Risk of Cd, Pb, Cr and Co accumulation in three soil series of the DR03, State of Hidalgo, Mexico

Abstract

The constant increase of human and industrial activities in Mexico City's metropolitan zone has been the cause of deterioration in sewage water quality. This water is used to irrigate the land now known as Irrigation District 03, State of Hidalgo, a water usage that dates from the beginning of this century. This water is characterized by its alkalinity, a fact that reduces the solubility of heavy metals. On the other hand, the soil mineralogy shows no evidence that parental material is the cause of possible abnormal accumulation of heavy metals. The Tepatepec series presents greater risks of a total heavy-metal retention due to the slow, but constant, increase in the contents of organic materials, and to its greater vulnerability as pH decreases. Mid textures and moderate permeability, which characterize the Actopan series, facilitate the loss and lixiviation of metals. The Progreso series presents less risks of heavy-metal solubilization due mainly to alkaline pH values and to high reserves of carbonates, sulphides and phosphates in soils supplied by calcareous parental material, thus originating insoluble compounds. All the extractable heavy metals studied show clearly an increase since 1974. From the soil characteristics in the three series, organic material had the greatest influence in the distribution of the heavy metals studied, being its greatest accumulation in the Ap horizons... In order to continue, download full text in PDF.