Distribution and sources of DDT and its metabolites in porewater and sediment from a typical tropical bay in the South China Sea

Shiyun Peng; Deming Kong; Liting Li; Chunlin Zou; Fajin Chen; Meiju Li; Tao Cao; Chiling Yu; Jianzhong Song; Wanglu Jia; Ping'an Peng

doi:10.1016/j.envpol.2020.115492

Distribution and sources of DDT and its metabolites in porewater and sediment from a typical tropical bay in the South China Sea

Environ Pollut. 2020 Dec:267:115492. doi: 10.1016/j.envpol.2020.115492. Epub 2020 Sep 8.

Authors

Shiyun Peng¹, Deming Kong², Liting Li², Chunlin Zou³, Fajin Chen², Meiju Li³, Tao Cao³, Chiling Yu⁴, Jianzhong Song⁵, Wanglu Jia⁴, Ping'an Peng³

Affiliations

¹ State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China; College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, 524088, China.
² College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, 524088, China.
³ State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
⁴ State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
⁵ State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China. Electronic address: songjzh@gig.ac.cn.

PMID: 33254672
DOI: 10.1016/j.envpol.2020.115492

Abstract

Dichlorodiphenyltrichloroethane (DDT) is well known for its harmful effects and has been banned around the world. However, DDT is still frequently detected in natural environments, particularly in aquaculture and harbor sediments. In this study, 15 surface sediment samples were collected from a typical tropical bay (Zhanjiang Bay) in the South China Sea, and the levels of DDT and its metabolites in sediment and porewater samples were investigated. The results showed that concentrations of DDXs (i.e., DDT and its metabolites) in bulk sediments were 1.58-51.0 ng g^-1 (mean, 11.5 ng g^-1). DDTs (DDT and its primary metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE)) were the most prominent, accounting for 73.2%-98.3% (86.1% ± 12.8%) of the DDXs. Additionally, high-order metabolites (i.e., 1-chloro-2,2-bis(4'-chlorophenyl)ethylene (p,p'-DDMU), 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU), 2,2-bis(p-chlorophenyl)ethanol (p,p'-DDOH), 2,2-bis(p-chlorophenyl)methane (p,p'-DDM), and 4,4'-dichlorobenzophenone (p,p'-DBP)) were also detected in most of the sediment and porewater samples, with DDMU and DBP being predominant. The DDTs concentration differed among the sampling sites, with relatively high DDTs concentrations in the samples from the aquaculture zone and an area near the shipping channel and the Haibin shipyard. The DDD/DDE ratios indicated a reductive dichlorination of DDT to DDD under anaerobic conditions at most of the sampling sites of Zhanjiang Bay. The possible DDT degradation pathway in the surface sediments of Zhanjiang Bay was p,p'-DDT/p,p'-DDD(p,p'-DDE)/p,p'-DDMU/p,p'-DDNU/ … /p,p'-DBP. The DDXs in the sediments of Zhanjiang Bay were mainly introduced via mixed sources of industrial DDT and dicofol, including fresh input and historical residue. The concentrations of DDXs in porewater samples varied from 66.3 to 250 ng L^-1, exhibiting a distribution similar to that in the accompanying sediments. However, the content of high-order metabolites was relatively lower in porewater than in sediment, indicating that high-order degradation mainly occurs in particles. Overall, this study helps in understanding the distribution, source, and degradation of DDT in a typical tropical bay.

Keywords: DDT and Its metabolites; Degradation; Dissolved organic carbon; Porewater.

MeSH terms

Bays
China
DDT* / analysis
Environmental Monitoring
Geologic Sediments
Water Pollutants, Chemical* / analysis

Substances

Water Pollutants, Chemical
DDT