Contamination of corn growing areas due to intensive fertilization in the High Plane of Mexico

Abstract

The agricultural activities practice often demands an intensive application of fertilizers. Phosphate and nitrogen fertilizers are the most employed in the corn growing areas of the central Mexico highlands. The first ones presents an uranium content ranging from 50 to 200 mg · kg−1 depending on the origin of the phosphate rock used in its production. It is crucial to analyze the rainwater, surface water, soil water at several depths, groundwater and soil to determine the simultaneous behavior of phosphate, nitrate and uranium, and their leaching in a specific agricultural land. Uranium concentration, 16 mg · kg−1, in the soil water was higher than that in the surface water and groundwater. The different concentrations are due to an unequal uranium distribution in the environment. The phosphate concentration, 37.4 mg · kg−1, diminished throughout the profile of the soil due to a sorption–precipitation process. The nitrates were leached toward groundwater after the application of fertilizers, but the nitrate concentration in it did not exceed the limit for drinking wáter.