title: Oxidation mechanism and overall removal rates of endocrine disrupting chemicals by aquatic plants.
abstract: The purpose of this study was to evaluate experimentally and theoretically the oxidation mechanisms and overall removal rates of phenolic endocrine disrupting chemicals (EDCs) by aquatic plants. EDCs used in this study were bisphenol-A (BPA), 2,4-dichlorophenol (2,4-DCP), 4-tert-octylphenol (4-t-OP), and pentachlorophenol (PCP). Referring to reported detection levels in aquatic environments and contaminated sites, the feed concentration of each EDC was set from 1 to 100μg/L. Experimental results showed that, except for PCP, phenolic EDCs were stably and concurrently removed by different types of aquatic plants over 70 days in long-term continuous treatments. Primal enzymes responsible for oxidation of BPA, 2,4-DCP, and 4-t-OP were peroxidases (POs). Moreover, enzymatic removal rates of BPA, 2,4-DCP, and 4-t-OP by POs were more than 2 orders of magnitude larger than those by aquatic plants. Assuming that overall removal rates of EDCs are controlled by mass transfer rates onto liquid films on the surface of aquatic plants, an electrochemical method based on the limiting current theory was developed to measure the mass transfer rates of EDCs. Because of extremely large removal rates of EDCs by POs, observed removal rates by aquatic plants were in reasonably good agreement with calculated results by a mathematical model developed based on an assumption that mass transfer limitation is a rate-limiting step.
authors: Department of Soil Science, Federal University of Lavras, Lavras, MG 37200-000, Brazil. Electronic address: andrereis@dcs.ufla.br.
authors: A R
authors: AR
authors: Reis
authors: Department of Civil and Environmental Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 Japan.
authors: K
authors: K
authors: Tabei
authors: Department of Civil and Environmental Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 Japan. Electronic address: sakaki@waseda.jp.
authors: Y
authors: Y
authors: Sakakibara
mesh_terms: D001673:Biodegradation, Environmental; D052244:Endocrine Disruptors / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D052244:Endocrine Disruptors; D010636:Phenols; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D010544:Peroxidases
keywords: Biological Fenton reaction; Endocrine disrupting chemicals; Hydrogen peroxide; Peroxidase; Phytoremediation