Differences in p,p 0 -DDE bioaccumulation from compost and soil by the plants Cucurbita pepo and Cucurbita maxima and the earthworms Eisenia fetida and Lumbricus terrestris Richard Peters a , Jason W. Kelsey a, * , Jason C. White b a Program in Environmental Science and Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, PA 18104, USA b Department of Soil and Water, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT 06504, USA Received 18 July 2006; accepted 26 November 2006 Availability of p,p 0 -DDE to earthworms and plants was dramatically different in soil and compost. Abstract Two plant species, Cucurbita pepo and Cucurbita maxima, and two earthworm species, Eisenia fetida and Lumbricus terrestris, were exposed to soil and compost with equivalent p,p 0 -DDE contamination. Pollutant bioconcentration was equal in plant roots in both media, but translocation was higher in C. pepo. Bioaccumulation by E. fetida was approximately 6- and 3-fold higher than that by L. terrestris in the soil and compost, respectively. For all species, p,p 0 -DDE uptake was significantly greater from soil than from compost; 7- to 8-fold higher for plant roots and 3- to 7-fold higher for worms. Abiotic desorption from soil was approximately twice that from the compost. When all the data are normalized for organic-carbon content of the media, the contaminant is more tightly bound by soil than compost. Although the risk associated with p,p 0 -DDE is higher in soil than compost, important mechanistic differences exist in contaminant binding to organic carbon in the two media. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Compost; Earthworm; Cucurbita; Bioavailability; Bioaccumulation; p,p 0 -DDE 1. Introduction Biological availability of soil pollutants is important because it controls the extent to which toxic substances can adversely affect organisms and ecosystems. Many variables affect bioavailability, including compound residence time in soil, pollutant chemistry, soil and environmental conditions, and species differences and interactions. A number of studies have demonstrated that aging of pollutants in soil can lead to reduced uptake by organisms (Nash and Woolson, 1967; Stein- berg et al., 1987; Scribner et al., 1992; Erickson et al., 1993; Hatzinger and Alexander, 1995; Kelsey et al., 1997; Riaz et al., 2004; Swindell and Reid, 2006). This decreasing bio- availability occurs even as the total contaminant soil concen- tration remains constant. In addition to residence time, soil organic matter content, cation exchange capacity, and soil surface area have also been shown to influence the bioavail- ability of organic compounds (Chung and Alexander, 2002). In a similar study, the extractability of phenanthrene, pyrene, and benzo(a)pyrene from soil by non-rigorous methods differed as a function of soil organic matter and clay content (Swindell and Reid, 2006). Soil moisture content and wet- ting/drying cycles have also been shown to alter the uptake and extractability of contaminants (Kottler et al., 2001; Rug- giero et al., 2002). Pollutant properties such as hydrophobicity, charge/polarity, and other chemical characteristics affect avail- ability as well (Alexander, 2000; Ruggiero et al., 2002). Finally, biological factors such as species differences and interactions appear to exert a substantial influence on the * Corresponding author. Tel.: þ1 484 664 3144; fax: þ1 484 664 3546. E-mail addresses: rp232604@muhlenberg.edu (R. Peters), kelsey@ muhlenberg.edu (J.W. Kelsey), jason.white@po.state.ct.us (J.C. White). 0269-7491/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2006.11.030 Environmental Pollution 148 (2007) 539e545 www.elsevier.com/locate/envpol