Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering最新文献

In indoor air the reaction of ozone (O₃) with terpenes may lead to the formation of irritating gas-phase products which may induce acute airway effects (i.e. sudden, short-term changes or symptoms related to the respiratory system). We aimed to perform an in vitro study on possible health effects of products from the O₃-initiated reaction of limonene with printer exhaust, representing real-life mixtures in offices. Human bronchial epithelial cells were exposed for 1 hour (h) to limonene and O₃, combined with printer exhaust. The resulting concentrations represented 34% and 6% of the generated initial concentrations of limonene (400 µg/m³) and O₃ (417 µg/cm³), respectively, which were in range of high end realistic indoor concentrations. We observed that the reaction of limonene with O₃ generated an increase of ultrafine particles within 1 h, with a significant increase of secondary reaction products 4-oxopentanal and 3-isopropenyl-6-oxo-heptanal at high end indoor air levels. Simultaneous printing activity caused the additional release of micron-sized particles and a further increase in reaction products. Relevant cellular endpoints to evaluate the possible induction of acute airway effects were measured. However, none of the test atmospheres representing office air was observed to induce these effects.

The ketamine (KET) and its analogs consumed by humans are becoming emerging contaminants (ECs), as they at present in surface waters after being carried through wastewater systems. Drugs in wastewater can be analyzed using the direct-injection method, a simple wastewater analysis (WWA) method that can provide objective, continuous and nearly to real-time findings. This article describes an ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification and confirmation of seven KET-based ECs in wastewater by direct injection. After optimization of the UPLC-MS/MS and sample pretreatment conditions, the method was validated and applied to samples (n = 157) collected from several wastewater treatment plants (WWTPs) in southern China in which KET had the highest detection rate. The established direct-injection method was not only simple to perform but also had better sensitivity, shorter detection times, and analyzed more KET-based ECs than currently published methods, meeting the requirements for the monitoring and high-throughput analysis of common KET-based ECs. We also analyzed the fragmentation pathway of KET-based ECs to obtain product ion information on other unknown substances. Additional studies are needed to establish a comprehensive direct-injection screening method of ECs in wastewater on model-based assessment.

Cellulose was isolated from recycled pulp and paper sludge and used to synthesize cellulose nanocrystals. Response surface methodology and Box-Behnken design model were used to predict, improve, and optimize the cellulose isolation process. The optimal conditions were a reaction temperature of 87.5 °C, 180 min with 4% sodium hydroxide. SEM and TEM results revealed that the isolated cellulose had long rod-like structures of different dimensions than CNCs with short rod-like structures. The crystallinity index from XRD significantly increased from 41.33%, 63.7%, and 75.6% for Kimberly mill pulp sludge (KMRPPS), chemically purified cellulose and cellulose nanocrystals, respectively. The TGA/DTG analysis showed that the isolated cellulosic materials possessed higher thermal stability. FTIR analysis suggested that the chemical structures of cellulose and CNCs were modified by chemical treatment. The cellulose surface was highly hydrophilic compared to the CNCs based on the high water holding capacity of 65.31 ± 0.98% and 83.14 ± 1.22%, respectively. The synthesized cellulosic materials portrayed excellent properties for high-end industrial applications like biomedical engineering, advanced materials, nanotechnology, sustainable packaging, personal care products, environmental remediation, additive manufacturing, etc.

The leaching laboratory experiment uses the artificial neural network (ANN) to predict and evaluate copper and cobalt recovery. This study aimed to evaluate the efficacy of using the shrinking core model in conjunction with an artificial neural network (ANN) as part of a machine learning strategy to improve the leaching process of cobalt (II) and copper (II). The numerous factors in the leaching process, such as acid concentration, leaching time, temperature, soil-to-solution ratio, and stirring speed, are adjusted using an ANN with several layers, feed-forward, and back-propagation learning methods. These variables are in charge of the high cobalt recovery during the reduced sulfuric acid leaching procedure. The ANN algorithm has 10 hidden layers, 5 input variables describing the leaching parameters, and two neurons as output layers corresponding to copper and cobalt leaching recovery. The optimum conditions were found to be acid concentration of 100 g/L, leaching duration 120 min, temperature 55 °C, soil-to-solution ratio of 1:40 g/mL, and stirring speed 300 rpm. The optimized trained neural networks tested, trained, and validated steps are represented by R² values of 0.94, 0.99, 0.97, and 0.97, respectively, equating to 97.5% copper recovery and 95.4% cobalt recovery.

Down-flow hanging sponge (DHS) reactors, employed in domestic wastewater treatment, have demonstrated efficacy in eliminating Escherichia coli and other potentially pathogenic bacteria. The aim of this study was to elucidate the mechanism of removal of E. coli by employing a cube-shaped polyurethane sponge carrier within a compact hanging reactor. An E. coli removal experiment was conducted on this prepared sponge. Escherichia. coli level was found to decrease by more than 2 logs after passing through five nutrient-restricted DHS sponges. Conversely, a newly introduced sponge did not exhibit a comparable reduction in E. coli level. Furthermore, under conditions of optimal nutritional status, the reduction in E. coli level was limited to 0.5 logs, underscoring the crucial role of nutrient restriction in achieving effective elimination. Analysis of the sponge-associated bacterial community revealed the presence of a type VI secretion system (T6SS), a competitive mechanism observed in bacteria. This finding suggests that T6SS might play a pivotal role in contributing to the observed decline in E. coli level.

The study was carried out to define the distribution of mercury in surface soils in the Mitrovica region, Republic of Kosovo and to assess the level and extent of contamination. A total of 156 soil samples were collected from a depth of 5 cm at each grid point of 1.4 × 1.4 km in an area of 301.5 km². The mercury content was found to be between 0.02 mg/kg and 11.16 mg/kg. The average Hg content (0.49 mg/kg) exceeded the mean content in European (0.037 mg/kg) and world (0.06 mg/kg) soils by 13.2 and 8.2 times, respectively. From the calculated enrichment factors (EF) and the geo-accumulation index (I-geo), as well as from the distribution map of Hg content, it is evident that the soils of the study area are highly contaminated with mercury, with extremely high enrichment of Hg in the soils of Zone I, which was classified as the most contaminated zone with Hg and other potentially toxic elements in the study area as well as in the towns of Zveçan and Mitrovica. The higher Hg content is of anthropogenic origin, mainly due to lead and zinc mining and metallurgical activities in the study area. The mercury levels were also found to exceed the New Dutch List target value (0.3 mg/kg) in 90 km² of the study area.

Despite incineration is an important emission source of toxic pollutants, such as heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), it is still one of the most widely used methods for the management of municipal solid waste. The current paper summarizes the results of a 20-year follow-up study of the emissions of PCDD/Fs by a municipal solid waste incinerator (MSWI) in Sant Adrià de Besòs (Catalonia, Spain). Samples of ambient air, soils and herbage were periodically collected near the facility and the content of PCDD/Fs was analyzed. In the last (2017) survey, mean levels in soil were 3.60 ng WHO-TEQ/kg (range: 0.40-10.6), being considerably higher than the mean concentrations of PCDD/Fs in soil samples collected near other MSWIs in Catalonia. Moreover, air PCDD/F concentrations were even higher than those found in a previous (2014) survey, as they increased from 0.026 to 0.044 pg WHO-TEQ/m³. Ultimately, the PCDD/F exposure would be associated to a cancer risk (2.5 × 10^-6) for the population living in the surrounding area. Globally, this information indicates that the MSWI of Sant Adrià de Besòs could have had a negative impact on the environment and potentially on public health, being an example of a possible inappropriate management for years. The application of Best Available Techniques to minimize the emission of PCDD/Fs and other chemicals is critical.

The photocatalytic technology for indoor air disinfection has been broadly studied in the last decade. Selecting proper photocatalysts with high disinfection efficiency remains to be a challenge. By doping with the incorporation of metals, the bandgap can be narrowed while avoiding the recombination of photogenerated charge. Three photocatalysts (Ag-TiO₂, MnO₂-TiO₂, and MnS₂-TiO₂) were tested in photocatalytic sterilization process. The results revealed that Ag-TiO₂ had the best antibacterial performance. Within 20 min, the concentration of Serratia marcescens (the tested bacteria) decreased log number of ln 4.04 under 640 w/m² light intensity with 1000 µg/mL of Ag-TiO₂. During the process of inactivating bacteria, the cell membranes of bacterial was destructed and thus decreasing the activity of enzymes and releasing the cell contents, due to the generation of reactive oxygen species (O₂•^- and •OH) and thermal effect. Spectral regulation has the greatest impact on the sterilization efficiency of MnO₂-TiO₂, which reduces the probability of photocatalytic materials being excited.

In Afghanistan, groundwater is widely used for drinking water, but its quality poses a health threat. This study investigates the physical, chemical, and bacteriological characteristics of groundwater in the Upper Kabul Sub-basin. Fifteen samples were collected and analyzed from different parts of the study area. The qualitative determination of parameters such as pH, Electrical conductivity (EC), Total dissolved solids (TDS), Salinity, Total hardness, Calcium, Magnesium, Sodium, Chloride, Fluoride, Sulfate, Phosphate, Potassium, Nitrite, Nitrate, Ammonia, Iron, Manganese, Copper, Aluminum, Arsenic, Total coliform, and Fecal coliform bacteria was carried out. The results were compared with WHO and ANSA standards to assess their suitability for drinking purposes. The analyzed samples indicate that physical parameters generally fall within permissible limits according to WHO and ANSA standards. However, certain wells exhibited elevated levels of chemical and bacteriological contaminants. Specifically, Magnesium concentrations exceeded the WHO guideline of 30 mg/L in all of the samples, and Calcium levels surpassed the recommended limit of 75 mg/L in 53% of the samples. Total coliform bacteria were detected in 33.33% of the samples, while fecal coliform bacteria were within the WHO and ANSA permissible limit for drinking water. The Pearson's correlation coefficient (R) suggested significant correlations between EC, TDS, and total hardness with other physical and chemical parameters. For instance, EC showed a strong positive correlation (R = 1.00) with TDS, EC and Salinity (R = 0.981), EC and Fluoride (R = 0.838) EC and Sulfate (R = 0.853), TDS and Salinity (R = 0. 981), TDS and Fluoride (R = 0.838), TDS and Sulfate (R = 0.853). The findings demonstrate that correlation coefficient analyses of water quality parameters provide a valuable means for monitoring water quality. These results offer critical insights for ensuring a safe water supply in the region.

High level of aluminum content in Enteromorpha prolifera posed a growing threat to both its growth and human health. This study focused on exploring the factors, impacts, and process of removing aluminum from Enteromorpha prolifera using humic acid. The results showed that under experimental conditions of 0.0330 g·L^-1 humic acid concentration, pH 3.80, 34 °C, and a duration of 40 min, the removal rate was up to 80.18%. The levels of major flavor components, proteins, and amino acids in Enteromorpha prolifera increased significantly after treatment, while polysaccharides and trace elements like calcium and magnesium decreased significantly. Infrared spectroscopy demonstrated that the main functional groups involved in binding with Al³⁺ during humic acid adsorption were hydroxyl, carboxyl, phenol, and other oxygen-containing groups. The adsorption process of Al³⁺ by humic acid was a spontaneous phenomenon divided into three key stages: fast adsorption, slow adsorption, and adsorption equilibrium, which resulted from both physical and chemical adsorption effects. This study provided a safe and efficient method in algae metal removal.