Microplastics as a potential carrier of DDT in the marine environment

DDT (dichlorodiphenyltrichloroethane) is a well-known organochlorinated pesticide that had been used in the past few decades, which successfully in control malaria and other diseases cause by insects. The chemical has been widely used in the 1940s but it was later discovered that DDT and its derivatives can disrupt organisms’ endocrine system, reducing or even prohibiting reproductive functions. Moreover, DDT has a half-life up to ten years and it can be stored in fatty tissue of organisms due to its high lipophilic property. These properties contribute DDT a highly persistent organic pollutant that can potentially accumulate and magnify in the food chain. DDT is banned in China in 1983. However, DDT is still found in sediment and water systems in the Pearl River Delta: indicating the existence of illegal uses. The objective of this study is to determine the DDT levels absorbed on microplastics, a type of marine plastic debris which is not readily visible to the naked eye. It is a concern that the pollutant DDT will transport by the small plastic debris downstream from the Mainland China, causing pollution on the local waters in Hong Kong, where many sensitive ecosystems, such as the habitat of Chinese White Dolphin and the Mai Po Marshes in Deep Bay, can be located. Samples have been collected from two beaches in Hong Kong: Fan Lau in Lantau and Sai Wan in Sai Kung. Sand samples were collected from the wreck line deposited by the monthly high tide and plastics were separated by density difference. Gas chromatographic method was adopted to determine DDT, DDD and DDE levels in the samples. Results illustrate that DDT and its metabolites are found on the microplastics in Hong Kong, their concentrations are also relatively high comparing to other countries. The poster will be focus on raising the attention of organochlorinated pesticide DDT pollutant on microplastic debris to the public.