فصلنامه سلامت و محیط زیست
سال چهاردهم شماره 1 (پیاپی 51، بهار 1400)

In the present research, the synthesis and characterization of ZnS nanoparticles in zinc blend crystallite phase via hydrothermal method were reported. Advanced oxidation processes using nanophotocatalysts are one of the most efficient methods for removing the dyes with complex organic compounds from textile and industrial wastewaters. The photocatalytic performance of nanoparticles is drastically affected by their structural and optical properties. One of the most important features affecting the photocatalytic degradation of nanoparticles is their optical bandgap width, which is an important factor in the radiant photons in the visible and UV region and the production of active radicals to destroy the complex carbon pollutants. The optical bandgap width, like other properties of nanoparticles is affected by three important geometric parameters, including particle size, dimension and shape. It is also a function of synthetic chemistry, i.e. the precursors and the fabrication methods. The aim of the present study was to investigate the nanostructure of zinc-sulfide synthesized nanoparticles, optical properties and photocatalytic effect on the degradation of Methylene Orange dye.

The experiment of degradation of dye consisted of 70 mg of synthesized nanoparticles in 100 mL of dye solution containing 3.75 ppm of Methylene Orange dye at pH = 5.5. The experimental steps were repeated three times. Nanostructure characterization of three-dimension ZnS nanoparticles was specified by X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, transmission electron microscopy, Furrier transform infrared, ultraviolet-visible spectroscopy and N2 adsorption-desorption.

The lattice characteristics such as density, specific surface area, size, strain, stress and deformation energy density are specified using Williamson-Hall (W-H) and Halder-Wagner (H-W) analysis. The photocatalytic degradation rate (k) of Methylene Orange was calculated to be 0.052 1/min, whilst after 60 minutes about 95% of the dye was photodegraded. The N2 adsorption-desorption calculations determined the mean pore diameter, specific surface area (SBET) and total porosity volume as 20.69 nm, 19.12 m2/g and 0.065 m3/g, respectively. The bandgap of fabrication ZnS has been evaluated from the Tauc's equation to be 3.47 eV. Compared with ZnS nanoparticles made by the hydrothermal method in the wurtzite crystallite phase (sample 2), the synthesized sample (sample 1) shows less lattice strain and stress, less crystallite size and also revealed the higher photocatalytic activity.

The pure zinc-sulfide nanoparticles without metal or ceramic dopants in the cubic zinc-blend crystallite phase are synthesized using the hydrothermal method. The precursors used in the synthesis of zinc-sulfide nanoparticles include zinc chloride and thioacetamide in the presence of oleic acid as a collecting agent. High photocatalytic activity of ZnS nanoparticles was confirmed by the degradation or dechlorination of Methylene Orange solution under UV light irradiation. Compared to similar studies, the results show that reducing the optical bandgap from 3.84 eV to 3.47 eV increases the degradation rate from 0.031 to 0.052. In this study, it was shown that synthesized zinc-sulfide nanoparticles by hydrothermal method, was able to decrease optical gap bandwidth and subsequently increased photocatalytic activity.

Due to the increasing trend of municipal solid waste (MSW) production, if a suitable management system is not applied, it will lead to environmental pollution and endanger human health. The aim of this study was to compare different scenarios of waste management in Chalous city with life cycle assessment (LCA) approach and to select the most efficient method in terms of environmental adaptation.

After investigation of the quantitative and qualitative characterization of the produced wastes and the current waste disposal method in Chalous city, the obtained results were used to evaluate the life cycle of six different waste management scenarios; including the combination of four methods of composting, recycling, incineration along with energy extraction and sanitary landfilling. Emissions from various scenarios were assessed using IWM-2 model.

The current system of municipal waste management in Chalus (scenario 1) with ecological index of 1.73+06 poses the highest pollution load into the environment. The inclusion of compost disposal methods in the organic waste sector and recycling of biodegradable materials significantly reduces the emissions of environmental pollutants by increasing the amount of materials for recycling and reuse, as well as preventing emissions from raw material production. The fifth scenario (60% compost, 30% recycling and 10% sanitary landfill) with ecological index of -2.00+05 was known as the lowest contamination scenario.

Considering that a high percentage of Chalous municipal solid waste composition is perishable materials (organic waste), simultaneous application of composting and recycling methods can be a suitable option for optimal management of wastes in Chalous city and play an important role in reducing the environmental pollution load.

Application of chemical fertilizers in agricultural industry is known as one of the methods of crop enhancement. However, chemical fertilizers application can lead to an increased risk of chemical pollutants entering the human food cycle.  The aim of current research was feasibility study and evaluation of nickel from paddy soils in Lorestan province.

Sampling was done from 15 stations and randomly from rice cultivation areas in Silakhor plain of Lorestan province. Then, electrokinetic modification method was carried out in three reactors with lengths of 5, 10 and 15cm. After sample preparation, the initial and final concentration of nickel were measured and calculated using inductively coupled plasma - optical emission spectrometry (ICP-OES).

The results showed that electrokinetic modification method was effective in reducing the concentration of heavy metals in agricultural soil samples and reduced the amount of nickel in soil to the permissible limits of the Iranian soil national standards (50 mg/kg). The initial values of nickel in paddy soil of composite samples were 108 mg/kg. Nickel maximum removal efficiency of 90.84% and 93.75% were observed in cathode and anode regions, respectively.

The health and quality of agricultural products depend on the use of safe soil within the limits of environmental standards. The results of this study showed that the EKR process is able to remove nickel from soil. As a result of the present process, nickel concentration has reached the permissible amount and even lower than the soil quality standard set by the Iranian Environmental Protection Agency.

Considering the fact that Iran is located in semi-arid climate and the harmful effects of dust storms on different ecosystems, this study aimed to identify and locate dust storms using fungal bio-aerosols (spores) and HYSPLIT model in southwestern region of Iran.

MODIS satellite images and HYSPLIT model were used to investigate the temporal changes of dust masses entering the Khuzestan province.  Sampling was carried out from dust storms in Abadan and Khorramshahr cities and from the soil of the dried parts of Hur al-Azim and Shadegan wetlands in a two-month period (from May to July 2019).

The results of numerical modeling show that Abadan and Khorramshahr cities were affected by dust storms of internal origin (from Hur-al-Azim wetland). After isolation of bioaerosols from air and soil samples, a total of 6 fungal genera were identified in soil samples and 6 genera in dust samples of internal origin by PCR-Sequencing method. Talaromyces, Alternaria, Penicillium and Aspergillus were identified as the predominant genera fungi in soil and air samples.

With 70% similarity of fungi found in soil and air samples, it can be concluded that the main source of fungi in Abadan and Khorramshahr is Hur al-Azim wetland.

Monitoring the amount of ultraviolet radiation from sunlight can provide a basis for assessing people's exposure, raise public awareness and warn people against this radiation. Measuring the sun's ultraviolet index over a working period is an accurate choice to achieve this goal.

In this study, the amount of solar UV index in one of the outdoor locations of Zanjan city was measured using Solarmeter model 5.6 UV index meter for one year period. Measurements were performed from 9 am to 5 pm every 30 minutes in direct sunlight in even days for one year period (2018-2019). Finally, the results were analyzed using Excel software.

The highest value of the maximum daily UV index was related to July, with an average value of 11.87 ± 0.649; while, the lowest value of the maximum daily UV index obtained in January, with an average value of 2.23 ± 0.944. In most months of the year, except for late November, December, January and cloudy days, the average value of the maximum daily UV index around noon exceeds the UV index alert threshold set by the World Health Organization (WHO). Even for the safe time period during spring and summer, the average UV index can exceed the UV index warning threshold.

Determining the intensity of the sun's hourly UV radiation is important and necessary to increase the peoples’ and workers’ awareness working in the open environment, as well as to plan for protective measures in any place, especially in Zanjan.

Due to the importance of Mordab river, the concentration and distribution of heavy metals in sediments and part of Caspian sea coast, mostly affected by the Mordab river, were evaluated. Additionally, considering the possibility of heavy metals release from sediments to water column and transfer to crops, the health risk of rice consumption in the region was assessed.

21 sediments samples and 4 rice samples from paddy fields along the Mordab River were collected. Heavy metal contents of the samples were measured using ICP-MS. Data analysis was performed using enrichment factor (EF), ecological risk index (RI), health risk index, principal component analysis (PCA) and Mann-Whitney test.

The maximum concentrations of elements was higher in coastal sediments than the Mordab River. The results showed low to moderate risk of elements in most stations except for two coastal stations which exhibited considerable risk of contamination with regard to Cr. Principal component analysis categorized the elements into three components of different origin. Moreover, the estimation of weekly intake of elements through rice consumption were less than their permissible concentration set by World Health Organization.

The concentration of chromium in sediments, especially coastal sediments, is high, which may be partly due to the concentration of heavy minerals (chromium) in this fraction. Therefore, the origin of elements, particularly chromium, should be determined through sequential extraction methods. On the other hand, despite the pollution of river sediments and high consumption of rice among the residents of the study area, there is no danger to rice consumers in terms of heavy metals.

Limited water resources in arid and semi-arid regions are one of the major limiting factors in agricultural production. Thus, unconventional water resources, such as urban treated wastewater, may be used for irrigation. Application of wastewater to the soil may cause accumulation of heavy metals (HMs). Soil pollution causes uptake of these metals by plants and their entrance to the food chain. In the present greenhouse research, concentration variations of HMs (lead (Pb) and cadmium (Cd)( in soil and sweet pepper (Capsicum annuum) plant were investigated.

The experiment was conducted as a completely randomized design with three replications and irrigation with different wastewater treated (well water, wastewater treatment and diluted wastewater). To evaluate the effects of different irrigation treatments on soil, parameters of acidity (pH), electrical conductivity (EC), the concentration of heavy metals Pb and Cd in soil were studied.  Additionally, for the effects of irrigation treatments on sweet pepper plant, parameters of biomass weight, fresh and dry weight and Pb and Cd concentrations (in branches, fruits and roots) were measured. The amount of Pb and Cd in the pepper were measured by ICP-OES. The obtained average concentrations were compared using one-way analysis of variance (ANOVA), and the Duncan test was used to determine the differences between groups (p <0.05). The independent t-test was also used to investigate the difference in concentrations of Pb and Cd in soil and water (p <0.05).

The results of chemical analysis of soil and pepper showed that irrigation with wastewater did not cause a significant increase in the concentration of Pb and Cd in the soil and in the branches, fruits and roots of the pepper. The concentration of Pb and Cd in the soil and in the branches, fruits and roots of the pepper was within the allowable and standard concentration range. The difference in lead and cadmium concentrations in the soil before planting was not significant; however, at the end of the study period, the Pb concentration in pepper was higher than the Cd concentration. The use of wastewater increased the fresh and dry weight of branches, fruits and roots of the pepper.

The results showed that Pb and Cd concentration in roots and aerial parts of pepper plant was not increased significantly as a result of wastewater irrigation (p <0.05). The results of this study are limited to one growing season and by the continued use of municipal wastewater, the concentration of Pb and Cd in the soil and then in the plant may exceed the standard. Especially in the case of Pb, which seems to have shown a slight tendency to increase relative to the primary soil and the pepper. Therefore, the continuation of this study is recommended to evaluate the long-term effects of Bushehr municipal treated wastewater on the concentration of heavy elements in soil and plants, and soil properties. Overall, it should be acknowledged that based on technical recommendations, the use of treated wastewater are not recommended.

Hydrolysis of fat, oil and grease by ultrasonic waves is a pre-treatment method before anaerobic digestion which can change their physical, chemical and biological properties. The main purpose of this study was to investigate the efficiency of ultrasonic waves to improve the hydrolysis process and its use as an auxiliary substrate to increase the efficiency of anaerobic digestion process along with municipal sewage sludge.

Sampling of fat and oil of the degreasing unit and physical preparation by conducting ultrasonic waves with frequencies of 20 kHz and current density of 0.012-0.14 W/mL within 0-12 min were performed. The efficiency of pretreatment process were performed through tests such as soluble chemical oxygen demand (SCOD), and lipase enzyme activity. In addition, the anaerobic digestion process were evaluated by measuring the TS, VS, VA (volatile acidity), alkalinity, biogas production and biogas methane content.

The results showed that the highest increase in the activity of lipase enzyme under ultrasonic effect with a power of 0.1 w/mL was obtained after 8 minutes. Organic loading with 10%, 20% and 40% FOG/MSS ratios: resulted in 55%, 66% and 64% increase in methane production compared to the control samples, respectively. Organic loading over the 40% FOG/MSS caused a limitation in the simultaneous digestion process.

The results show that ultrasonic wave pretreatment with optimal power and time can improve the hydrolysis of TFOG while increasing the activity of lipase enzyme and also its use as an auxiliary substrate can enhance digestion performance and make digestion more stable.

The aim of this study was to investigate dust origin particulate (PM2.5) in Mashhad city in a long period of time (2014-2019) based on unhealthy days. Furthermore, changes in meteorological parameters and their relationship with dust storms have also been investigated.

In order to locate dust pollution hotspots in mashhad air, first, information about unhealthy days of Mashhad city in a 5-year period was obtained from the site of Mashhad Pollutants Monitoring Center and then HYSPLIT model was used to locate air pollution hotspots caused by particulate matter. To verify the results, the outputs obtained from this model were also compared with the DREAM8b model.

By examining the meteorological parameters and its relationship with the outputs obtained from THEHYSPLIT and DREAM8b models, the maximum wind speed and relative humidity were obtained in autumn. There was no rainfall in the studied days (19 days) and the highest temperature was related to summer, indicating the relationship between the occurrences of polluted days due to particulate matter less than μ 2.5, wind speed and relative humidity in autumn. The results of the two models showed that the southern and northeastern regions of Mashhad city had the highest source of dust particles during the studied days.

 Although in previous articles, the origin of dust in Mashhad city was announced outside the geographical boundaries of the province, long-term investigation at low altitude (below 10m) showed that local origin of dust have an essential role in air pollution in Mashhad city under unstable atmospheric conditions. Inappropriate use of agricultural lands and severe changes in land use often in the northern region and implementation of construction projects such as the southern belt of Mashhad city play essential roles in increasing PM2.5 particles in the air of Mashhad. This finding shows the importance of decision making for the implementation of soil stabilization projects etc... at the local level.

N-methylpyrrolidine is a highly potent solvent with toxic and adverse ecological properties that has historically been widely used in the chemical and petrochemical industries. Due to the health and safety، toxicity and environmental effects of effluents containing NMP، these effluents should be pre-treated before biological treatment methods. The aim of this study was to remove N-methylpyrrolidone by photo- Fenton process.

For testing, solutions such as sulfuric acid, iron sulfate 7, oxygenated water, sodium hydroxide and distilled water were added to N-methypyrrolidine compounds in the reactor. Then, the removal process was investigated in two stages: complete mixing and adding solutions.

The results revealed that the Fenton process cannot be used successfully to treat the hypothetical refinery effluent containing NMP. However، the photo-phanton process mineralized and degraded the NMP composition. Increase in 30% H2O2 concentration to the optimal dose of 1 mL led to the highest degradation (94%) and decrease in COD level of solution (42.1%).

It can be concluded that advanced oxidation by photo-phanton reaction can be a promising advanced oxidation technology for decomposition and pre-treatment of NMP-containing wastewaters for further biological treatment.

Today, soil and water pollution with heavy metals is one of the major challenges around the world. The aim of this study is to investigate the contamination of soils around a lead and zinc mine.

In the summer of 2019, 100 soil samples were taken from the mine vicinity and the characteristics of texture, acidity, salinity, calcium carbonate, organic matter and heavy metals chromium, cobalt, zinc, lead and cadmium were measured. Pollution indices including pollution factor (PI), enrichment coefficient (EF), geoaccumulation (Igeo), toxicity probability (MERMQ), contamination load (PLI), background enrichment (PIN), pollution security (CSI) and Nemerow index (PINemerow) ) Were calculated. Correlation between soil variables and determination of metal origin were determined using Pearson correlation and principal component analysis (PCA) analysis.

The average concentrations of chromium, cobalt, zinc, lead and cadmium were obtained as 92, 21.33, 453.98, 351.24 and 4.28 mg/kg, respectively. The metals pollution evaluated based on PI, EF and Igeo indices were moderate for chromium and cobalt, considerable for zinc and significant for lead and cadmium. The results of MERMQ, PLI, PIN, CSI and PINemerow indices showed high soil contamination with heavy metals. According to the PCA test, the elements lead, zinc and cadmium are in a group with high correlation with each other that are of anthropogenic origin. Chromium and cobalt with a correlation of 88% also showed the same geological origin.

mining activities should be done with more caution and measures should be taken to reduce pollution.

Recently, microplastics (MPs) have been found in the aquatic and terrestrial environments, air, and food. Other pollutants can be transported by MPs and pose a threat to the human, animal, and environment. Measurement and evaluation of microplastics can either increase knowledge about them or boost understanding of their possible harmful effects. However, no standard method has been established to measure microplastics and the measurement of microplastics has been done by various methods in different published studies. The aim of current study was to investigate different methods of measuring microplastics in water and wastewater environment and identifying the strengths and weaknesses of these methods.

The present review study was conducted during the winter 2021, by searching the papers cited in PubMed, Google Scholar, Web of Science, and Scopus databases using the keywords "Microplastic", "Water", "Drinking-water", "Wastewater", "Surface", "Bottled-water" and "Marine" and selecting articles published between 2015 and 2021 in reputable journals.

The main stages of MPs measuring in various studies included sampling and sieving, pretreatment and digestion, density separation, counting and Identification of MPs by their chemical composition.

Digestion using H2O2, density separation using NaCl, counting by stereomicroscope, and Spectroscopy using FTIR and micro-RAMAN are the most widely used methods in the studies related to detecting MPs in water and wastewater environment. However, different methods of measuring and identifying microplastics have made comparing the results of studies difficult and it seems that efforts should be made to standardize these methods.