Investigation and Identification of Types and Amounts of Heavy Metals in Soil of an Industrial Area

Abstract

This study was mainly designed to investigate and identify the amounts and types of heavy metals in the soils of National Iranian Oil Refining & Distribution Company in Shahrood region and tried to establish a logical relation between the presence of heavy metals and their damage on vegetation. In addition, considering the power of drained soil and due to the proximity of ground water in Shahrood region, conducting this study provides a better insight into recognition of the possible contamination centers of drinking waters. The gridding and selective method was used for sampling step. Accordingly, five sub-samples were taken from each grid and finally after mixing all of the sub-samples, the final samples were obtained with an average weight of 400 grams prior to sending to the laboratory. To determine the total concentration of heavy metals in soil, extraction was done using concentrated solutions of HCl and HNO3. The total concentration of the heavy metals of chromium, cobalt and nickel were measured using an ICP-MS instrument, and the rest of the elements using an XRF device. The results explicitly indicated that the quantities of nickel, lead, zinc and strontium in patient samples exceeded the standard, and the other elements were lower than their standard limits. More specifically, the contents of lead and strontium in both normal and patient samples were higher than their standard contents. Moreover, the majority of the vegetation loss across the affected areas was caused by heavy metal accumulation, particularly nickel, lead, zinc, and strontium.