Terrestrial environment

Adsorption characteristic of bensulfuron-methyl at variable added Pb2+concentrations on paddy soils


WU Weihong , WANG Haizhen , XU Jianming , XIE Zhengmiao

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Received September 29, 2008,Revised February 08, 2009, Accepted , Available online

Volume 21,2009,Pages 1129-1134

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The combined pollution of heavy metal Pb2+ and bensulfuron-methyl (BSM), originating from chemical herbicides, in agroecological environments has become commonplace in southern China. The adsorption of BSM on three paddy soils in the presence of Pb2+ was examined using high-performance liquid chromatograph (HPLC). Results indicated that adsorption of BSM could accurately be described by a Freundlich isotherm equation with correlation constant (R) > 0.98, irrespective of the presence of spiked Pb2+. Of the various factors influencing BSM sorption, soil pH appeared to be the most influential. The constant Kf of Freundlich isotherm equation tended to increase with increasing Pb2+ concentration in soil which indicated that the spiked of Pb2+ in paddy soils would promote the sorption of BSM. G of BSM in three paddy soils was less than 40 kJ/mol in all treatments, indicating the adsorption of BSM is mainly physical in nature. The elution of soil dissolved organic matter (DOM) enhanced the adsorption of BSM in paddy soils. The mechanisms involved in the promotion e ects of the spiked Pb2+ on BSM adsorption might be the modified surface characteristics of paddy soil solids due to the soil acidification and the increase of soil organic matter concentration because of DOM binding.

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