Organic chlorine and chloride in submerged paddy soil: a case study in Anhui province, southeast China |
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Authors: | E. Johansson,Zhang Bjö rn Xin,Hu Zhengyi,P. Sandé n,G. Ö berg |
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Affiliation: | Department of Thematic Studies, Linköpings Universitet, SE–60174 Norrköping, Sweden.;State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Science, Nanjing, China. |
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Abstract: | Abstract. Efforts to understand the fate of organochlorine compounds in arable soil have concentrated on anthropogenic compounds, in spite of the fact that organochlorine compounds are both produced and mineralized in soil through natural processes. In order to understand the fate of chlorinated pesticides, it is necessary to take account of the natural chlorine cycle. The present study is a first attempt to illuminate the relationship between the natural chlorine cycle and agricultural practices. The concentration and storage of organic chlorine (Clorg) and chloride (Clinorg) were determined in topsoil of a paddy field compared to an adjacent afforested hill at a sampling site in the Meicun area, Anhui Province, China. The concentration of Clorg, as well as the chlorine-to-carbon ratio, was significantly lower in the paddy field samples than in the forest soil samples. A weak relationship between the concentration of Clorg and the organic carbon content was observed in the paddy field, in contrast to the observations made in the adjacent forest soil as well as those made in previous studies, which have suggested a positive correlation between organic carbon content and Clorg. The similarity between our results at the forest site and the previous studies, which have been carried out in temperate regions, suggests that it is the land use rather than the climate that makes the current paddy soil results different. Our results suggest that the contribution of Clorg to the paddy soil from above-ground litter and from production within the soil are small or negligible compared with the contribution from pesticide application and wet and dry deposition. |
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Keywords: | Organic chlorine chloride paddy soil mineralization |
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