Iranian Journal of

Background and Objective: Electrochemical methods as one of the advanced oxidation processes (AOPs), have been applied effectively to degrade recalcitrant organics in aqueous solutions. In the present work, the performance of electro-Fenton (EF) method using iron electrodes on the degradation of phenol was studied. Materials and Methods: In this study, a lab-scale EF batch reactor equipped with four electrodes and a DC power supply was used for removing phenol. The effect of operating parameters such as pH, voltage, H₂O₂ and initial phenol concentration and operating time were evaluated. We added H₂O₂ manually to the reactor while iron anode electrode was applied as a ferrous ion source. Results: It was found that initial pH of the solution, initial H₂O₂ concentration, applied voltages were highly effective on the phenol removal efficiency in this process, so that 87% of phenol after 15 min of reaction at pH=3.0, voltage 26 V and H₂O₂ 100 mg/L was removed. Phenol removal efficiency decreased with increasing pH, so that at pH 10, after 15 min, efficiency was 11%. To remove 99.99% phenol at pH 3, 100 mg/L concentration of H₂O₂ and voltage 26 V for 60 min was required. Conclusion: Electro-Fenton process using iron electrodes for phenol degradation and remediation of wastewater could be a promising process.

Background and Objectives: Chemical spillage of equipment is possible in petrochemical processes. Occurrence of such event can result in firing and explosion and consequently would bring about some risks to the environment affected. The aim of this study was to assess environmental risks in Olefin Plant, Arya Sasol Petrochemical Company in order to identify environmental risks at producing source. Methods: The basic data was gathered through using the results of monitoring and measurement of ambient air pollutants and stack exhaust gases, safety review method and field observation. For determination the effects of hydrocarbons leakage from equipment on the environment, measuring BTEX in ambient air was performed as per EPA0030 Standard method with using Gas Chromatography at 4 stations of the complex and a portable Testo 350 XL device was used for monitoring stack exhaust gases, from 9 stacks from May 2011 to April 2012. Assessment and risk management tool used in this study was the fault tree analysis method. The main part of the risk assessment in fault tree method is selecting a top event. According to the statistics of accidents and environmental aspects of ethane cracking operations, hydrocarbon leakage is detected as top event and then composition and relationship between risk factors is determined in the form of terminal event, intermediate event and the gate “and” and “or”. With qualitative and quantitative analysis of fault tree of this accident, the main causes of the accident and the likelihood of the top event was calculated for a year. Results: Comparing with other stations, it was found that benzene with concentration of 0.37 mg/m³ in autumn, toluene with concentration of 0.13 mg/m³ in spring, and ethyl benzene with concentration of 0.09 mg/m³ in autumn, and xylene with the concentration of 1.01 mg/m³ in autumn season had the highest concentration. The fault tree developed had 16 events (including final, intermediate, and initial), which were connected to each other with seven logic gates. The maximum error percentage in the terminal events was attributed to the hardware failures such as malfunction in equipment with 55.55 percent followed by human and administrative errors in the next ranking. The highest percentage (22.2%) of the terminal events was related to the gasket unsuitable material the main reason is due to the economic sanctions and the lack of effort to provide high quality products. Conclusion: Most likely occurrence of the final event was related to the gasket unsuitable material (2×10^-2). Control action to prevent the occurrence of leakage could be supplying high quality gaskets and the failure is classified in the hardware failure category.

Background and Objectives: Increased growing nuclear industry has increased the researchers concerns on uranium presence in the environment and its effects on human health. Uranium is a dangerous radioactive heavy metal with high half-life and chemical toxicity. Therefore, the main objective of this study was to removal uranium (VI) from aqueous solution by uranium benzamide complex using AC_Fe3O4 nanocomposite. Materials and Methods: AC_Fe3O4 nanocomposite was synthesized using co-precipitation method. The experiments were designed as one factor at the time method. The optimum range of pH, contact time, amounts of adsorbent, and concentration of benzamide were determined. Then, kinetic and isotherm of uranium adsorption were studied. In addition, the properties of this adsorbent were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). Results: The SEM and FTIR analysis confirmed that activated carbon is coated with Fe3O4 nanoparticles and the magnetic property of AC-Fe₂O₃ was approved. According to the results, the optimum conditions were pH =6, contact time =30 min, and 0.06 g of adsorbent dose. The adsorption of uranium on the AC_Fe₃O₄ nanocomposite fitted to Langmuir isotherm and pseudo-second order kinetic model. The removal of U(VI) was increased about 6% with increasing in benzamide concentration to 50 mg/L. The best percentage removal of uranium in aqueous solution was 95%. Conclusion: The removal of U(VI) on AC_Fe₃O₄ nanocomposite with the aid of benzamide is a rapid and highly pH depended process. The maximum sorption capacity (15/87 mg/g) of AC_Fe₃O₄ nanocomposite shows that this method is a suitable method for Uranium removal.

Background and objective: Benzene is one of the main pollutants in air and one of the most extensive chemical compound used in both natural and industrial processes. Benzene exposure leads to the most dangerous adverse health effects, particularly blood cancer. The aim of this study was to evaluate the gas station workers’ exposure to benzene by measuring benzene in breathing air and urinary trans, trans-muconic acid. Materials and Methods: This cross-sectional study conducted in summer 2014 investigated 40 gas station workers and 40 occupationally non-exposed persons. Spot urine samples were obtained prior to and at the end of the work shift from each subject. The urinary levels of trans, trans-muconic acid was determined by liquid chromatography (HPLC) with diode array detector. At the end of the work shift, the benzene collected on sorbing cartridges was desorbed using carbon disulfide and was analyzed using gas chromatography and mass spectrometry detection. Results: The mean value for exposure to benzene in breathing zone of gas station workers was 5.90 ±1.93 ppm, which was significantly greater than the occupationally non exposed group (1.15±0.744 ppm). The mean urinary concentrations of trans, trans-muconic acid differed significantly between samples of gas station workers (64.75±19.47 µg/L) and occupationally non-exposed persons (47.10±13.67 µg/L). Conclusion: A good correlation (r = 0.581) between the mean values of benzene in breathing zone and the urinary concentration trans, trans-muconic acid was observed. Gas station workers were found to be probably the most exposed groups in this study. Inhalation is presumably the main route of exposure in gas station workers.

Objective and Background: Fluoride is an element widely found in the earth crust. Advantages and disadvantages of fluoride in the human body are depended on its concentration. Long-term consumption of drinking water contaminated with arsenic can cause adverse health effects such as skin lesions and cancer in humans. The aim of this study was to study efficiency of nano alumina on multi walled carbon nano tube  for removal As(V) and fluoride from aqueous solution.

Materials and Method: In this study, nano-scale crystalline alumina was synthesized on single walled carbon nanotube by sol-gel method for using as a sorbent for solid phase extraction of Fluorine ion and arsenic(V). Response surface methodology based on Box-Behnken was used to assess the effect of independent variables on the response function and prediction of the best response value. In this study, effect of different parameters, such as contact time (10 to 120 min), pH (3-9), adsorbent dosage (0.25-1.5 g/L) and initial concentration of fluoride (2-8 mg/L) on efficiency of process was investigated. The structure of nano-scale alumina on multi walled carbon nano tube was determined by XRD and SEM techniques. Moreover, Freundlich and Langmuir isotherm models were used to calculate equilibrium constant.

Results: It was found that by increasing contact time and adsorbent dosage the rate of fluoride removal increased. However, by increasing pH and initial concentration the efficiency of fluoride removal decreased. High value for R² (0.94) shows that removal of arsenic(V) can be described by this model. The Freundlich isotherm was the best fitted graph for experimental data with R² more than 0.997.

Conclusion: In this study, it was observed that efficiency of arsenic(V) and fluoride  removal was greatly increased by using nano-scale alumina on multi walled carbon nanotubes (MWCNTs).

Background and purpose: Soil contamination resulted from either natural or anthropogenic factors reduces environmental quality. The aim of this study was to evaluate the geoaccumulation, contamination factor, and principal component analysis indices to estimate topsoil contamination in Aran-Bidgol town.

Materials and methods: 135 topsoil samples were collected from Aran-Bidgol town and the metal concentrations of Cd, Pb, Ni, Cu, and Zn in each sample were determined. The index of geoaccumulation (Igeo), contamination factor (CF), and principal component analysis (PCA) techniques were applied to determine  the status and trends of soil contamination in this region. The inverse distance weighting (IDW) was then used to map these soil contamination indices.

Results: The research found that the means concentrations of Cd, Pb, Ni, Zn, and Cu were 0.72, 11.41, 29.87, 48.59, and 14.82 mg/kg respectively all exceeded the background values. Mean Igeo and CF of elements followed the order: Cu> Cd> Ni> Zn≈ Pb. The Igeo and CF maps showed higher values of Cd, Pb, and Zn in areas near industrial estates, brick kilns, and urban areas whereas higher levels of Cu and Ni occurred in urban and agricultural areas. According to the PCA index, two principal components were identified that Cu, Ni and Zn were highly loaded in PC1 and Cd and Pb occurred in PC2.

Conclusion: Results indicated that the concentration of Pb and Cd are mostly affected by human activities, whereas Ni, Zn, and Cu contents are controlled by both anthropogenic and natural sources.

Background and Objective: Arsenic is one of the most toxic pollutants in groundwater and surface water. Arsenic could have lots of adverse impacts on human health. Therefore, access to new technologies is required to achieve the arsenic standard.

Materials and Methods: The present study was conducted at laboratory scale in non-continuous batches. The adsorbent of zero-valent iron nanoparticles -Chitosan was produced through reducing ferric iron by sodium borohydride (NaBH₄) in the presence of chitosan as a stabilizer. At first, the effect of various parameters such as contact time (5-120 min), pH (3-10), adsorbent dose (0.3-3.5 g/L) and initial concentration of arsenate (2-10 mg/L) were investigated on process efficiency. Then optimum conditions in terms of contact time, pH, adsorbent dose and initial concentration of arsenate were determined by RSM method. Freundlich and Langmuir isotherm model equilibrium constant, pseudo-first and second order kinetic constants were calculated. The residual arsenate was measured y using ICP-AES.

Results: The optimum values based on RSM for pH, absorbent dose, contact time, and initial concentration of arsenate were 7.16, 3.04 g/L, 91.48 min, and 9.71 mg/L respectively. Langmuir isotherm with R²= 0.9904 for Arsenate was the best graph for the experimental data. According to Langmuir isotherm model, the maximum amount of arsenate adsorption was 135.14mg/g. . The investigation of arsenate adsorption kinetics showed that arsenate adsorption follows the pseudo-second kinetics model.

Conclusion: This research showed that the adsorption process is depended on pH. With increasing pH, the ability of amine groups in chitosan are decreased to protonation, caused to decrease the efficiency of arsenate removal at high pH.

Background and Objective: Predicting municipal solid waste generation has an important role in solid waste management. The aim of this study was to predict municipal solid waste generation in Isfahan through time series method and system dynamics modeling.

Materials and Methods: Verified data of solid waste generation was collected from Waste Management Organization and population information was collected from the National Statistics Center, Iran for the period 1996-2011. Next, the effect of   factors on solid waste generation such as population, urbanization, gross domestic product was investigated. Moreover, the relationship between each of these factors was identified using generalized estimating equation  model. Finally, the quantity of the solid waste generated in Isfahan city was predicted using system dynamics modeling by Vensim software and time series method by ARMA technique.

Results: It was found that population and gross domestic product have a significant relationship with the amount of solid waste with P value 0.026 and 0 respectively. The annual average of municipal solid waste generation would be 1501.4 ton/day in 2021 estimated by the time series method and 1436 ton/day estimated by the system dynamics modeling. In addition, average annual growth rate achieved was 3.44%.

Conclusion: According to the results obtained, population and gross domestic product have a significant effect on MSW generation. Municipal solid waste generation will increase in future. Increasing solid waste is not the same in different areas and methods. The prediction of the time series method by ARMA technique gives precise results compared with other methods.

Background and Objectives: Phenol is a toxic and persistent substance in the environment. The aim of this study was to evaluate the performance of silica aerogel synthesized using sodium silicate in the adsorption of phenol from aqueous solutions.

Material and Method: Silica aerogel was prepared by Sol-Gel process. The influence of effective variables such contact time, initial pH of the solution, adsorbent dose, and initial phenol concentration on the adsorption efficiency was investigated. The characterization of prepared silica aerogel and confirmation of phenol adsorption was determined through SEM, XRD analysis and NMR, FTIR spectra respectively. The adsorption data was evaluated via Langmuir and Freundlich isotherms and pseudo-first and pseudo-second-order kinetics.

Results: This research found that the phenol adsorption efficiency increased by increasing pH from 3 to 11, so that after 60 min, the absorption efficiency at the 100 mg/L initial phenol concentration and 0.5 g adsorbent obtained 84 and 96.4 % at pH 3 and 11, respectively. The SEM image and XRD patternof synthesized silica aerogel confirmed the creation of porous and amorphous structure. After the phenol absorption, the NMR and FTIR spectra of silica aerogel, confirmed the creation of new bands because of phenol molecule at the adsorbent structure. The absorption of phenol was compatible with Freundlich isotherm and pseudo-second-order kinetic. The maximum absorption capacity (q_m) obtained was 47.39 mg/g.

Conclusion: Silica aerogel as an adsorbent, due to special characteristics in the structure and usage, can be a promising treatment process for adsorption of toxic and persistent substances.

Background and Objective: In this study, WQI was estimated using an Iranian software called IWQIS to assess drinking water quality in Ray Township distribution systems.

Materials and Methods: The assessment of 73 samples of drinking water during 2013 and the comparison of 18 physicochemical parameters with the standard Code of 1053 (Iran National Standard) was done.

Results: The results showed that the concentration of 7 parameters is out of normal range in special percentage of the samples. Those parameters are as follow: total hardness (31.5%), Mg (46.6%), nitrate (50.68%), Na (45.2%), F (42.46%), Cl (2.7%), Sulfate (28.76%) of samples. The medium concentration of theses parameters was: total hardness (375 mg/L), Mg (32 mg/L), Nitrate (47.43 mg/L), Na (187 mg/L), F (0.5 mg/L), Cl (169 mg/L), and Sulfate (263 mg/L). It is estimated that 5.6% of the population of this township are highly exposed to nitrate, 79.1% to fluoride and 13.5% are exposed to sodium. The average WQI in Rey Township in a good spectrum is 71.22.

Conclusion: 17 samples (23.2%) were assessed in excellent spectrum, 54 samples (74%) in good and 1 sample (1.4%) in very poor spectrum and 1 sample in unsuitable condition were assessed. No sample was assessed in poor situation. The samples of the autumn showed the worst quality.

Background and Objective: The presence of fungal bioaerosols in hospitals indoor environments have affected the health of patients with the defect in immunity system. Therefore, determination of the rate and species of these agents is essential. This study aimed to investigate association between fungi contamination and particulate matter (PM₁₀, PM_2.5 and PM₁) concentrations in the main indoor wards and outdoor environment and to determine I/O ratio in two educational-medical hospitals of Khorramabad City.

Materials and Methods: In this description-analytical study, the concentration of fungal bioaerosols and particulate matter was measured in 10 indoor parts and 2 outdoor stations over 6 mounts. The sampling was conducted using Quick Take-30 at an airflow rate of 28.3 L/min and sampling period of 2.5 min onto Sabouraud dextrose agar medium containing chloramphenicol. The particulate matters were measured using Monitor Dust-Trak 8520. Moreover, the relative humidity and temperature were recorded using digital TES-1360.

Results: Analysis of 288 fungi samples and 864 particulate matter samples showed that the average of fungi accumulation was 59.75 CFU/m³ and the mean concentrations of PM₁₀, PM_2.5 and PM₁ in the indoor environment was  27.3, 23, and 20.2 µg/m³ respectively. In addition, in ambient air the mean concentration was 135.3 CFU/m³ for fungal bioaerosols and 40.2, 35.7, and 29.8 µg/m³ for PM₁₀, PM_2.5 and PM₁ respectively. At the total of fungi samples, 12.5% were negative and 87.5% were positive. Having 101.7%, Infection ward was the most contaminated ward. The operation ward in both hospitals showed the minimum fungal contamination.

Conclusions: The results of the present study showed that at all of the samplings the ratio of I/O was lower than one. It was noticed the dominancy of fungal bioaerosols and particulate matter of outdoor source on the indoor environment. In addition, a significant correlation (P < 0.001( was found between fungal bioaerosols frequency and particulate matter and as well as fungal bioaerosols frequency, relative humidity and temperature.

Background and objectives: Swimming is one of the most popular sport fields and entertainments that has considerable benefits for human health, but on the other hand microbial water contamination in swimming pools through transmission and spread of infectious diseases is a significant threat against public health. In this study, microbial water quality of all public swimming pools in Tehran were assessed and effective factors on microbial water quality were analyzed.

Materials and Methods: This cross-sectional study with the analytical approach was performed in 2013. The whole public swimming pools in Tehran were inspected and water samples were taken for measurement of microbial indicators including thermotolerant coliforms, heterotrophic plate count (HPC), and physicochemical parameters affecting the microbial water quality including turbidity, free residual chlorine and pH and an integrated swimming pool microbial water quality index were used to describe the overall situation. Operational parameters with probable effects on microbial water quality were checked through inspection using a checklist.

Results: The assessment of the swimming pool microbial water quality indicated that the compliance rates of thermotolerant coliforms and HPC were 91.4 and 84.5%, respectively. Compliance rates of free residual chlorine, turbidity, Ph, and temperature were also obtained to be 82.7, 45.5, 85.6, and 65.4% respectively. Based on the integrated swimming pool microbial water quality index, the proportions of swimming pools with excellent and good microbial water quality were 39.6 and 50.4% respectively and the others had not proper microbial water quality. The parameters of water free residual chlorine and turbidity, swimmer density, water recirculation period, dilution amount, cleaning, usage rates of shower and disinfection basin and operation of water treatment systems had significant effects on the microbial indicators (P<0.05).

Conclusion: The study showed that the overall microbial water quality status of public swimming pools in Tehran was acceptable and analysis of the results determined the most efficient interventions for improvement of the microbial water quality of the pools.

Background and Objective: Formaldehyde is a toxic volatile organic compound, which its removal from polluted air is essential. One of the techniques available for removing such compounds is photocatalytic degradation. The aim of this study was to investigate the photocatalytic degradation of gaseous formaldehyde on TiO₂ nanoparticles coated on reduced graphene oxide

Materials and Methods: The synthesized reduced graphene oxide- TiO₂ nanocomposite was characterized using SEM, EDS, and FTIR spectra. The photocatalytic activity of prepared reduced graphene oxide- TiO₂ nanocomposite was investigated for degradation of gaseous toluene under different operational conditions such as different initial concentration, flow rate, and time.

Results: The photocatalytic degradation efficiency of the RGO-TiO₂ nanocomposite was much higher than P25 TiO₂. The photocatalytic degradation efficiency of the RGO-TiO₂ nanocomposite decreased by increasing the flow rate so the flow rate is a key factor for the use of RGO-TiO₂ nanocomposite as a photocatalyst. The results showed that the photocatalytic degradation rates decreased from 89 to 30% with increasing formaldehyde initial concentration from 0.1 to 1 ppm.

Conclusion: This research indicated that RGO-TiO₂ nanocomposite can be effectively used as suitable photocatalyst to remove gaseous pollutants. One of the advantages of the as-prepared composite was using visible light instead of UV to activate the oxidation process.

Background and Objectives: Money as a common tool is exchanged between people all over the world. Thus, it can be a source of chemical and biological contaminations causing serious diseases. The purpose of this research was to determine bacterial contamination of the currency notes and coins collected in Kermanshah.

Materials and Methods: 160 currency notes and 96 coins were randomly chosen from different jobs and parts of the city. Total count experiment was done and bacteria were identified and isolated through standard methods.

Results: Average total count in 1000, 2000, 5000, 10000, and 20000 Rials currency notes were 147.6, 147.8, 148.5, 96.3, and 87.9 and in 500, 1000, and 2000 Rials coins were 104.66, 77.66, and 96.56 CFU/cm², respectively. The research showed that currency notes carries more bacterial load than coins (P<0.05). Additionally, contamination to E. coli on money (13.7 %) and on coins (3.9%) were at maximum levels while Pseudomonas on currency notes was at the minimum level (1.6%) and coins contained 0.2% Enterobacter that was at the lowest amount.

Conclusion: In summary, the most important microorganisms isolated from currency notes and coins (E.coli and Staphylococcus aureus) were pathogenic, causing serious food poisoning and gastroenteritis infectious. Therefore, preventing food from cross contamination with money is necessary.

Background and Objective: Increasing air pollution and consequently adversely effects on the quality of life for many people has resulted in the use of the air quality indice for determination of the actual amount of pollutants and air quality, as one of the most important and effective measures for air quality control, to be considered further. The air quality health index (AQHI) is a new index related to air pollution developed in collaboration with Environment Canada and Health Canada, in 2001. The purpose of this study was to design and develop a software system for calculating AQHI for the first time in the country that calculates the health effects caused by the presence of several pollutants (NO_2, O_3,PM_10, and PM_2.5) at the same time with a new approach.

Materials and Methods: To achieve those aims, the software was designed and coded in Visual Basic. Net. After preparation of the software, it was tested using the real-time database of  six air pollution monitoring stations in Tehran including Aghdasyeh, Setad Bohran, Shahrdari 4, Golbarg, Park-e- Roz, and Shahrdari 11.

Results: This program is a software package installed on the computer with the possibility of exporting Excel file. The performance of software testing was verified using real data.

Conclusion: The results of the verification tests show that the index calculated by the software introduced and presented in this study can be used as a useful tool to assess air quality.

Background and Objective: About 1.35×10⁵ tons of pistachio waste are produced in annually Iran that can result in environmental problems if managed improperly. . The purpose of this study was to investigate in-vessel composting of pistachio residuals with addition of cow manure and dewatered sludge as a recycling alternative.

Materials and Methods: Pistachios wastes were combined with weight ratio of 5.5:10 (dewatered sludge: pistachio waste) and weight ratio of 1:10 (Cow manure: pistachio waste) to achieve the carbon to nitrogen ratio of 25:1. The parameters measured were pH, EC, percentage of moisture, total and volatile solids, ash, organic carbon, temperature, and phenol. The 20^th edition of SPSS software was used for t-test statistical analysis and comparing the results with standards and Microsoft Excel 2007 was used for drawing the plots.

Results: During the 60-days process of in-vessel composting of pistachio residuals with addition of cow manure, the ratio of carbon to nitrogen reduced from 25:1 to 13:1, dewatered sludge from 25:1 to 14:1; phenol amount in cow maneuver decreased from 4980 to 254 ppm and in dewatered sewage sludge from 6100 to 254 ppm. The maximum temperature in cow manure and dewatered sewage sludge treatments in the composting process reached to 51.9 and 48.9 ˚C respectively.

Conclusion: Results showed that the produced compost with cow manure has a higher fertilizing value compared with the dewatered sewage sludge due to its better organic degradation.

Improper and incorrect implementation of sewage collection networks can cause environmental and health problems. It also causes dissatisfaction in urban residents. The purpose of this study was to design a questionnaire for evaluating satisfaction level of urban residents from sewage collection network. Face validity index, content validity ratio and Cronbach-coefficient were used to evaluate validity and internal consistency. The evaluated indexes were assessed in acceptable levels. The designed tool that was included 25 variables can be used to assess satisfaction level by researchers and wastewater companies.

Background and Objective: Dewatered sewage sludge is a by-product of wastewater treatment process which can cause health and environmental problems if not properly managed. The aim of this study was to determine the feasibility of composting of Yazd WWT dewatered sludge with windrow method using different treatments.

Materials and Methods: In this study, the dewatered sewage sludge was mixed with two treatments of agricultural wastes (straw) and green waste (leaves), respectively. The mixture was done based on weight ratio of 20:1 and 10:1 (agricultural waste: dewatered sludge, and green waste: dewatered sludge) to achieve a ratio of C/N:20. The windrows were built with a length of 2 m, width of 75 cm and height of 1.5 m. Composting process was controlled by measuring the temperature, humidity, volatile solids, ash, pH, EC, organic carbon and estimating the C/N ratio. The results were compared with those of the Institute of Standards and Industrial Research of Iran.

Results: After 100 days of composting, C/N ratio was 13.08±6.25 in the treatment with green waste and reached to 15.46±5.35 in the treatment with agricultural waste. The amount of volatile solids decreased to 19.8±14.01% and 20.71±16.06% in the treatments with green waste and agricultural waste, respectively. The amount of EC had an increasing trend in both treatments.

Conclusion: composting with both treatments was led to an improvement in indicators of organic fertilizers in dewatered sewage. However, the windrow containing green waste reached to the mature compost standards sooner than the windrow containing agricultural waste.

Background and Objective: There are major mobile and non-mobile pollution sources due to human activities that can influence aquifers and reduce groundwater quality. Vulnerability assessment is an inexpensive procedure in to identify areas prone to the pollutants. Identification of these sources is essential in water resources management. Mahidasht Plain is one of the important regions of Kermanshah province and plays a significant role in the production of agricultural products. Water supply for agriculture may be at risk due to the indiscriminate withdrawal of groundwater resources of the plains, the recent droughts and potable water requirements. Therefore, analysis and evaluation of the area helps to make better decisions on proper management and control of water pollution.

Materials and Methods: Vulnerability, which is defined as the sensitivity of groundwater quality to pollution load, was applied and determined using intrinsic features of the aquifer. In this study, we have studied inherent vulnerability of the Mahidasht aquifer against pollution by using DRASTIC model and GIS. Seven parameters for the zoning of aquifer vulnerability was used in the DRASTIC method, including depth to the water table, net recharge, aquifer material, soil type, topography, impact of vadose zone and hydraulic conductivity. These parameters were prepared as seven layers of information in Arc GIS10 Software. The data collected for the purpose of this study were taken fromwells log, 44 piezometer in the area, pumping experiments and three rain-gauge stations. The layers prepared in Arc GIS10 software were weighted, ranked and eventually integrated.

Results: The DRASTIC index calculated for the plain ranged from 34 to 120 units. On this basis and according to the standards listed for DRASTIC index, the aquifer was in a vulnerable group with a low or no risk.

Conclusion: DRASTIC model output showed an inherent vulnerability of the aquifer. The model can be used as a primary tool in the development and management of water resources in the future. In addition, this model is not able to produce information about amount and type of pollutants. Therefore, it is recommended to examine the salinity zoning in the future research due to less rainfall and decreasing underground water level and consequently the higher probability of salinity in underground water. Additionally, the domestic and industrial wastewater, sewage irrigation and the fraction used for groundwater recharge should be considered in order to validate the results of Drastic model.

Background and Objective: Optimum number of air quality monitoring stations in Mashhad is an essential task for management of the urban environment. However, real monitoring and accurate information on the status of air quality require proper spatial distribution of air quality monitoring stations in the city of Mashhad. The aim of the present study was to determine optimum site locations for air quality monitoring, including Downtown Pedestrain Exposure Station, Downtown Background Exposure Station, and Residential Population Exposure Station by three Multiple-Criteria Decision-Making (MCDM) techniques.

Materials and Methods: In the precent study, sites for new air quality monitoring stations t in Mashhad were determined based on a proposed protocol in the United States. Accordingly, the criteria effective for site selection such as population density, distance from existing stations, vicinity to vegitation, vehicle density and other factors were used by applying Analytic Hierarchy Process (AHP), Fuzzy set, and Probability Density Function (PDF).

Results: Location similarity of the sites proposed by decision making methods was evaluated to know its reliability. The compactness of distribution of the proposed sites were compared by applying spatial statistic methods auch as Average Nearest Neighbor (ANN) and Standard. The results from ANN indicated that fuzzy set mapped the suggested sites was fully scattered within the entire city of Mashhad and was statistically significant at 99% confidence level. The PDF method also offered the same spatial pattern as fuzzy set. Overall results of this study indicated spatial optimization of suggested sites location for fuzzy set and PDF.

Conclusion: The overall results of the decision-making methods used in this study indicated that it is necessary to increase number of air quality monitoring stations at Northwest of Mashhad due to the urban growth in the city. The results also showd the possibility of using Probability Density Function (PDF) as a method of decision-making in GIS for locating and ranking of new air quality monitoring stations.