Heavy metals concentrations in groundwater used for irrigation

The main objective of this study was characterization of selected heavy metals concentrations (Lead, cadmium, copper, zinc, nickel and chromium) in groundwater used for ir-rigation in Tabriz City's countryside.

After consulting with the experts of agriculture department and site survey, 38 irriga-tion water samples were taken from different farms (34 wells) without primary coordination with farm owners. All of samples were acidified to achieve pH≈2 and then were concentrated from 10 to 1 volume. The concentrations of Cd, Pb, Cu, Cr, Ni, and Zn in the samples (totally 228) were determined with a flame atomic absorption spectrophotometer.

In none of 38 farms, irrigation with surface runoff and industrial wastewater was ob-served. The average concentrations of Cd, Pb, Cu, Cr, Ni, and Zn in the irrigated water were de¬termined 6.55, 0.79, 16.23, 3.41, 4.49, and 49.33µg/L, respectively. The average and even maxi¬mum concentrations of heavy metals in the irrigation water at the studied area were less than toxicity threshold limits of agricultural water.

Currently, not using of surface runoff and industrial wastewater as irrigation water by farmers indicates that the controlling efforts by authorities have been effective in the area. Water used for irrigation of the farms and groundwater of the studied area are not polluted with heavy metals and there is no risk from this viewpoint in the region.