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Edaphic and physiographic factors affecting the distribution of natural gamma‐emitting radionuclides in the soils of the Arnás catchment in the Central Spanish Pyrenees
Author(s) -
Navas A.,
Soto J.,
Machín J.
Publication year - 2002
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1046/j.1365-2389.2002.00488.x
Subject(s) - radionuclide , soil water , environmental science , regosol , hydrology (agriculture) , soil science , edaphic , soil classification , geology , physics , geotechnical engineering , quantum mechanics
Summary Gamma‐emitting radionuclides are a natural source of radiation that can be a concern for human health, therefore it is important to know the radionuclide backgrounds in soils and to assess their mobility and transfer in ecosystems. Concentrations of natural radionuclides were determined in soils from a small catchment in the middle mountain environment of the Central Spanish Pyrenees. Radioisotope activities were well within the natural ranges for soil, averaging 27, 26, 32 and 500 Bq kg −1 for 238 U, 226 Ra, 208 Tl and 40 K, respectively. Their distributions in the soil profile were analysed along three transects of contrasting physiography and soil type. Uranium was depleted in upper layers of the soil and slightly enriched in deeper sections, while 226 Ra, 40 K and 208 Tl were more uniformly distributed. Radionuclide activities in the Calcaric Regosols on the shrub slope were less than those in the deeper and better developed Haplic Kastanozems under forest and in Calcaric Fluvisols in the valley bottom. These spatial patterns seem to be affected by the soil type; other landscape features, such as slope orientation and vegetation cover, appeared to have an indirect effect. The results indicate that the depth distribution of the radionuclides is affected by some soil properties, including pH, carbonates, organic matter and particle size, and soil processes, such as leaching and adsorption.