Assessment of Heavy Metals in Street Dusts of Tehran Using Enrichment Factor and Geo-Accumulation Index: A

Abstract

: Street dust contains small matters coming from motor combustion and other anthropogenic sources. These elements are known as indicators of heavy metals, which have an important role in environmental pollution. The purpose of this study is to evaluate the degrees of arsenic, cadmium, copper, lead, and zinc pollution in street dust by using of the geo-accumulation index and enrichment factor. For sampling, 35 points are randomly defined by using the geographic information system. The metals were detected using acid digestion inductively coupled plasma optical emission spectrometry. The order of geo-accumulation index of analyzed heavy metals were: arsenic < lead < cadmium < zinc < copper. The copper levels can be considered as “moderately to heavily polluted” status. The assessment results of enrichment factor and geo-accumulation index showed that Arsenic did not have any noticeable concern, while enrichment factor of lead and zinc had moderate enrichment, and cadmium and copper had moderately severe enrichment. The average levels of studied metals were higher than the mentioned background level. There are variant elements causing high levels of heavy metals in street dust of Tehran. For instance, the extensive traffic following by the vehicles speed and braking, power plants, and industrial emissions are the main factors. Therefore, considering this information as an alarming sign for the safety of our environment is needed.