JWSS - Journal of Water and Soil Science

Dust particles are suspended particles created from various natural and anthropogenic sources. Dust particles contain toxic metals, such as mercury (Hg), which can have harmful effects on the human health. In this study, to investigate the contamination level of Hg in the street dust in Ahvaz, 95 dust samples were collected from the pavements in the main streets. The concentration of Hg in the collected samples was determined by the atomic absorption method (ASS). The contamination level was estimated based on indicators such as contamination factor (Cf), enrichment factor (EF), geo-accumulation index (Igeo) and ecological risk index (Er). The concentration value of mercury ranged from 0.02 to 8.75 mg/kg with an average of 2.53 mg/kg. The results of pollution indicators showed that the level of Hg contamination in the street dust of Ahvaz was a high level of contamination. In addition, the results of ecological risk assessment indicated that the ecological risk of Hg in the study area was very high. Spatial distribution pattern of Hg concentration showed that in areas with high population density, high traffic volume and industrial activities, there was a high pollution level of Hg.

The present study was conducted to evaluate the ecological risk indices of Zn, Cu, Cd, Pb and Ni in the soils from Urmia region (Ghahramanloo village), as irrigated with treated wastewater. Accordingly, six different soil sites (five soil sites under wastewater irrigation and one soil site under well water irrigation as the control) were selected and sampled (AP horizon, 0-30 cm depth). Soil samples were air dried, passed through a 2-mm sieve, and analysed to determine the chemical properties and the studied heavy metals. The results showed that irrigation with the treated wastewater significantly increased the total elements in the order of Cd (228%)> Zn (118.5%)> Ni (81.5%)> Pb (54.2%)> Cu (23.5%). Nevertheless, with the exception of cadmium, other elements were within the admissible range based on the national and international standards. Ecological risk index (min = 125, max = 152, mean = 140) showed a considerable risk in all studied soils and Cd could be regarded as the major metal affecting the index yield.

Dusts contain heavy metals such as Pb, Zn, Cu, Cr, Cd and As that can threat human's health and environment. Therefore, the spatial distribution of heavy metals concentration and soil pollution monitoring and environmental quality protection seem to be essential. To assess heavy metals pollution level in Ahvaz street dust, 115 street dust samples were collected from main pedestrians. The samples were analyzed by Atomic Absorption (AAS). The pollution level was estimated based on the geo-accumulation index (I_geo), contamination factor (CF) and the enrichment factor (EF). The average concentration values of Pb, Zn, Cu, Cr, Cd and As were found to be 197.6, 150.1, 179.7, 101, 5.6 and 14.2 mg/kg, respectively. Pearson's correlation coefficient also indicated that Pb, Zn, Cu and Cr had a significant correlation showing similar possible anthropogenic sources. On the other hand, Cd and As showed a lower correlation with other metals, indicating that they belonged to the geogenic sources. The results of contamination factor, enrichment factor and geo-accumulation index also indicated that Pb, Zn, Cu and Cd had a high contamination level.  Also, areas with high population density, heavy traffic volume, and industrial activities exhibited a high level of heavy metals contamination.