Multiple classes of chemical contaminants in soil from an e-waste disposal site in China: Occurrence and spatial distribution

Yanxiao Zhou; Junjun Sun; Ling Wang; Guohua Zhu; Mufei Li; Jinsong Liu; Zuguang Li; Hongping Gong; Chenwang Wu; Ge Yin

doi:10.1016/j.scitotenv.2020.141924

Multiple classes of chemical contaminants in soil from an e-waste disposal site in China: Occurrence and spatial distribution

Sci Total Environ. 2021 Jan 15:752:141924. doi: 10.1016/j.scitotenv.2020.141924. Epub 2020 Aug 22.

Authors

Yanxiao Zhou¹, Junjun Sun², Ling Wang², Guohua Zhu², Mufei Li², Jinsong Liu³, Zuguang Li⁴, Hongping Gong², Chenwang Wu², Ge Yin⁵

Affiliations

¹ College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
² Zhejiang Key Laboratory of Ecological and Environmental Monitoring, Forewarning and Quality Control, Zhejiang Ecological and Environmental Monitoring Center, Hangzhou 310012, China.
³ College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China; Zhejiang Key Laboratory of Ecological and Environmental Monitoring, Forewarning and Quality Control, Zhejiang Ecological and Environmental Monitoring Center, Hangzhou 310012, China. Electronic address: liu70923@163.com.
⁴ College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China. Electronic address: lzg@zjut.edu.cn.
⁵ Shimadzu (China) Co., Ltd., Shanghai 200233, China.

PMID: 32898803
DOI: 10.1016/j.scitotenv.2020.141924

Abstract

E-waste recycling is well known for releasing halogenated organic compounds (HOCs) and heavy metals. This study investigated the occurrence and distribution of traditional and novel classes of contaminants, including chlorinated, brominated, and mixed halogenated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs, PBDD/Fs, PXDD/Fs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polyhalogenated carbazoles (PHCZs), in soil from an e-waste disposal site in Hangzhou. PBDEs were the most abundant, at 343-69306 ng kg^-1, followed by PHCZs (896-41,362 ng kg^-1), PCDD/Fs (349-19,396 ng kg^-1), PCBs (51.3-1834 ng kg^-1), PBDD/Fs (2.99-524 ng kg^-1) and PXDD/Fs (0.104-21.2 ng kg^-1). The detected target compound concentrations were generally lower than those reported in the literature for informal e-waste sites. Nevertheless, they can serve as a basis of information for evaluation and subsequent control. The toxic equivalent (TEQ) contributions from these contaminants (except PBDEs) decreased as follows: PCDD/Fs > PXDD/Fs > PHCZs > PCBs > PBDD/Fs. ΣDioxins (PCDD/Fs + PBDD/Fs + PXDD/Fs) accounted for 47.7%-97.2% of the total TEQs in the soil. OCDD, 1,2,3,4,6,7,8-HpBDF and OBDF were the dominant congeners, mainly derived from combustion and transport because of their low saturated vapor pressure. PXDFs were more abundant than PXDDs, and homologue profiles suggested a similar formation mechanism for PXDFs and PBDFs involving successive Br-to-Cl exchange. PHCZs were reported in soil from an e-waste disposal area for the first time, and their concentrations were several orders of magnitude higher than those of the other contaminants. Although the risk of human exposure in this study was estimated to be lower than the values recommended by the WHO (1-4 pg TEQ/kg bw/day), health implications still exist, and further investigations are necessary.

Keywords: Brominated flame retardants; E-waste; Halogenated organic compounds; Mixed halogenated dibenzo-p-dioxins/dibenzofurans; Soil.