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Title: APPLICATION OF CESIUM-137 IN A STUDY OF SOIL EROSION AND DEPOSITION IN SOUTHEASTERN BRAZIL

Author
item GUIMARAES, M - STATE UNIV OF LONDRINA
item NASCIMENTO FILHO, V - CENA/USP
item Ritchie, Jerry

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2003
Publication Date: 1/15/2003
Citation: Guimaraes, M.F., Nascimento, F.V.P., Ritchie, J.C. 2003. Application of Cesium-137 in a study of soil erosion and deposition in southeastern Brazil. In: Guimarães, M.F., Nascimento Filho, V.F., and Ritchie, J.C. Application of Cesium-137 in a study of soil erosion and deposition in southeastern Brazil. Soil Science 168(1):45-53.

Interpretive Summary: Cs-137 concentration in our sampled sites indicated that this radionuclide is present in the soils in extremely low amounts, requiring a detection times of 10 to 24 hours for samples of 800 to 1,000 g of soil. With the Cs-137 methodology it was possible to evaluate soil movement and redistribution as a function of slope, land use and conservation practices, identifying sites of soil loss and accumulation that occurred since 1960, without the need for installing field equipment or the collection of data for long periods, which are essential in the classic methodologies. The application of the Cs-137 technique is viable, however it is necessary to establish a relationship between Cs-137 concentrations and soil losses or accumulation for Brazilian conditions, to avoid the use of equations developed for the Northern hemisphere. Application of models of Walling and He (1999) may give improved insights into erosion and deposition patterns at the study site. The Cs-137 methodology can facilitate a better understanding of soil dynamics occurring in different ecosystems and will allow monitoring of the soil movement under different land uses and managements. From our study and results from other research using fallout Cs-137, the application of techniques using Cs-137 to evaluate erosion and sediment deposition is potentially very promising in Brazil, in spite of the low levels of radioactive fallout deposition in the Southern hemisphere and offers advantages in relation to conventional methods for measuring or estimating soil losses and gain.

Technical Abstract: A study using Cs-137 a component of the radioactive fallout, to estimate soil erosion and deposition was carried out on a small watershed in Piracicaba District, Sao Paulo State, southeastern Brazil. Soil samples were collected along three transects, covering different land use and conservation practices on different slopes. Cs-137 concentration was measured with a high-resolution germanium semiconductor detector coupled to a multi-channel analyzer. Cs-137 estimates of soil movement and redistribution were related to slope, land use and conservation practices, allowing the identification of sites with soil loss and accumulation. This study shows that the application of the Cs -137 technique is viable for Brazil. A relationship between Cs-137 concentration in soil profiles and soil losses or accumulation for Brazilian conditions needs to be established to avoid the use of equations developed for the Northern hemisphere.