Levels, Sources and Potential Risks of Polychlorinated Biphenyls and Organochlorine Pesticides in Sediments of Qingduizi Bay, China: Does Developing Mariculture Matter?

Mingshan Song,Xing Liu,Liang Qu,Humin Zong,Lili Wang,Gorka Bidegain,Xiutang Yuan,Chunjiang Guan,Wei Huang,Anguo Zhang,Xiaolong Yang

doi:10.3389/fmars.2019.00602

Abstract

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), were studied in the surface sediments of Qingduizi Bay (Yellow Sea, China). The goal was to identify whether their distribution and levels can be influenced by aquaculture activities in ponds. The total concentration of PCBs in mariculture ponds (MP) and the outer bay (OB) ranged from 0.61 ng g−1 dry weight (dw) to 2.10 ng g−1 dw and from 0.79 ng g−1 dw to 2.41 ng g−1 dw, respectively. The concentrations of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), ranged from 0.03 ng g−1 dw to 0.18 ng g−1 dw and from 0.24 ng g−1 dw to 31.14 ng g−1 dw, respectively. The levels of PCBs were significantly different between MP and OB, whereas no significant differences of DDTs and HCHs were detected between the two areas. Among the PCB congeners, tri-PCB and tetra-PCB were dominant, implying a historical input and atmospheric deposition for PCBs. The isomeric ratios of the compositions implicated mixture sources of new and historical inputs for HCHs. However, DDT-containing feed and pesticides in aquaculture activities could be the primary source of newly inputted DDTs. A parallel ecological risk assessment analysis showed the impact of DDTs on marine organisms. In conclusion, aquaculture in ponds influences the occurrence and distribution of persistent halogenated compounds in coastal areas, causing potential ecological impacts. This result should be a baseline for the management of aquaculture ponds regarding these compounds.

Highlights

Coastal ecosystems are the environments most vulnerable to pollution due to anthropogenic stresses worldwide (Ricciardi and Atkinson, 2004)
In China, the manufacture and agricultural usage of most Polychlorinated biphenyls (PCBs) and Organochlorine pesticides (OCPs) were banned in 1974 and 1983, respectively (Wang et al, 2005), these organic chemicals can still be routinely detected in various environmental compartments (Adeleye et al, 2016; Li et al, 2017; Zhao et al, 2018)
The primary objectives of this study are to (i) perform a comparative study concerning the occurrence and distribution of PCBs and OCPs in the surface sediments of mariculture ponds and the adjacent outer areas in a bay; (ii) clarify whether the increasing aquaculture activities cause a fresh input of the pollutants; and (iii) assess the potential ecotoxicological risks of PCBs and OCPs in sediments for benthic organisms

Summary

Introduction

Coastal ecosystems are the environments most vulnerable to pollution due to anthropogenic stresses worldwide (Ricciardi and Atkinson, 2004). Organochlorine pesticides (OCPs) encompass a wide range of chemicals, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), dieldrin, endrin, and aldrin. They have been widely used for pest management in agriculture and aquaculture because of their high efficiency and low cost (Wu et al, 2015). Due to the slow degradation of PCBs and OCPs, the residues and their catabolites would persist in the ecosystem for a long time (Yu et al, 2014; Wu et al, 2015) These pollutants in environmental mediums could provide valuable records and represent potential ecological risks that should be seriously considered. There are few available reports focusing on the levels and risk assessments of PCBs and OCPs in riverine bays

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Methods

Results