Evolution and coupling of “seepage field and chemical field” under regional grouting disturbance

In Huaibei coalfield, the technology of ground directional drilling and high-pressure grouting is widely used to control the karst water disaster of coal measures floor. After grouting, the filling and drainage path of the seepage field changes, and the grouting high pressure and the slurry water will change the distribution characteristics of the groundwater seepage field and chemical field of the injected target aquifer in a certain period of time. Taking Taoyuan Coal Mine in Huaibei Coalfield as the research object, the evolution model of seepage field and chemical field (referred to as “double field”) of the target layer under regional grouting disturbance is built by using the software of Feflow, the coupling mechanism of “double field” is discussed, and the Cl− which is less affected by the environment is selected as the simulation factor, and the analysis of the factors affecting solute transport under the “double field” coupling effect is carried out. On this basis, the mathematical model of solute diffusion under regional grouting disturbance is constructed. The results show that in the seepage field model after identification and verification, 71.9% of the points where the error between the simulated water level and the measured water level is less than 3m, and the simulation effect is good; Among the identified and verified chemical field models, the simulation effect of solute transport in mining area II4 is good, and the simulation value in mining area II1 is about 14.4 mg/L lower, with an error of about 6.6% of the actual value, less than 10%. The overall simulation effect is good. The Cl− in mining area II4 and II2 with relatively high permeability coefficient is easy to migrate and diffuse, while the rock in mining area II1 with low permeability coefficient is dense and has poor permeability. During the 50 years of model operation, it basically exists in the state of “stagnant water”. Based on the evolution characteristics of local seepage field in II4 mining area under grouting disturbance, it is considered that solute transport is mainly controlled by permeability coefficient, dispersion, hydraulic gradient, seepage velocity, grouting time, slurry specific gravity and other parameters. It is found that the concentration of Cl− reaches a peak within 18−22 years after the completion of grouting, and then begins to decrease, and reaching the equilibrium state before regional grouting approximately 40 years later. Based on the data obtained from multiple parameter setting operations, a mathematical model of solute diffusion under the “double field” coupling is established. The data with error rate less than 10% accounts for 81.4%, which indicates that the established mathematical model of solute diffusion is basically reliable. This study can provide scientific basis for the study of the water environment evolution of the injected target aquifer under the regional grouting disturbance and the prediction and early warning of coal mine water disasters, and has important theoretical and practical significance

Water rock interaction in deep groundwater aquifers of coal mining area: qualitative and quantitative approaches based on hydrochemistry

877-883Present study indicates that groundwater from three aquifer systems have different concentrations of major ions. This implies that kinds and degrees of water rock interactions in them are different with each other. Relationships between major ions or their ratios (e.g. Gibbs diagrams, Na+-Cl- relationships), as well as statistical analyses (correlation and factor analyses) suggested that water rock interaction is the main mechanism controlling the groundwater chemistry. EPA Unmix model has identified two sources responsible for the hydrochemistry of the groundwater, sulfate-carbonate (source 1) and silicate-chloride (source 2) sources. Groundwater from the limestone and coal bearing sandstone aquifer systems are mainly contributed by source 1 and 2, respectively. As to the groundwater from the loose layer aquifer system, the contributions of the source 1 and 2 are 4: 6, respectively, and the result is consistent with previous exploitation

Factors Influencing Urban Residents’ Intention of Garbage Sorting in China: An Extended TPB by Integrating Expectancy Theory and Norm Activation Model

With the deepening of the garbage classification policy strength, making urban household garbage sorting mandatory in China, it is imperative to clarify the key factors affecting the urban residents’ intention to behave in garbage classification. Though it has attracted the attention of researchers, there are still several aspects that need to be supplemented and improved. Thus, this study aims to investigate the critical factors affecting the urban residents’ intention of garbage sorting and develop an extended model of planned behavior by integrating expectancy theory (ET) and norm activation model (NAM). Given the positive externalities of urban residents’ garbage sorting behaviors, awareness of consequences and attribution of responsibility are correspondingly interpreted as environmental benefits (EB) and environmental concerns (EC). The sample data of 668 urban residents who lived in four pilot cities of garbage classification in China were collected and adopted to the structural equation modeling (SEM) with bootstrapping estimation method to assess the causal relationship between variables. The results indicated that the expectation (Exp) was a significant positive predictor of garbage sorting intention. Attitude (AT), perceived behavior control (PBC) and subjective norm (SN) positively affected urban residents’ expectation of garbage sorting, with SN having the most significant direct impact. The results also found that the EB has significant influences EC, which strongly influences urban residents’ expectation of garbage sorting. Furthermore, the total effect of EC on Exp is higher than other paths, and the mediating effect of SN on Exp by AT and PBC is greater than other indirect paths, which accounted for about 27.1% of the total effect. Finally, we discuss both theoretical and practical implications, along with recommendations for future research

Health Risk Assessment of Heavy Metals in Shallow Groundwater of Coal–Poultry Farming Districts

This study aimed to assess the heavy metal (Mn, Ni, Cu, Zn, Sr, Cd, Pb, and Cr) pollution characteristics, sources, and human health risks in shallow groundwater in the impact zones of urban and rural semi-intensive poultry farms in Suzhou City. Ordinary kriging interpolation showed that poultry farming contributed substantially to the pollution of shallow groundwater by Mn, Zn, and Cu. Positive matrix factorization was applied to identify the sources of heavy metals, and the health risks were assessed based on the hazard index and carcinogenic risks of the various sources. Heavy metal enrichment was closely related to anthropogenic activities. In addition, four sources were identified: poultry manure (29.33%), natural source (27.94%), industrial activities (22.29%), and poultry wastewater (20.48%). The main exposure route of carcinogenic and non-carcinogenic risks to adults and children was oral ingestion. The non-carcinogenic risk of oral ingestion in children was higher than that in adults; the carcinogenic risk was higher in adults than in children. Poultry manure (42.0%) was considered the largest contributor to non-carcinogenic risk, followed by poultry wastewater (21%), industrial activities (20%), and natural sources (17%). Industrial activity (44%) was the primary contributor to carcinogenic risk, followed by poultry wastewater (25%), poultry manure (19%), and natural sources (12%)

Thermochemical and Toxic Element Behavior during Co-Combustion of Coal and Municipal Sludge

The thermochemical and kinetic behavior of co-combustion of coal, municipal sludge (MS) and their blends at different ratios were investigated by thermogravimetric analysis. Simulation experiments were performed in a vacuum tube furnace to determine the conversion behavior of toxic elements. The results show that the combustion processes of the blends of coal and municipal sludge are divided into three stages and the combustion curves of the blends are located between those of individual coal and municipal sludge samples. The DTGmax of the sample with 10% sludge addition reaches a maximum at the heating rate of 20 °C/min, indicating that the combustion characteristics of coal can be improved during co-combustion. Strong interactions were observed between coal and municipal sludge during the co-combustion. The volatilization rates of toxic elements decrease with an increasing proportion of sludge in the blends during co-combustion, which indicates that the co-combustion of coal and sludge can effectively reduce the volatilization rate of toxic elements. The study reflects the potential of municipal sludge as a blended fuel and the environmental effects of co-combustion of coal and municipal sludge

Presentation1_Break point identification and spatiotemporal dynamic evolution of air pollutants: An empirical study from Anhui province, east China.zip

The new modality of inter-regional joint prevention and control is increasingly important to the integrated process of collaborative governance of air pollutants. Therefore, it has become necessary to analyze the degree of interaction among air pollutants within and between cities, master the dynamics of their spatiotemporal distribution and its influencing factors, and diagnose the primary obstacle factors. Long-term data on the concentrations of six air pollutants among 16 cities of Anhui province from 2015 to 2020 were analyzed using harmonic regression, the coupling coordination degree model, the obstacle degree model, the logarithmic mean Divisia index (LMDI), and exploratory spatial data analysis (ESDA). Over all, the annual mean concentrations of five of these pollutants (NO2, SO2, CO, PM10, and PM2.5) decreased to a certain extent over time, whereas O3 concentrations increased. The biggest decrease was observed in BZ city, where SO2 decreased by 80.60% (halving time: −2.03 ± 0.02 years), and the biggest increase was observed in CZ city, where O3 increased by 113.85% (doubling time: 1.74 ± 0.01 years). The O3 concentrations in most cities reached their break points starting in 2018, but the break points of other air pollutants appeared earlier than that of O3, mostly before 2018. With the exception of NO2 and O3, the halving times of other air pollutants were basically shorter than the doubling times. The high degree of interaction among air pollutants within and between cities contrasted sharply with the low degree of coordination. An analysis of hotspot evolution revealed that particulate matter (PM10 and PM2.5) migrated to northern Anhui, NO2 and O3 agglomerated to central Anhui, and CO eventually gathered in the Wanjiang City Belt. The primary obstacle factors of air pollutants in Anhui were particulate matter, SO2 and NO2. The seasonal differences in primary obstacle factors were most evident in 2020: NO2 dominated in winter (in 10 cities), SO2 dominated in southern Anhui, and particulate matter dominated in northern and central Anhui in spring. Other seasons were almost entirely dominated by particulate matter. Industrial structure was found to be more effective in reducing industrial carbon emissions, and technological improvement was found to be more advantageous in reducing industrial particulate matter, NOx and SO2. Finally, the policy implications of these results and suggestions for strengthening the inter-city joint prevention and control of air pollutants are discussed.</p

Quantifying nitrate pollution sources of shallow groundwater and related health risks based on deterministic and Monte Carlo models: A study in Huaibei mining area, Huaibei coalfield, China

Nitrate pollution in groundwater is a global environmental concern. As a result, accurate identification of potential sources for such pollution is of critical significance to the effective control of groundwater quality. In this study, forty-nine shallow groundwater samples were collected from the Huaibei mining area. Hydro-chemical characterization, geospatial analysis technique, dual nitrate isotopes (δ15N-NO3- and δ18O-NO3-), Bayesian model and health risk assessment model were adopted for exploring the conditions, sources, proportion, and potential health risks of nitrate pollution for the first time in the study area. The results showed that the nitrate concentration ranged from 0.00 to 293.21 mg/L, and that 18.37% groundwater samples exceeded the standard of drinking water in China (GB 5749–2006). Based on the dual isotopic values of nitrate, it could be concluded that nitrification was dominated migration and transformation process of nitrogen. The results of Bayesian model showed that the proportional contributions of the potential nitrate pollution sources in shallow groundwater were manure and sewage (M&S) (39.54 %), NH4+ in fertilizer and precipitation (NHF&P) (34.93 %), soil nitrogen (SN) (14.89 %), and NO3- in atmospheric deposition (NAD) (10.64 %). The health risk assessment indicated that non-carcinogenic risks posed by NO3--N was higher for children than adults. The primary exposure pathway was oral ingestion. Monte Carlo simulation were applied to evaluate model uncertainty. The probabilities of non-carcinogenic risks were up to 12.54 % for children and 5.22 % for adults. In order to protect water quality and drinking water safety, it was suggested that effective nitrate reduction strategies and better management practices can be implemented

Arsenic release : insights into appropriate disposal of arsenic-loaded algae precipitated from arsenic contaminated water

Limited information is available on arsenic (As) release from As-loaded algae precipitated from As contaminated water and its subsequently appropriate disposal. In this study, selected M. aeruginosa as algal model, changes of As concentrations and its speciation were thus investigated in the in-situ treated algae water by optimal coagulation. Meanwhile, after ex-situ disposal, As release kinetics were also examined from its precipitated algae with living and heat-treated conditions. Results showed that in the in-situ treated water, total dissolved As slowly decreased for 6 days, but arsenite increased largely after 3 days partly caused by its reduction status. While being disposed ex-situ, As release from precipitated algae depended not only on intracellular As content but also on the living or heat-treated status of algae. Additionally, potential risks arised from As release in short-term duration (24 h) from both the precipitated algae at 1.0 mu M As(V) pre-exposure with the living and heat-treated conditions due to their higher release. Furthermore, As release in long-term (6 d) duration from heat-treated algae at 10.0 mu M As(V) pre-exposure also resulted in potential risks. Accordingly, this study offers insights into the appropriate methods at a proper time of disposing precipitated algae with As-contamination

Hydrogeochemical Characteristics and Water Quality Evaluation of Carboniferous Taiyuan Formation Limestone Water in Sulin Mining Area in Northern Anhui, China

The Taiyuan formation limestone water in the Huaibei coalfield is not only the water source for coal mining, but also the water source for industry and agriculture in mining areas. Its hydrogeochemical characteristics and water quality are generally concerning. In this paper, conventional ion tests were carried out on the Taiyuan formation limestone water of 16 coal mines in the Sunan and Linhuan mining areas of the Huaibei coalfield. Piper trigram, Gibbs diagram and an ion scale coefficient map were used to analyze the hydrogeochemical characteristics of the Taiyuan formation limestone water. The water quality was evaluated in a fuzzy comprehensive manner. The results show that the main cation and anion contents in the Taiyuan formation limestone water were Na+ &gt; Mg2+ &gt; Ca2+ &gt; K+, SO42&minus; &gt; HCO3&minus; &gt; Cl&minus;. There were differences in the hydrogeochemical types of the Taiyuan formation limestone water in the two mining areas; HCO3-Na type water was dominant in the Sunan mining area and SO4&middot;Cl-Na type water was dominant in the Linhuan mining area. The chemical composition of the Taiyuan formation limestone water is mainly affected by the weathering of the rock and is related to the dissolution of the evaporated salt and the weathering of the silicate. The fuzzy comprehensive evaluation results show that the V-type water accounts for a large proportion of the Taiyuan formation limestone water in the study area and the water quality is poor. This study provides a basis for the development and utilization of the Taiyuan formation limestone water and water environmental protection in the future

Study on the Influence of Mining Activities on the Quality of Deep Karst Groundwater Based on Multivariate Statistical Analysis and Hydrochemical Analysis

Long-term mining activities have changed the hydrogeochemical evolution process of groundwater and threatened the safe use of groundwater. By using the methods of hydrochemistry and multivariate statistical analysis, this study determined the hydrogeochemical evolution mechanism affecting the quality of karst groundwater by analyzing the conventional hydrochemistry data of the karst groundwater of the Carboniferous Taiyuan Formation in Hengyuan Coal Mine in the recent 12 years. The results show that, under the disturbance of mining, the quality of karst groundwater in Taiyuan Formation is poor, mainly because the contents of Na++K+ and SO42&minus; are too high to allow usage as drinking water. The reason for the high content of SO42&minus; in karst groundwater lies in the dissolution of gypsum and the oxidation of pyrite, and the high content of Na++K+ lies in the cation exchange. Influenced by the stratum grouting, the circulation of karst groundwater is improved, the cation exchange is weakened, and the desulfurization is enhanced. In the future, it is predicted that the hydrochemical type of karst groundwater in Taiyuan Formation in the study area will evolve from SO4-Ca&middot;Mg type to HCO3-Ca Mg type