Iranian Journal of

Background and Objective: Climate change in recent years has led to a crisis of drought in many countries around the world, including Iran. In such a situation, the supply of safe drinking water is very important and knowing the climate impacts on the chemical quality of these resources can play a significant role in their proper exploitation.
Materials and Methods: Using GIS geomorphology models, the effect of climatic factors including minimum and maximum temperatures, mean precipitation, evaporation, transpiration and vegetation index on the quality of groundwater resources of Varamin Plain include pH, electrical conductivity, total dissolved solid, anions and cations concentrations and total hardness were studied and their maps were produced. Correlation between these factors was investigated using spatial correlation analysis tool at a confidence level of 0.95 (p = 0.05).
Results: The results showed that these parameters (except pH) along the plain are highly variable and the spatial distribution of data in this region is not normal around the mean, and the frequency of pixels with values ​​less than the spatial mean of the region is higher. Spatial distribution of the factors showed that their amounts (except pH) are low in the central area of ​​the plain and reach its peak in the western and northwest regions. The spatial distribution of pH was almost uniform in all the plain.
Conclusion: Correlation analysis showed that the quality of water resources is influenced by climatic factors and the maximum temperature has the highest impact.
 

Background and Objective: Marine sediments are the most important component of monitoring the health of aquatic ecosystems. The present study uses sediment quality indices to determine the contamination status in Qeshm ecosystems and to evaluate the toxicity of the elements studied for its organisms.
Materials and Methods: Sampling of surface sediments of seven stations was carried out on Qeshm coastal areas. The samples were digested by a combination of nitric acid and perchloric acid, and the concentration of metals was measured by atomic absorption spectrometry.
Results: The results of modified Hazard Quotient indicated a high pollution rate for copper and nickel metals in most stations, which was consistent with the results of the Potential Contamination Index in relation to nickel metal. Additionally, the results of the Potential Contamination Index and Contamination Factor agreed with the amount of lead element. According to the results, the pollution index of Hamoon Lake and Zakeri pier was highly contaminated and Modified Pollution Index demonstrated a contamination in Romacha, Hamoon Lake, Zakeri pier and Nazes areas. The enrichment factor associated with contamination regarding most of the heavy metals confirmed the indices used to evaluate the comtamination in the study area.
Conclusion: Due to the higher concentrations of the heavy metals in the sediments than that of the quality guidelines, the high toxicity of sediments for the aquatic ecosystems was confirmed. The Romachah, Hamoon, Zakeri stations showed higher pollution levels and sever toxicity for aquatic life. Copper, nickel and in some cases lead, were the main heavy metals that contaminated the sediments in the region.
 

Background and Objective: Chahnimeh water reservoirs in Sistan and Baluchestan Province are the most important sources for drinking water and irrigation purposes. Many factors such as precipitation, the geography of the watershed, atmosphere, geology and Human activities affect on the chemical, physical, and biological compositions of Chahnimeh water reservoirs. Therefore, the main goal of the present study was to monitor and assess water quality in four Chahnimeh reservoirs during two sampling periods.
Materials and Methods: 84 water samples were taken based on the standard methods (in September 2017 and April 2018) for measurement of the most important physicochemical parameters including major anions, total coliform, BOD, EC, TDS, pH and nitrate. Water quality index (WQI) was used to evaluate the overall water quality status in the Chahnimeh reservoirs.
Results:  The results of hydro-geochemical analysis indicated that the water type changed from sodic bicarbonate and sulfur dioxide to radicle chloride during sampling periods. The Gibbs chart showed that weathering of rocks mainly controlled the chemistry of the main water ions. The results of statistical analyses revealed that there was a high correlation between parameters such as chlorophyll, nitrate, sulfate and chlorine with water quality index. Water quality zoning results based on the WQI index indicated a decrease in the water quality of the wells by 3, 2, 1, and 4, respectively.
Conclusion: In this study, the use of WQI was helpful for fast data interpretation for drinking water purposes in the area. Based on the WQI classification, majority of the samples are falling under good to poor water category.
 

Background and Objective: Air pollution is a leading environmental risk factor on health and it is the major cause of death and disease at global level. Air pollution has been shown to have a significant share in the non-communicable diseases (NCDs) burden. After smoking, it is the second cause of deaths due to NCDs, associated with an increased risk of developing acute and chronic diseases and mortality.
Materials and Methods:  In this study, a review was initially conducted on the basis of indices conducted in the world, the status of ambient air pollution and its effects on health in Iran and other countries, and then the status of ambient air quality and its effects on health in Tehran metropolitan between 2006 and 2017 were shown, based on the results of the studies conducted by the Environmental Research Institute of Tehran University of Medical Sciences.
Results: The results showed that the annual mean of ambient air population-weighted PM_2.5 exposure concentration in Iran was about 48 μg/m³, which is relatively lower than its global mean concentration (51 μg/m³). Based on the most recent study (in 2018) about 8.9 (7.5-10.3) million deaths in those aged above 25 years were attributed to exposure to outdoor air PM_2.5 in the world. Although there are substantial differences between the results of studies have been done regarding the number of air pollution attributed deaths, numerous studies showed that air pollution is a major cause of death. Results regarding temporal variations of air quality in Tehran that is performed by the Institute for Environmental Research (IER) of Tehran University of Medical Sciences (TUMS), indicated that PM concentration had an increasing trend from 2006 to 2011. The maximum mean concentration of PM_2.5 over the past 12 years has occurred in 2011, which was 38 μg/m³. The PM concentration had a decreasing trend from 2012 to 2015, reaching about 30 μg/m³. However, in the years 2016 and 2017, the annual mean PM_2.5 concentration in Tehran was increased compared to its corresponding value in 2015. Furthermore, results of this study demonstrated that, in Tehran, not even one day was classified as "good” (AQI=0-50) from 2011 to 2017 based on the air quality index (AQI), but the number of days in which AQI was “moderate” (AQI=51-100) was increased from 2011 to 2015, and the number of days with the AQI of “moderate” reached 80 in 2015, while the rest of the days having an unhealthy air quality. In 2017, AQI was “moderate” in 20 days, “unhealthy for sensitive groups” in 237 days, “unhealthy” in 107 days, and "very unhealthy” in 1 day. The obtained results indicated that about 4878 (3238, 6359( of deaths due to all (natural) causes were attributable to long-term exposure to PM_2.5 in Tehran in 2017.
Conclusion: Studies showed that air pollution has a considerable share in the number of attributed deaths. Moreover, there were substantial differences between the results of national and international studies in the burden of disease attributed to air pollution. Therefore, there is a crucial need for accessing to reliable data on air pollution as well as baseline mortality and morbidity in order to study the status of air quality and its effects on health over the country. 

Background and Objective: Surface water and underground water quality in countries that facing dehydration have increased the interest of the community to use Household Water Treatment devices. The aim of this study was the evaluation of the quality of drinking water of Household Water Treatment devices and general distribution network in Garmsar, which is under the control of the water safety plan.
Materials and Methods: A descriptive cross-sectional study administered in 6 regions and 41 cities of Garmsar city in spring and summer seasons in 2018. Chemical tests performed according to the standard methods for the examination of water and wastewater, general measurements were performed using the multi-tube fermentation method and counting of heterotrophic bacteria by pour plate method. The results analyzed by using Excel and SPSS software.
Results: The average values during two seasons were reported as: EC= 1507 (μS/cm), TDS= 786.8 (mg/L), F= 0.048 (mg/L), residual free chlorine= 0.67 (mg/L), pH=7.9, total coliform= 0.16 (MPN/100 mL), fecal coliform= 0.14 (MPN/100 mL) and HPC= 112 (CFU/mL). No significant difference found between the chemical and microbial parameters in the general distribution network and the output of the Household Water Treatment devices during the two seasons.
Conclusion: Household water treatment devices did not affect the microbial burden but caused a change in the amounts of some chemical parameters. Drinking water from the distribution network, with the proper application of the water safety plan, is of good quality.
 

Background and Objective: Increased untreated wastewater and unsustainable development of agriculture has deteriorated water quality of rivers. The aim of this study was to determine the quality of water in Gorganrud River basin using NSFWQI IRWQISC and Liou Pollution Index and compare them with the global standards. To do this, GIS software.was used
Materials and Methods: In this study, 5 sampling stations were selected based on standard criteria including land use type, accessibility and standard distributions along the river. 12 water quality parameters including dissolved oxygen, fecal coliform, pH, biochemical oxygen demand, chemical oxygen demand, temperature, organic phosphate, nitrate, ammonium, turbidity, total dissolved solids and electrical conductivity in river for one year were measured from June 2019 to May 2019 follwoing standard methods.
Results: The amount of phosphate and turbidity was increased along the river from station 2 to the mouth of the river. This was due to the presence of agricultural and municipal sewage. There was a significant difference in BOD, fecal coliforms and nitrates with those of the standard values. Water quality indicators showed the great effects of urban wastewater and human waste in the river area. The best quality was observed in Station 1 (75; Good Quality), which was less exposed to human activity and development. Based on the conformity of the results of the indicators with the terrestrial reality, the results of the IRWQIsc index (Iranian surface water quality) showed the best results due to compatibility to the land uses and the trend of variables.
Conclusion: The presence of urban sewage and unsustainable agricultural in the city of Gonbad Kavous is the most important reason for the decline in water quality (poor quality class). In this regard, a comprehensive management in water resources and environmental impact assessment is needed.

Background and Objective: Surface water is usually highly variable in chemical composition due to contact with different geological formationsand other surface and groundwater resources.  Knowledge on water quality and the impact of human activities are particularly important for sustainable management and planning of water resources. The aim of this study was to investigate the physicochemical and hydrochemical quality of Chehelchai river water in Golestan province.
Materials and Methods: In this study, 6 sampling stations were selected based on standard criteria including land use type, accessibility and standard distributions along the river in 2018. 10 river water quality parameters including pH, electrical conductivity, total soluble solids, sulfate, chloride, bicarbonate, sodium, potassium, calcium and magnesium - were measured according to standard methods for one year period. Piper, Schuler, Durov, Wilcox and Gibbs diagrams were applied for hydrochemical analysis using RockWorks.17 software.  Statistical analysis was performed using one-way ANOVA.
Results:  Results indicated the abundance of major ions was found in the order of HCO₃^- > SO₄^2- > Cl^- and Ca²⁺ > Na⁺ > Mg²⁺ > K⁺. The river water type was predominantly determined as calcic bicarbonate. The findings revealed that the water of the study area is acceptable for drinking purpose based on Schuler diagram and also appropriate for agricultural uses considering Wilcox diagram (80% of the samples in class S1-C3 (saline - usable for agriculture)) and the average sodium uptake ratio (0.79).
Conclusion: The presence of dolomite ores, the absence of factories and domestic sewage and adhering to hygiene regulations by the residents, are the main reasons which have increased the quality of Chehelchai river water.

Background and Objective: Since industrial waste management requires accurate knowledge of quantity and quality of solid wastes, this study was conducted to assess quantitative and qualitative characterization of industrial solid waste in Qazvin province, Iran and investigate its related pattern management.
Materials and Methods: Based on the guideline of Iranian Environment Protection Organization, industries were classified into 10 groups. Then according to the abundance of industries in each group, 276 industries and 4 wastewater treatment plants were selected. The Basel Convention criterion was used to identify special solid wastes. Quantitative and qualitative characteristics and management pattern of industrial wastes were determined by referring to the industries and completing a researcher-made questionnaire.
Results: The total types of identified industrial solid wastes were 1726. According to the guideline of Basel Convention, 33.7% of identified wastes were classified as special wastes. The total amount of solid wastes was 38826 ton/month. The maximum solid wastes production was in the chemical industries with 14,380 ton/month. The recovery and recycling rates were 8.96 and 6.44%, respectively, and 36.44 % of industrial waste was sold directly.
Conclusion: The results of the study showed that the management of industrial solid wastes in Qazvin province does not follow a specific pattern. In addition, the quantity and the composition of solid wastes in the study area is a serious potential for environmental pollution and threatening human health. Therefore, it is necessary to establish a center responsible for industrial wastes management and design a centralized industrial waste disposal system.

Background and Objective: One of the most important goals for urban environmental management system is the monitoring of air quality. Allocating optimum air quality monitoring stations (AQMS), is a key factor in establishing effective and accurate air quality monitoring program. The objective of this study was to determine optimal allocation for AQMS in Karaj.
Materials and Methods: Based on two stages approach, at first, the suitability map was obtained by WLC method. For AQMS implementation, municipal districts were ranked. The extracted alternatives were graded using TOPSIS. In the next stage, the position of preferred sites were investigated by site visiting and detailed criteria. Finally, the AQMS locations were introduced.
Results: Ten suitable stations were suggested based on population and number of municipal districts. During the first stage important criteria such as distance from roads and street cross-section were weighted and standardized. The distance from roads and green space were the lowest and highest important criteria, respectively. The lowest and highest ranks for AQMS implementation were Nos. 9 and 3 districts, respectively. During the first phase 30 alternatives were obtained. At the second stage, 10 best alternatives were selected following field observation and considering implementation criteria (eg. distance from trees, cross section and pollutants emission sources).
Conclusion: In this study, at the first stage the preferred alternatives were determined. In the next stage the best alternatives for AQMS implementation were selected considering reasonable time and effort. The suggested approach could be used to implement AQMS for other areas.

Background and Objective: The aim of this study was to evaluate the chemical and microbial quality of bottled water in Iran and to calculate the water quality index (WQI).
Materials and Methods: Different brands of bottled water (4 samples from 71 brands) were randomly collected from the market. Chemical and microbial characteristics of the samples were examined and determined. Finally, the calculations related to the WQI index were performed and the water samples were classified as excellent, good, poor, very poor and unsuitable.
Results: None of the samples exhibited concentration of heavy metals beyond Iranian water standards, and the concentration of sulfate (SO₄), chloride (Cl) and fluoride (F) did not exceed international standards. However, in some samples, nitrite (NO₂) and nitrate (NO₃) concentrations were higher than recommended standards. With Regard to other water quality parameters, 8% to 89% of the samples exhibited concentration higher than the values provided on the water bottle label. 5 species of different bacteria were found in 15 water samples. According to the WQI index, about 63% of the samples were of excellent quality. Also, the water quality of 34% and 3% of the samples fell in good and poor quality categories, respectively. None of the bottled water samples was of very poor quality.
Conclusion: The quality of bottled water investigated in this study was generally suitable, but due to the wide range of bottled water in Iran based on brand and seasons, continuous evaluation of water treatment methods in companies and careful monitoring of chemical and microbial quality of bottled water in all seasons is recommended.

Background and Objective: Groundwater is the primary water source for drinking and agricultural activities in arid and semi-arid regions. Rainfall, land use, geological structure, aquifer mineralogy, and duration of water contact with the environment in the basement are the main factors affecting the chemical quality of groundwater. This study aimed to determine the physicochemical properties of groundwater by considering the water quality index (WQI) and its quality assessment for drinking water.
Materials and Methods: In this study, 71 wells of Kashan were sampled in summer 2020 with three samplings from each well, and physical and chemical parameters were studied, water quality index was determined using mathematical methods, and Pearson correlation coefficient was determined. Correlation analysis was used. Finally, the collected data were analyzed using SPSS-16 software, Excel 2013, and statistical tests. 
Results: The calculated WQI of 71 wells in Kashan shows that 67% of the wells were of excellent quality, and 33% were of good quality in terms of water quality parameters. In total, out of 71 samples, the numerical index of water quality was 44.94, and the water was of excellent quality.
Conclusion: The results show that ions such as sodium, sulfate, and chlorine are directly related to the counting in an area and increase the concentrations of EC and TDS, and can impair the balance of anionic and cationic aqueous solution. It was also found that more than half of the wells have excellent quality due to using water wells for drinking.

Background and Objective: With the industrialization of communities, population increase and use of surface water, river pollution has been increased by agricultural, industrial pollutants and urban wastewater. Therefore, investigation of river pollution for regional and environmental planning is of great importance. To evaluate surface water pollution, a number of surface water quality indices have been investigated.
Materials and Methods: Iran water quality index for surface water resources (IRWQI_SC) approach was used to evaluate the water quality of the Mahabadchai river, Iran. Sampling was carried out along the Mahabadchai river based on some criteria such as approximately to drainage areas for landfills/domestic and agricultural effluents.
Results: Pearson correlation coefficient between physical, chemical and microbial parameters of water showed that fecal coliform, BOD, COD, nitrate, ammonium, phosphate, turbidity and total hardness had a significant positive relationship with each other at 99% confidence. According to this index, upstream samples of the river are classified as good, mid-stations relatively good to moderate category, and downstream samples of the river are classified as relatively bad.
Conclusion: Based on the relationship between each variable, fecal coliform, BOD, COD, ammonium, and turbidity were more effective in determining the IRWQI_SC. Most of the examined variables showed low concentrations in upstream areas of the river while their concentration gradually increased along the river to downstream areas, especially close to urban and industrial districts.
 

Background and Objective: Nowadays, the application of procedures to minimize oxidative and microbial spoilage in marine products is economically and hygienically important. This study was performed to determine the effect of free and nanoliposome forms of poneh (Mentha pulegium L.) essential oil to increase the shelf life and improve the sensory characteristics of silver carp minced fish (Hypophthalmichthys molitrix) during storage time.
Materials and Methods: In this study, the antibacterial properties of 1 and 2% essential oil and nanoliposomes form on the microbial population of minced silver carp fish inoculated with Bacillus cereus and Escherichia coli were measured. Also, chemical tests (DPPH (2,2-Diphenyl-1-picrylhydrazyl assay, measurement of iodine peroxide (PV), pH, total volatile nitrogen (TVB-N) and thiobarbituric acid (TBARs)) and sensory properties of minced silver carp were evaluated during 12 days of refrigerated storage.
Results: The results showed that the addition of poneh essential oil (free and nanoliposomes) according to the microbial results and the results of chemical experiments can effectively prevent microbial growth and chemical spoilage (p<0.05). Treatment containing 2% nano essential oil of poneh showed the greatest effect on the chemical, microbial and sensory properties of minced fish during the experimental period in comparison with control treatments, 1% poneh nanoliposomes essential oil and 2 and 1% free essential oils.
Conclusion: Therefore, the nanoliposomes form of 2% poneh essential oil can be used as a suitable additive to increase the shelf life of Silver carp fish in the fish industry.

Background and Objective: Increasing the productivity of surface water, the unsustainable development of agriculture in the boundaries of rivers, and human sewage have reduced the quality of these water resources. Therefore, investigating the amount of pollution and its sources is very necessary for regional planning. This study aimed to evaluate the water quality of the Golin River using WQI and Liou indexes.
Materials and Methods: Sampling of Golin river water was performed to check water quality based on (WQI) and (Liou) indices in Najjar village station for one year from April 2019 to March 2020.
Results: Water quality, according to the Liou index, during the research period in the sampling station in September and March, was in a good category and other months were slightly polluted. According to the results of the WQI index, water quality in September and March were in the excellent descriptive category, with values of 47.82 and 49.74, respectively, but in other months it was in a good category. In September and March, water quality improved compared to other months because of lower BOD5 due to reduced agricultural activities, and both indicators showed these quality changes well.
Conclusion: Due to the lack of stable conditions in water quality affected by seasonal changes and its departure from the category of high-quality water according to the results of the WQI index and also a little water pollution according to the Liou index, the direct use of Golin River water for drinking purposes is recommended and for this purpose, regular purification should be done and accurate and continuous evaluations of water quality in Golin River are necessary.
 

Background and Objective: One of the main limitations of using compost is the possibility of heavy metals with high concentrations. Unlike organic contaminants, these elements resist decomposition by microorganisms and, when present at elevated levels, pose a toxicity risk to soil, plants, aquatic ecosystems, and human health.
Materials and Methods: This study was a descriptive cross-sectional study conducted in 2021-2022w. Samples were collected from three compost factories in Mazandaran (Babol, Behshahr, and Tonekabon) using random sampling methods and prepared according to the acid digestion method (National Standard Institute 5615). The concentration of heavy metals in the samples was measured using an ICP-OES.
Results: The average concentration of arsenic, zinc, lead, cadmium, cobalt, chromium, copper, and nickel in the analyzed samples were 1.38±3.47, 490±151.5, 74±12, 2.56±0.65, 4.5±1.46, 31.72±16.47, 186.11±49.9, 22.72±4.2 mg/kg dry weight of compost, respectively. The average concentration of heavy metals in different cities was compared using the Kruskal-Wallis test, based on which the concentration of heavy metals in none of the cities was significantly different from each other (p>0.05).
Conclusion: The concentration of heavy metals in the investigated compost samples was lower than the limits specified in both domestic and international standards. Therefore, the final product of the examined compost factories meets the health standards for heavy metals and is safe for use in environmental applications.
 

Background and Objective: In today's society, preparing healthy food has become challenging due to the variety of food production methods. Oil is produced in several ways in our country. In the cold pressing method, there is insufficient monitoring of the manufactured product. The aim of the present study is to investigate the physicochemical characteristics and the levels of heavy metals of industrial oil compared to cold-pressed oil.
Materials and Methods: In this research, 54 samples of sunflower, sesame, and canola oil produced by both cold pressing and industrial refiningmethods were prepared. Their physicochemical characteristics, including refractive index, acid value, iodine value, saponification value, peroxide value, anisidine value, as well as the concentrations of lead, iron, arsenic and copper were determined. Additionally, the effect of storage time on these characteristics was investigated.
Results: The Iodine number showed the highest deviation from the standard (61%), with an average of 136.70 gI/100g for the cold-pressed oil and 134.48 gI/100g for industrially refined oiland. The average value of the physicochemical characteristics, except for the saponification value, were higher in the cold-pressed oil samples  compared to the industrially refined oil samples, but the observed difference was not statistically significant. An investigation into the effect of storage time on physicochemical properties revealed a significant increase in peroxide value (p<0.01) and anisidine (p <0.05) in both oil groups over a two-month period. The average concentration of arsenic, lead, iron and copper in the studied oils was 0.03, 0.78, 0.05 and 0.05 mg/kgoil, respectively. A deviation from the standard was observed only in one sample of cold-pressed sunflower oil, with an arsenic concentration of 0.11 mg/kgoil).
Conclusion: Based on the obtained results, the refined industrial oils exhibited more favorable chemical characteristics and stability.  It is suggested that cold-pressed oils should be consumed within a short period of time. For frying purposes, refined industrial oils are preferable.
 

Background and Objective: Identifying the quality of non-conventional waters and exploring their optimal utilization are fundamental measures for maintaining public health. This study aims to investigate the effluent quality of the irrigation canals in Pakdasht farms.
Materials and Methods: In this cross-sectional descriptive study, 120 samples were collected from 6 irrigation canals in Pakdasht fields over a period of 5 months. The physicochemical and microbial characteristics of the canal effluents were determined based on the standard methods of water and wastewater tests. The concentration of heavy metals was measured using an ICP device. To determine the possibility of using the effluent of Pakdasht canals for agricultural purposes, the Environmental Protection Organization of Iran and FAO standards were used.
Results: The average concentrations of COD, BOD₅, TSS, TDS, NO₃^-, SO₄^-2, PO₄^-3 parameters were 259, 125, 105, 697, 4.5, 94.4, 13.5 mg/L. Additionally, the average number of total and fecal coliforms in the effluent of the canals exceeded the standard values set by IRNDOE and FAO. The mean pH was 6.97, the electrical conductivity (EC) was 1014 μm/cm, and the turbidity was 76.2 NTU. The detected concentrations of heavy metals were awithin the following ranges: Cr (0.025-0.045 mg/L), Cd (0.0006-0.001 mg/L), Pb (0.0006-0.001 mg/L), Co (0.038-0.059 mg/L), and Ni (0.05-0.06 mg/L), which were roughly lower than the suggested standards. However, both HEI and WWQI indices confirmed that the water was unsuitable for agricultural irrigation.
Conclusion: Based on the comparison of the results of the parameters measured in this study with the environmental and FAO standards, the effluent from the irrigation canals of Pakdasht city is deemed unsuitable for the irrigation of warm-season crops but suitable for fodder and industrial crops.
 

Background and Objective: The air quality index (AQI) does not account the interaction of multiple pollutants, meaning the high concentration and health risk of one pollutant may amplify the effects of others. The main aim of this study was to characterize the ambient air quality of Arak by assessing the combined effects and health risks associated with criteria air pollutants.
Materials and Methods: This study evaluated the ambient air quality of Arak for the year 1401 on the Persian Calendar, using the concentrations of criteria air pollutants averaged over appropriate timeframes. Additionally, the AQI, aggregate air quality index (AAQI), and health risk-based air quality index (HAQI) were calculated.
Results: Findings showed that the 1-hour concentrations of NO₂, SO₂, PM₁₀, and PM_2.5 exceeded national standards in 0.05%, 0.2%, 12.1%, and 35.5% of hours, respectively. The AQI, AAQI and HAQI values were above 100 in 54.4%, 77.3%, and 56.2% of hours, respectively. PM_2.5 was the major pollutant in over 99% of cases.
Conclusion: The results indicated that AAQI and HAQI, in comparison to AQI, characterized the air quality as more polluted. This stricter assessment by AAQI and HAQI may encourage more precautionary measures by authorities and the public. Thus, it is recommended that the decision-makers in Iran’s air quality monitoring in consider adopting these indices.
 

Background and Objective: People spend over 90% of their time indoors, where air pollutant concentrations—including volatile organic compounds (VOCs)—are significantly higher than outdoors. Among these VOCs, benzene is particularly critical due to its carcinogenic properties. Phytoremediation offers a sustainable solution for removing such pollutants from indoor environments. This study evaluates the benzene-reduction efficiency of two ornamental plant species, Aglaonema ‘Silver’ and Chlorophytum comosum, under controlled temperature and humidity conditions.
Materials and Methods: The plants were exposed to two temperature levels (18°C and 24°C) and two relative humidity conditions (35% and 50%). Benzene was introduced into sealed chambers at concentrations of 1, 0.5, 0.25, and 0.125 µL/mL. After 12 hours of exposure, benzene reduction was quantified using gas chromatography.
Results: At 20°C and 35% RH, Aglaonema 'Silver' removed 96% of benzene, outperforming Chlorophytum comosum (38%). Removal efficiency depended on species, environmental conditions, and initial concentration. Predictive models (Eq. 2–3) correlated strongly with experimental data (R² > 0.9).
Conclusion: Aglaonema 'Silver' demonstrated superior benzene removal compared to Chlorophytum comosum under lower temperature and humidity conditions. Our findings highlight that selecting plant species adapted to specific environmental parameters can significantly improve phytoremediation effectiveness. Furthermore, the proposed model indicates that elevated temperature and humidity levels may enhance benzene removal efficiency by indoor plants.
 

Background and Objective: This study aimed to assess the chemical and microbial quality of sludge generated at the Khoy wastewater treatment plant using an SBR process, and to compare the results with established agricultural standards.
Materials and Methods: In this study, monthly sludge samples were collected and analyzed using standard EPA methods, including the 15-tube technique for coliforms, flotation for Ascaris eggs, and acid digestion for heavy metals. Data were analyzed using SPSS v.25 and statistical analyses included Pearson correlation tests.
Results: The analyzed sludge exhibited an acceptable pH (7.14) and a high organic carbon content (27.32%). However, its elevated salinity (9891 µS/m) and low C/N ratio (6.38) indicated biological instability and limitations for direct agricultural application. The concentrations of heavy metals—including arsenic (10.27 mg/kg), copper (134.86 mg/kg), and zinc (530.93 mg/kg)— exceeded Iran’s national standards. Heat-map analysis confirmed a significant correlation between salinity, and the levels of chloride (Cl^-), and sulfate (SO₄^2-). Despite its nutritional value, the sludge is not recommended for direct agricultural use without prior treatments such as stabilization, salinity reduction, and pathogen removal.
Conclusion: Despite the substantial nutrient content of the sludge, including nitrogen, phosphorus, and organic carbon, its direct application in agriculture faces serious limitations due to high salinity, an imbalanced C/N ratio, severe microbial contamination (e.g., nematode eggs), and the exceedance of permissible levels for several heavy metals. Safe utilization of this sludge requires corrective treatments such as stabilization, disinfection, desalination, and regular monitoring of heavy metal concentrations.