study, nine congeners of polybrominated diphenyl ethers (PBDEs) and sixteen congeners of polycyclic aromatic hydrocarbons (PAHs) were measured in water samples to elucidate their spatial distribution, congener profiles, sources and ecological risks in the Guanlan River during both the dry season (DS) and the wet season (WS). The concentration of Σ9PBDE ranged from 58.40 to 186.35 ng/L with an average of 115.72 ng/L in the DS, and from 8.20 to 37.80 ng/L with an average of 22.15 ng/L in the WS. Meanwhile, the concentration of Σ16PAHs was ranged from 121.80 to 8371.70 ng/L with an average of 3271.18 ng/L in the DS and from 1.85 to 7124.25 ng/L with an average of 908.11 ng/L in the WS. The concentrations of PBDEs and PAHs in the DS were significantly higher than those in the WS, probably due to the dilution of the river during the rainy season. Moreover, the spatial distribution of pollutants revealed decreasing trend in the concentration from upstream to downstream and almost identical pattern was observed during both seasons. The source apportionment suggested that penta-BDE and to some extent octa-BDE commercial products were major sources of PBDEs in the study area. However, the sources of PAHs were mainly comprised of fossil fuels and biomass burning, followed by the petroleum products and their mixtures. The results of the ecological risk assessment indicated PBDEs contamination posed high ecological risks, while PAHs exhibited low or no ecological risks in the study area. Consistent with the environmental levels, the ecological risks of pollutants were relatively lower in the WS, compared to that in the DS. The results from this study would provide valuable baseline data and technical support for policy makers to protect the ecological environment of the Guanlan River.

Introduction

A group of synthetic compounds, polybrominated diphenyl ethers (PBDEs) belong to a broad class of brominated flame retardants (BFRs), which are widely used for more than four decades in a multitude of products including televisions, computers, textiles, furniture upholstery, etc. (Li et al., 2016; Rahman et al., 2001). PBDEs significantly reduce fire hazards in polymeric substances by releasing bromine atoms that capture H and OH radicals formed during combustion at a temperature 50 °C below the ignition temperature of the polymer matrix (Vane et al., 2010). PBDEs have been produced and used in three commercial mixtures: decabromodiphenyl ether (deca-BDE) octabromodiphenyl ether (octa-BDE), and pentabromodiphenyl ether (penta-BDE). These compounds have been ubiquitously present in various environmental media such as water, soil and sediment, as well as in aquatic organisms (Mahmood et al., 2015; Oros et al., 2005; Pei et al., 2018) and human tissues (Hites and Ronald, 2004). Due to persistence and bio-accumulative nature, these compounds can cause serious environmental problems and induce toxicity to both animals and humans. These are the potential reasons that lead towards the classification of penta- and octa-BDEs as persistent organic pollutants (POPs), and production of these chemicals is banned in Europe and the United States of America (USA) (Deng et al., 2011; Golnoush, 2015; Klosterhaus et al., 2012). Among PBDEs, a popular commercial penta-BDE mixture DE-71 (including BDE-47 and BDE-99), has been extensively used as flame retardant for many years (Kuiper et al., 2006; Schecter et al., 2006; Yen et al., 2009).

Polycyclic aromatic hydrocarbons (PAHs), a typical group of chemicals containing two or more aromatic rings, are prevalent in the environment. The United States Environmental Protection Agency (USEPA) has regulated and prioritized 16 PAHs congeners concerning to their environmental persistence, carcinogenicity, toxicity and mutagenicity (Fernandes and Marin-Morales, 2009; Zedeck, 1980). Exposure to PAHs has been implicated in cancer and other diseases such as reproductive and neurological disorders (Bolden et al., 2017). Previous studies have also reported elevated environmental levels of PAHs and associated cancer risks in China (Han et al., 2019; Hong et al., 2016; Meng et al., 2019; Wang et al., 2018; Zhang et al., 2019b; Zhu et al., 2019a; Zhu et al., 2019b).

In recent years, the detection rate and concentration of PBDEs and PAHs in human and environment have been on the rise and most of these compounds have been identified as carcinogenic, mutagenic, and teratogenic (Jin et al., 2018; Ju et al., 2016; Ouyang et al., 2018; Rombola et al., 2019). PBDEs commonly originate from industrial activities (Zhang et al., 2014). Reportedly, penta-BDE and octa-BDE were used predominantly in polyurethane foam and the casings for electronic products, respectively (Wang et al., 2015). Regarding PAHs sources, an increase in energy consumption has been identified as a leading factor in increasing PAHs emissions (Kim and Chae, 2016; Zhang et al., 2019b). Source appointment of PAHs in water samples can be a good indicator of the local energy consumption pattern, which can also provide both the qualitative and quantitative information about emission sources (Blanchard et al., 2001; Katsoyiannis et al., 2007; Kong et al., 2012; Mansuyhuault et al., 2009). The diagnostic molecular ratios (DMRs) directly use the physiochemical properties of PAHs to discriminate pollution sources, while principal component analysis (PCA) mainly provides the qualitative information (Dai et al., 2007; Sicre et al., 1987). Previously, the distribution and sources of PBDEs and PAHs have been the focus of numerous investigations (Barakat et al., 2011; Chen and Chen, 2011a; Doong and Lin, 2004; Men et al., 2009; Soclo et al., 2000). However, studies are still elusive that highlighted the current environmental levels, sources, and ecological risks of PBDEs and PAHs in the catchment areas of an urban river such as the Guanlan River, which is stretched along the rapidly urbanizing areas in Shenzhen City.

Shenzhen is a fastest growing industrial city with significant emissions of PBDEs and PAHs through consumer and industrial products, which ultimately dump into the water bodies through atmospheric deposition and surface runoff (Meng-Yao et al., 2007). Previously, considerable studies have been conducted on the occurrence of POPs in large rivers such as the Yellow River, the Hai River, the Liao River and the Pearl River in China. However, limited information is available about the contamination of POPs and associated environmental concerns in rapidly urbanizing river catchment areas such as Shenzhen, where the runoff, land uses and underlying surface have been greatly changed by extensive anthropogenic activities over the years (Li et al., 2010; Mulligan et al., 2017; Qian et al., 2009; Wang et al., 2013). In Shenzhen, the sewage treatment facilities have treatment capacity of 1.12 million tons/d, which accounted for the treatment of only 80% wastewater, and around 374,000 tons/d of wastewater is discharged directly into the Guanlan River without treatment. Therefore, it is worthy to systematically investigate the contamination level, potential sources and ecological risks of anthropogenic pollutants such as PBDEs and PAHs in the Guanlan River (Cloutier et al., 2017). Two types of typical organic pollutants (PBDEs and PAHs) have been frequently investigated in the previous studies (Bi et al., 2018b; Jarova et al., 2016; Liu et al., 2018; Malik et al., 2011; Pei et al., 2018; Qi et al., 2016; Zhang et al., 2015; Zhang et al., 2019a) (Supplementary Information Table S1). OCPs are also commonly studied legacy organic pollutants, however, Shenzhen is a rapidly urbanizing city and agriculture activities are rarely existed in the area (Luo and Cai, 2007). Consequently, the use and detection rate of pesticides are very low. Therefore, this study focuses only on PBDEs and PAHs, while OCPs are not discussed here. The objectives of this study are designed to: (i) determine the spatial distribution, seasonal variation and compositional pattern of PBDEs and PAHs in the Guanlan River; (ii) identify the possible sources of PBDE and PAHs by using PCA and DMRs methods; and (iii) the ecological risk assessment of PBDEs and PAHs in the Guanlan River.

Section snippets

Chemicals and standards

Individual standard solutions of 9 PBDEs (named by IUPAC number: BDE-28, BDE-47, BDE-66, BDE-85, BDE-99, BDE-100, BDE-138, BDE-153, and BDE-154) and 16 PAHs (classified as priority pollutants by the USEPA, i.e., naphthalene (Nap), acenaphthylene (Ace), acenaphthene (Ac), fluorene (Flu), phenanthrene (Phe), anthracene (Ant), fluoranthene (Fla), pyrene (Pyr), benzo[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP),

Spatiotemporal distribution and compositional profiles of PBDEs

The concentrations and detection frequencies of PBDEs in water samples collected from the Guanlan River are summarized in Table 1. In all of the samples (except Sb) analyzed, the Σ9PBDE ranged from 58.40 to 186.35 ng/L with an average of 115.72 ng/L in the DS, and 8.20–37.80 ng/L with an average of 22.15 ng/L in the WS. PBDEs were not detected at the Sb during both the DS and WS. Importantly, the Sb was located at the upstream of the Longhua River with less anthropogenic activities and

Conclusions

In this study, the contamination levels, spatiotemporal distribution, sources and ecological risks of PBDEs and PAHs were investigated in the Guanlan River. Penta-BDE had higher contribution to the total PBDEs in the study area, indicating that penta-BDE was the widely used BFRs in this study area. Three-ring and four-ring PAHs were the dominant compounds in the Guanlan River. The source apportionment indicated that the sources of PAHs were mainly from the burning of fossil fuels and biomass,

Acknowledgements

The present study was supported by the National Natural Science Foundation of China (51579003), the Shenzhen Municipal Development and Reform Commission (Discipline construction of watershed ecological engineering), the Government of Longhua Distrcit, Shenzhen, China (0851-1461SZ01CL87), and the basic scientific research special fund of Nonprofit Research Institutions at the central level of China (HKY-JBYW-2016-05). The authors also acknowledge the contribution of Research group members in the

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