Irrigation wastewater and heavy metals in agricultural soils of Mixquiahuala, Hidalgo, Mexico

Abstract

Agricultural soils irrigated with wastewater pose a significant risk in the accumulation of heavy metals, 
a problem that affects agriculture and human health. An investigation was conducted on the 
concentration of heavy metals in agricultural soils and wastewater used for irrigation in plots of 
Mixquiahuala, Hidalgo. It analyzed the potential of hydrogen (pH), electrical conductivity (EC) and total 
extractable heavy metals in water and soil: As, Cd, Cr, Hg, Ni, Pb and Zn. Heavy metals were determined 
by using an Inductively Coupled Plasma (ICP) Perkin Elmer Optima 5300 (Inductively Coupled Plasma), 
using the methods recommended by the EPA (Environmental Protection Agency) and APHA (American 
Public Health Association). The study was conducted in November 2009. The sampling was conducted 
in two replications for both soils and wastewater. It compared the concentration of heavy metals with 
the criterion of Norma Oficial Mexicana-001-ECOL-1996. Based on these results, the concentration of 
extractable metals in agricultural soils of Mixquiahuala, Hidalgo, was presented in the following order: 
Pb > Ni > Cd > As > Cr > Hg. Water for agricultural irrigation did not present problems for use based on 
the concentration of As, Cd, Hg, Ni, Cr and Zn. However, lead concentration exceeded the maximum 
permissible limits in 40% of water samples analyzed. Considering the limits established in Spain, the 
concentrations of As, Ni and Cd exceeded permissible levels in 20, 60 and 60% respectively, of the 
samples analyzed.