Adsorption and desorption of arsenate in Louisiana rice soils |
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| Authors: | Kenan Gedik Manoch Kongchum Muhammet Boran Ronald D Delaune |
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| Institution: | 1. School of the Coast and Environment, Wetland Biogeochemistry, Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA;2. Faculty of Marine Science, Karadeniz Technical University, Trabzon, Turkey;3. Rice Research Station, Louisiana State University Agricultural Center, LA, USA;4. Faculty of Marine Science, Karadeniz Technical University, Trabzon, Turkey |
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| Abstract: | Adsorption and desorption of arsenic (As) in the soil are dominant parameters that affect the mobility and bioavailability of arsenic. Batch arsenate adsorption and desorption experiments were conducted using soils collected from three Louisiana, USA, aquaculture ponds representing different crayfish farming and rice cultural practices. Arsenate adsorption behavior in the soils was investigated using Freundlich and Langmuir sorption equations. Results demonstrated that the Langmuir isotherm model was the best fit based on statistical correlation with soil properties governing adsorption, for the entire range of arsenate concentrations for all soils. Adsorption of As(V) was governed by soil physicochemical properties especially Fe and Al oxides, clay and organic matter. Desorption of As(V) was initially fast, but with increasing incubation times desorption occurred progressively slower. Chemical fractionation of arsenic in the soils showed that the most mobile fraction represented 4.74–5.18% of the total arsenic. A part of this mobile fraction could potentially be taken up by rice and enter the food chain, but would require additional research to quantify. |
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| Keywords: | Arsenate bioavailability sorption isotherms arsenic fractions |
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