Changing the life style and using the machinery gadgets are being varied daily. The main value of the heavy metals are toxic to the living organism and even those considered as essential could be toxic if present in excess. The heavy metals can follow significant biochemical process posing a threat to human health, plant growth and animal life. [1-7]. Accumulation of metals in soil could affect the ecosystem safety and pose a threat to animals, plants, and human. High concentrations of metals in the plant could inhibit the ability of the plant to produce chlorophyll, increase the plant oxidative stress and weaken stomata resistance. Roads, plastics, industrial effluents, and sewage have polluted and occurred many issues for vegetation, animals, and humans [8-25]. One of the most pointed chemical contaminants is heavy metals, causing irreparable damage [26]. Human activity increases the level of heavy metals pollution in the nature [27]. Because these compounds are not metabolized in the body, they could be stored in body tissues such as muscles and bones. Heavy metals have the potential to cause illnesses such as mental retardation, hearing impairment, immune system dysfunction, brain diseases, blindness, muscle weakness, and cancer [28,29]. Roads are usually rich in Pb, Zn and copper [30-32].

The pollution of soils by heavy metals from automobile source is a serious worldwide environmental issue. These metals are released during different operations of the road transport such as combustion, component wear, fluid leakage and corrosion of metals. Lead, cadmium, copper and zinc are the major metal pollutants of the roadside environments and are released from burning of fuel, wearing out of tyres, leakage of oils, and corrosion of batteries and metallic parts such as radiators etc. The presence of these metals on the road is usually due to leaded gasoline, tire wear, corrosion of roadside safety fences, and wear of brake linings [33,34]. Also, the source of Ni and chromium in road dust is probably due to corrosion of vehicular parts. Moreover, heavy metals can enter the environment through natural paths, such as mineral erosion, wind, river, groundwater, and volcanic activities where all the items are connected each other. Malkoc (2010) did the research on the levels of heavy metal pollution in roadside soils of Eskisehir, Turkey. Fifteen soil samples were taken from three different lines: only - tramway lines, only - traffic lines, and both traffic and tramway lines and analysed for different heavy metals viz., Cd, Cu, Cr, Fe, Hg, Mn, Ni, Pb, and Zn. The level of pollution in soil was estimated based on the geoaccumulation index (Igeo), enrichment factor (EF), pollution index and integrated pollution index (IPI). The values of the integrated pollution index (IPI) were found to be in the order of Pb > Zn > Cu > Fe > Mn > Ni > Cr > Cd [34-40]. In this research, the concentrations of heavy metals such as lead ( Pb ), Zinc (Zn), Nickle (Ni), Cobalt (Co), and Cadmium (Cd) in road in Rasht province areas (Iran northern) were studied using inductively coupled plasma atomic emission spectroscopy (ICP-OES).

Experimental

Study Area

Rasht city center was the place for selecting the samples. All samples were randomly selected from several points, where mainly the vehicles running on these roads use gasoline and diesel engines which were or target. A mass of people traveling daily on these roads are subjected to its dusty environment to introduce as a point.

Measurements and Characterization

A PerkinElmer (Shelton, CT, USA) Optima 3300 DV ICP-OES instrument was used for determinations.

Preparation of Samples

Totally, we have tried prepare samples according to routine methods which were used in literatures. At each of these points, dust samples were collected within 0.5 m distance from the edge of the pavement. These surface soil samples were taken from the top (0-2) cm of soil. At each sampling point, three sub-samples were taken and then mixed to achieve a bulk sample. Such a sampling strategy was adopted in order to decrease the possibility of random effect of urban waste not obviously visible. Samples were placed in plastic bags, labeled by attention, and taken to the laboratories for further processes. Soil samples were digested with HCl, NHO3, and H2O2 according to U. S. EPA 3050B method and prepared for results [35-39].

Results and Discussion

The results of heavy metals from the samples are given in (Tables 1 & 2). The results have shown that all heavy metal amounts except Cd, are higher than reasonable values in natural soils which were investigated. The average concentration of Pb was 822.1 mg/kg. Pb is remarkably affected by car exhaust and vehicle emissions, eg tire wear, bearing wear. This high concentration of lead mostly is due to the non-standard gasoline applications. The average concentration of Zn was 712.2 mg/kg, which is due to the application of Zn compounds as antioxidants and as detergent/dispersants improving agents for motor oil in the car and machinery industries. We express that the source of Ni in street dust is cause of the corrosion of vehicular parts or related industries. The high rate of corrosion and wear from old vehicles (due to the use of worn-out cars in Iran) plying these roads could have accounted for the significant levels of anthropogenic contributions of Ni in the road dust. The average street concentration of Co was 32.20 mg / kg, which was reasonable value.

Table 1: Mean concentration of metals (mg/kg) in street dust (dense traffic).