Use of U-isotope disequilibrium to evaluate the weathering rate and fertilizer-derived uranium in São Paulo state, Brazil
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Data
2003-07-01
Autores
Conceicao, F. T.
Bonotto, Daniel Marcos [UNESP]
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Editor
Springer
Resumo
The U-disequilibrium method was utilized to evaluate the velocity of alteration of rocks and fertilizer-derived uranium in the Corumbatai River basin, São Paulo state, Brazil. The Corumbatai River basin is affected by the continuous use of fertilizer-derived uranium utilized in sugar cane crops, increasing the dissolved uranium concentration in the Corumbatai River (Santa Terezinha station) in the wet period to 43%. The weathering rate in the Corumbatai River basin utilizing the U-isotope modeling was 0.0265 mm/year (corresponding to 38,000 years to weather 1 m of rock under actual climatic conditions). However, when the inputs of anthropogenic uranium were considered, then a weathering rate of 0.022 mm/year (corresponding to 45,500 years to weather 1 m of rock) was determined. The removed material in the Corumbatai River basin is mainly from two sub-basins (the Cabecas River and Passa Cinco River), where the sandstones weather easier than the siltstones and claystones in the basin.
Descrição
Palavras-chave
weathering rate, uranium, phosphate and anthropogenic influences, Brazil
Como citar
Environmental Geology. New York: Springer-verlag, v. 44, n. 4, p. 408-418, 2003.