Estudio de la distribución de 137Cs en suelos de Zacatecas

Environmental radiation comes from the radionuclides distributed in the earth's crust, the cosmic rays and the radiation produced by man. That is, many radionuclides are found naturally in the soil (due to decay series of uranium, Actinium and Thorium, where the 238U, 235U and 232Th are the series nuclei parents), and some others such as the 137Cs, which is an artificial radionuclide product of the 235U fission. 137Cs is deposited on the ground by the radioactive rains resulting from the essays with nuclear weapons since 1944 and accidents in nuclear plants, such as the Three Miles Island, Chernobyl 1986, Fukushima 2011. The dispersion of 137Cs in soil is associated with the dynamics of soil particles. This radionuclide is widely used in erosion investigations. Recent studies on the 137Cs presence in Zacatecas soil have been limited to determine its surface abundance; the objective of this study is to determine the concentration profile of 137Cs to a depth of 25 cm to infer its migration pattern and the possibility of using it as a marker for erosion studies. The methodology consisted of choosing representative localities of the municipalities of Tabasco, Pinos, Loreto and Fresnillo to perform In Situ and Lab measurements by taking nuclei (25 cm deep) of soil samples divided into 5 cm strata. Both gamma spectrometry measurements were performed with a gamma spectrometer based on a germanium detector. The measurements In Situ were doubled in the 4 locations. Only in 3 sites, 137Cs was able to be determined by in situ measurements (AMD 1.02 Bq/kg). Laboratory measurements (AMD 0.459 Bq/kg) provided non-uniform profiles up to depths of 15 cm. 137Cs was not found at greater depth. The greatest abundance was found in the first strata. 137Cs concentrations above AMD are only reported. The profiles are not uniform and behave according to what is reported in the literature. The absence of 137Cs at depths greater than 15 cm implies that there is no migration and its low concentration prevents its use for erosion studies.