Organochlorine pesticides (OCPs) mainly including dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexanes (HCHs) are synthetic compounds with great chemical stability and listed as persistent organic pollutants (POPs). Due to the wide use throughout the world since the middle of the last century, these compounds are ubiquitous in the environment and pose an environmental and human risk.
GeJing under the supervision of Wang Jun from Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden investigatedthe composition, distribution and risk assessment of 18 OCPs in soils from the Midway Atoll, North Pacific Ocean. Results revealed that six OCPs were detected in the Midway Atoll, including α-HCH, γ-HCH, p,p′-DDT,o,p′-DDT, p,p′-DDE and p,p′-DDD with predominance of α-HCH, p,p′-DDD and p,p′-DDT. The 111 soil samples analysis from the Midway Atoll showed that the total concentrations ranged from 0 to 127 ng g-1 with a median concentration of 17 ng g-1 for HCHs and 1.4 to 643 gn g-1 with a median concentration of 168 ng g-1 for DDTs. The possible degradation pathways and potential sources of DDTs and HCHs were investigated. The total concentrations of DDTs and HCHs were used to evaluate the cancer risk probabilities in humans via ingestion, dermal contact and inhalation of soil particles. The study found that there was low cancer risk in all soil samples caused by ΣDDTs and ΣHCHs.
Since the Midway Atoll is a wildlife refuge, and a breeding and feeding habitat for seabirds, threatened green sea turtles and Hawaiian monk seals, this study provided the reference for the composition, distribution and risk assessment of OCPs and data for environment protection and restoration.
This project was supported in part by the U.S. Fish and Wildlife Service (QXL) and the Open Funding Project of the Key Laboratory of Aquatic Botany and Watershed Ecology, Chinese Academy of Sciences (JW). Relevant results published in Science of the Total Environment (10.1016/j.scitotenv.2013.03.015) entitled “Composition, Distribution and Risk Assessment of Organochlorine Pesticides in Soils from the Midway Atoll, North Pacific Ocean”.
Frequency distribution for concentration of seven OCPs in all soil samples fromthe Midway Atoll (image by WBG)
Ternary diagram of the relative amounts of the metabolic form of DDT in the soil samples collected from the Midway Atoll (image by WBG)
