Natural Water Research Articles

Microplastics Meet Metoprolol in Natural Water: Sorption Behavior and Mechanism

As an ideal carrier for the spread of pollutants in the aquatic environment, microplastics (MPs) can adsorb pharmaceutical β-blockers, which can affect their migration and lead to some unpredictable adverse consequences. In this paper, the sorption behaviors and mechanism of MPs (polyvinyl chloride (PVC) and polypropylene (PP)) for typical β-blocker metoprolol (MTL) were investigated. The effects of pH, salinity and humic acids (HAs) on the sorption were studied, which proved that the sorption behavior was different under different environmental conditions. Both low pH and high salinity inhibited the sorption of MTL by the MPs. Specifically, the sorption capacity of MTL increased, with pH increase from 3 to 10. When pH = 10, the sorption capacities of MTL on PVC (1.75 mg/g) and PP (3.34 mg/g) reached the maximum. After pH > 10, the amount of MTL adsorbed on PVC was slightly decreased, while that on PP was essentially the same. The addition of salt ions inhibited the sorption in the concentration range of 5–250 mg/g for both NaCl and CaCl2, with the inhibitory effect of Ca2+ being stronger than that of Na+. Moreover, the presence of HAs promoted the sorption of MPs for MTL. In the absence of HAs, the sorption capacities of PP and PVC for MTL were 0.34 mg/g and 0.79 mg/g, respectively. When HA concentration was 100 mg/L, the highest sorption capacities of PP and PVC reached 0.79 mg/g and 1.37 mg/g, respectively. This indicated that the promoting effect of HAs on PP was stronger than that on PVC. In general, based on the study of the sorption behavior of MTL and the characterization of the MPs, the sorption mechanism was speculated to consist mainly of electrostatic interactions, cation exchange, hydrophobic interaction and halogen bonding. The sorption kinetics of MTL on the two MPs were well-fitted by the pseudo-second-order model with R2 > 0.99. The sorption isotherms both fitted the Freundlich model, which substantiated that the sorption of MTL on the MPs (PVC and PP) was multilayered and heterogeneous. Collectively, these findings provided a theoretical basis for revealing the complex interactions between MPs and MTL in natural water and a new insight into the fate and migration of MPs and β-blockers in the environment.

Carbon fate and potential carbon metabolism effects during in-situ cyanobacterial inhibition by artemisinin sustained-release algaecides.

Carbon pools and microbial carbon metabolism can be significantly altered due to the diverse organic matter properties and low pH characteristics of artemisinin sustained-release algaecides (ASAs). These effects have still not been systematically studied, leading to uncertainty in the application of ASAs for cyanobacterial management in natural waters. This study assessed the effects of ASAs on carbon fate, carbon metabolism and potential ecological impacts during in-situ cyanobacterial inhibition. In the initial phase of ASAs-induced cyanobacterial inhibition (2-10 days), the carbon pool underwent significant changes due to the increased proportion of C4 plant-derived organic matter (97%), humification level (FI =0.9-1.5), and inorganic carbon concentration (TIC = 80-110mg/L). The cyanobacterial apoptosis triggered by ASAs produced particulate organic carbon, which provided a bioavailable carbon source for bacterial metabolism. ASAs enhanced the connection between bacteria and the carbon pool, as well as their carbon metabolism capabilities, by increasing the relative abundance of Proteobacteria (33.1%-37.3%), bacterial diversity, the proportion of Alphaproteobacteria and Betaproteobacteria (19.3%-29.5%) involved in carbon metabolism, and the complexity of the environment-bacteria co-occurrence network. These effects contributed to maintaining long-term ecosystem stability and resistance to cyanobacterial proliferation. Our findings elucidate the influence of bacterial carbon metabolism by ASAs as one of an important mechanism for achieving cyanobacterial inhibition in natural water, and emphasize the important role of bacteria in maintaining ecological stability during in situ cyanobacterial management.

Tritium determination in natural water samples in Fukushima from 2022 to 2023 using an ultra-low-level tritium counting system.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident created large stockpiles of tritium containing cooling water, which is to be gradually released into the Pacific Ocean, gaining attention from surrounding countries, environmental groups, and local residents concerned with the possibility of increasing tritium concentrations in the water and food cycle. Establishing baseline concentration levels and monitoring tritium immission values are important for assuring public safety, providing data for scientific research and risk communication. Tritium concentrations in the environment are very low; therefore, tritium measurements require enrichment in order to estimate the radiation exposure from drinking water intake and provide information on the water cycle. Natural water samples were collected at Tomioka Town located south of the FDNPP. Samples were distilled, enriched by electrolysis, and re-distilled using an improved SPE method to preconcentrate tritium to measureable levels. Tritium concentrations were determined by a low-background liquid scintillation counter. The observed tritium concentrations were relatively low, rainwater had a mean and SD value of 0.40±0.13Bq/L, and freshwater samples showed similar concentrations, while brackish coastal water samples were below 0.13±0.02Bq/L. The observed tritium concentrations in this study are considered safe as effective doses based on annual drinking water intake; however, continous monitoring is necessary to assure public safety.

Groundwater Quality Prediction and Analysis Using Machine Learning Models and Geospatial Technology

The most prominent source of drinking water is groundwater, followed by lakes and reservoirs. Hydrological parameters like temperature, dissolved oxygen, pH, conductivity, ORP, and turbidity often change due to waste dumping into natural drinking water sources, particularly in densely populated areas. As a result, the water quality must be tested before public consumption to ensure healthy living in society. This research collected water samples from 129 wells in the Kanchipuram district in Tamil Nadu, India. An efficient integrated machine-learning-based prediction model has been proposed and modeled to determine the groundwater quality index (GQI). Several machine learning models were used to predict the water’s quality, including the naïve Bayes model, the KNN classifier, and the XGBoost classifier. Water quality predictions in 2024 were made using a combination of classification algorithms and models based on long short-term memory (LSTM) neural networks. The projected water quality characteristics were analyzed using geographical information system (GIS) technology to better understand and visualize the results. The XGBoost classifier model outperforms prior findings in the literature, with an accuracy of roughly 94.6%. The classification and prediction model was validated using collected and tested current data samples from a selected well. The findings were accurate within the 5% error range, promoting sustainability.

Microplastics in Water and Food: [Not]Awareness

Currently, the spread of micro- and nanoplastics in the food chain and the environment has become a relevant and social issue. They enter the human body mainly through food, water and drinks packaged in various plastic materials, bottles or containers. It has been established that most urban water sources are contaminated with microplastics due to wastewater. The main objective of the article was to study the awareness of microplastic sources, exposure levels and potential health risks associated with microplastic contamination of food and water by surveying a heterogeneous audience of Internet users. The preventive focus of the survey included: 1) holding an action at the medical faculty of KRSU “Day without plastic”; 2) development, publication and distribution of an information leaflet in the Internet community on the key sources of microplastics in the daily human diet. The test group consisted of 502 Internet users. The author's questionnaire included 26 questions: personal data (5 questions), the size of microplastics, sources of information, an assessment of the risk factors for microplastics entering the body, its content in food and water and the impact on human health (a list of 16 diseases associated with microplastics is provided). Statistical processing of the obtained results was carried out using SPSS version 28.0.1 software. Questionnaires of 502 respondents aged 14–50 years were obtained through an online survey from October 2023 to January 2024 using Google forms. The demographic structure reflected the predominance of female representatives - 52.4%, men accounted for 47.6%. In terms of education level, students dominated among the subjects, incomplete higher education (67.3%), then secondary (14.8%), higher (9.9%) and primary education (8.8%). Most of the respondents lived in the city (80.3%), compared to rural areas (19.7%). Since the survey involved young people, 49.8% of respondents correctly answered the question that microplastics are small particles measuring 5 microns. 50.2% of respondents answered incorrectly, indicating sizes of 10 and 15 microns. Respondents noted that microplastics are most often found in bottled water (29.5%), tea bags (17.3%), natural water (10.3%), fish (8.1%), salt (6.3%), seafood (5.5%) and honey (4.5%). All of the above were noted by 29.5% of respondents. Most respondents to the question: which vegetables are most often contaminated with microplastics, answered that none (38.5%), followed by root vegetables (30.4%), onions (13.1%), cabbage (9.7%) and legumes (8.3%). Among the presented sample - the correct answer is - root crops are most susceptible to contamination. The results of the survey show that in everyday life 45.8% of respondents most often used plastic bags (55.7%), food packaging (18.7%), then cosmetics and hygiene products (17.4%), toys (5.9%) and cutlery (2.3%). Living in a “plastic world”, Internet users somehow do not notice it, to the question of how often the respondents use plastic products, 64.7% of them answered that every day, 26.7% - sometimes, 8.6% — rarely. As the results of the survey showed, most often Internet users received information about the harm of microplastics from social networks 26.5%, Google search engine — 20.7%, scientific articles — 18.9%, news — 17.1%, while communicating with friends, family — 5.5%. At the same time, 11.3% of respondents were not interested in the problem. When comparing the assessment of awareness of the direct and indirect impact of plastic on human health during plastic production and consumer use of plastics, they were aware (46.0% and 37.1%, respectively), slightly aware (31.9% and 37.8%) and did not know (22.1% and 25.1%). The risk that plastic pollution poses to wildlife, as well as to human health, well-being and prosperity, was assessed by respondents as average. 34.6% of respondents were in favor of actively reducing the use of plastic products. 33.7% of survey participants are still at the level of awareness of the problem and attempts to reduce plastic consumption. 31.7% find it difficult to answer, since they do not see an alternative. When asked about awareness of the impact of microplastics (the silent killer) on the development of 16 specific diseases, respondents were most aware of: digestive diseases, allergies, chronic inflammation, respiratory problems, cancer and reproductive problems.

Adsorption potential of spherical ZnO particles for sufficient antibiotic removal: isotherm, kinetic and thermodynamics

Due to the improvements of pharmaceutical industry, tetracycline (TC) is commonly detected in natural water environments, resulting in significant adverse impacts on living species. In this study, the TC adsorption over commercial spherical zinc oxide (ZnO) samples was systematically examined by considering adsorption isotherm models, kinetic model and thermodynamic behavior. The Langmuir kinetic model displayed the highest correlation coefficient (R2 = 0.97) with a maximum adsorption capacity of 86.35 mg/g. According to the results of the kinetic studies, the adsorption could be driven by both the bulk transfer of adsorbate molecules towards the adsorbent surface within the solution and chemisorption on the surface and inside the pores. In addition, the TC adsorption on the ZnO particles promoted by increasing temperature. The commercial spherical zinc oxide can be considered as a sustainable strategy to eliminate the emerging toxic contaminant of tetracycline.

A Comprehensive Review of Water Quality Analysis

The effluent discharge of domestic wastewater and industrial effluents into watercourses has necessitated the development of monitoring systems with the purpose of characterizing levels of pollution. Substantial levels of pollution in emerging nations have been exacerbated by rapidly growing populations and inefficient enforcement of sustainable management initiatives. The Water Quality Index (WQI) can help fill the gap between water quality reporting and monitoring by offering a simple and effective way to assimilate and communicate results from a large amount of data. WQIs are the kind of communication tools that can facilitate knowledge sharing between scholars and the general public. The degradation of natural water resources, such as lakes, streams, and estuaries, is the most significant problem facing humanity. Water that is not clean has far-reaching effects on all aspects of life. Water resource management is therefore essential if it is to maximize water quality. If data are analyzed and water quality can be predicted in advance, water pollution may be efficiently addressed. Although this subject has been the subject of numerous earlier studies, additional research is still required to fully understand the effectiveness, reliability, accuracy, and application of the present approaches to water quality management. In this research work, a comprehensive review has been conducted on water quality assessment using artificial techniques. It reviews 75 research works on water quality analysis. The data collected in each research work have been analyzed. Moreover, the type of water resource surface water, groundwater, drinking water as well has been analyzed. The parameters considered in each work are “Dissolved Oxygen (DO), Potential of Hydrogen (pH), Biochemical Oxygen Demand (BOD), Total Dissolved Solids (TDS), and Chemical Oxygen Demand (COD), chloride, hardness, alkalinity, nitrate–nitrite”. In addition, the Artificial Intelligence technique utilized for water quality analysis is also assessed. Finally, the research gaps identified in water quality detection are exhibited.

Analysis of Paddy Field Changes (1989–2021) Using Landsat Images and Flooding-Assisted MLC in an Urbanizing Tropical Watershed, Vientiane, Lao PDR

Paddy fields are essential for food security and sustaining global dietary needs, yet urban expansion often encroaches on agricultural lands. Analyzing paddy fields and land use/land cover changes over time using satellite images provides critical insights for sustainable food production and balanced urban growth. However, mapping the paddy fields in tropical monsoon areas presents challenges due to persistent weather interference, monsoon-submerged fields, and a lack of training data. To address these challenges, this study proposed a flooding-assisted maximum likelihood classification (F-MLC) method. This approach utilizes accurate training datasets from intersecting flooded paddy field maps from the rainy and dry seasons, combined with the Automated Water Extraction Index (AWEI) to distinguish natural water bodies. The F-MLC method offers a robust solution for accurately mapping paddy fields and land use changes in challenging tropical monsoon climates. The classified images for 1989, 2000, 2013, and 2021 were produced and categorized into the following five major classes: urban areas, vegetation, paddy fields, water bodies, and other lands. The paddy field class derived for each year was validated using samples from various sources, contributing to the overall accuracies ranging from 83.6% to 90.4%, with a Kappa coefficient of between 0.80 and 0.88. The study highlights a significant decrease in paddy fields, while urban areas rapidly increased, replacing 23% of paddy fields between 1989 and 2021 in the watershed. This study demonstrates the potential of the F-MLC method for analyzing paddy fields and other land use changes over time in the tropical watershed. These findings underscore the urgent need for robust policy measures to protect paddy fields by clearly defining urban expansion boundaries, prioritizing paddy field preservation, and integrating these green spaces into urban development plans. Such measures are vital for ensuring a sustainable local food supply, promoting balanced urban growth, and maintaining ecological balance within the watershed.

Analysis of Natural Water Quality in the Dniester River Basin for Economic Utilization

Analysis of Natural Water Quality in the Dniester River Basin for Economic Utilization

Application of an 800 Gold Microelectrode Array for Rapid Voltammetric Detection of Nitrite Pollution in Environmental Waters

Abstract A simple voltammetric procedure for direct determination of nitrites in natural water samples is described. Measurements are carried out in an inert medium of 0.1 M KCl. The procedure is based on the oxidation of N(III) to N(V) as a result of a change in electrode potential from +0.40 V to +0.96 V. The use of a combined electrode consisting of approximately 800 gold microelectrodes enables undisturbed determinations to be performed in the presence of high concentrations of organic compounds at a level of 20 mg L−1. The calibration plot for NO2− was linear in the range from 2 × 10−6 to 8 × 10−4 M with a detection limit of 6 × 10−7 M. The proposed procedure was successfully applied to nitrate determination in three natural water samples with passable results.

Review of recent advances in utilising aquaculture wastewater for algae cultivation and microalgae-based bioproduct recovery.

Aquaculture operations produce large amounts of wastewater contaminated with organic matter, nitrogenous compounds, and other emerging contaminants; when discharged into natural water bodies, it could result in ecological problems and severely threaten aquatic habitats and human health. However, using aquaculture wastewater in biorefinery systems is becoming increasingly crucial as advancements in valuable bioproduct production continue to improve economic feasibility. Research on utilisingmicroalgaeas an alternative to producing biomass and removing nutrients from aquaculture wastewater has been extensively studied over the past decades. Microalgae have the potential to use carbon dioxide (CO2) effectively and significantly reduce carbon footprint, and the harvested biomass can also be used as aquafeed. Furthermore, aquaculture wastewater enriched with phosphorus (P) is a potential resource for P recovery for the production of biofertiliser. This will reduce the P supply shortage and eliminate the environmental consequences of eutrophication. In this context, the present review aims to provide a comprehensive overview of the current state of the art in a generation, as well as the characteristics and environmental impact of aquaculture wastewater reported by the most recent research. Furthermore, the review synthesized recent developments in algal biomass cultivation using aquaculture wastewater and its utilisation as biorefinery feedstocks for producing value-added products, such as aquafeeds, bioethanol, biodiesel, biomethane, and bioenergy. This integrated process provides a sustainable method for recovering biomass and water, fully supporting the framework of a circular economy in aquaculture wastewater treatment via resource recovery.

THE EFFECTIVENESS OF COAGULANTS FOR TURBIDITY AND COLOR REMOVAL FROM NATURAL WATER

In this work, the effectiveness of the use of coagulants Al2(SO4)3·18H2O and RM-1 in reducing the level of turbidity and colour (reduction in colour) of natural water was investigated. The object of the study is natural water, namely water from the Dnipro River. The results showed that the optimal dose of coagulant Al2(SO 4)3‧ 18H2O was 10.0 mg dm-3. The optimal dose of coagulant RM-1 was also 10.0 mg dm-3. Residual turbidity and colour are reduced to 0.0 mg dm-3, 12.50, 190, when using Al2(SO4)3·18H2O and RM-1, respectively. Since the residual concentration of aluminium in purified water in all samples after purification with coagulants was less than 0.05 mg dm-3, it is reasonable to use these coagulants, as they do not have a negative effect on the health of consumers. The efficiency of using the RM-1 coagulant to remove turbidity and reduce the colour of the natural water of the Dnipro is high, so this coagulant has the potential to be chosen as a new coagulant.

A robust numerical method for the generation and propagation of periodic finite-amplitude internal waves in natural waters using high-accuracy simulations

Abstract. The design and implementation of boundary conditions for the robust generation and simulation of periodic finite-amplitude internal waves is examined in a quasi two-layer continuous stratification using a spectral-element-method-based incompressible flow solver. The commonly used Eulerian approach develops spurious, and potentially catastrophic small-scale numerical features near the wave-generating boundary in a non-linear stratification when the parameter A/(δc) is sufficiently larger than unity; A and δ are measures of the maximum wave-induced vertical velocity and pycnocline thickness, respectively, and c is the linear wave propagation speed. To this end, an Euler–Lagrange approach is developed and implemented to generate robust high-amplitude periodic deep-water internal waves. Central to this approach is to take into account the wave-induced (isopycnal) displacement of the pycnocline in both the vertical and (effectively) upstream directions. With amplitudes not restricted by the limits of linear theory, the Euler–Lagrange-generated waves maintain their structural integrity as they propagate away from the source. The advantages of the high-accuracy numerical method, whose minimal numerical dissipation cannot damp the above near-source spurious numerical features of the purely Eulerian case, can still be preserved and leveraged further along the wave propagation path through the robust reproduction of the non-linear adjustments of the waveform. The near- and far-source robustness of the optimized Euler–Lagrange approach is demonstrated for finite-amplitude waves in a sharp quasi two-layer continuous stratification representative of seasonally stratified lakes. The findings of this study provide an enabling framework for two-dimensional simulations of internal swash zones driven by well-developed non-linear internal waves and, ultimately, the accompanying turbulence-resolving three-dimensional simulations.

Radiological characterization related to lithology and risk assessment of bottled natural mineral water

The enhancement of natural radioactivity in groundwater, specifically in natural mineral water, is related to the lithological formations through which water bodies or courses pass. Although natural mineral waters are exempt from monitoring for radioactive substances according to Council Directive 2013/51/EURATOM, this study focuses on the radiological characterization of natural mineral water under Spanish Royal Decree 3/2023. The water studied was taken from Catalan aquifers with different lithological characteristics (sedimentary, metamorphic or granitic) and is sold on local markets. Moreover, radiological data on the water was correlated with its lithological origin and the health risk for different age groups was assessed. Our results showed that of the 26 natural mineral waters studied, 10 exceeded gross alpha screening value (100 mBq/L), all from granitic aquifers. Further research on natural individual radionuclides was conducted on these ten samples. 234U and 238U were at around 1100–1600 mBq/L. In addition, 210Pb was found in two samples, which also presented the highest 226Ra activity, associated with granitic bedrock and the presence of 210Po. The annual effective dose was 179.0 µSv/year and 145.9 µSv/year, exceeding 100 µSv/year mainly due to the contribution of 210Pb > 234,238U > 210Po > 226Ra, in this order. After assessing the lifetime cancer risk, these two samples were determined not to pose a health risk due to ingestion. Although no radiological monitoring is required for natural mineral water, further surveillance is recommendable.

Hydrophobic deep eutectic solvent-ferrofluid microextraction followed by liquid chromatography-mass spectrometry for the enantioselective determination of chiral agrochemicals in natural waters.

The increasing use of chiral agrochemicals sold as racemic formulations raises concern for the negative impacts that inactive enantiomers can have on aquatic life and human health. The present work just focuses on the determination of ten chiral pesticides in river water samples by applying a ferrofluid-based microextraction followed by their stereoselective liquid chromatography analysis. To develop the ferrofluid, magnetite nanoparticles were prepared and coated with oleic acid and then dispersed in a hydrophobic natural deep eutectic solvent (NaDES), composed ofL-menthol and thymol (1:1). The stable colloidal dispersion was characterised by scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. The analyte microextraction from 5ml river samples was performed using 50µl of ferrofluid, while acidified acetonitrile (150µl) was used to break down the ferrofluid and solubilise the NaDES containing the analytes. All the extracts were analysed by high-performance liquid chromatography-tandem mass spectrometry. For each analyte, the baseline separation of isomers was achieved on a Lux i-Amylose-3 column (amylose tris(3-chloro-5-methylphenylcarbamate) working in reversed-phase mode; the combination with mass spectrometry detection allows the overall separation of 24 isomers (ten chiral analytes among which eight containing a single (one) chiral centre, one with two chiral centres and the last one existing in four stereoisomeric forms, due to the presence of two regioisomers with a chiral carbon) within 37min. The method showed very good figures of merit in terms of recoveries (77.7-97.5%), intra-day and inter-day precision (2.7-7.7% and 6.9-14.9%, respectively), limit of detection (0.01-0.35µg/L), limit of quantitation (0.03-1.20µg/L), linear dynamic range, and intra-day and inter-day accuracy (1.2-14.8% and 1.8-15.0%, respectively). The presented method was able to detect 14 out of 24 isomers at the preventive limit established by the Italian legislation for single pesticide (that for a chiral pesticide is the sum of all its isomers) in surface waters, set at 0.1µg/l. Finally, the method was evaluated using AGREEprep and ComplexGAPI metrics, compared with other ferrofluid-based methods, and applied to the analysis of water samples from two Italian rivers (the Nera River and the Tiber River), providing to be sustainable and reliable for the application to real river matrices.

Al-N3 Bridge Site Enabling Interlayer Charge Transfer Boosts the Direct Photosynthesis of Hydrogen Peroxide from Water and Air.

Manipulating the electronic environment of the reactive center to lower the energy barrier of the rate-determining water oxidation step for boosting the direct generation of H2O2 from water, air, and sunlight is fascinating yet remains a grand challenge. Driven by a first-principles screening across a series of metal single atoms in carbon nitride, we report a class of an Al-N3 bridge site enabling interlayer charge transfer in carbon nitride nanotubes (CNNT-Al) for the highly efficient photosynthesis of H2O2 directly from water, oxygen, and sunlight. We demonstrate that the interlayered Al-N3 bridge site in CNNT-Al is able to activate the neighboring surface N atom for promoting the rate-determining step of the two-electron water oxidation to H2O2. It is also able to act as a bridge for enhancing the vertical interlaminar charge transfer due to the hybridization between the 3s and 3p states of the interstitial Al atom and the conduction band of two adjacent carbon nitride layers. Collectively, these factors lead to a highest photocatalytic mass activity of 1410.2 μmol g-1 h-1 (with a photocatalyst concentration of 1 g L-1) for direct photosynthesis of H2O2 out of all CN-based photocatalysts and a 7-fold higher solar-to-chemical conversion efficiency (0.73%) compared to that of the natural photosynthesis of typical plants (∼0.1%). Most importantly, the CNNT-Al-based flow reactor can steadily produce H2O2 for 200 h and be directly used for the on-site degradation of organic dye in water. The CNNT-Al-based flow reactor can also kill a 10 times higher concentration of bacteria in deionized water than that in natural water with 100% efficiency, which makes our design economically appealing for practical water treatment.

Characteristics and genesis of high-quality metasilicate mineral water in Liaocheng City, Shandong Province.

Drinking natural mineral water often contains minerals and trace elements essential for human beings, such as strontium and silicon. As people's quality of life improves, so do their requirements for drinking water. Therefore, it is crucial to identify and develop high-quality groundwater that is rich in metasilicate and other minerals. The aim of this study is to reveal the distribution pattern and causes of high-quality metasilicate-rich groundwater in Liaocheng City through scientific methods, so as to provide a theoretical basis for the rational development and protection of mineral water resources. The results shown that Dong'e County was the main concentration area of high-quality metasilicate mineral water in Liaocheng City. The main reason for its high concentration of metasilicic acid was due to water-rock interaction. There was bedrock fissure water in the underlying water supply rock groups in Dong'e County, and the reaction between the metasilicate minerals in the rock groups and water was the main source of metasilicic acid. In addition, the development of fissures in the area provided a good storage and conductivity system for the enrichment of metasilicic acid in groundwater. Based on the analysis of hydrogeological conditions and the mechanism of formation of enriched areas, the enriched areas were divided into developable areas, protected and restricted development areas, and restricted development areas. The results of the study can lay a theoretical foundation for the systematic and scientific development, utilization, and protection of high-quality metasilicate mineral water in Liaocheng City.

Cadmium-Assisted Photochemical Vapor Generation of Arsenic from Low Concentration of Formic Acid Media.

A highly sensitive method for the determination of total arsenic (As) has been developed using photochemical vapor generation (PVG) coupled with inductively coupled plasma mass spectrometry (ICP MS). The efficient PVG of As is reported for the first time in the presence of Cd(II) in diluted formic acid (FA) medium. The PVG efficiency of 93 ± 1% can be achieved in the system with 0.15% (v/v) FA and 40.0 mg L-1 Cd(II) under 100 s UV irradiation. The limit of detection (LOD, 3σ) for As was determined to be 0.2 ng L-1, which was enhanced about 43-fold over the traditional solution nebulization method. The anti-interference capability against sample matrices was enhanced compared to previous PVG systems that used diluted formic acid alone or a combination of sodium formate and sodium sulfite as the medium. The established method was applied for the analysis of natural waters and certified reference materials (CRMs) of rice with satisfactory results. The mechanism of the PVG system was investigated, and the generation of volatile As species as AsH3 was found in all investigated systems, including monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), As (III), and As(V). Additionally, volatile cadmium species were also generated simultaneously. The efficient reduction of As in diluted FA observed in this study is beneficial to understanding the interaction between As and Cd in the photochemical process.

Bayesian inversion of bacterial physiology and dissolved organic carbon biodegradability on water incubation data

In aquatic ecosystems, dissolved organic carbon (DOC) plays a significant role in the global carbon cycle. Microorganisms mineralize biodegradable DOC, releasing greenhouse gases (carbon dioxide, methane) into the atmosphere. Extensive research has focused on the concentrations and biodegradability of DOC in aquatic systems worldwide. However, little attention has been given to uncertainties regarding the physiological characteristics of heterotrophic bacteria, which are crucial for biogeochemical modeling. In this study, the physiological properties of heterotrophic bacteria and the properties of DOC biodegradability in water are inferred through a Bayesian inversion approach. To achieve this, treated and natural water samples collected from the Seine River basin, were inoculated and incubated in laboratory. During incubation, the concentrations of DOC and heterotrophic bacteria biomass were measured. Then, a multiple Monte Carlo Markov Chains method and the HSB model (High-weight polymers, Substrate, heterotrophic Bacteria) are applied on the water incubation data. The results indicate a higher biodegradable fraction of DOC in natural water compared to treated water and significant variability in the fraction of fast biodegradable DOC within 5 days in both water samples. The significant variability highlights the uncertainties/challenges in the HSB model parameterization. The seven water samples used in the paper serve as a proof of concept. They are from various origins and display the potential of the method to identify parameter values in a large range of values. Because mortality rate of heterotrophic bacteria at 20 ∘C (kd20) showed a remarkable stability at 0.013 h−1, we considered that this parameter can be fixed at this value. The maximum growth rates at 20 ∘C (μmax20) was 0.061 h−1 while optimal growth yield (Y) estimated at 0.34 for treated water and at 0.25 for natural water. All these parameter values are well in accordance with previous determinations.

Indirect photodegradation of pharmaceutical and personal care products in dissolved black carbon solution: The role of microheterogeneous distribution of hydroxyl radical and sorption

Dissolved black carbon (DBC) with a hyperconjugated structure is ubiquitous in nature, and plays a crucial role in the migration and transformation of environmental contaminants due to its prominent properties of accepting electrons and sorption. However, little is known about the DBC-induced phototransformation of pharmaceutical and personal care products (PPCPs) in natural waters. Herein, the photodegradation kinetics of PPCPs were investigated in DBC solution under simulated solar irradiation and compared with those in Suwannee River natural organic matter (SRNOM) solution. The decay rates for the positively charged PPCPs (mean 1.484 ± 0.041 h-1) were significantly higher than those for the negatively charged PPCPs (mean 0.014 ± 0.002 h-1) in DBC solution due to the charge interaction. Moreover, the decay rates for the positively charged PPCPs in DBC solution were approximately 3–16 times of those in SRNOM solution due to the discrepant sorption and ability to produce bonded HO•. Finally, a microheterogeneous photodegradation mechanism of HO•-labile PPCPs in DBC solution involving the sorption and subsequent reaction with bonded HO• in the DBC microphase was proposed, which was verified using isopropanol and isopropamide as selective HO• scavengers. This work will provide useful insights into the photochemistry of DBC and also the DBC-involved phototransformation of PPCPs in aquatic environments.