Assessment of heavy metal contamination in urban dusts and road dusts of Tehran

摘要

This study was carried out to assess and compare the status of heavy metals pollution (lead, chrome, cadmium, nickel and zinc) present in PM10 particles in the road and city of Tehran. For this purpose, in August 2014 from the zone 22 of Tehran city 14 samples and from the road, i.e. Hemmat expressway 28 samples were collected with the help of the system. The sampling filters were digested using the concentrated nitric acid and the metals rate of heavy metals (lead, chrome, cadmium, nickel and zinc) present in the samples was determined via flame atomic absorption system. The average concentration of metals; lead, chrome, nickel, zinc and cadmium in the city PM10 particles were 0.115, 0.020, 0.019, 1.144, 0.004 ug/m3 respectively. In case of heavy metals in PM10 particles, the average heavy metals concentration, i.e., lead, chrome, nickel, zinc and cadmium were 0.0943, 0.011, 0.0135, 0.0567, 0.003 ug/m3 respectively. In both the cases, nickel value was higher than the standard. It can be safely mentioned that with the increase of distance from the road the concentration of pollutants reduces. The spatial distribution map of these metals was prepared with Arc GIS software. Even the statistical and clustering analysis was calculated for sourcing of metals in the two conditions. The results showed that the majority of the metals have a traffic source and only zinc that has the highest rate in the city, besides has the other varied source. This led to analysis of carcinogenesis and noncarcinogenesis risk of heavy metals in PM10 particles of city and the road. The results showed that as far as carcinogenesis and non-carcinogenesis risk is concerned, there is nil anxiety in the city and the road.