Traceability of arsenic in agricultural irrigation water from center-south of Chihuahua State, Mexico

Abstract

The natural presence of arsenic in groundwater is a global problem since it affects human health. The metalloid has been detected in crops irrigated with As-contaminated water, especially in Asia. Therefore, the objective of this research was to determine the total As concentration (As-tot) in agricultural wells at the south-central part of Chihuahua State, as well as its traceability to soil and crops in the territory. 119 wells for agricultural irrigation were sampled. The soil sampling was realized in six sites, in each one 24 samples were collected; in the same sites, 32 onion and 37 chili plants were collected. As-tot concentration was determined by atomic absorption spectrometry with hydride generator. 11 % of the wells exceeded the maximum permissible level (MPL) of As-tot in water for agricultural use (100 μg/L). The highest As-tot concentration was 576 μg/L. In the quadrant with the highest As-tot concentration in soil, 42 % of the samples exceeded the MPL for agricultural soil (22 mg/kg), displaying a maximum concentration of 47.5 mg/kg. The highest As-tot presence on plants was in root, 7.4 mg/kg in chili and 28.8 mg/kg in onion. However, 0.16 mg/kg in chili and 0.38 mg/kg in onion were also identified in fruits. It was demonstrated that, in the study region, the crops irrigation with water high As levels generates the metalloid movement to matrices that are related to the population intake.