The main aims of the present research were (1) investigation of the temporal trends of atmospheric benzene concentrations in Tehran city during the period 2010 to 2013 and (2) assessment of carcinogenic and non-carcinogenic health risks of inhalation exposure to benzene. For the first objective, the data of ambient air benzene concentrations were derived from 15 air quality monitoring stations (AQMSs) in Tehran during the years 2010 to 2013 and they were temporally investigated after data cleaning and missing data imputation. The excess lifetime cancer risk (ELCR) and hazard quotient (HQ) were estimated to reveal the carcinogenic and non-carcinogenic health effects of exposure to ambient benzene. Our findings indicated that over 2010–2013, annual mean concentrations of benzene were in the range of 1.84 to 2.57 μg m⁻³, and the highest annual mean concentration was observed in 2011 with a mean of 2.57 μg m⁻³. The four-year average concentration of benzene during the period from 2010 to 2013 was 2.14 μg m⁻³. Furthermore, the HQ for inhalation exposure to ambient benzene was lower than the acceptable risk level (HQ < 1) over the study time period which indicated that the non-carcinogenic effects are very unlikely to happen. In addition, health risk assessment for ELCR showed that the potential cancer risk for inhalation exposure to benzene was 1.67 × 10⁻⁵ over the study period, which is significantly higher than the limits recommended by the U.S. EPA (1 × 10⁻⁶). Our study clearly proves that the ambient benzene concentration in Tehran has substantially higher carcinogenic effects on the population. Appropriate sustainable control measures should be taken to reduce air benzene concentration and protect public health.

Previous studies have demonstrated the side effects of tooth whiteners on the gastric mucosa. However, the impact of dental bleaching products on the liver, kidney, and heart remains obscure. The present study investigated the toxic potential of 35% carbamide peroxide (CPO) containing tooth whitening product (TWP) on the liver, kidney, heart, and stomach of mice, pointing to the role of oxidative stress and inflammation. Mice received 250 or 500 mg/kg body weight CPO-TWP orally for 3 weeks and samples were collected for analyses. Both doses of CPO-TWP induced a significant increase in circulating liver, kidney, and heart function markers. CPO-TWP-administered mice showed several histological alterations and a significant increase in liver, kidney, heart, and stomach lipid peroxidation levels along with diminished glutathione, superoxide dismutase, and catalase. In addition, administration of CPO-TWP provoked anemia, leukocytosis, and a significant increase in circulating levels of pro-inflammatory cytokines. In conclusion, exposure to 35% CPO-TWP induced functional, histological, and hematological alterations, oxidative stress, and inflammation in mice. Therefore, the frequent use of tooth bleaching agents should be monitored very carefully to avoid the application of excess amounts as well as the intake.

To investigate the emission characteristics of the dissolved N₂O in distilled water and activated sludge mixture, the total volume mass transfer coefficients of N₂O in distilled water and activated sludge mixture were determined by batch experiments. The results indicated a difference between emission processes of N₂O in distilled water and activated sludge mixture. At different initial N₂O concentrations, the total volume mass transfer coefficients of N₂O in distilled water were relatively stable, while the total volume mass transfer coefficients of N₂O in activated sludge mixture increased with increasing initial N₂O concentrations, due to endogenous denitrification by microorganisms in the mixture. Since N₂O was reduced and consumed by heterotrophic bacteria in activated sludge, biochemical reactions were involved in the transfer process of N₂O escaping from the mixture to the atmosphere. Therefore, use of distilled water was suggested to determine the total volume mass transfer coefficient in experiments calculating N₂O emission rates for biological nitrogen removal processes.

The present study aims to investigate the optimum condition of stationary diesel engine’s operating parameters to obtain better performance and emission level, where the diesel engine is fueled with different concentrations of soybean biodiesel (SB), water, and alumina (Al) nanoadditive. Taguchi method coupled with gray relational analysis has been implemented in this study to obtain the optimum concentration of SB, water, and Al nanoparticle, and statistical analysis of variance (ANOVA) is applied to obtain the individual response of operating parameters on overall engine performance and emission level. Various concentration of SB (10%, 20%, and 30%), water (10%, 20%, and 30%), and Al nanoparticle (50 ppm, 100 ppm, and 150 ppm) are mixed with base diesel (BD) by mechanical agitation and followed by an ultra-sonication process. The fuel properties are measured based on EN590 standards, and the experiments are conducted in a single-cylinder, four-stroke, natural aspirated stationary diesel engine based on an L₉ orthogonal array fuel combination. From the obtained gray relational co-efficient (GRC) and signal-to-noise (S/N) ratio, the optimum concentration of SB, water, and nanoadditive are identified as 20%, 10%, and 100 ppm, respectively, and a confirmation experiment has also been carried out to confirm the improvements at optimum condition. The ANOVA results imply that water concentration (WC) has the maximum influence on overall diesel engine’s performance and emission level followed by nanoparticle and SB concentrations. Overall, it can be concluded that the engine exhibits better performance and greener emissions at optimal condition.

This study focused on the presence of three biocidal products specific to healthcare facilities, i.e. chlorhexidine digluconate (CHD), bis(aminopropyl)laurylamine (BAPLA), and didecyldimethylammonium chloride (DDAC), in a hospital sewage system. Five sampling campaigns were conducted in 2016 and 2017 throughout the entire Poitiers University Hospital sewage system. DDAC concentrations ranging from 933 ± 119 to 3250 ± 482 μg/L were detected in 24-h composite samples, while lower concentrations (both within the same range) were detected for the two other compounds (i.e. 25 ± 5 to 97 ± 39 μg/L for CHD and 18 ± 3 to 142 ± 16 μg/L for BAPLA). Based on these findings, a mass balance was determined for these discharged compounds to compare the quantities detected in discharges to the amounts used for healthcare in the hospital. Hence, 60–90% of the quantities of DDAC used were found to be present at the hospital sewage outfall. Higher percentages of CHD (100–242%) were noted because of the high presumably quantities used for antiseptic applications, which were not considered in mass balance calculation. Finally, only 10–30% of BAPLA quantities used were detected at the site outfall. Analysis of the results for the different sampling points revealed the nature of the emission sources. For surface applications of DDAC and BAPLA, management of hospital linen is thus a major source of discharged biocidal products, probably following the washing of biocide-soaked textiles used for hospital facility maintenance. Moreover, discharge of biocidal products from a healthcare establishment depends especially on biocide handling practices in the emitting establishment. For BAPLA, compliance with hospital recommended dosages and practices whereby operators are required to prepare tailored quantities of detergents and disinfectants for each specific task could largely explain the limited release of this compound.

Surplus phosphorus (P) above agronomic requirements can negatively affect the water status of connected surface and subsurface water bodies. The in situ stabilization of soil P through soil amendment has been recognized as an efficient way to reduce this environmental pressure. However, the mechanism of how P is stabilized during this process and how plant available P is affected are unknown. This can be achieved by sequential chemical extraction and synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy investigations. Therefore, in the present study, P-enriched calcareous and red soils were amended with alum, dolomite, and a 1:1 mixture of alum and dolomite (MAD) at a 20 g/kg soil rate, and soil properties and P fractions were measured after a 45-day period. Results showed that alum amendment significantly decreased CaCl₂-P and Olsen-P contents in calcareous and red soils when compared with dolomite. However, dolomite incorporation maintained relatively high P availability and even increased CaCl₂-P and Olsen-P contents by 1.32% and 40.5% in red soil, respectively, compared to control. Amendment with MAD was not as effectively as the alum in P stabilization. Sequential inorganic P extraction indicated that alum dominantly contributed labile P transformed to Al-P in both soils. P K-edge XANES spectroscopy measurements further explained that alum adsorbed phosphate in calcareous soil and precipitated phosphate as AlPO₄ in red soil. Results of P fractionation and Mehlich-3-extracted Ca showed that dolomite mainly adsorbed loosely bound P in calcareous soil and red soil. However, dolomite incorporation in red soil led to Al-P and Fe-P release. The P sorption isotherms showed that dolomite and alum increased soil P sorption maxima and decreased the degree of P saturation (DPS) in both soils, while dolomite declined the Langmuir bonding energy in red soil. Differences in P stabilization by alum and dolomite addition across soil types were closely related to their characteristics, and soil properties changed, especially soil pH.

Mires and peatlands in general are heavily influenced by anthropogenic stressors like acidification, eutrophication, desiccation and fragmentation. Groundwater-fed mires are, in contrast to rainwater-fed mires, often well protected against desiccation due to constant groundwater discharge. Groundwater-fed mires can however be influenced by groundwater pollution such as groundwater nitrate enrichment, a threat which has received minor attention in literature. The present case study demonstrates how groundwater nitrate enrichment can affect the biogeochemical functioning and vegetation composition of groundwater-fed mires through direct nitrogen enrichment and indirect nitrate-induced sulphate mobilisation from geological deposits. Biogeochemical and ecohydrological analyses suggest that the Dutch groundwater-fed mire studied is influenced by different water sources (rainwater; groundwater of local and regional origin) with differing chemical compositions. The weakly buffered and nitrate-enriched groundwater leads, where it reaches the uppermost peat, to nitrogen enrichment, enhanced isotopic nitrogen signatures and altered the vegetation composition at the expense of characteristic species. Nitrate-induced sulphate mobilisation in the aquifer led to enhanced sulphate reduction, sulphide toxicity and elemental sulphur deposition in the mire. Despite sulphate reduction and nitrate enrichment, internal eutrophication did not play an important role, due to relatively low phosphorus concentrations and/or low iron-bound phosphorus of the peat soil. Future management of groundwater-fed mires in nitrate-polluted aquifers should include the reduction of nitrate leaching to the aquifer at the recharge areas by management and ecohydrological restoration measures on both a local and landscape scale.

In this study, we investigated the effect of acute administration of gold nanorods (AuNRs) on testicular function, sexual hormones, and oxidative stress parameters in male albino rats. Forty mature male albino rats were divided into two equal groups (n = 20/each). The first group received 1 ml saline solution intraperitoneally (i.p.). The second group received single i.p. injection of 75 μg 50 nm AuNRs/kg/bwt. Five rats from each group were sacrificed on days 1, 3, 7, and 14 post treatment and blood samples were collected for hormonal and biochemical analysis. Testes were collected from each group at each time point for histopathology, morphometric, and transmission electron microscope analyses of testis and epididymis. Results indicated that i.p. injection of AuNRs did not produce any histopathological changes. Morphometric analysis of testicular samples revealed that the height of lining epithelium was significantly (P < 0.05) higher in AuNR group on days 3 and 14 post treatment, and the minor axis of seminiferous tubules was higher (P < 0.05) in AuNR-injected rats than in control group. For the epididymis, the number of spermatozoa was significantly (P < 0.05) higher on days 7 and 14 after AuNR injection when compared with control rats. AuNRs were not detected by TEM at all time points of the experiment. Serum analysis demonstrated that total and free testosterone values significantly (P < 0.05) increased on days 1, 3, 7, and 14 post AuNR injection. LH was higher (P < 0.05) in AuNRs-injected rats on days 3, 7, and 14 post injection, while FSH values were higher (P < 0.05) in AuNR group on days 3 and 14. Malondialdehyde significantly (P < 0.05) decreased on days 3, 7, and 14 in AuNR group, while catalase, glutathione peroxidase, and superoxide dismutase values were significantly (P < 0.05) elevated on days 3, 7, and 14 in AuNRs-injected rats compared with control group. In conclusion, intraperitoneal injection of 50 nm AuNRs is safe on the reproductive function and has an antioxidant action.

Iron-incorporated silica (Fe/SiO₂) with different Fe/Si molar ratio was successfully prepared from rice husk pyrolytic residues (RHR) through alkali pretreatment, co-precipitation, and calcination. Various characterization methods indicated that the Fe/SiO₂ samples possessed mesoporous structure with Fe species incorporated into the framework of silica. The obtained materials were applied in the treatment of hazardous banknote printing wastewater, and under the optimal conditions, colored pollutants, humic acid-like and soluble microbial by-product-like organics were removed significantly. It was found that Fe/SiO₂ acted as both flocculant and catalyst, and the framework iron species catalyzed the oxidative degradation of refractory organics in the presence of H₂O₂. A heterogeneous Fenton-like system was formed in the wastewater treatment process.

Extended stochastic impact by regression on population, affluence, and technology model incorporating ridge regression was used to analyze the driving mechanism of energy-related CO₂ emissions in Kazakhstan during 1992–2014. The research period was divided into two stages based on GDP of Kazakhstan in 1991 (85.70 × 10⁹ dollars), the first stage (1992–2002), GDP < 85.70 × 10⁹ dollars, the stage of economic recovery; the second stage (2003–2014), GDP > 85.70 × 10⁹ dollars, the stable economic development stage. The results demonstrated that (1) population scale and the technological improvement were the dominant contributors to promote the growth of the CO₂ emissions during 1992–2014 in Kazakhstan. (2) Economic growth and industrialization played more positive effect on the increase of the CO₂ emissions in the stable economic development stage (2003–2014) than those in the stage of economic recovery (1992–2002). The proportion of the tertiary industry, the trade openness, and foreign direct investment were transformed from negative factors into positive factors in the stable economic development stage (2003–2014). (3) Due to the over-urbanization of Kazakhstan before the independence, the level of urbanization continued to decline, urbanization was the first factor to curb CO₂ emissions during 1992–2014. Finally, some policy recommendations are put forward to reduce energy-related carbon emissions.