Chlorsulfuron Adsorption by Selected Soil Samples

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Abstract
Ten selected soil samples from Denmark and Tanzania were extracted with ammonium acetate, EDTA, and dithionite-EDTA (DE) to fractionate aluminium and iron oxides. During these treatments various amounts of organic matter were also removed. Chlorsulfuron adsorption by the pretreated soil samples was investigated under concentration and pH conditions similar to those in most natural soils, using 0.01 M CaCl2 as background electrolyte and a soil: solution ratio 1:5. Chlorsulfuron adsorption was highly correlated with the organic matter content of the pretreated samples. In addition, multiple regression analysis showed that iron oxides and possibly also aluminium oxides are important chlorsulfuron adsorbents in soils. Furthermore, chlorsulfuron adsorption was found to be highly pH dependent, with strong adsorption at acidic pH but decreasing adsorption as pH increases and negligible adsorption at pH >7–8. Therefore, chlorsulfuron application to neutral and alkaline soils low in organic matter and oxides may lead to ground water pollution, unless application is strictly controlled.