Sorption of endocrine disrupting chemicals by condensed organic matter in soils and sediments Ke Sun a,b , Bo Gao c , Zheyun Zhang a , Guixiang Zhang a , Xitao Liu a , Ye Zhao a , Baoshan Xing b, * a State Key Laboratory of Water Simulation, School of Environment, Beijing Normal University, Beijing 100875, China b Department of Plant, Soil, and Insect Sciences, University of Massachusetts, Amherst, MA 01003, USA c Department of Water Environment, China Institute of Water Resources and Hydropower Research, Beijing 100038, China article info Article history: Received 26 February 2010 Received in revised form 18 May 2010 Accepted 19 May 2010 Available online 25 June 2010 Keywords: Adsorption Condensed organic matter Bisphenol A 17a-Ethinyl estradiol p–p bond abstract Sorption of 17a-ethinyl estradiol (EE2) and bisphenol A (BPA) by nonhydrolyzable carbon (NHC), black carbon (BC), and bulk soils and sediments was examined. All sorption isotherms were nonlinear and fit- ted both Freundlich and Dubinin–Ashtakhov (DA) models. The single-point organic carbon (OC)-normal- ized distribution coefficient (K OC ) of EE2 for the isolated NHC and BC was 2.7–4.8 times and 5.4–12.9 times greater, respectively, than that of the bulk samples. However, no clear trend in BPA K OC values was observed. Based on the contribution of soil/sediment organic matter (SOM) fractions to the overall sorption of BPA or EE2 by the bulk samples, condensed SOM (NHC and BC) generally played a dominant role to the overall sorption. The BPA adsorption capacity (Q 0 OC ) from the DA model was higher than that of EE2 on NHC and there was obvious difference in isotherm nonlinearity (n) between EE2 and BPA. These results suggest that BPA may have more access to the pore sites of NHC samples than EE2. The p–p bonds formed between BPA and NHC or BC may be stronger than that between EE2 and NHC or BC. This would be attributed to the fact that BPA has two benzene rings, and can also be used to explain the difference in hexadecane-water partition coefficient (K HW )-normalized K OC values (K OC /K HW ) of BPA and EE2 after fac- toring out the hydrophobic effect. These findings could be useful for predicting fate and ecological risks of endocrine disrupting chemicals (EDCs) (e.g., EE2 and BPA) in natural environments especially when soils or sediments become receptors for EDCs. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Sorption is an important process which often limits the biodeg- radation of pesticides and other organic contaminants by decreas- ing their aqueous concentration and reducing their accessibility by enzymes and microorganisms. The predominant sorbent of hydro- phobic organic contaminants (HOCs) in soils and sediments is or- ganic matter (OM) (Rutherford et al., 1992; Senesi, 1992; Senesi et al., 1995; Chefetz and Xing, 2009). Sorption of HOCs in soils and sediments is greatly affected by the type and amount of differ- ent soil/sediment organic matter (SOM), which in turn can affect HOCs fate and transport (Cornelissen et al., 2005). Significant ef- forts have been made to identify SOM fractions that control sorp- tion in soils and sediments. Several studies revealed that kerogen and black carbon (BC) materials can be important SOM compo- nents in soils and sediments (Karapanagioti and Sabatini, 2000; Accardi-Dey and Gschwend, 2002; Cornelissen et al., 2005), and these materials may dominate the sorption of HOCs, including polychlorinated biphenyles (PCBs), polycyclic aromatic hydrocar- bons (PAHs) and organochlorine pesticides (OCPs). (Cornelissen et al., 2005; Jeong et al., 2008; Sun et al., 2008). However, few stud- ies have examined the sorption of emerging contaminants by con- densed SOM in soils and sediments. Endocrine disrupting chemicals (EDCs), as one type of emerging contaminants, can alter endocrine function, and consequently cause adverse health effects. Published evidence has raised public and scientific concerns. Several studies showed the abnormalities in the sexual development of aquatic species and wildlife as well as humans even at exposure to low (ng L 1 ) concentrations (Col- born et al., 1993; Jobling et al., 1996, 1998; Sonnenschein and Soto, 1998; Thorpe et al., 2003). Among EDCs, 17a-ethinyl estradiol (EE2) and bisphenol A (BPA) are frequently used in environmental and toxicological research. Synthetic EE2 is mainly used in oral contraceptives. Toxicity tests using fish as acceptors showed that EE2 has a potency 10–50-fold greater than estrone (E1) and 17b- estradiol (E2) due to its longer half-life and bio-concentration po- tential (Segner et al., 2003). BPA is widely used in the plastics industry as a monomer for the production of polycarbonate and epoxy resins. Threats of BPA to human health and reproductive biology have been reported (Chen et al., 2002). The solubility of BPA in water is 50 times greater than EE2, and thus these two 0045-6535/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2010.05.028 * Corresponding author. Tel.: +1 413 545 5212; fax: +1 413 545 3958. E-mail address: bx@pssci.umass.edu (B. Xing). Chemosphere 80 (2010) 709–715 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere