Location: Hydrology and Remote Sensing Laboratory
Title: Utilizing thin-film solid-phase extraction to assess the effect of organic carbon amendments on the bioavailability of DDT and dieldrin to earthworms Authors
Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 10, 2013
Publication Date: February 1, 2014
Citation: Andrade, N.A., Centofanti, T., McConnell, L.L., Hapeman, C.J., Torrents, A., Nguyen, A., Beyer, W.N., Chaney, R.L., Novak, J.M., Anderson, M.O., Cantrell, K.B. 2014. Utilizing thin-film solid-phase extraction to assess the effect of organic carbon amendments on the bioavailability of DDT and dieldrin to earthworms. Environmental Pollution. 185:307-313. Interpretive Summary: DDT and dieldrin are insecticides that were heavily used from the 1940's to the 1960's. Both compounds were banned from agricultural uses in the early 1970's because they are highly toxic, do not degrade into harmless compounds, and can bioaccumulate in the fatty tissues of organisms. DDT degrades into DDD and DDE which are both toxic and are frequently found where DDT has been used. The soil of historic orchards can contain these compounds, and they are sometimes at sufficiently high levels to be of concern to wildlife. Assessing the potential exposure of these chemicals is a lengthy, laborious, and expensive process. In this study, a polymer was evaluated as a simpler method to mimic the fatty tissue of earthworms. The polymer and earthworms (Lumbricus terrestris) were exposed to soil from an historic orchard that contained high levels of DDT, DDE, DDD, and dieldrin. The polymer levels and the earthworm levels of the contaminants were similar. This polymer was then used to examine the effects of compost and other amendments on the availability of DDT, DDE, DDD, and dieldrin in the historic orchard soil. The amendments decreased the availability of dieldrin, DDD, and DDE, but not DDT. This polymer method provides scientists with a simpler technique to examine the availability and potential exposure of pollutants. These results will also be useful to land managers and policy makers who are considering converting historic orchards to other land uses.
Technical Abstract: While DDT and dieldrin have been banned in most countries, contaminated agricultural sites exist in many areas and wildlife exposure is still of concern. Soil was obtained from a historical orchard that received routine pesticide applications more than 40 years ago. Bioavailability of DDT and dieldrin to earthworms was assessed using earthworm bioassay, which is time-consuming and costly, and a thin-film solid-phase extraction (TF-SPE) assay. Earthworm bioassays resulted in bioaccumulation factors (d.w.) in the orchard soil of 1.52 ± 0.22, 4.69 ± 0.54, 4.86 ± 0.46, and 2.65 ± 0.22 for 4,4’-DDT, 4,4’-DDE, 4,4’-DDD, and dieldrin, respectively. Ethylene vinyl acetate polymer utilized in the TF-SPE accumulated analytes at the same level as Lumbricus terrestris lipids, therefore, the TF-SPE assay was utilized to assess bioavailability. The orchard soil was amended with different types of organic matter and bioavailability of chemicals was compared to the unamended soil. Bioavailability of 4,4’-DDE, 4,4’-DDD, and dieldrin decreased with increasing organic carbon content but not for 4,4’-DDT, indicating that interactions between analytes and amendments is complex in nature and needs further investigation.