Assessing the impact of wastewater irrigation on some toxic heavy metals concentration in grains of Sorghum bicolor

Abstract

The impact of waste irrigation on the concentrations of the metals Cu, Fe, Ni, and Zn contents in grains of Sorghum bicolor was investigated through analyzing (for three seasons 2008-2010) four different-irrigation sorghum grains samples grown on four different-irrigation soil areas according to the experimental design. The two original soils: Soil, historically and experimentally, irrigated with Wastewater (SHEwastewater), and Soil, historically and experimentally, irrigated with wells water (SHEwells water), were analyzed in the 1st season. Wastewater and wells water samples were analyzed in the 1 st and 2 nd seasons. According to the procedures used in the literature, Samples were collected, pretreated, preserved, digested according to the microwave assisted acids digestion procedures, and analyzed for metals by ICP-AES. Quality control was performed and %R(s) we got were in the acceptable ranges for real samples analysis. Fe contents of the two types of soil samples were not significantly different. Cu and Ni contents of SHEwastewater were higher than that of SHEwells water whereas Zn content of SHEwastewater was lower than that of SHEwells water. In addition, not all metal levels of the two types of soil samples have exceeded the upper EU standards except nickel in SHEwastewater. The average means (of 1 and 2 seasons) levels of Cu, Fe, Ni of wastewater was higher than that of wells water, but for Zn, the case is reversed. In addition, the average means of all metal ions of both wastewater and wells water was lower than Yemeni standard for irrigation water. Sorghum grains analysis results, for at least two of the three seasons, indicated that: wastewater irrigation resulted in an increase of nickel content of grains of Sorghum bicolor. Wells water irrigation resulted in an increase in zinc content. In addition, there is no significant difference between the effect of wastewater and wells water irrigation on copper and iron contents of grains of Sorghum bicolor.