Degreee of contamination between Vertisols and Entisols in agricultural regions of Guanajuato (Mexico)

Abstract.

In the last decades, agricultural activities have exerted a great impact in natural resources all over the world. Nowadays, Mexico is suffering a great pressure in agricultural soils caused by the excessive use of fertilizers, compaction, salinity and irrigation with contaminated waters from deep wells. The purpose of this work was to evaluate the degree of contamination between two Vertisols and two Entisols profiles (1.20 m deep) in agricultural zones of Guanajuato by using contamination indexes (Index of geoaccumulation, contamination factor and degree of contamination) with respect to Earth‘s crust as reference values. Four trace elements (Zn, Cu, Pb and As) were analyzed for total concentration by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The Vertisols resulted uncontaminated (mean Igeo<0) for Zn, Cu, Pb and As with a dominant low factor and degree of contamination (Cdeg= 2.17). In contrast, the Entisols registered moderate to considerable degree of contamination for all the elements (Cdeg= 8.86). The higher amounts of toxic elements in the Entisols suggest an accumulation from anthropogenic sources, governed probably by metal enriched parent materials transported from mining areas. Further investigation will explore the metal(oid)s mobility in order to assess the capacity of these toxic elements to entry into the food chains of the edaphic systems.