Factors influencing the atmospheric concentrations of PCBs at an abandoned e-waste recycling site in South China

doi:10.1016/j.scitotenv.2016.08.131

Science of The Total Environment

Volume 578, 1 February 2017, Pages 34-39

https://doi.org/10.1016/j.scitotenv.2016.08.131 Get rights and content

Highlights

•
Seasonality of air PCBs at the e-waste site was mainly driven by the temperature.
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Diurnal variations of air PCBs were caused by the emission of e-waste recycling.
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E-waste recycling activities may still exist in the abandoned recycling area.

Abstract

The diurnal atmospheric concentrations of polychlorinated biphenyls (PCBs) were investigated at an abandoned e-waste recycling site in South China during winter and summer. Total PCB concentrations during winter and summer were 27.6–212 and 368–1704 pg/m³ in the particulate phase and 270–697 and 3000–15,500 pg/m³ in the gaseous phase, respectively. Both gaseous and particulate PCB concentrations and compositions exhibited significant difference between winter and summer samples, but no diurnal variations during the measurement period. The correlation analysis between PCB concentrations and meteorological conditions, including atmospheric temperature, humidity, and mixing layer height, suggested that the seasonal variability of atmospheric PCB concentrations was strongly temperature-dependent, while the diurnal variability was probably source-dependent. The temperature-driven variations can also be proved by the significant linear correlation between ln P and 1/T in the Clausius-Clapeyron plot. Although government has implemented controls to reduce e-waste pollution, both the relatively high concentrations of PCBs and the diurnal variation in the air suggested that emissions from occasional e-waste recycling activities may still exist in this recycling area. These results underline the importance of continuing e-waste recycling site management long after abandonment.

Graphical abstract

Introduction

Rapid development and short life cycles of electronic products have led to serious environmental problems resulting from toxic emissions from electronic waste (e-waste) recycling activities (Labunska et al., 2014, Luo et al., 2011, Wu et al., 2008). Polychlorinated biphenyls (PCBs) comprise a relatively high proportion of these toxicants, due to outdated e-waste recycling processes, such as open burning (Wang et al., 2005). Over the past few decades, PCBs have received much attention for their potential risks, as they are highly persistent, toxic, and bio-accumulative, and are classified as persistent organic pollutants (POPs) banned by the Stockholm Convention (Wang et al., 2008, Wong et al., 2007, Zheng et al., 2015).

For several decades, China has been one of the largest dumping sites of global e-waste (Chen et al., 2009, Wang et al., 2011). Intensive e-waste recycling actives in Qingyuan, Guiyu, and Taizhou of China have resulted in numerous environmental problems and have become the primary source of pollutants in these regions (Bi et al., 2007, Wu et al., 2010, Xing et al., 2011). Organic pollutants in e-waste disposal emissions, such as PCBs, polybrominated diphenyl ethers (PBDEs), and other flame retardants, have resulted in high levels of atmospheric pollution (Chen et al., 2009, Chen et al., 2011, Chen et al., 2014, Deng et al., 2007). These pollutants can undergo short- or long-range atmospheric transport and contaminate nearby or distant regions (Chen et al., 2009, Wang et al., 2011).

To mitigate heavy contamination, local governments have taken steps to manage e-waste pollution by prohibiting open burning and acid washing at small family workshops, centralizing e-waste recycling in factories and disposal centres with advanced technology, such as the “three waste” collection system (Zhang et al., 2012), and covering exposed contaminated soil with uncontaminated soil. Although these methods have partially controlled and reduced pollution from e-waste recycling sites, they also have disadvantages, including increasing the number of abandoned sites, contaminating additional soil, and producing secondary emissions, which are the main sources of organic pollutants in these regions. Furthermore, the subtropical climate of these low-latitude regions can increase organic pollutant emissions from primary (e-waste and its burning ash) and secondary (contaminated soil) sources (Breivik et al., 2011).

Previous studies have confirmed that atmospheric levels of organic pollutants can be significantly influenced by seasonal or diurnal temperature variations (Gouin et al., 2002, Valach et al., 2015), atmospheric boundary layer height (Gioia et al., 2014, Moeckel et al., 2008, Wang et al., 2015), hydroxyl radical reaction (Iacovidou et al., 2009, Zhang and Lohmann, 2010), and local sources (Wang et al., 2016). However, few studies have pay close attention to the factors influencing the atmospheric levels of PCBs at e-waste recycling sites, especially those under the control of environmental protection policies and regulations. Therefore, this study aimed to (1) characterize the seasonal and diurnal variations in atmospheric PCB levels at an abandoned e-waste dismantling site of South China and (2) determine the main factors influencing the atmospheric concentrations of PCBs at the e-waste recycling site.

Section snippets

Air sampling

Active air samples were collected within a subtropical e-waste recycling area (~ 0.5 km²) in Longtang, Qingyuan, Guangdong Province, South China (23.57°N, 113.01°E). This is one of the three most intensive e-waste recycling regions in China and is severely contaminated due to primitive e-waste recycling activities, such as open burning or acid washing. However, a centralized recycling factory replaced the outdated recycling sites, and the abandoned sites were covered with uncontaminated soil. The

Atmospheric PCB concentrations

Total particulate PCB concentrations were 27.6–212 pg/m³ (mean, 77.5 ± 53.5 pg/m³) and 368–1704 pg/m³ (mean, 831 ± 419 pg/m³) during winter and summer, respectively (Fig. 1). Total gaseous PCB concentrations were 270–697 pg/m³ (mean, 441 ± 130 pg/m³) and 3000–15,500 pg/m³ (mean, 6950 ± 3710 pg/m³) during winter and summer, respectively. The maximum particulate PCB concentration occurred at dusk during summer, while the minimum occurred at dawn during winter. The maximum gaseous PCB concentration occurred at

Conclusions

This study focused on the potential factors influencing the emission of particulate and gaseous PCBs in the atmosphere at an abandoned e-waste recycling site in South China. The significant difference of atmospheric PCBs at this e-waste recycling site between winter and summer suggested that their annual release was strongly dependent on temperature, while the lack of diurnal variability was due mainly to random emissions caused by variations in e-waste recycling intensity. Despite laws,

Acknowledgements

This study was supported by the National Natural Science Foundation of China (Nos. 21307133 and 41322008).

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Factors influencing the atmospheric concentrations of PCBs at an abandoned e-waste recycling site in South China

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Air sampling

Atmospheric PCB concentrations

Conclusions

Acknowledgements

Atmos. Environ.

Environ. Pollut.

Environ. Pollut.

Environ. Int.

Journal of Environmental Sciences-China

Chemosphere

J. Hazard. Mater.

Chemosphere

Chemosphere

Environ. Pollut.

Atmos. Environ.

Environ. Pollut.

Environ. Pollut.

Environ. Int.

Chemosphere

Atmos. Environ.

Exposure of electronics dismantling workers to polybrominated diphenyl ethers, polychlorinated biphenyls, and organochlorine pesticides in South China

Environ. Sci. Technol.