Iranian Journal of

Background and Objectives: city bus drivers, during driving, are always exposed to the whole body vibration. This can lead to central- neural, musculoskeletal, and blood circulation disorders and develop occupational diseases due to vibration. The objective of this descriptive- analytic study is to investigate Tehran bus drivers&apos exposure to the whole body vibration.
Materials and Methods: We measured parameters related to the whole body vibration, such as acceleration of the frequency weighted root sum of squares, the overall equivalent acceleration, vibration dose value, and crest factor were measured separately at three directions (X, Y, Z) in 80 buses in 5 different types, which were selected randomly. The results obtained were compared with ISO 2631: 1997 Standard, and finally permitted driving time was calculated for different buses.
Results: Acceleration of the frequency weighted root mean of squares at X, Y axes in all of the buses was below the district of health warning and at Z axis, it was in the district of health warning, while the overall equivalent acceleration in Icarus buses was above the district of health warning and in other buses it was in the district of health warning according to standard ISO 2631: 1997. Vibration dose value (VDV) was less than 8.5 and crest factor was less than 9 and in all of the buses, it was less than the suggested permitted limits of ISO 2631: 1997 standard. Moreover, permitted driving time was estimated less than 8 hours per day and Icarus buses had the most and Man buses had the least vibration acceleration, crest factor, and vibration dose value respectively.
Conclusion: According to the results obtained, there is the possibility of developing potential health risks in bus drivers therefore, it is recommended that the health and safe managers consider decrease of working hours and increase of rest time while purchasing new buses.

Background and Objectives: Reuse of treated wastewater in agriculture is becoming more attractive due to the growing demand for water, particularly in arid and semi-arid regions like Iran.In some areas, industrial wastewaters distribute arsenic in the water and vegetables, among the other plants, are mainly irrigated by municipal and industrial wastewater. This study aimed to evaluate the outcome of radish irrigation using water contaminated with arsenic and zinc and to measure the zinc concentration in the edible parts of radish plant. Materials and Methods: The experiments were designed in the form of a factorial completely randomized design with three replications in which radishes were planted in pots about five kilograms. Arsenic concentration at four levels (0, 100,300 and 600 µg/l) and zinc concentration at three levels (0, 10, and 50 mg/l) were added to the irrigation water. The pots were equally irrigated once every 3 to 4 days. After harvesting and laboratory operations, zinc concentration was measured using atomic absorption spectroscopy. Results: The study indicated that zinc concentration in radish tubers is correlated with the concentration of zinc in water. The results of the analysis of variance table for the effect of zinc and arsenic-contaminated irrigation water on zinc concentration in radish roots, tubers and leafs show only one treatment (zinc concentration in water) on the property is significant at 5 and 1%. The results of the comparison table revealed that Zn uptake was decreased with increasing arsenic up to 300 µg/l. Conclusion: It was found that zinc concentration in radish roots, tubers, and leafs is correlated with the concentration of zinc in water. Moreover, there was a competition between the absorption of zinc and arsenic in plants. With increasing arsenic in irrigation water, transition of Zn was reduced to aerial part.

Background and Objective: Petroleum hydrocarbons are a bunch of pollutants hazardous to the environment. Nowadays, biodegradation of petroleum contaminants is considered as one of the most efficient and most cost effective methods of removing oil contamination from the environment. The main objective of this study is to investigate the potential of cyanobacterium Schizothrix vaginata ISC108 in the biodegradation of crude oil and to evaluate oil effects on growth rates, dry weight, and chlorophyll content. Material and Methods: In this experimental study, the cyanobacterium Schizothrix vaginata ISC108 was obtained from the algal culture collection of Research Institute of Applied Science, ACECR, Tehran, Iran. First, purification of the cyanobacterium was performed using agar plate method on solid medium of BG11. Growth rate, chlorophyll content and dry weight of cyanobacteriaum was measured using spectrophotometry method. The biodegradation rate of crude oil was calculated using gas chromatography (GC) analysis. Results: Measuring the growth rate of cyanobacterium Schizothrix vaginata at 1% treatment of crude oil and control samples showed that the growth of cyanobacterium in the presence of crude oil as the sole carbon source increases at the same rate as the control sample. Moreover, it was found that increasing the concentration of crude oil will result in increasing dry weight of Schizothrix vaginata however, and the chlorophyll content reduced in various crude oil treatments. The average biodegradation of petroleum hydrocarbon after 14 and 28 days of treatment was 54.78 and 93.98% respectively. Conclusions: It was found that cyanobacterium Schizothrix vaginata ISC108 has great potential in biodegradation of crude oil. Therefore, since oil is a product toxic to biological systems and is one of the main pollutants of bioecosystem, it has a great potential to be used as an indicator to eliminate pollution in contaminated areas.

Background and Objectives: Among the different types of antibiotics, tetracycline antibiotics are the second most common group around the world that their entrance into domestic sewage can result in contamination of water sources. The aim of this study was to investigate the efficacy of the nano-sonocatalytic process on removal of tetracycline antibiotics from aqueous solutions. Materials and Methods: In this study, the effectiveness of ultrasonic irradiation without and with TiO₂ nanoparticles and hydrogen peroxide were studied in tetracycline antibiotics removal. For this purpose, a reactor different concentrations of tetracycline was exposed to two irradiation frequencies of 35 and 130 KHz. Concentration of residual antibiotic was measured using HPLC equipped with a C18 reverse phase column and a UV detector. Results: It was found that the efficacy of ultrasonic irradiation alone in removal of this pollutant was negligible and at the best conditions only 20.3% removal was achieved at the frequency of 35 KHz. Addition of TiO2 nanoparticles improved the removal efficiency the removal rate increased with the increase in TiO₂ concentration until 250 mg/L, after which it remained approximately stable. The best removal efficiency was achieved by adding 100 mg/l hydrogen peroxide to US/TiO₂ process at pH 4 in which 94.3% removal was achieved after 60 minute. Conclusion: The results of this study showed that the sonocatalytic process using TiO₂ nanoparticles and along with adding H₂O₂ as an oxidant is very effective and can be used for removal of tetracycline antibiotics from aqueous solutions.

Backgrounds and Objectives: Quantity of trace metals in the wet precipitation can illustrate the environmental pollution of different urban areas. Up to now, there is no study regarding the chemistry of wet precipitation in Tehran .The objectives of this study are: measurement of heavy metal concentrations and identification of the main factors affecting the heavy metal concentrations in wet precipitation using factor analysis method.

Materials and Methods: This was a cross-sectional study in which measurements of heavy metals were performed in 53 wet precipitation samples collected from a central site of Tehran City, capital of Iran. The samples were collected during November to May in 2010, 2011 and 2012 on the roof of the student’s dormitory building of Tehran University of Medical Sciences and then the concentration of heavy metals in each sample was measured with ICP-MS.

Results: pH ranged from 4.2 to 7.1 with a mean value of 5.1 indicating in acidic range. Result of EF calculations revealed that samples were not enriched with Fe and Cr but were enriched with Zn, Cd, Ni, Pb and Cu. Factor Component Analysis with Varimax normalized rotation showed Al, Fe and Cr are originated from crustal source and Zn, Cd, Ni, Pb and Cu are originated from anthropogenic sources. 

Conclusion: EF and acidic pH values indicate Tehran is under the influence of extremely anthropogenic activities. Large number of vehicles and industrial activity in the city are undoubtedly responsible for the emission of a wide range of pollution.

Background and Objective: Polycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutants that are mostly generated during the incomplete combustion. The main objective of this study was to characterize potential sources of PAHs in Tehran.

Materials and Methods:, Samples of PM₁₀ were collected at 10 monitoring stations belonging to Tehran Air Quality Control Company (AQCC) and transferred to laboratory for analysis. Besides, a SKC Flite 2 Air Sampling Pump (SKC, USA) equipped with a sampling head and PM₁₀ size-selective inlet was used at four stations to compare the results obtained by collecting AQCC monitors (AQCCMs) tapes with the standard sampling procedures for assessing the interchangeability of two field sampling methods. The principal component analysis (PCA) and diagnostic ratios were applied to identify emission sources and source contribution.

Results: The average diagnostic ratios of phenanthrene (Phe)/ (Phe+anthracene (Ant)), benzo(a)anthracene (BaA)/ (BaA+chrysene (Chry)), fluorantene(Flu)/ (Flu+pyrene (Py)), and indeno(1,2,3cd) pyrene (IcP)/(IcP+benzo(ghi)perylene (BghiP)) in samples were 0.79, 0.52, 0.43 and 0.38, respectively. These ratios showed that the combustion, especially fossil fuels and motor vehicles, was the main sources of PAHs emission in Tehran. The results of  PCA analysis also indicated that 49, 29 and 22% of PAHs sources in Tehran atmosphere were attributed to gasoline-driven vehicles, diesel vehicles and other sources, respectively.

Conclusion: According to the results, the combustion, especially fossil fuel and motor vehicle, was the main sources of PAHs emission in Tehran.