Heavy metals contamination in wheat (irrigated and rainfed) in the farms of Hamadan

Heavy metals contamination of soil and agricultural products due to the rapid development of industries and improper use of chemical fertilizers and manure on agricultural land have cuased a great concern. The purpose of this study was to investigate the accumulation of heavy metals such as cadmium, lead and zinc in soils and in irrigated wheat and rainfed wheat in some farms in Hamadan city.

Soils under cultivation of wheat (irrigated and rainfed) was sampled. Composite soil samples were taken from a depth of 0-20 cm. The location of the sampling stations was recorded by GPS. The composite samples were collected edible sections of the mentioned plants. Absorbent concentrations of heavy metals were extracted using DTPA. The experiments were done independently in the form of a completely randomized design with three replications. Concentrations of heavy metals (lead, zinc and cadmium) were read using an ICP varion 710 in the laboratory of Islamic Azad University of Hamedan.

Statistical analysis showed that the mean concentrations of cadmium in the soil of irrigated and rainfed wheat were4/61, 1/60 mg/kg and in the plant of irrigated and rainfed wheat were 2/29, 1/86 mg/kg, with a significant difference of 0/05. The mean concentrations of lead in the soil of irrigated and rainfed wheat were 4/61, 1/60 mg/kg respectively, and in the plant of irrigated and rainfed wheat they were 12/26, 12/84 mg/kg respectively, showing a significant difference of 0/05. The amounts of zinc in the soil of irrigated and rainfed wheat were 32/12, 21/26 mg/kg respectively, and in the plant of irrigated and rainfed wheat they were 13/99, 11/58 mg/kg, showing no significant differences with the the permissable standards.
Discussionand

The result showed the risk indices of over 1 for cadmium and lead, implying that these two elements can be of a greater potential threat to human health in the study area