Mobility of sulphate in experimentally acidified soils from Galicia (NW Spain) |
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| Authors: | Agustin Merino Eduardo Garcia-Rodeja |
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| Institution: | 1. Departamento de Edafología y Química Agrícola, Facultad de Biología Universidad de Santiago de Compostela, E-15706, Santiago de Compostela, Spain
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| Abstract: | Retention of S04 2? was investigated in Galician soils throughout an intense regime of acidification. Experiments consisted of the addition of an H2SO4 solution (pH 2.7) to columns of 6 soils of contrasting properties over 1, 2, or 5 months. Leachates were obtained continuously throughout the experiment for analysis, and analysis made of the solid fractions after 1, 2 or 5 months. The greatest capacities for retention of S04 2? were found in soil developed from serpentine and micaschist; the lowest in soils from granite, slate and sandy sediments. The surface horizons, especially those rich in organic matter, displayed low retention of 5042-. The amount of S04 2? adsorbed throughout the experiment depended on the content of crystalline forms of Fe and with the Fe and Al extracted with dithionite-citrate.The low retention of S04 2? in the organic horizons and the slightly negative relation with the organic matter suggest an inhibitory effect of the organic matter on the S04 2? retention process. Results of the study show, that under conditions of moderate acidity, SO4 2? retention occurs in the form of adsorption; in strongly acidic conditions, the precipitation of aluminium-sulphate minerals may provide an additional retention mechanism. |
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