Iranian Journal of

Background and Objective: Since mobile resources are the most important sources of air pollution in the metropolis of Rasht and due to the importance of air pollution in wet weather condition in Rasht, this research was carried out in a specific area to determine the pattern governing the change in the monthly emissions of pollutants on a small scale, using the results obtained from that area.
Materials and Methods: In this study, the amount of air pollutants was estimated on a small scale by continuous monitoring of traffic throughout the year (four days per month and six hours per day) and using MOVES software.
Results: The maximum annual average emissions of CO and NOx in the study area were 15.76 (between Gas and Razi squares) and 2 (between Imam Hossein Square and Nirou Daryaee square) g/(m.hr), respectively. In addition, the results showed that the average monthly emission of NO_X throughout the year in each of the sections was constant and the average monthly emission of CO in the first half and the second half of the year was constant, and its value in the first half was higher than that in the second half.
Conclusion: Hourly distribution of CO emission in different months was affected by events and, in general, the pattern of people's life styles. But the hourly distribution for NO_X was roughly constant throughout the year. Also, according to the results, with a single measurement (for CO) and twice measurement (for NO_X) of traffic instead of monthly measurements, the pollutant emission estimation in other parts of the city was possible with an acceptable accuracy. Because the generalization of the method used in this study to estimate the emission of pollutants in all roads of the city is not reasonable and cost-effective.
 

Background and Objective: Contamination of roadside soils with heavy metals is a serious threat to soil ecosystems and organisms and human health. Therefore, the purpose of this study was to determine the concentration of heavy metals in the roadside soils of the Rasht-Qazvin old road.
Materials and Methods: 10 out-of-town sampling sites were selected via the field observation of the entire area. surface soil sampling with three replicates was performed around the Rasht-Qazvin old road.  Heavy metals concentrations were measured using ICP-OES following samples preparation and acid digestion. The pollution level of heavy metals was assessed using geoaccumulation index (I_geo) and potential ecological risk index (PERI).
Results: The results showed that the average concentrations of Zn, Cu, Ni and Pb in the roadside soils were 58.07, 19.96, 20.26 and 23.21 mg/kg, respectively. The findings showed that concentration of Zn and Ni were higher than background values and the amount of Zn exceeded WHO standard limit. The potential ecological risk index (PERI) with an average value of 86.24, indicated low level of pollution for all of the studied metals. The results of geoaccumulation index (I_geo) revealed moderately contamination level of Ni.
Conclusion: Old roads are generally known as one of the sources of pollution for the surrounding lands. Although the concentration of pollutants around the road is expected to be very high, we did not detect elevated levels of heavy metals. This fact can be explained by the current road repairs and widening, agricultural activities on marginal lands and wind blows in mountainous regions which leads to the dispersion of the soil pollutants.

Background and Objective: Transportation sector generates the largest share of greenhouse gas emissions (CO₂ and CH₄) which causes global warming. “Stop-and-go” driving and congested traffic flow results in a decrease in average car speeds, an increase in traffic incidents, and finally escalates GHGs emissions. Hence, congestion is directly related to carbon emissions. The objective of this study was to estimate the GHGs emissions of urban transportation sector using the congestion index.
Materials and Methods: The traffic flow in the main street of Hamadan city was continuously monitored in 8 time periods from 8 am to 12 pm in August 2018. Then, a traffic congestion map was prepared. Subsequently the surface area and weight coefficient of each road were obtained based on the traffic assignment model. Finally, the amount of GHGs emissions from transportation sector, CO₂ emission per capita, and annual amount of CO₂ and CH₄ release in each street were calculated and estimated.
Results: Results showed that the total CO₂ and CH₄ emissions from the transportation sector of Hamadan city are 776000 and 396 ton/year, respectively. Imam Khomeini Highway (29166 ton CO₂/year) and Mirzadeh Eshghi Street (24453 ton CO₂/year) recorded the highest level of carbon emission due to the highespeed and more width “stop and go” driving conditions.
Conclusion: The conformity of the congestion index with the traffic assignment model can be used to estimate the amount of urban traffic pollution. Finally, because of the high growth rate of CO₂ and CH₄ and the role of forests in maximizing carbon sequestration, it is imperative to manage and increase green spaces to reduce CO₂.