Impact of industrial effluents, domestic wastewater and natural dams on heavy metals concentrations in vegetables cultivated in Northern Nigeria

摘要

Vegetable cultivation is increasing because of its health benefit. However, in areas with limited fresh water, irrigation is from industrial and domestic wastewaters. Consumption of crops with high heavy metal content poses concern to health. A comparative analysis was conducted using AAS (Atomic Absorption Spectrophotometer) to determine the concentration of heavy metals in some vegetables irrigated with industrial effluent, domestic wastewater, and water from natural dams in Kano State. The results indicated that for all the sites, Fe and Zn had mean concentrations above the WHO/FAO permissible limits for edible vegetables with ranges 115 - 4041 mg/kg and 0.00 - 621 mg/kg. There was no mean significant difference at the p < 0.05 level within all the sites for Fe but, Zn showed significant variations between industrial and natural sites. Cr and Ni had a mean significant difference within all the sites and Ni had mean value below the allowable limit, Cr only had below for natural site. The mean concentration for Mn and Cu were below the permissible limit and there was mean significant difference between natural and domestic sites for Mn but, there was none for Cu. Vegetables cultivated from natural dams were relatively safe from contamination. The results highlight the need for the remediation of heavy metal contamination in irrigation waters from domestic and industrial sources to reduce the associated health hazards in the long run.