Evaluation of fluoride exposure using disability-adjusted life years and health risk assessment in south-western Iran: A novel Monte Carlo simulation.

Consumption of fluoride-contaminated water is a worldwide concern, especially in developing countries, including Iran. However, there are restricted studies of non-single-value health risk assessment and the disease burden regarding fluoride intake nationwide. Prolonged exposure to excessive fluoride has been linked to adverse health effects such as dental and skeletal fluorosis. This can lead to under-mineralization of hard tissues, causing aesthetic concerns for teeth and changes in bone structure, increasing the risk of fractures. As such, we aimed to implement probability-based frameworks using Monte Carlo methods to explore the potential adverse effects of fluoride via the ingestion route. This platform consists of two sectors: 1) health risk assessment of various age categories coupled with a variance decomposition technique to measure the contributions of predictor variables in the outcome of the health risk model, and 2) implementing Monte Carlo methods in dose-response curves to explore the fluoride-induced burden of diseases of dental fluorosis and skeletal fractures in terms of disability-adjusted life years (DALYs). For this purpose, total water samples of 8053 (N=8053) from 57 sites were analyzed in Fars and Bushehr Provinces. The mean fluoride concentrations were 0.75 mg/L and 1.09 mg/L, with maximum fluoride contents of 6.5 mg/L and 3.22 mg/L for the Fars and Bushehr provinces, respectively. The hazard quotient of the 95th percentile (HQ>1) revealed that all infants and children in the study area were potentially vulnerable to over-receiving fluoride. Sobol' sensitivity analysis indices, including first-order, second-order, and total order, disclosed that fluoride concentration (Cw), ingestion rate (IRw), and their mutual interactions were the most influential factors in the health risk model. DALYs rate of dental fluorosis was as high as 981.45 (uncertainty interval: UI 95 % 353.23-1618.40) in Lamerd, and maximum DALYs of skeletal fractures occurred in Mohr 71.61(49.75-92.71), in Fars Province, indicated severe dental fluorosis but mild hazard regarding fractures. Residents of the Tang-e Eram in Bushehr Province with a DALYs rate of 3609.40 (1296.68-5993.73) for dental fluorosis and a DALYs rate of 284.67 (199.11-367.99) for skeletal fractures were the most potentially endangered population. By evaluating the outputs of the DALYs model, the gap in scenarios of central tendency exposure and reasonable maximum exposure highlights the role of food source intake in over-receiving fluoride. This research insists on implementing defluoridation programs in fluoride-endemic zones to combat the undesirable effects of fluoride. The global measures presented in this research aim to address the root causes of contamination and help policymakers and authorities mitigate fluoride's harmful impacts on the environment and public health.

Enhancing the coagulation process for the removal of microplastics from water by anionic polyacrylamide and natural-based Moringaoleifera.

The existence of microplastics (MPs) in water is a significant global concern since they have the potential to pose a threat to human health. Therefore, there is a need to develop a sustainable treatment technology for MPs removal, as the conventional methods are inadequate to address this problem. Coagulation is a typical process in treatment plants that can capture MPs before releasing them into the environment. In this work, the removal behaviors of polyamide (PA), polystyrene (PS), and polyethylene (PE) MPs were systematically investigated through coagulation processes using aluminum sulfate (Al2(SO4)3) and Moringa oleifera (MO) seeds extract. Subsequently, the coagulation performance of Al2(SO4)3 was improved by the separate addition of anionic polyacrylamide (APAM) and naturally derived MO. Results showed that Al2(SO4)3 in combination with APAM had better performance than Al2(SO4)3 or MO alone. In the Al2(SO4)3+APAM system, the removal efficiencies were 93.47%, 81.25%, and 29.48% for PA, PS, and PE MPs, respectively. Furthermore, the effectiveness of the Al2(SO4)3 and MO blended system was approximately similar to the Al2(SO4)3+APAM system. However, the required amount of Al2(SO4)3 was decreased to 50% in the Al2(SO4)3+MO system compared to the optimal dosage in the Al2(SO4)3 system alone. The combination of 40 mg/L of Al2(SO4)3 and 60 mg/L of MO resulted in removal efficiencies of 92.99%, 80.48%, and 28.94% for PA, PS, and PE MPs, respectively. The high efficacy of these enhanced methods was due to the synergic effects of charge neutralization and agglomeration adsorption, which were validated through zeta potential assessments and visual analysis using scanning electron microscopy (SEM) images. In the case of experimental conditions, initial pH had little impact on removal efficiency, while NaCl salinity and stirring speed directly affected MPs removal. Consequently, this research took a step toward finding a green strategy to remove MPs from water systems.

Surface water quality analysis using multivariate statistical techniques: a case study of Fars Province rivers, Iran.

This study aimed to transform the input of a large dataset into the output of interpretable information. Hence, multivariate statistical methods were carried out to analyze physicochemical parameters in 34 rivers during a 17-year period (1997-2014). Cluster analysis divided the study area into spatially different riverine water quality sub-regions described in ascending order of water quality as severely polluted (SP), highly polluted (HP), polluted (P), moderately polluted (MP), lightly polluted (LP), and not polluted (NP). By diagnosing threats and identifying fragile zones, water contamination sources responsible for impaired water quality in the study area recognized as natural pollutants in LP, municipal wastes in P, discharge of industrial effluents in MP, natural geochemical formations in SP and HP, and superficial flows of agricultural lands in SP, HP, and MP. The dominant water type in each zone was classified into Na-Cl, Na-Cl, Na-Mg-Ca-Cl-SO4, Na-Ca-Mg-Cl-SO4, Na-Ca-Cl, and Ca-Mg-HCO3-SO4 groups for SP, HP, P, MP, LP, and NP, respectively. To explore aesthetic aspects of drinking water application, hazard quotient (HQ) was applied for children and adults in terms of ingestion and dermal exposure. Overall health risk assessment revealed the order of impacts of the secondary water quality parameters as Cl- > Na+ > total dissolved solids (TDS) > Ca2+ > SO42- > Mg2+. Furthermore, hazard index (HI) ranged from 0.011 to 31.439 and 0.010 to 30.122 for children and adults, respectively, indicating a potential health risk regarding chloride throughout the whole region excluding NP. To identify significant agents in water quality, principal component analysis extracted 3 varifactors (VFs), with the eigenvalues of 4.74, 1.19, and 0.85, respectively, explained about 83% of the variance. The most important parameters in the first factor were TDS, electrical conductivity, SAR, TH, Na+, Cl-, and SO42- accounting for 58% of the total variance. The most influenced parameters in the second and third factors were pH and HCO3-, respectively, with variance coverage of 26%. These factors indicated that the hydrochemical characteristics of the water originated by natural interactions (existing salt domes, evaporation, weathering, and soil erosion) and anthropogenic activities (fertilizer-rich flows of agro-fields and domestic/industrial disposals), which must be minimized in rivers to supply the population with hygienic water.

Abundance of antibiotic resistance genes in bacteria and bacteriophages isolated from wastewater in Shiraz.

Generally, the high widespread presence of antimicrobial resistance, and the next freeing into aquatic environments which provide a situation for transmission of these genes in water is because of the abuse of the antimicrobial drugs in both medicine and veterinary medicine. In aquatic environment, bacteriophages could have an important role in sharing antimicrobial resistance genes. The purpose of this study was to assess three important antibiotic resistance genes including two ß-lactamases (blaTEM, blaSHV) and sul1 gene, referring to resistance to sulfonamides, in both bacteria and phage DNA fractions of wastewater samples, Shiraz, Iran, using polymerase chain reaction. The prevalence of those genes was extremely high and equal to 100% in bacterial DNA, while these rates were lower in phage DNA fractions as 66.66%, 66.66% and 58.33% for blaTEM, blaSHV and sul1, respectively. In conclusion, detection of mentioned genes in bacterial and phage DNA fractions from ambient water is considerable, so the possibility of harbouring and transferring of antibiotic resistance genes by phages needs to be explored in the future. Also, available data is a reputable endorsement that wastewater is a hotspot for these kinds of genes to spread in the environment. Based on our knowledge, this is the first report of blaTEM and bla SHV and sul1 genes in bacterial and phage DNA fractions insulated from urban wastewater and environment in Iran.

Evaluation of analytical and numerical solutions of mass transfer model for breakthrough curves simulation: Co2+ adsorption by hydrogen peroxide-bio-originated composite.

Accurate estimation of breakthrough curve (BTC) is required to scale -up the column adsorption process. A mathematical model (unsteady advection-dispersion-diffusion-adsorption equation) was solved analytically and numerically to simulate the dynamic adsorption of Co(II) ions on hydrogen peroxide-modified bone waste. The performance of both analytical and numerical approaches was evaluated under varying initial Co(II) concentrations (25, 50 and 75 mg L-1), bed heights (3, 6 and 9 cm), flow rates (0.6, 1.2 and 1.8 mL min-1), and pH (2, 4, 6, 8). Both analytical (R2 = 0.990) and numerical (R2 = 0.993) approaches described the experimental data well. The comparison results indicate that in spite of the capability of the analytical modeling for predicting the BTC (NRMSE = 9.32%), numerical modeling is more efficient in the simulation of Co(II) adsorption by adsorbent (NRMSE = 7.56%). So, it can be concluded that analytical modeling can be an easy and quick alternative to numerical modeling for predicting BTC with acceptable accuracy.

Evaluation of HYDRUS-1D and modified PRZM-3 models for tribenuron methyl herbicide transport in soil profile under vetiver cultivation.

Tribenuron methyl (TBM) is widely used in weed control. Due to its phytotoxicity, concerns on TBM pollution to soil have been raised. In this research, TBM concentration in the soil profile and vetiver grass were measured and simulated using HYDRUS-1D and modified PRZM-3 models. The treatments were two herbicide concentrations to soil with vetiver (C1V and C2V) and without vetiver (C1S and C2S). In control treatment (Co) no herbicide was applied to the soil. In general, according to the measured data, TBM soil residues in C1V and C2V treatments were 39.8% and 30.1% lower than that obtained in C1S and C2S treatments, respectively. The TBM was leached to 90 cm soil depth and it was limited to about 50 cm in the treatments with vetiver grass. The simulated herbicide residue in the soil profile in modified PRZM-3 model was more accurate than the HYDRUS-1D model. The dissipation processes of herbicides in soil and solving method of water movement in soil, considered in the modified PRZM-3 model, are more precise than that obtained in the HYDRUS-1D model. However, the prediction of TBM uptake by vetiver in the HYDRUS-1D model was closer to the measured values than that obtained in the modified PRZM-3 model.

Groundwater quality analysis using multivariate statistical techniques (case study: Fars province, Iran).

This research investigated the quality of groundwater of 298 wells during 10 years, in Fars province, southern Iran, to survey spatial variation of groundwater quality and also major sources of hydro-chemical components for drinking and agricultural uses. To classify the sampling stations in each year, hierarchical cluster analysis, using the Euclidean distances and "Ward" method, was used. According to the results of cluster analysis, there were three quality groups in groundwater of the research area: first group of 170 wells with type of Ca-HCO3, second group of 98 wells with type of Ca-HCO3, and third group of 30 wells with type of Na-Cl. Hydro-chemical parameters were increased from the first to the third group, and on the basis of Schoeller and USSL diagrams, the water of wells of the third group was considered unsuitable for irrigation and drinking. Principal component (PC) analysis and factor analysis reduced the complex and voluminous data matrix into three main components, accounting for more than 80 % of the total variance. The first PC contained TDS, EC, TH, Na(+), Cl(-), Mg(2+), SO4 (2-), Ca(2+), and SAR parameters. Therefore, the first dominant factor was salinity. In PC2, HCO3 and pH were the dominant parameters, which may indicate weathering of silicate minerals. The PC3 contained high loadings for NO2 (2-) and NO3 (-). This factor indicates anthropogenic contaminants that may be caused by improper disposal of domestic wastes or the use of chemical fertilizers in agriculture and leaching of them.