Evaluation of Trace Metal Contamination in Soil and Native Maize From Tehuacán-Cuicatlán Biosphere Reserve, Mexico

Abstract

Trace metal enrichments in soil and native maize ( Zea mays L.) in Tehuacán-Cuicatlán Biosphere Reserve was analyzed due to its direct relation with food security. pH and organic matter (OM) content were obtained in soil, concentrations trace metals were determined in agricultural soil and plant collected from 10 maize plots using ICP-OES. Soil contamination was evaluated using contamination factor (CF), enrichment factor (EF), and geoaccumulation index (Igeo), plant contamination was evaluated using bioconcentration factor (BCF). Soils characteristics indicates higher pH values (8–8.9), which favors metal’s translocation from soil > plant. Mean concentrations (mg/kg) of Cr (soil: 0.02–0.04; plant: 0–0.01), Fe (soil: 0.77–1.17; plant: 0–0.40), and Zn (soil: 0–0.01; plant: 0–0.01) were within the FAO/WHO and Mexican government soil standards. CF values were classified as “low contamination,” however, Cd, Mn, and Fe indicates “medium contamination” in maize crops. EF values of metals in farmlands were recorded as “lower enrichment values.” BCF showed accumulation of trace metals (especially Fe and Mn) in roots, which acts as a binding element for other trace metals, where OM is low. Overall results in this study suggest that the selected trace metals in the agricultural soils and plant have no appreciable threat to food safety.