Conventional Ions Research Articles

Quality evaluation parameter and classification model for effluents of wastewater treatment plant based on machine learning

With the growing consensus of emerging pollutants and biological toxicity risks in wastewater treatment plant (WWTP) effluents, traditional water quality management based on general chemical parameters no longer meets the new challenges. Here, a first-hand dataset containing 9 conventional parameters, 22 mental and inorganic ions, 25 biotoxicity parameters, and 54 emerging pollutants from effluents of 176 municipal WWTPs across China were measured. Four clustering algorithms and five classification algorithms were applied to 65 well-performing models to determine a novel evaluation parameter system. A total of 14 parameters were selected by semi-supervised machine learning, including TN, TP, NH4+-N, NO2--N, Se, SO42-, Caenorhabditis elegans body width, 72 hpf zebrafish embryo hatching rate, tetracycline, acetaminophen, gemfibrozil, PFBA, PFHxA, and HFPO-DA. These parameters were then used to construct a Healthy Effluent Quality Index model (HEQi). The application efficiency of HEQi was compared with other common methods such as the Water Quality Index (WQI), Fuzzy Synthesized Evaluation (FSE), and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) in classifying 176 effluents. Results implicated that under the new evaluation criteria, the major task in North and Northeast China remains to reduce the conventional parameters, especially NO2--N. However, it is necessary to strengthen the removal of biotoxicity and emerging pollutants in parts of Central and Eastern China. This study offers new methodological tools and scientific insights for improving water quality assessment and safe discharge of wastewater.

Synergistic photocatalysis of oxygen-enriched vacancy BiOBr based on rice husk biochar: Efficient seawater purification achieved by carrier directional migration

Addressing seawater pollution is crucial for the efficient utilization of seawater resources. Employing solar-driven seawater purification emerges as an ideal solution for the future renewable energy landscape. Herein, biomass carbon and oxygen-enriched defect materials were selected to design a high-performance photocatalyst for seawater purification. The strategic combination of defect energy levels and electron-conducting carbon enhances the directional migration and separation of photogenerated particles, thereby boosting the overall photocatalytic efficiency in seawater purification. In the simulated seawater experiment, ROV-BOB/RHC-3 exhibits significant resistant to conventional ions interference during purification. Transitioning to real seawater experiments, ROV-BOB/RHC-3 exhibits impressive removal performance for RhB and TC, achieving substantial purification in 10 L of seawater under natural sunlight. Combine free radical trapping experiments and electron spin resonance (ESR) analysis shows that reactive oxygen species (•O2- and 1O2) are responsible in purification. The project provides a practical and effective basis for further research on efficient biomass carbon-based photocatalysts to seawater purification.

Efficient nanopatterning of Ge surface induced by oblique argon cluster ion beam

The evolution of the self-assembled nanostructures formed on the Ge (100) surface as a result of sputtering by an obliquely incident argon cluster ion beam is studied. The bombardment was carried out with Ar1000+ ions at energy of 10 keV and angle of incidence of 60˚ from the normal while varying the ion fluence from 8 × 1014 up to 2 × 1016 ions/cm2. It is found that parallel-mode ordered ripples with significant aspect ratios can be produced on the Ge surface at a minimum sputtering depth. Such nanostructures have not previously been formed on the Ge surface with conventional argon ions. Our findings prove that argon cluster ion beam is effective for nanopatterning the surface of single-component semiconductors.

Research on Discriminant Model of Water Inrush Source By Principal Component-cluster Analysis in Jiaozuo Mining Area

This paper takes Jiaozuo Mining Area as the research object, based on the analysis of the hydrogeological conditions of the mining area, expounds the characteristics of coal strata, aquifers and groundwater recharge, runoff and discharge in the mining area; analyses the water inrush sources and water diversion channels in the mining area, analyses the routine water chemical data of each aquifer in the mining area, draws the piper three-line diagram and confirms it. To determine the hydrochemical type of groundwater in aquifer, six common water chemical ions are used as discriminant factors, a discriminant model of water inrush source is established by combining principal component analysis and cluster analysis, and the principal component of conventional water chemical ions is extracted as cluster variable to discriminate Water Inrush Source in Jiaozuo Mining Area. In order to prove the rationality and validity of the model, another group of inrush sources in Jiaozuo Mining Area is discussed. The water sample data are discriminated and the results obtained by cluster analysis are compared to verify the accuracy of the model. The results show that the model is feasible. To sum up, the identification model of inrush water source by principal component-cluster analysis can accurately and effectively identify the source of inrush water in Jiaozuo Mining Area.

Hydrogeochemical characteristics and evaluation of groundwater resources of Jilin Province, China

As one of China's nine border provinces, Jilin Province is an important window for China's “Belt and Road” to open up to the north, and an important channel for China's foreign trade and foreign exchanges. Therefore, understanding hydrogeochemical characteristics is very important for effective water resources management in Jilin Province. A total of 64 groundwater samples were collected from 32 monitoring Wells in Jilin Province. Use of hydrogeochemical analysis techniques, WQI index and human health risk index methods to assess hydrogeochemical processes and groundwater quality, including the determination of hydrogeochemical parameters, conventional ions, trace elements and stable isotopes (δD and δ18O). The results show that the groundwater is slightly alkaline, the cations are mainly Na+, Ca2+, Mg2+, and K+, and the anions are mainly HCO3-, Cl−, and SO42-. Most of the groundwater samples belong to Ca-HCO3 and Na-HCO3 types, which are formed by the dissolution of calcite, dolomite, gypsum, silicates and carbonates. Stable isotope analysis shows that groundwater recharge in Jilin mainly comes from atmospheric precipitation at an altitude of 1,430~2,348 m. The strong correlation between trace elements indicates a common source. Most of the groundwater quality index (WQI) in the study area is Class I to Class III, and hazard quotient (HQ) and hazard index (HI) are both below 1. This indicates excellent water quality and minimal health risks associated with human consumption. It is worth noting that trace elements are enriched in the Tanlu fault zone. It provides scientific guidance for the utilization and allocation of groundwater resources in Jilin Province.

Geochemical Characteristics and Productivity Evaluation of Water Produced from Coalbed Methane Wells in the Laochang Block, Eastern Yunnan.

The water produced from coalbed methane (CBM) wells contains abundant hydrogeochemical information, which is of great significance for the productivity evaluation of CBM wells. Based on the analysis of the conventional ions, hydrogen and oxygen isotopes, and trace elements in the water produced from three CBM wells in the Laochang Block, eastern Yunnan, the geochemical characteristics of the water produced from three CBM wells and their impacts on productivity are analyzed. The results show that the conventional ions in the water produced from all the three CBM wells in the study area exhibit similar characteristics, with low concentrations of Ca2+, Mg2+, SO42-, and F-, medium concentrations of K+, and high concentrations of Na+, Cl-, and HCO3-. As the drainage time increased, the water produced from wells S-2 and S-3 changed from the Na-Cl-HCO3 type to the Na-HCO3 type, while the water produced from well S-1 remained the Na-Cl-HCO3 type. The concentrations of HCO3- and F- are roughly positively correlated with the gas production, with higher gas production at concentrations of approximately 2000 and 2 mg/L, respectively. The gas production from well S-1 is relatively low, and it is speculated that this situation is caused by reservoir damage. The gas production from well S-2 is the lowest among the three wells in the study area, and it is speculated that the cause of this phenomenon is roughly due to breakage of the sandstone at the top of the coal seam or collapse of the wellbore, which communicates with the aquifer. Based on the characteristics of the water production from well S-3 with a good gas production, a quantitative characterization range of trace element changes in the water production from CBM wells is proposed. σY values of around 1500 μg/L and σM values of 0.4-0.5 μg/L are beneficial for the long-term gas production.

Metal organic framework as a matrix for laser desorption/ionisation of environmental pollutants and other small molecules

ABSTRACT Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is a widely used method for analysing environmental pollutants and proteins. However, this technology has been limited in its ability to analyse small molecules (<700 Da) due to interference from conventional organic matrix background ions, leading to poor signal-to-noise ratios and reproducibility. In an effort to address this limitation, we have developed a new method for synthesising titanium metal organic frameworks (MOFs) as matrices for MALDI-TOF analysis. Specifically, we used a microwave-assisted facile synthesis method that results in smaller MOF particle sizes and requires less reaction time and simpler procedures. Our MOF, also known as NTU-9, was constructed using 2,5-dihydroxybenzoic acid as a ligand and titanium as a metal site. These constituents make NTU-9 highly efficient for photon absorption and target ionisation, allowing for improved MALDI-TOF analysis of diverse molecules, including environmental pollutants and other small molecules.

Removal of Cr(VI) by hollow micron zero-valent iron in groundwater containing different ions: Mechanisms and mineralized products

The development of zero-valent iron in-situ reactive zone technology is restricted by the poor mobility and reactivity of zero-valent iron. Hence，hollow micron zero-valent iron (H-mZVI) was prepared through rapid liquid reduction and used to remove Cr(VI) from aqueous solution. Scanning electron microscopy confirmed that H-mZVI had a hollow structure, particle size of approximately 1 µm, and rough surface. X-ray diffraction indicated that H-mZVI was mainly composed of ZVI. Brunauer–Emmett–Teller results showed that H-mZVI had a large specific surface area (25.54 m2/g) and pore volume (0.12 cm3/g). The Cr(VI) removal efficiency of H-mZVI was 6.18 times that of solid micron zero-valent iron (S-mZVI), and the removal reaction conformed to first-order reaction kinetics. Electrochemical test results revealed that the electron transport efficiency was stronger, Fe2+ concentration in aqueous solution was larger, and the decrease in oxidation–reduction potential was more obvious in H-mZVI than in S-mZVI. Desorption experiment and X-ray photoelectron spectroscopy showed that H-mZVI removed Cr(VI) primarily through reduction and secondarily through adsorption. The effects of conventional ions and humic acid (HA) on Cr(VI) removal by H-mZVI were in the order of PO43->HA>NO3->CO32->HCO3->Cl-=Mg2+=Ca2+. The corrosion products and their proportions varied in the presence of different ions.

Discriminant Analysis of Water Inrush Sources in the Weibei Coalfield, Shaanxi Province, China

Water inrush disasters in mining areas are one of the most serious geological disasters in coal mining. The purpose of this study is to study the establishment of a water chemical database and water inrush source discrimination model in the Weibei coalfield to provide the basis for regional hydrogeological conditions for future mining under pressure in the Weibei area, as well as a basis for the rapid identification of water inrush sources in the Weibei coalfield. In this paper, a conventional hydrochemical and trace element discrimination model for mine water inrush was established, and the hydrochemical characteristic files of the entire mining area were integrated. Based on 10 indicators, three hydrochemical discrimination models of rock stratum aquifers were established. Through the Mahalanobis distance test, it was found that the six selected variables, K+ + Na+, Mg2+, NH4+, Cl−, SO42−, and pH, have significant discrimination ability and good effect and can effectively distinguish the three main water inrush aquifers in the Weibei mining area. Then, the clustering stepwise discriminant analysis method was used to select 24 water samples and 14 trace element indicators from the conventional water chemistry test results. Based on principal component analysis, a principal component analysis discriminant model of trace elements was established for the four main aquifers. The accuracy and misjudgment rate of the Bayes multi-class linear discriminant using conventional ions as explanatory variables were 64.3% and 35.7%, respectively, showing a poor discriminant effect. On this basis, seven characteristic trace elements were analyzed according to Bayes multi-class linear discriminant analysis, the mutual influence and restriction relationship regarding the migration of these seven trace elements in the groundwater system of the mining area was determined, and the modified Bayes multi-class linear discriminant analysis model of trace elements for the water inrush source was established, which was more accurate than the conventional ion Bayes multi-class linear discriminant analysis model. The accuracy rate reached 92.9%. This research is of great significance for mine water-source identification and water-inrush prevention guidance.

Sulfonate-functionalized ionic liquids for pH-sensitive alginate beads preparation: Macromolecular structure study and drug release evaluation

Aiming at a new application of ionic liquids in the formation of biomaterials, polymeric hydrogel beads sensitive to pH were produced based on alginate, using sulfonate ionic liquids (ILs) in a novel way as crosslinking agents. Among the tested ILs, the new functionalized IL A1 [1-(4-ethoxy-1-butylsulfonic)-3-methylimidazolium bromide] was synthesized for the first time. The IL A1 and the IL A2 (triethylammonium hydrogen sulfate) resulted in the formation of beads by drip method. Their structural representation was obtained from the molecular docking, allowing a study of their molecular interactions. Tests of variation in the degree of swelling showed that under pH 6.0 and 7.4, the beads dissolved in a few minutes; while under pH 1.2, they remain stable for at least 7 h. The lower degree of swelling in relation to time obtained for the systems resulted in beads with more compact structures, when compared to swelled beads formed with alginate and conventional bivalents ions. Cumulative release point of 5-fluorouracil and indomethacin remained sustained until at least 8 h, under pH 1.2. The lower energy conformations were calculated for each macromolecule combination of bead-drug, and was obtained that the 5-fluorouracil interacts more strongly with the beads structural network than indomethacin, resulting in a slower release that reached 9.84% (w/w) against 25.00% (w/w). These results indicate a potential application for the ionic liquids-beads as a site-specific drug carrier.

Seasonal Differences in the Hydrochemical Characteristics of Karst Wetlands and the Associated Mechanisms in Huixian, China

The present study aimed to identify the seasonal changes in the hydrochemical characteristics of the Huixian karst wetland and the underlying mechanism. Conventional ions and isotopes of 130 groundwater samples collected during the wet and dry seasons were analyzed. The hydrochemical characteristics of groundwater in the Huixian karst wetland were clarified using mathematical statistics and hydrochemical methods, including Durov diagrams, ionic ratios, Gibbs diagrams, and H and O isotopes. The hydrochemical evolution and sources of major ions in the Huixian karst wetland were also investigated. The results showed that cations and anions in groundwater in the study area were dominated by Ca2+ and HCO3−, respectively, sourced mainly from calcite weathering. The ions of some groundwater samples were regulated by weathering of dolomite, dolomitic limestone, and pyrite, resulting in relatively high concentrations of Mg2+ and SO42−. K+, Na+, SO42−, NO3−, and Cl− in groundwater originated from precipitation, Na+ and Cl− originated from domestic sewage, K+ was related to the application of potassium fertilizer in agriculture, and NO3− mainly originated from chemical fertilizer. Groundwater ions were primarily controlled by rock weathering, followed by evaporative concentration. The sources of major ions were dependent on the dissolution and precipitation of carbonate rock, as well as the chemical weathering of silicate rock and evaporite. Samples from the various water sources were scattered on both sides of the local meteoric water line (δD = 3.13δ18O − 13.9), which indicated isotopic composition was affected by evaporation and precipitation.

Characterization of the Internal Energy of Ions Produced by Electrospray Ionization Using Substituted Benzyl Ammonium Thermometer Ions.

We propose the use of substituted benzyl ammonium species as thermometer ions to characterize the internal energy distribution of the ions produced by electrospray ionization (ESI). Crucially, we found that the activation of the benzyl ammonium species preferentially provided a benzyl cation via N-Cα bond cleavage. In addition, calculations at the CCSD(T)/cc-PVTZ//M06-2X-D3/6-311++G(d,p) level of theory revealed that the threshold energies of fragmentation of the tested model ions ranged from 86 to 192 kJ mol-1, significantly lower than those of conventional 4-substituted benzylpyridinium thermometer ions. Thus, the substituted benzyl ammoniums are suitable for the characterization of the ESI process under typical experimental conditions. Further, the internal energies of the ions were found to depend on the radiofrequency voltage of the ion funnel, which is used to increase the transport efficiency of the ions from atmospheric to vacuum conditions. Our reported method will aid the determination of the optimum ion-funnel radiofrequency voltage for the analysis of small molecules such as metabolites. Furthermore, benzyl ammoniums are commercially available, which will facilitate the routine and widespread measurement of the internal energy distributions of ions.

Permanent Electrochemical Doping of Quantum Dot Films through Photopolymerization of Electrolyte Ions.

Quantum dots (QDs) are considered for devices like light-emitting diodes (LEDs) and photodetectors as a result of their tunable optoelectronic properties. To utilize the full potential of QDs for optoelectronic applications, control over the charge carrier density is vital. However, controlled electronic doping of these materials has remained a long-standing challenge, thus slowing their integration into optoelectronic devices. Electrochemical doping offers a way to precisely and controllably tune the charge carrier concentration as a function of applied potential and thus the doping levels in QDs. However, the injected charges are typically not stable after disconnecting the external voltage source because of electrochemical side reactions with impurities or with the surfaces of the QDs. Here, we use photopolymerization to covalently bind polymerizable electrolyte ions to polymerizable solvent molecules after electrochemical charge injection. We discuss the importance of using polymerizable dopant ions as compared to nonpolymerizable conventional electrolyte ions such as LiClO4 when used in electrochemical doping. The results show that the stability of charge carriers in QD films can be enhanced by many orders of magnitude, from minutes to several weeks, after photochemical ion fixation. We anticipate that this novel way of stable doping of QDs will pave the way for new opportunities and potential uses in future QD electronic devices.

Combining hydrochemistry and hydrogen and oxygen stable isotopes to reveal the influence of human activities on surface water quality in Chaohu Lake Basin

The input of pollutants caused by human activities induces the deterioration of surface water quality. To reveal the characteristics of surface water quality in Chaohu Lake Basin and the influence of human activities, the hydrochemistry and stable isotope composition of hydrogen and oxygen in lake water and inflow river water were analyzed. The results show that the hydrochemical type of lake water is the Na–Cl type,while river water is the Na–Cl, Ca–Cl and mixed types. The ion proportional coefficient method and principal component analysis show that surface water is controlled by weathering of evaporated salt rocks and silicate rocks, in which Cl- and SO42- are affected by fertilizers and sewage to some extent. There is a strong correlation between conventional ions and nutrient indexes, which indicates that dissolved ions are affected not only by rock weathering but also by human activities (such as the discharge of domestic sewage or nitrogen-containing wastewater and the use of fertilizers). The stable isotope values of hydrogen and oxygen in surface water are distributed at the lower right portion of the local precipitation line and are close to it, indicating that surface water mainly originates from precipitation. The high value of d-excess values in surface water indicates that evaporation is weak. As pollution indicators, EC, Cl- and NO3- indicates that the Nanfei River, Dianbu River, Shiwuli River and Pai River flow in northwestern of Chaohu Lake Basin through Hefei urban city are severely polluted, NO3- originates from manure and sewage. Rivers flowing through farmland areas are less polluted, and the use of agricultural fertilizer contributes greatly to NO3-.

Groundwater quality assessment and hydrogeochemical processes in typical watersheds in Zhangjiakou region, northern China.

It is of significance to elucidate the groundwater quality and hydrogeochemical processes for sustainable utilization of groundwater resources in water shortage regions. A total of 256 groundwater samples were collected in typical watersheds in Zhangjiakou, northern China. The hydrochemical parameters, conventional ions, and trace elements were measured, and δD and δ18O data were collected to delineate the groundwater quality and hydrogeochemical processes. The results showed that 32.91% of the groundwater could be directly used for drinking water sources in the Bashang Plateau, north of the study area. The F- and NO3--N were the main parameters above the standard threshold for drinking water. In contrast, the groundwater quality in the Baxia River Basins, south of the study area, was of a better scenario. Nonetheless, high concentrations of F-, total hardness, and SO42- were still observed. Most samples in the Bashang Plateau had relatively higher salinity than the Baxia River Basins. Both surface water and groundwater in the study area originated from local meteoric water with considerable hydraulic connections. The high-fluoride groundwater was primarily formed by dissolution of fluoride-rich minerals under conditions of high pH and Na+, low Ca2+, and rich in HCO3-. The dissolution of carbonate and silicate minerals accompanied by strong cation exchange and weak evaporation was the dominant water-rock interaction affecting the hydrochemical composition of groundwater, and anthropogenic NO3- input had an extra influence on hydrochemical process. This study provides a scientific guideline for the protection and allocation of local groundwater resources.

DNA double-strand breaks in cancer cells as a function of proton linear energy transfer and its variation in time

Purpose The complex relationship between linear energy transfer (LET) and cellular response to radiation is not yet fully elucidated. To better characterize DNA damage after irradiations with therapeutic protons, we monitored formation and disappearance of DNA double-strand breaks (DNA DSB) as a function of LET and time. Comparisons with conventional γ-rays and high LET carbon ions were also performed. Materials and Methods In the present work, we performed immunofluorescence-based assay to determine the amount of DNA DSB induced by different LET values along the 62 MeV therapeutic proton Spread out Bragg peak (SOBP) in three cancer cell lines, i.e. HTB140 melanoma, MCF-7 breast adenocarcinoma and HTB177 non-small lung cancer cells. Time dependence of foci formation was followed as well. To determine irradiation positions, corresponding to the desired LET values, numerical simulations were carried out using Geant4 toolkit. We compared γ-H2AX foci persistence after irradiations with protons to that of γ-rays and carbon ions. Results With the rise of LET values along the therapeutic proton SOBP, the increase of γ-H2AX foci number is detected in the three cell lines up to the distal end of the SOBP, while there is a decrease on its distal fall-off part. With the prolonged incubation time, the number of foci gradually drops tending to attain the residual level. For the maximum number of DNA DSB, irradiation with protons attain higher level than that of γ-rays. Carbon ions produce more DNA DSB than protons but not substantially. The number of residual foci produced by γ-rays is significantly lower than that of protons and particularly carbon ions. Carbon ions do not produce considerably higher number of foci than protons, as it could be expected due to their physical properties. Conclusions In situ visualization of γ-H2AX foci reveal creation of more lesions in the three cell lines by clinically relevant proton SOBP than γ-rays. The lack of significant differences in the number of γ-H2AX foci between the proton and carbon ion-irradiated samples suggests an increased complexity of DNA lesions and slower repair kinetics after carbon ions compared to protons. For all three irradiation types, there is no major difference between the three cell lines shortly after irradiations, while later on, the formation of residual foci starts to express the inherent nature of tested cells, therefore increasing discrepancy between them.

Spatial segregation of mixed-sized counterions in dendritic polyelectrolytes

Langevin dynamics simulations are utilized to study the structure of a dendritic polyelectrolyte embedded in two component mixtures comprised of conventional (small) and bulky counterions. We vary two parameters that trigger conformational properties of the dendrimer: the reduced Bjerrum length, lambda _B^*, which controls the strength of electrostatic interactions and the number fraction of the bulky counterions, f_b, which impacts on their steric repulsion. We find that the interplay between the electrostatic and the counterion excluded volume interactions affects the swelling behavior of the molecule. As compared to its neutral counterpart, for weak electrostatic couplings the charged dendrimer exists in swollen conformations whose size remains unaffected by f_b. For intermediate couplings, the absorption of counterions into the pervaded volume of the dendrimer starts to influence its conformation. Here, the swelling factor exhibits a maximum which can be shifted by increasing f_b. For strong electrostatic couplings the dendrimer deswells correspondingly to f_b. In this regime a spatial separation of the counterions into core–shell microstructures is observed. The core of the dendrimer cage is preferentially occupied by the conventional ions, whereas its periphery contains the bulky counterions.

Charged Dendrimers with Finite-Size Counterions.

We report on the structure of dendritic polyelectrolytes accompanied by counterions in a good, salt-free, implicit solvent using Langevin dynamics simulations and a Flory-type approach. Our focus is on the modification of charged dendrimer conformations via the strength of electrostatic interactions and the counterion excluded volume. We study the effects caused by charges by varying the reduced Bjerrum length, λB*, between the extremes of weak and strong electrostatic interactions. The counterion excluded volume was controlled by the size of ions. We investigate counterions ranging from conventional ones, with the size comparable to the monomer size, to bulky ions. Our results indicate that, as compared to neutral dendrimers, dendritic polyelectrolytes exist in swollen conformations, and the degree of swelling changes non-monotonically with increasing λB*. For weak electrostatic couplings, counterion density within dendrimers is minor and their radius of gyration subtly exceeds the size of neutral dendrimers. For intermediate electrostatic couplings, Coulomb attraction between opposite charges promotes absorption of ions into dendrimers' pervaded volume and counterion condensation on charged monomers. As a result, counterion density inside dendrimers abruptly increases and the ionic size starts to play a crucial role. In this regime, we observe that swelling of dendrimers reaches its maximum and is more pronounced for bulky counterions. For strong electrostatic couplings, complete condensation of conventional counterions proceeds, whereas for bulky ions condensation remains partial. In this regime, dendrimers deswell. In particular, in the presence of conventional ions, dendrimers collapse into globules, while, for bulky counterions, deswelling is suppressed.

Hydrogeochemical characteristics of coal mine based on box-plot and its application in water inrush source identification

ABSTRACT In order to meet the growing energy needs, more and more people pay attention to the deep coal resource (>1000 m). Compared with shallow coal mining, deep coal mining is facing more complex problems. Among them, mine water inrush disaster is a difficult problem, which needs to be solved urgently. In this paper, 45 groundwater samples from three deep-seated aquifers (the Quaternary, the Coal bearing, and the Limestone ) are collected. Based on the box-plot analysis of conventional ions, a discriminant model is established. When [K++Na+] >500 mg/L, [Cl−]>450 mg/L, [TDS]>1500 mg/L, the Coal bearing can be distinguished; when [K++Na+]<200 mg/L, [HCO3 −]<250 mg/L, [SO4 2-]>35 mg/L, pH>9, the Limestone can be recognized, and the remaining may the Quaternary. The discriminant model accuracy can reach 96%, 100% and 94% for the three aquifers, respectively. In addition, cluster analysis shows that the water-inrushing identification model is still very satisfactory. The results show that the model based on box-plot has a good discriminant effect and can be used to identify water sources in coal mines, and it can also provide theoretical guidance for the prevention and control of water damage in other coal mines around the world.

Geochemical Characteristics and Productivity Response of Produced Water from Coalbed Methane Wells in the Yuwang Block, Eastern Yunnan, China

Coalbed methane (CBM) well-produced water contains abundant geochemical information that can guide productivity predictions of CBM wells. The geochemical characteristics and productivity responses of water produced from six CBM wells in the Yuwang block, eastern Yunnan, were analyzed using data of conventional ions, hydrogen and oxygen isotopes, and dissolved inorganic carbon (DIC). The results showed that the produced water type of well L-3 is mainly Na-HCO3, while those from the other five wells are Na-Cl-HCO3. The isotope characteristics of produced water are affected greatly by water-rock interaction. Combined with the enrichment mechanisms of isotopes D and 18O, we found that the water samples exhibit an obvious D drift trend relative to the local meteoric water line. The 13C enrichment of DIC in the water samples suggests that DIC is mainly produced by the dissolution of carbonate minerals in coal seams. The concentration of HCO3-, D drift trend, and enrichment of 13CDIC in produced water are positively correlated with CBM production, which can be verified by wells L-4 and L-6.