Heavy metal pollution in soils and sediments of rural developing district 063, Mexico

Abstract

For over 100 years the Rural Developing District 063 (RDD-063), which is located in Hidalgo State, has received wastewater without treatment from Mexico City. This wastewater has been used as irrigation water in agriculture, so high amounts of toxic substances have been deposited in the soils and sediments of this area, including heavy metals. Heavy metals are not biodegraded and persist in the environment for long time, so the goal of this study was to evaluate the bioavailable concentration of four heavy metals (Cd, Co, Cr, and Pb) by atomic absorption spectrophotometry during three sampling periods in 1993. The results show increasing levels of cadmium and lead during July (second sampling period), while cobalt had its highest level in March (first sampling period). Finally, chromium data presented an irregular pattern during the whole year. The high levels of these elements indicate major pollution problems in RDD-063, which may represent increased health risks for humans and animals. © 1996 by John Wiley & Sons, Inc.