Resumo

GOMEZ-PUENTES, Francisco Javier; REYES-LOPEZ, Jaime Alonso  e  AMADO-MORENO, María Guadalupe. Heavy metals fractionation in Mexicali Valley contaminated soil. Tecnología en Marcha [online]. 2020, vol.33, n.4, pp.103-113. ISSN 0379-3982.  http://dx.doi.org/10.18845/tm.v33i4.4586.

Heavy metals contamination is one of the greatest challenges related to the environment quality and human health. The introduction of these elements into natural systems may be due to various types of human activities such as agriculture and solid wastes disposal. In Mexicali Valley, agriculture represents the most important economic activity, however, the use of agrochemicals as well as the clandestine disposition of urban solid wastes have generated severe pollution problems affecting soil fertility and groundwater quality. The purpose of this research was to evaluate the heavy metals content in the different fractions of soil through the vadose zone (ZV) in a site located in Mexicali Valley, B.C. influenced by agriculture and solid wastes disposal. Soil samples were subjected to the sequential extraction procedure and then analyzed by atomic absorption spectrometry. The results obtained reveal a marked accumulation of metals from the surface until 50 cm depth. Seasonal variations in the water table, as well as agricultural irrigation, favors the solutes transport with heavy metals concentrations in groundwater higher than the standards for drinking water. The elements Cd, Cr y Ni are preferably distributed in the residual fraction of soil, limiting their mobility. Cu presented a strong association with organic matter, while Zn and Pb presented the greatest association with the exchangeable fraction.

Palavras-chave : Chemical partitioning; heavy metals; vadose zone; groundwater.

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