Determination of chloroform concentration and human exposure assessment in the swimming pool

Associations between atmospheric PM2.5 exposure and carcinogenic health risks: Surveillance data from the year of lowest recorded levels in Beijing, China

Scant research has pinpointed the year of minimum PM2.5 concentration through extensive, uninterrupted monitoring, nor has it thoroughly assessed carcinogenic risks associated with analyzing numerous components during this nadir in Beijing. This study endeavored to delineate the atmospheric PM2.5 pollution in Beijing from 2015 to 2022 and to undertake comprehensive evaluation of carcinogenic risks associated with the composition of atmospheric PM2.5 during the year exhibiting the lowest concentration. PM2.5 concentrations were monitored gradually in 9 districts of Beijing for 7 consecutive days per month from 2015 to 2022, and 32 kinds of PM2.5 components collected in the lowest PM2.5 concentration year were analyzed. This comprehensive dataset served as the basis for carcinogenic risk assessment using Monte Carlo simulation. And we applied the Positive Matrix Factorization (PMF) method to identity the sources of atmospheric PM2.5. Furthermore, we integrated this source appointment model with risk assessment model to discern the origins of these risks. The findings revealed that the annual average PM2.5 concentration in 2022 stood at 43.1 μg/m3, marking the lowest level recorded. The mean carcinogenic risks of atmospheric PM2.5 exposure calculated at 6.30E-6 (empirical 95% CI 1.09E-6 to 2.25E-5) in 2022. The PMF model suggested that secondary sources (35.4%), coal combustion (25.6%), resuspended dust (15.1%), biomass combustion (14.1%), vehicle emissions (7.1%), industrial emissions (2.0%) and others (0.7%) were the main sources of atmospheric PM2.5 in Beijing. The mixed model revealed that coal combustion (2.41E-6), vehicle emissions (1.90E-6) and industrial emissions (1.32E-6) were the main sources of carcinogenic risks with caution. Despite a continual decrease in atmospheric PM2.5 concentration in recent years, the lowest concentration levels still pose non-negligible carcinogenic risks. Notably, the carcinogenic risks associated with metals and metalloids exceeded that of PAHs. And the distribution of risk sources did not align proportionally with the distribution of PM2.5 mass concentration.

Application of montmorillonite/octadecylamine nanoparticles in the removal of textile dye from aqueous solutions: Modeling, kinetic, and equilibrium studies

In the study, the proliferation of industries has been associated with an increase in the production of industrial wastewater and subsequent environmental pollution, wherein dyes emerge as prominent pollutants. The characteristics of nanoclay modified with octadecylamine, were elucidated throughvarious techniques, including Field Emission Scanning Electron Microscopy/Energy Dispersive Spectroscopy (FE-SEM/EDS), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), and Brunauer-Emmett-Teller Surface Area Analysis (BET). The research delved into the impact of variables such as pH, initial dye concentration, adsorbent dose, temperature, and ultrasonication time on the removal of Acid Black 1 (AB1) through an ultrasonic process, employing a central composite design (CCD). Optimal conditions for the adsorption process were determined: pH at 5.46, adsorbent mass at 4 mg/30 mL, initial dye concentration at 20 mg/L, ultrasound time at 20 min, and temperature at 50 °C, resulting in a remarkable 96.49% adsorption efficiency. The fitting of experimental equilibrium data to different isotherm models, including Langmuir, Freundlich, and Temkin, indicated thatthe Freundlich model was the most suitable. Analysis of the adsorption data with various kinetic models such as pseudo-first and second-order models, and intraparticle diffusion models, revealed the applicability of the second-order equation model. A thermodynamic study unveiled that the adsorption process was spontaneous and endothermic. In conclusion, the study highlights the significant capability ofmontmorillonite nanoclay modified with octadecylamine in removing AB1 dye, rendering it a viable option for wastewater treatment.

Comparison of hydrophobic cellulose nanofibrils modified with different diisocyanates for circulating oil absorption

A large number of polluting substances, including chlorinated organic substances that were highly stable and hazardous, has been emitted due to the rapidly developing chemical industry, which will affect the ecological environment. Nanocellulose aerogels are effective carriers for adsorption of oil substances and organic solvents, however, the extremely strong hydrophilicity and poor mechanical properties limited their widespread applications. In this study, TEMPO-oxidized cellulose nanofibrils was modified with 2, 4-toluene diisocyanate (TDI) and 4,4'-diphenylmethane diisocyanate (MDI) to prepare strong and hydrophobic aerogels for oil adsorption. The main purpose was to evaluate and compare the effects of two diisocyanates on various properties of modified aerogels. It was found that the modified aerogel had better hydrophobic properties, mechanical properties and adsorption properties. In particular, the modified aerogel with TDI as crosslinker showed a better performance, with a maximum chloroform adsorption capacity of 99.3 g/g, a maximum water contact angle of 131.3°, and a maximum compression stress of 36.3 kPa. This study provides further evidence of the potential of functional nanocellulose aerogel in addressing environmental pollution caused by industrial emissions.

Single extraction and integrated non-target data acquisition with data mining workflow for analysis of hazardous substances in agricultural plant products

Identifying contaminants in agricultural plant food products (APFPs) is a major problem. In this study, we developed a single-step extraction and integrated non-target data acquisition (INDA) workflow for increasing hazardous substances coverage. D-optimal experimental designs were applied to optimize filter plate extraction (FPE) for one-single extraction of multipolar hazardous substances. The vDIA mode was used to collect all precursor ion fragments within the range to supplement data loss caused by DDA mode. The underlying principle of vDIA is to increase the utilization rate of MS2 spectra that are likely to identify a maximum number and minimum amounts of hazardous substances. Compared with traditional DDA mode alone, a combination of the two modes increased the rate of identification of hazardous substances by 18.5%. The molecular network of hazardous substance provided by GNPS could enable some metabolites and structure-related products to discover potentially hazardous substance.

Advances and research needs for disinfection byproducts control strategies in swimming pools

The control of disinfection byproducts (DBPs) in swimming pools is of great significance due to the non-negligible toxicity and widespread existence of DBPs. However, the management of DBPs remains challenging as the removal and regulation of DBPs is a multifactorial phenomenon in pools. This study summarized recent studies on the removal and regulation of DBPs, and further proposed some research needs. Specifically, the removal of DBPs was divided into the direct removal of the generated DBPs and the indirect removal by inhibiting DBP formation. Inhibiting DBP formation seems to be the more effective and economically practical strategy, which can be achieved mainly by reducing precursors, improving disinfection technology, and optimizing water quality parameters. Alternative disinfection technologies to chlorine disinfection have attracted increasing attention, while their applicability in pools requires further investigation. The regulation of DBPs was discussed in terms of improving the standards on DBPs and their preccursors. The development of online monitoring technology for DBPs is essential for implementing the standard. Overall, this study makes a significant contribution to the control of DBPs in pool water by updating the latest research advances and providing detailed perspectives.

Nitrate in Groundwater Resources of Hormozgan Province, Southern Iran: Concentration Estimation, Distribution and Probabilistic Health Risk Assessment Using Monte Carlo Simulation

High nitrate concentration in drinking water has the potential to cause a series of harmful effects on human health. This study aims to evaluate the health risk of nitrate in groundwater resources of Hormozgan province in four age groups, including infants, children, teenagers, and adults, based on the US EPA methodology and Monte Carlo technique to assess uncertainty and sensitivity analysis. A Geographic Information System (GIS) was used to investigate the spatial distribution of nitrate levels in the study area. The nitrate concentration ranged from 0.3 to 30 mg/L, with an average of 7.37 ± 5.61 mg/L. There was no significant difference between the average concentration of nitrate in all study areas (p > 0.05). The hazard quotient (HQ) was less than 1 for all age groups and counties, indicating a low-risk level. The HQ95 for infants and children in the Monte Carlo simulation was 1.34 and 1.22, respectively. The sensitivity analysis findings showed that the parameter with the most significant influence on the risk of toxicity in all age groups was the nitrate content. Therefore, implementing a water resources management program in the study area can reduce nitrate concentration and enhance water quality.