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Chemosphere

Title:		Characterizing kinetics of transport and transformation of selenium in water-sediment microcosm free from selenium contamination using a simple mathematical model
Author(s):		Fujita M; Ike M; Hashimoto R; Nakagawa T; Yamaguchi K; Soda SO;
Address:		"Department of Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan"
Journal Title:		Chemosphere
Year:		2005
Volume:		58
Issue:		6
Page Number:		705 - 714
DOI:		10.1016/j.chemosphere.2004.09.042
ISSN/ISBN:		0045-6535 (Print) 0045-6535 (Linking)
Abstract:		"This study developed a seven-compartment model for predicting the fate of selenium (Se) in an aquatic environment containing a water-sediment boundary. Speciation of Se in water-sediment microcosms under microaerobic conditions was measured to evaluate first-order kinetics of Se transportation and transformation. The microcosm consisted of a 10-ml solution containing 1mM soluble Se as selenate (Se6+) or selenite (Se4+) and 8 g wet sediment that was free from Se contamination, sampled from the Senri, Yamato, or Yodo Rivers in Osaka, Japan. Stepwise reaction coefficients describing transportation and transformation were determined using an inverse method on this model which includes: selenate (Se(W)6+) and selenite (Se(W)4+) in ponded water; selenate (Se(S)6+) and selenite (Se(S)4+), elemental Se (Se0), organic Se (Se2-) in sediment; and gaseous Se (DMSe). During this 1-month experiment, soluble Se was transported from ponded water to the sediment and Se was transformed sequentially to other Se species through biochemical reactions. Experimental and kinetic analyses indicated quantitatively that the Yamato River microcosm, with its high organic matter content, had a high adsorption rate of soluble Se. The Yodo River microcosm had a low adsorption rate for Se6+ and a low Se reduction rate. The Senri River microcosm had an apparent high volatilization rate of DMSe. The model developed in this study is extremely useful for predicting fate of Se in aquatic environment in the field"
Keywords:		"Biological Transport Biotransformation Ecosystem *Geologic Sediments Kinetics Mathematics *Models, Theoretical Organoselenium Compounds/metabolism Selenium/*metabolism/pharmacokinetics Soil Pollutants/metabolism/pharmacokinetics Water Water Pollutants, Ch;"
Notes:		"MedlineFujita, M Ike, M Hashimoto, R Nakagawa, T Yamaguchi, K Soda, S O eng England 2004/12/29 Chemosphere. 2005 Feb; 58(6):705-14. doi: 10.1016/j.chemosphere.2004.09.042"