Natural Water Research Articles

Fatigue mechanical properties and Kaiser effect characteristics of the saturated weakly cemented sandstone under different loading rate conditions

Weakly cemented sandstone (WCS) is a unique rock type widely distributed on the surface. Environmental factors such as groundwater and stress variations easily influence its fatigue mechanical properties and fracture characteristics. To design and evaluate the long-term stability of surrounding rock support in tunnel excavation and underground resource mining projects, investigating the fatigue mechanical properties and acoustic emission (AE) response characteristics of saturated WCS under different loading rates is of great practical and theoretical significance. This study employed experimental techniques such as X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and natural water absorption tests to investigate the mineral composition, pore size, and connectivity characteristics of WCS. The multi-level cyclic loading-unloading tests (MCLU) combined with the AE system were conducted on dry and saturated WCS specimens at different loading rates. The results reveal that the deformation modulus of these specimens initially increases and then decreases under cyclic loading conditions. Water significantly influences the fatigue strength and deformation resistance of sandstone. As the loading rate increases, the range of RA values broadens, accompanied by a marked increase in the number of AE signals with high RA values. Saturated sandstone specimens are more prone to developing macroscopic shear fracture surfaces. Water has a more substantial effect on the stress distribution ranges corresponding to the response of the Kaiser effect in WCS than loading rates. The capacity of the Kaiser effect to indicate the extent of rock damage is intricately linked to the progression of internal micro-cracks. When internal damage surpasses the critical value of the Kaiser effect memory damage, the accelerated propagation of shear cracks becomes pivotal in the internal damage of the sandstone. It seems that the presence of water within the interior of the rock may facilitate the dissolution of K-feldspar in WCS, which could result in the formation of kaolinite, which will be further transformed into illite. The hydration expansion of illite may further exacerbate the deterioration effect of the mechanical properties of WCS.

Assessment of water quality variation: tool for effective water treatment system operations

Water quality and treatment systems are dynamic because they constantly undergo seasonal variations in water chemistry, varying plant operating conditions, and new environmental laws, among others. Because of this, proper monitoring is essential to ensure that the water supplied by the treatment system safeguards public health from waterborne diseases. Selected surface water quality parameters as inflow were obtained before treatment against the treated water for different hydrological periods (2009 – 2019) from a water treatment system to determine the trend in water quality variation, water quality index, and effectiveness of the treatment process. Each hydrologic year had varying concentrations of selected parameters for raw and treated water quality. The concentration values of pH, electrical conductivity, total hardness, calcium and magnesium hardness, chloride, and total dissolved solids of the natural source water were within the recommended limit. Turbidity concentrations were above the recommended value for each hydrologic year, values ranging from 14.65 – 57.98 NTU, and iron concentration was above the permissible for 2010 and 2012. Selected parameters were all within the threshold limit after treatment with a water quality index (WQI) ranging between 1.09 – 39.39, rated as good/excellent water quality. The treatment system operations were effective throughout the observation period. However, turbidity, iron and hardness should be tested more frequently during the operational and verification monitoring process.

Investigation of bioelectricity generation potential of pharmaceutical wastewater through microbial fuel cells operation

Pharmaceutical wastewater (PWW) as an industrial wastewater presents a potential hazard to natural water systems. This wastewater contains organic matter, which is toxic to the various life forms of the system. PWW is one of the major health problems nowadays, not only for aquatic life but also for human beings and the environment. There are several methods such as filtration, advanced oxidation, coagulation and biological membranes been used for the treatment of PWW, however, all of these methods are limited in their results and applications. In this present study, Microbial Fuel Cells (MFCs) represent a new method for treating wastewater, generating electricity, and reducing COD simultaneously. A novel H-type MFC connected with a graphite electrode has been designed for bioelectricity generation, COD reduction as well as PWW treatment. The treatment of PWW showed adequate bioelectricity generation such as Voltage, Current, and Power, of about 775 mV, 0.421 mA, and 583.70 mW at 100 Ω respectively. The percentage of the COD removed ranged from 95.2-96.7% and 12-34% at the different process variables. This study established bioelectricity generation and bio-treatment of PWW.

Synergistic on engineering layered N-doped carbon/MXene heterostructure: A potential scaffold for simultaneous electrochemical detection of Cu2+ and Hg2+ ions

The presence of heavy metal ions (HMIs) like Cu2+ and Hg2+ in natural water and foods is a major health and environmental concern. Thus advanced electrochemical sensors are required to monitor these ions. Herein, we introduce a nitrogen-rich carbon-MXene composite (layered N-doped carbon/MXene) as an electrochemical sensor suitable for the simultaneous detection of Cu2+ and Hg2+. Synthesizing 2D/2D heterostructure interfaces using controlled thermal decomposition conditions with the incorporation of quaternary nitrogen from choline chloride and the formation of hydrogen bonds of urea within the MXene (Ti3C2Tx) provided active surfaces area that is suitable for the detection of Cu2+ and Hg2+. The intermediate structure of layered N-doped carbon/MXene, had a nitrogen content of ∼6 %, maximized sensitivity for Cu2+ and Hg2+. The layered N-doped carbon/MXene composite exhibited excellent electrochemical sensing for Cu2+ and Hg2+ in 0.1 M acetate buffer at low sensing potentials. The limits of detection (LODs) of layered N-doped carbon/MXene were 0.019 and 0.056 µM with a sensitivity of 114.54 and 64.317 µA µM−1 cm−2 for Cu2+ and Hg2+, respectively. Furthermore, the layered N-doped carbon/MXene heterostructure exhibited high selectivity for Cu2+ and Hg2+ in the presence of potentially interfering common metal ions. This study introduces a promising advanced material for rapid Cu2+ and Hg2+ detection in food and environmental applications.

Dissolved ammonia catalyzes proto-dolomite precipitation at Earth surface temperature

Marine carbonate rocks are the major reservoir of carbon through CaCO3 and CaMg(CO3)2 precipitation extracting CO2/HCO3- from the atmosphere/oceans; hence dolomite is one of the major sinks in the global carbon cycle. Most ancient dolomite has been considered as mainly precipitated under Earth surface conditions. Previous studies have demonstrated that microbes can mediate dolomite formation. However, the “microbial dolomite” model is not sufficient to explain the dolomite that shows no or little evidence of a microbial origin. Although attempted for decades, the synthesis of inorganically-produced dolomite at normal temperatures (<50 °C) has been relatively unsuccessful. Hence, this "dolomite enigma" has been one principal research focus this century. Here we demonstrate that NH3 catalyzes proto-dolomite precipitation inorganically with higher Mg/Ca molar ratios and CO32- activity at normal temperatures of 30 °C and 40 °C. NH3 dissolution increases the alkalinity of the solution and transformes into NH4+ ions, which prefer to bond with H2O on Mg[(H2O)6]2+ rather than free H2O, thus releasing Mg2+ to facilitate proto-dolomite nucleation. Furthermore, the low dielectric constant and low dipole moment allow NH4+ absorbed on crystal surfaces to lower the energy barrier of Mg[(H2O)6]2+ dehydration, promoting proto-dolomite nucleis growth. The system for proto-dolomite precipitation in our experiments closely simulates the natural aqueous environment. This study brings new insights to understanding the mechanisms of dolomite precipitation in natural waters.

Calcium self-release bioremediation system combined with microbially induced calcium precipitation for the removal of ammonium nitrogen, phosphorus and heavy metals

Natural landscape water and substrate were taken to simulate the release of substrate pollutants in micropolluted water bodies, and a calcium silicate- sodium alginate (CS-SA) bioremediation system was constructed. The removal of ammonium nitrogen (NH4+-N), total nitrogen (TN) and Phosphate (PO43--P) were 99.14 %, 98.90 % and 84.44 %, respectively. The Ca2+ continuously released by CS-SA provided good microbial-induced calcium precipitation (MICP) conditions for Acinetobacter calcoaceticus strain HM12, and the removal efficiency of both Zn2+ and Cd2+ was 100 %, and the pH after remediation was consistent with that of natural water bodies. NH4+-N was removed by heterotrophic nitrification- aerobic denitrification (HN-AD) of strain HM12, and heavy metals and phosphorus were removed by co-precipitation and adsorption by MICP. High-throughput sequencing results showed that strain HM12 was effective as a bioinoculant for the remediation of the aquatic environment. The construction and operation of this bioremediation system provided a method for micropolluted water treatment and recovery of phosphorus and heavy metals.

Reconstruction of regional regulations on the development of natural tourism and river water tourism in the Muria mountains based on sustainable tourism

The potential for developing nature-based tourism and water tourism in Kudus Regency has quite good potential, but its development is not yet in line with the principles of sustainable tourism. This is also supported by regional regulations that have not fully implemented sustainable tourism. This research uses normative research methods by conducting a study of the synchronization of legal regulations, namely regional laws and regulations with the principles of sustainable tourism and ecological justice. The first result of this research is the threat of environmental damage and a pollution crisis that will occur in the Mount Muria area, if it is not followed up with special regional regulations, second, ecological justice is needed in the substance of regional regulations based on sustainable tourism, third, the concept of new regional regulations must contains the substance of sustainable tourism, green economy and ecological justice.

Eminent Red Sea water hydrogen generation via a Pb(ii)-iodide/poly(1H-pyrrole) nanocomposite photocathode

Abstract The development of a photocathode based on a Pb(ii)-iodide/poly(1H-pyrrole) porous spherical (PbI2/P1HP PS) nanocomposite has been successfully achieved in the efficient production of H2 gas from Red Sea water. The distinguishable spherical and porous shapes of these nanocomposites are characterized by a minimum surface measuring approximately 25 nm. This structural configuration, coupled with the nanocomposite’s substantial light absorbance, results in a modest bandgap of 2.4 eV. This turns the nanocomposite into a highly promising candidate for renewable energy applications, particularly for H2 gas generation from natural sources like Red Sea water. The economic viability of the PbI2/P1HP PS nanocomposite, relying on a glass substrate, mass production, and straightforward fabrication techniques, adds to its promising profile for H2 gas evolution. The photocathode exhibits significant potential for H2 gas production, with a notable current density (J ph) value of 1.0 mA·cm−2 in a three-electrode cell configuration. The IPCE reaches 3.1%, reflecting the successful evolution of 24 µmol·h−1 10 cm2 of the photocathode. Importantly, the use of natural Red Sea water as an electrolyte underscores a key feature for H2 gas production: utilizing freely available natural resources. This aspect holds considerable promise for industrial applications, emphasizing the environmentally sustainable nature of the photocathode.

A detailed practical and theoretical study of the adsorptive potential of synthesised ceria impregnated activated graphite for aqueous Se(IV) and Te(IV) removal: Process optimisation, characterisation and mechanistic approach

A cost-effective, simple, and earth friendly nanocomposite adsorbent was synthesized by in - situ penetration of ceria nanocrystals on graphite to remove aqueous selenium (IV) and tellurium (IV). Batch experiments optimize parameters such as pH, temperature, sorbent dosage and equilibration time of 30 minutes. The adsorbent exhibited the maximum adsorption capacities of 144.5 mg/g for Te(IV) and 29.3 mg/g for Se(IV). BET analysis revealed a specific surface area of 16.44 m²/g, an average pore diameter of 4.24 nm, and a high pore volume of 0.0519 cm³/g. The adsorbent was characterized before and after adsorption by SEM-EDX, XRD and FTIR. The sorption data could be well interpreted by the Langmuir model for both Se and Te and by the DR isotherm for Te(IV) at ambient temperature. Kinetic empirical data correlated positively with pseudosecond order for both Se and Te and the Elovich model for Te at room temperature. Kinetics and equilibrium isotherms suggested that the adsorption occurred through surface adsorption using electrostatic bonding along with physisorption involving steady diffusion and accommodation of analyte ions into mesopores and defects of the adsorbent. Chemisorption by electron transfer of the oxyanions of Se/Te with Ce3+/Ce4+ of the cerium impregnated graphite (CIAG) and ion exchange with functional groups on the activated graphite edges were other probable mechanisms. The adsorbent demonstrated the ability to be regenerated and reused over multiple cycles, with minimal interference from coexisting ions emphasizing its selectivity. All measurements were conducted in triplicate with the relative standard deviation (RSD) below 5 %. The optimised method was successfully applied in natural water samples from various sources, demonstrating strong potential for scaling up to field applications.

Теоретичне підґрунтя публічного управління у сфері водопостачання та водовідведення

The sphere of water supply and drainage is a critically important component of the socio-economic mechanism, which is characterized by numerous challenges that were actualized in wartime. Aim of this paper is to analyze the main theoretical approaches of public management in the field of water supply and drainage in order to identify the main principles and tools that affect the efficiency and sustainability of the field. The tools of strategic planning, operational management and emergency response are considered as key components of successful management in this area. Emphasis is placed on the special role of developing fair tariff policies and financial support for infrastructure investments. The importance of the legal framework that regulates the sphere, ensuring compliance with environmental standards and protection of consumer rights is highlighted. The environmental aspect of resource management in the field, which includes modern methods of wastewater treatment and minimizing the negative impact on natural water bodies, is considered. It was emphasized that state intervention is a key factor in ensuring equal access to clean water, which is a basic human right according to the United Nations. The problem of natural monopoly in the field is considered through the prism of high capital investments and low elasticity of demand, which limit market competition. Strategies to stimulate competition and improve service quality are explored, including regulating tariffs and encouraging innovation. The example of Scotland, where water supply management is centralized through the creation of a single national company Scottish Water, reveals the effectiveness of such an approach in improving infrastructure and ensuring high quality services with public participation. The importance of a multidisciplinary approach to management in the field is emphasized, with a special emphasis on the stability of the service in wartime. The research may be useful to researchers, state and local authorities, and international organizations. Further perspectives of research include the study of the peculiarities of the application of the theoretical base in the solution of scientific and practical problems in the field in Ukraine during the war.

Contamination of Arsenic Speciation in Rice

Rice is the staple food of people in Asian countries, especially in Laos, where it is carbohydrate stuff that plays an essential role as a source of energy to support human beings. Arsenic (As) is a heavy metal of which naturally occurring; it can be found in soil, rocks, and natural water sources; and is caused by human activities such as mining activities, the use of agro-chemicals (pesticides, herbicides, etc.) in agriculture. Therefore, it is possible to deposit and contaminate the environment such as the paddy soil and the irrigation; afterward, it can initiate the arsenic residues in the agricultural productions that harvesting from the contaminated area, which is the rice grain. Furthermore, the arsenic residue can give rise to a health impact on those who consume the toxic rice. According to the analysis results of arsenic contamination in the 3 types of rice samples revealed that: in the HSV sample, the total amount of arsenic was 0.11 mg/kg, and the total inorganic arsenic (iAs) was 0.09 mg/kg which included the amount of inorganic arsenic AsV was 0.02 mg/kg, the inorganic arsenic AsIII was 0.07 mg/kg; the total arsenic in the TDK8 sample was 0.19 mg/kg, the (iAs) was 0.01 mg/kg, and the amount of arsenic AsV was 0.01 mg/kg, the amount of arsenic AsIII was 0.08 mg/kg; the total arsenic in the Composite rice was 0.14 mg/kg, the (iAs) was 0.08 mg/kg, the AsV and AsIII were 0.006 mg/kg and 0.08 mg/kg, respectively. In conclusion, the arsenic residue was contaminated in all three rice samples, but the residue of total arsenic and inorganic arsenic (iAs) did not exceed the maximum permissible limit of the international standard or CODEX which is 0.3 and 0.2 mg/kg, respectively.

Amide/urea-based simple fluorometric receptors for iodide and Hg2+ ions in aqueous medium: Aggregation induced emission and DFT studies

Herein, we report pyrene-tagged amide and urea-based sugar derivatives 1 and 2 in a simple synthetic pathway to recognize I− and Hg2+ ions. Both molecules showed absorbance and fluorescence selectivity towards iodide ions in THF/H2O (7/3, v/v) medium. The selectivity and sensitivity of 2 for iodide ions are superior to 1 due to more H-bond donors in 2. Interestingly, fluorometric receptor 2 exhibited aggregation-induced emission (AIE) at higher pH with a remarkable fluorometric color change. The AIE phenomenon might be explained by the self-association of 2 after forming imine functionality in the alkali medium. The Stern-Volmer plot showed the fluorescence quenching constant of each receptor with an iodide ion and indicated the quenching pathway. The LODs of 1 and 2 for iodide ions were evaluated as 0.84 and 0.17 µM, respectively. The 1:1 binding stoichiometry of 1 or 2 with iodide was found from the Job plot and verified by measuring the complex mass.Further, the complexes of each receptor with I− ions can detect Hg2+ ions selectively by fluorescence turn-on method with low sensitivities (LODs: 0.008 µM for 1 and 0.01 µM for 2). DFT results were used to understand the binding mode of receptors 1 and 2 with iodide ions and the quenching process in the aqueous THF medium. The real application of the receptors was established for the recovery of iodide and Hg2+ ions from natural water samples.

Predicting soil hydraulic conductivity using random forest, SVM, and LSSVM models

AbstractUnderstanding the hydraulic properties of soil is essential to solve many management problems in agriculture and the environment. Water quality affects soil hydraulic conductivity. Soil hydraulic properties play an important role in nature's water cycle and are used as basic information in designing irrigation and drainage systems, hydrological issues, and soil quality assessment. In the current study, soil sampling is performed from different areas and its hydraulic conductivity was measured using the drop load method and then predicted using support vector machine (SVM) and least‐squares support vector machine (LSSVM) models. The model inputs were: soil texture (percentage of sand, silt, and clay particles), salinity (electrical conductivity), pH, sodium adsorption ratio, soil porosity, and bulk density and the output was soil hydraulic conductivity. Correlation coefficient, root mean square error (RMSE), mean bias error (MBE), and Nash–Sutcliffe efficiency (NSE) were used to evaluate the models and compare them. Based on evaluation criteria the best performance was obtained for random forest (RF) (R = 0.89, RMSE = 0.53, mean absolute error (MAE) = 0.54, and NSE = 0.72). Following RF, the SVM with (R = 0.69, RMSE = 1.32, MAE = 0.69, and NSE = 0.48) performed better than LSSVM model.

Effect of microplastic ingredient on the removal of microplastics by calcium alginate flocculation

The widespread presence of microplastics induce a serious threat to the survival of living organisms. Herein, calcium alginate hydrogel was selected as a flocculant to remove microplastics from water. To determine the variability of the flocculation method for the removal of microplastics with different properties, 11 microplastics of different sizes or components were used. The results showed the removal of different microplastics were 99.5% (PSMP 5 µm), 99.5% (24 h aged PSMP), 98.6% (72 h aged PSMP), 97.1% (48 h aged PSMP), 92.0% (PMMA 15 µm), 84.0% (PAMP 5 µm), 82.0% (PVCMP 1 µm), 80.2% (PLAMP 500 mesh), 68.0% (PEMP 100 mesh), 52.0% (PE 20 µm), and 52.0% (PP 1000 mesh). Microplastics were mainly wrapped and swept by flocs. The density and surface hydrophilicity of microplastics are the main reasons for the discrepancy in their removal efficiency. Calcium alginate also performed well in the removal of microplastics in natural water. When the initial concentration of the polystyrene microplastic suspension was 5 mg/L, the removal rates of microplastics in the five water samples were 99.60% (pipe water), 98.19% (lake water), 98.71% (river water), 100.44% (sludge supernatant), and 100.00% (seawater). Also, flocculation method could almost completely remove fibrous microplastics from washing wastewater. It is aim to provide reference data for the removal of different microplastics in water by flocculation, and also expect to increase the emphasis on microplastic variability in the future removal exploration.

Mechanical Properties of Permeable Concrete Reinforced with Polypropylene Fibers for Different Water–Cement Ratios

Permeable concrete is a material that allows water filtration, reduces surface runoff, and maintains the natural water cycle. Previous studies have shown that its mechanical properties, particularly its compressive and flexural tensile strengths, are generally lower than those of conventional concrete, with significant variability observed among similar tests. This study investigates the compressive strength, flexural strength, and permeability of polypropylene fiber-reinforced permeable concrete specimens at two water–cement ratios (0.30 and 0.35). The mix design was conducted using the ACI 522R-10 method. Forty-eight cylinders measuring 200 mm × 100 mm were fabricated for permeability and compression tests. Additionally, 12 beams measuring 100 mm × 100 mm × 350 mm were produced and subjected to simple flexural testing in accordance with ASTM C78 guidelines. Compressive strength versus permeability and load versus deflection graphs were plotted, and the fracture energy was calculated for various deflections. The results indicate that the addition of fibers increased permeability and tensile strength but decreased compressive strength. Furthermore, an increase in the water–cement ratio led to higher compressive and flexural tensile strengths.

OH radical initiated oxidative degradation of imidacloprid in the environment: An assessment of breakdown kinetics and environmental hazards

Imidacloprid (IMI) is a common neonicotinoid pesticide that acts via a similar mechanism of action to nicotine, a naturally occurring insecticide. It is therefore important to understand its chemical fate in the environment. Hydroxyl radicals (HO) are significant oxidizing species in natural aquifers due to their strong reactivity towards organic substrates. Therefore, principal photo-oxidation products are expected to form with the involvement of HO in the self-cleaning process of water in nature. Here quantum chemical calculations are used to examine the reaction of IMI with HO in the atmosphere and aqueous environments. It was found that the principal mechanism of the HO + IMI reaction is the hydrogen transfer that, in a two-step process, produces stable cations in the gas phase. Within the atmospheric temperature range of 253–323 K, the overall rate constants for the HO + IMI reaction decreased from 4.35 × 1010 to 2.13 × 1010 M−1 s−1. Consequently, IMI can undergo rapid gaseous degradation within a comparatively brief period of 2.81 × 10−4 – 5.75 × 10−4 years. However, differences in environmental temperature and pH in aqueous environments influence the processes, rate constants, and products of IMI breakdown by the HO radical. The data indicate that IMI breakdown by OH radicals is strongly temperature and pH-dependent, resulting in the generation of different reaction products. The results imply that at all pH levels, the interaction between IMI and the ambient HO radical in water produces toxic chemical species. According to the computed data, it appears that IMI and the vast majority of degradation products present potentially carcinogenic and/or mutagenic hazards, and they also lack downstream biodegradability.

Organic Capillary Barriers for Soil Water Accumulation in Agriculture: Design, Efficiency and Stability

Acute shortage of water resources and high unproductive water losses are the key problems of irrigated agriculture in arid regions. One of the possible solutions is to optimize soil water retention using natural and synthetic polymer water absorbers. Our approach uses the HYDRUS-1D design to optimize the placement of organic water absorbents such as peat and composite hydrogels in the soil profile in the form of water-storing capillary barriers. Field testing of the approach used a water balance greenhouse experiment with the cultivation of butternut squash (butternut squash (Cucurbita moschata (Duchesne, 1786)) under sprinkler irrigation with measurement of the soil moisture profile and unproductive water losses in the form of lysimetric water outflow. In addition, the biodegradation rate of organic water absorbents was studied at the soil surface and at a depth of 20 cm. Organic capillary barriers reduced unproductive water losses by 40–70%, retaining water in the topsoil and increasing evapotranspiration by 70–130% with a corresponding increase in plant biomass and fruit yield. The deepening of organic soil modifiers to the calculated depth not only allowed capillary barriers to form, but also prevented their biodegradation. The best results in soil water retention, plant growth and yield according to the “dose-effect” criterion were obtained for a composite superabsorbent with peat filling of an acrylic polymer matrix. The study showed good compliance between the HYDRUS design and the actual efficiency of capillary barriers as an innovative technology for irrigated agriculture using natural and synthetic water absorbents.

Increasing our knowledge about the epidemiology of Helicobacter pylori in Nunavik’s Inuit population (Québec, Canada) using Qanuilirpitaa? 2017 cross-sectional survey

ABSTRACT Helicobacter pylori is a bacterium that may colonise and proliferate in human stomachs, leading invariably to chronic inflammation and, to a lesser extent, to peptic ulcers and cancer. The main objective of this study is to describe the epidemiology surrounding H. pylori in Nunavik’s Inuit population using the 2004 and 2017 Health Surveys. Estimated prevalences were 70.9% for bacterial colonisation using a stool antigens test (SAT), 72.5% for anti-H. pylori antibodies, 12.7% for faecal occult blood in participants aged ≥ 50 and respectively of 28.4%, 11.2% and 2.4% for a prior diagnosis of colonisation, gastritis and peptic ulcer in the medical charts, with under five cases of gastric cancer reported. Variables associated with higher SAT+ prevalence were the number of household members (prevalence ratio [PR] = 1.03) and age (quadratic relationship), whereas mainly drinking municipal (PR = 0.84) and natural water (PR = 0.72) compared to bottled water, and increasing alcohol consumption (PR = 0.96) were associated with reduced prevalence. Despite current regional guidelines targeting high risk individuals in the context of high prevalence, Nunavik’s health authorities must remain vigilant by following gastric cancer incidence and the rapid evolution of guidelines, while considering local realities.

Phototransformation of tetrabromobisphenol A bis (allyl ether) in an aqueous solution: Role of environmentally persistent free radicals

Tetrabromobisphenol A bis (allyl ether) (TBBPA-BAE) represents an extensively used brominated flame retardant (BFRs) in the production of many fields and their phototransformation in natural water is still unclear. The environmentally persistent free radicals (EPFRs) with preserved activities could exist in the environment for a long time and involve in the phototransformation of many organic pollutants. Here, the photodegradation of TBBPA-BAE with the degradation rate constant (k = 0.060 h−1) under simulate sunlight and the promoting effect of EPFRs on TBBPA-BAE photodegradation (k = 0.135 h−1) were investigated. According to the detected photogenerated electrons (e−) and singlet oxygen (1O2) rather than hydroxyl radicals (•OH) by the electron paramagnetic resonance (EPR), the effect mechanism may not be related to the typical •OH induced by EPFRs. The possible transformation pathways of the ether cleavage, hydrolysis and hydroxylation of propenyl bond and the debromination were proposed by the primary byproducts identified by UPLC-Q-Exactive Orbitrap MS. EPFRs caused a further debromination and ether cleavage and probably be due to EPFRs directly providing electrons to TBBPA-BAE which promoted the photodegradation of TBBPA-BAE, and their reaction mechanism needed further attention. Overall, this study provided useful information to understand the role of EPFRs on phototransformation of TBBPA-BAE in water.

The unique chemical and microbiological signatures of an array of bottled drinking water.

The bottled drinking water market has seen significant growth and diversification, yet the selection criteria lack scientific basis, as all must adhere to stringent health standards. Prior studies predominantly focused on chemical quality, with limited assessments of microbial quality using methods prone to underestimation. Moreover, insufficient research explores the impact of packaging materials and temperatures optimal for mesophilic growth on microbial quality. To understand the unique characteristics and justify the distinction among different types of bottled waters, a comprehensive analysis encompassing both chemical and microbiological aspects is imperative. Addressing these gaps, our study examines 19 diverse bottled water brands comprising purified, mineral, artesian, and sparkling water types from Saudi Arabia and abroad. Our findings reveal distinct chemical compositions among bottled waters, with notable variations across types. Flow cytometry analysis reveals significant differences in bacterial content among water types, with natural mineral waters having the highest concentrations and treated purified waters the lowest. Bacterial content in plastic-bottled mineral water suggests it may be higher than in glass-bottled water. Flow cytometry fingerprints highlight separate microbial communities for purified and mineral waters. Additionally, temperatures favorable for mesophilic growth reveal varying microbial responses among different types of bottled waters. Some variation is also observed in mineral water bottled in plastic versus glass, suggesting potential differences that warrant further investigation. 16S rRNA gene sequencing identifies unique microbial taxa among different mineral waters. Overall, our study underscores that all bottled waters meet health regulations. Furthermore, the combined chemical and microbial profiles may serve as authenticity indicators for distinct bottled water types. This study can serve as a basis for future research on the environmental impact of bottled water transportation, suggesting that locally produced water may offer a more sustainable option.