DDT is an organochlorine insecticide that was banned in the US in the 1970s. However, DDT and its main metabolite DDE are still widely detected in sediments. Given their strong hydrophobicity, bioavailability plays a critical role in the actual risk of DDT derivatives to aquatic organisms. Chemically based approaches have been explored for predicting the bioavailability of organic compounds due to their reproducibility, simplicity, and low cost. In this study, a stable isotope exchange method (IEM) was developed to measure the exchangeable pool (E) of both p,p'-DDT and p,p'-DDE in sediments as an indicator of bioavailability. The measured E values showed a decreasing trend with an increase in sediment organic carbon (OC) content. The capability of IEM to estimate bioavailability was validated by comparing with other methods, including solid phase microextraction (SPME) and Tenax-aided desorption. There was generally a good agreement among these biomimetic methods.

Isotope exchange method (IEM) to study the bioavailability of DDTs in sediment

244th National Meeting (2012)

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