The application of U-isotopes to assess weathering in contrasted soil-water regime in Brazil

Author(s)

Rosolen, Vania ^[1] ; Bueno, Guilherme Taitson ^[2] ; Bonotto, Daniel Marcos ^[1]

Affiliation

^[1] Univ Estadual Paulista UNESP, Dept Petrol & Metalogenia, Campus Rio Claro, Av 24-A, 1515, CP 178, BR-13506900 Rio Claro, SP - Brazil

^[2] Univ Fed Goias, Inst Estudos Socioambientais, Campus II, BR-74001970 Goiania, Go - Brazil

• Document type: Journal article
• Source: Applied Radiation and Isotopes; v. 132, p. 157-163, FEB 2018.
• Web of Science Citations: 0

Abstract

This paper presents the use of U-series radionuclides U-238 and U-234 to evaluate the biogeochemical disequilibrium in soil cover under a contrasted soil-water regime. The approach was applied in three profiles located in distinct topographical positions, from upslope ferralitic to downslope hydromorphic domain. The U fractionation data was obtained in the samples representing the saprolite and the superficial and subsuperficial soil horizons. The results showed a significant and positive correlation between U and the Total Organic Carbon (TOC). Soil organic matter has accumulated in soil due to hydromorphy. There is no evidence of positive correlation between U and Fe, as expected in lateritic soils. The advance of the hydromorphy on Ferralsol changes the weathering rates, and the ages of weathering are discussed as a function of the advance of waterlogged soil conditions from downslope. Also, the bioturbation could represent the other factor responsible to construct a more recent soil horizon. (AU)

• FAPESP's process: 17/14168-1 - Soil-landscape, caracterization of the phases organo-metallic and prospection of refractory clay in the Ferralsol-Gleysol cover (Western of Minas Gerais State).
• Grantee: Vania Silvia Rosolen
• Support type: Regular Research Grants