Geographical distribution of nitrate pollution and its risk assessment using GIS and Monte Carlo simulation in drinking water in urban areas of Fars province-Iran during 2017-2021.

Pollution of water resources with nitrate is currently one of the major challenges at the global level. In order to make macro-policy decisions in water safety plans, it is necessary to carry out nitrate risk assessment in underground water, which has not been done in Fars province for all urban areas. In the current study, 9494 drinking water samples were collected in four seasons in 32 urban areas of Fars province in Iran, between 2017 and 2021 to investigate the non-carcinogenic health risk assessment. Geographical distribution maps of hazard quotient were drawn using geographical information system software. The results showed that the maximum amount of nitrate in water samples in 4% of the samples in 2021, 2.5% of the samples in 2020 and 3% of the samples in 2019 were more than the standard declared by World Health Organization guidelines (50 mg/L). In these cases, the maximum amount of nitrate was reported between 82 and 123 mg/L. The HQ values for infants did not exceed 1 in any year, but for children (44% ± 10.8), teenagers (10.8% ± 8.4), and adults (3.2% ± 1.7) exceeded 1 in cities, years, and seasons, indicating that three age groups in the studied area are at noticeably significant non-carcinogenic risk. The results of the Monte Carlo simulation showed that the average value of non-carcinogenic risk was less than 1 for all age groups. Moreover, the maximum HQ values (95%) were higher than 1 for both children and teenager, indicating a significant non-carcinogenic risk for the two age groups.

Distributing and assessing fluoride health risk in urban drinking water resources in Fars Province, Iran, using the geographical information system.

Excessive fluoride intake has been reported in many studies, which can lead to diseases such as autism, mental retardation, low birth weight, reproductive disorder, as well as dental and bone fluorosis. The potential risk assessment of fluoride intake for the health of people living in Fars Province, Iran, is investigated. Hence, 1700 drinking water samples were taken from April 2018 to March 2020 in four seasons in 29 cities of Fars Province and were analyzed. Non-carcinogenic health risks of exposure to fluoride through drinking water were evaluated. Moreover, the spatial distribution maps of fluoride and hazard quotient (HQ) risk index were prepared using GIS software. The results showed that the concentration of fluoride in the drinking water of the studied area was in the range of 0.086 to 2.61 mg/L. Accordingly, in 48.27% of the cities, fluoride was in the range below the national and international standards, 34.48% of the cities were in the permissible range of 0.5 to 1.5 mg/L, and 17.24% of the urban areas of the province had fluoride contents above the permissible range. Hazard quotient index had the health risk of HQ > 1 in 27.58% of children, 17.24% of teenagers, and 10.34% of adults in the urban areas of Fars Province. In the cities with HQ > 1, there was risk of diseases associated with excessive fluoride intake. Therefore, it is necessary to replace water supply sources in these cities.

Modeling of chromium (VI) removal from aqueous solution using modified green-Graphene: RSM-CCD approach, optimization, isotherm, and kinetic studies.

BACKGROUND: The aim of this study was to investigate the removal of Cr (VI) using Green-Graphene Nanosheets (GGN) synthesized from rice straw. METHODS: Synthesis of the GGN was optimized using response surface methodology and central composite design (CCD). The effect of two independent variables including KOH-to-raw rice ash (KOH/RRA) ratio and temperature on the specific surface area of the GGN was determined. To have better removal of Cr (VI), GGN was modified using the grafting amine group method. In the Cr (VI) removal process, the effects of four independent variables including initial Cr (VI) concentration, adsorbent dosage, contact time, and initial solution pH were studied. RESULTS: The results of this study showed that the optimum values of the KOH/RRA ratio and temperature for the preparation of GGN were 10.85 and 749.61 °C, respectively. The maximum amount of SSA obtained at optimum conditions for GGN was 551.14 ± 3.83 m 2 /g. The optimum conditions for Cr (VI) removal were 48.35 mg/L, 1.46 g/L, 44.30 min, and 6.87 for Cr (VI) concentration, adsorbent dosage, contact time, and pH, respectively. Based on variance analysis, the adsorbent dose was the most sensitive factor for Cr (VI) removal. Langmuir isotherm (R2 = 0.991) and Pseudo-second-order kinetic models (R2 = 0.999) were the best fit for the study results and the Q max was 138.89 mg/g. CONCLUSIONS: It can be concluded that the predicted conditions from the GGN synthesis model and the optimum conditions from the Cr (VI) removal model both agreed with the experimental findings.

Determination of bacterial and fungal bioaerosols in municipal solid-waste processing facilities of Tehran.

PURPOSE: The concentration and distribution characteristics of airborne bacteria and fungi were assessed at municipal solid-waste processing and disposal facilities (SWPDFs) of Tehran (Arad Kouh Site). METHODS: Air samples were obtained from the indoor air of a laboratory and refectory as well as from the air surrounding a conveyor belt, rotary screen, and bailer. Sampling was conducted according to the standard procedure to determine two bacterial species (Klebsiella spp. and Staphylococcus aureus), total bacteria and fungi, and Aspergillus fumigates. RESULTS: The maximum concentration of Staphylococcus aureus was in the air surrounding the conveyer belt with the average of 993.2 CFU/m3. The highest concentrations of total fungi (4958.8 CFU/m3) and Aspergillus fumigates (2114 CFU/m3) were measured in the air surrounding the rotary screen. The mean concentrations of bacterial bioaerosols in a more contaminated sampling location in summer and winter were 1687.6 and 1479.4 CFU/m3, respectively. CONCLUSIONS: There were significant differences between the concentration of bioaerosols in cold and warm seasons. The concentrations of bioaerosols in the air surrounding the rotary screen and conveyer belt were significantly more than those in other sampling locations, but were within the recommended maximum of 103 and 104 CFU/m3.

Enhanced fluoride removal over MgFe2O4-chitosan-CaAl nanohybrid: Response surface optimization, kinetic and isotherm study.

In this work an effective adsorption route was developed for fluoride removal from aqueous solution. For this purpose MgFe2O4, MgFe2O4-chitosan and a three component nanocomposite of were synthesized and used. Characterization of the sorbents was performed with FESEM, TEM, FTIR, BET, VSM, SEM mapping and XRD techniques. Effective parameters on the adsorption process such as pH, contact time, adsorbent dosage and fluoride concentration was optimized by response surface methodology (RSM) using Box-Behnken design (BBD). Results showed that solution pH is a significant factor in fluoride adsorption with all adsorbents. However, adsorbent dosage was a significant factor when MgFe2O4-chitosan and three component adsorbents are employed. Kinetic study was performed based on pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich model and results confirmed fluoride adsorption followed the pseudo-second order model. Isotherm study was studied at two concentration ranges of 0.5-10 mg/L and 10-100 mg/L of fluoride ions. Results showed that adsorption process followed Langmuir model with capacity of 263.15 mg/g. Regeneration was performed with NaOH solution (0.1 mol/L). It was found that removal percentage is in the range of 91-73% in five cycles of adsorption and regeneration.

Investigation and Comparison of In Vitro Genotoxic Potency of PM10 Collected in Rural and Urban Sites at Tehran in Different Metrological Conditions and Different Seasons.

The particulate matter has become a serious health problem in some large cities in the world. These particles are a complex mixture of chemical compounds which change based on location and time and, consequently, can cause different health-related effects. The exact mechanism of the effect of these particles is not yet known for certain. However, it seems that numerous mechanisms through the production of ROS and, eventually, DNA destruction, which are related to a wide range of diseases, are among the causes of particles' health-related effects. The present study is aimed to evaluate and compare the genotoxicity potential of particles collected in Tehran, Iran, in urban and rural regions during spring and autumn as well as dusty and inversion conditions. These effects were examined using the comet assay on human pulmonary epithelial cells (A549). Results showed that all the particles had the potential for genotoxicity at the concentration used in this study (75,150 and 300 µg/ml). Moreover, DNA destruction changed with season, site, and even dusty and inversion atmospheric conditions. These changes mostly belonged to urban particles. In general, urban particles in autumn and, specifically, on days with inversion had higher genotoxicity (p < 0.01). Difference was observed between dusty and regular days so that regular days were more potent (p < 0.05). A strong correlation was observed between the effects of most PAH compounds and other metals such as Cr, Co, Cd, Mn, As, and also SO4, which were mostly the result of combustion in vehicle engines in urban regions. No difference was observed for rural particles at different conditions and seasons.

Correction to: Investigation and Comparison of In Vitro Genotoxic Potency of PM10 Collected in Rural and Urban Sites at Tehran in Different Metrological Conditions and Different Seasons.

The original version of this article unfortunately contained a mistake. Figure 6 caption should be "The light microscopic image (a) and transmission electron microscopic image (b) of A549 cell after 24 h of exposure to PM10 (150 µg/ml).

Data on bioassay of toxicity reduction of treated textile wastewater by using nanophotocatalytic process by Daphnia magna.

Practicability and possibility of photocatalytic degradation of Ro16 textile dye and the actual wastewater of textile were studied on pilot scale. The amount of reduction in solution toxicity was studied and assessed by the application of a bioassay using Daphnia magna. The solution toxicity at the beginning of the process has an increasing procedure and this is caused by the intermediate products that are produced during the photocatalytic process from the mother compounds, and are more toxic compared to them, and their toxicity declines at the end of the process with the completion of mineralization. The procedure of toxicity increase and its decrease in the course of photocatalytic process has a direct relation with the amount of mineralization.

Potential of amino-riched nano-structured MnFe2O4@cellulose for biosorption of toxic Cr (VI): Modeling, kinetic, equilibrium and comparing studies.

In this work, amine riched MnFe2O4-cellulose was employed to remove toxic Cr (VI). To find out the optimum conditions R (3.3.1) software was used. The results of Cr (VI) adsorption onto three-step adsorbents were compared by interpreting kinetic and isotherm studies. The kinetic studies reveal that the adsorption of Cr (VI) onto cellulose and magnetic cellulose (MC) followed pseudo-first order model whereas the adsorption of Cr (VI) onto amine modified cellulose (AFMC) followed pseudo-second order kinetic model. From the obtained intraparticle diffusion model results it is evident that the adsorption is an external surface process. The adsorption isotherm parameters for Cr (VI) adsorption onto MC and AFMC showed that the correlation coefficient (R2: 0.96, 0.88) of Freundlich isotherm is more than that of Langmuir isotherm (R2: 0.50, 0.76); hence, it is suggested that the adsorption of Cr (VI) onto these sorbents occurs in multilayer possessing heterogeneous sorption sites whereas the adsorption onto cellulose followed Langmuir model. The maximum adsorption capacities of cellulose, MC and AFMC under optimum conditions were found to be 25, 125 and 250mg/g, respectively; thus, it is confirmed that adsorption efficiency has been improved after modification steps.

Determination of fluoride concentration in powdered milk in Iran 2010.

High concentrations of fluoride (F) in powdered milk (formula milk) can have adverse health effects on the body. The F concentration in powdered milk was analysed in Iran in 2010. A total of twelve commercial brands of highly consumed powdered milk were selected to analyse the F content through the standard F ion-selective electrode method. From each brand, three samples with different production dates were selected. The means and standard deviation for F concentration in all the samples was 1·73 (sd 0·3) µg F/g. The minimum and maximum F content in powdered milk brands Humana2 and Humana3 was 1·32 (sd 0·1) and 2·36 (sd 0·3) µg F/g, respectively. The study revealed that there was no significant difference in F concentration in the samples that belonged to various dates. Humana3 had a high F concentration (with an average of 2·36 (sd 0·3) µg F/g), which can be a risk factor for increased dental fluorosis, especially when being prepared using water with a high content of F.