Examining total concentration and sequential extraction of heavy metals in agricultural soil and wheat

Abstract

Soil contamination by heavy metals not only directly affects soil physical and chemical properties, reduces biological activity, and reduces soil biological nutrient achievement, but also is considered a serious risk to human health by entering the food chain and environmental security through penetrating groundwater. In this study we examined the concentrations and sequential extractions of such heavy metals as iron, lead, copper, zinc, and nickel in soil and wheat in the central part of Sistan, Iran. 160 soil samples and 160 samples of wheat from 20 specified units of soil of agricultural land of central Sistan were randomly sampled. The values of iron, lead, zinc, nickel, and copper were measured using atomic absorption spectrometry according to the standard method. Average concentrations of iron, nickel, copper, zinc, and lead in terms of mg/kg, respectively, were 9,647.34, 18.56, 7.26, 19.80, and 29.90. After examination of sequential extraction, the metals’ mobilities were as follows: iron (99%)> nickel (33%)> copper (31%)> lead (27%)> zinc (6%). Wheat measurement results showed that metal accumulation in wheat grain was less than other parts. And also the comparison with the standard shows that the values of the metals in agricultural soil in the area were below the World Health Organization standard and in this sense there is nothing wrong with the health of the soil.