Table of Content

20 February 2025, Volume 31 Issue 01

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The Generation of Acid Mine Drainage: Insights from Reactive Transport Modeling and Stable Isotope

QIU Wenjie, DU Zhuoran, YIN Ziyue, SUN Yuanyuan, ZHU Xiaobin, WU Jianfeng

2025, 31(01):  1-13.  DOI: 10.16108/j.issn1006-7493.2024091

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Acid mine drainage (AMD) resulting from mining activities is a global environmental issue. Investigating the acid generation mechanisms of AMD and the biogeochemical processes affecting the release, migration, and transformation of heavy metals and sulfates provides a scientific basis for quantitatively predicting AMD formation and developing remediation strategies.
In this paper, a multiphase reactive transport model for water-gas two-phase flow is constructed based on the TOUGHREACT/EOS3 code to simulate the acid generation process of sulfide minerals (such as pyrite) in tailings impoundment under the influence of atmospheric precipitation and oxygen. It further considers the physical and geochemical reaction processes of associated species in the migration and transformation within the aqueous medium. The reaction network includes the release of H⁺ from the oxidation and dissolution of sulfide minerals, the migration and transformation of iron ions and sulfate, and the pH buffering processes caused by the dissolution and precipitation of major minerals. Finally, by incorporating sulfur stable isotopes into the reactive transport model, the study identifies the bacterial sulfate reduction processes and corresponding sulfur isotope fractionation occurring during the formation of AMD. The model quantitatively assesses the acid production contributions under different oxidation pathways of pyrite, revealing that simultaneously considering the parallel oxidation processes of O₂(aq) and Fe³⁺ increases the concentrations of acid, iron ions and sulfate. The pH is controlled by the release of H⁺ from pyrite oxidation and the neutralization reactions corresponding to mineral dissolution and precipitation. Stable isotope reactive transport model indicates significant differences in δ³⁴S values under different fractionation kinetic enrichment factor, and using the Rayleigh fractionation model in an open system can greatly overestimate the enrichment factor. This research aids in understanding and predicting the formation and migration processes of acidic water in mining environments, which is crucial for addressing environmental pollution issues caused by mining activities. 

Numerical Simulation and Software Development of Fracture Flow and Reactive Transport Based on Upscaled Discrete Fracture Matrix Model

LIU Dianguang, YANG Yun, YUAN Yiliang, DOU Zhi, WU Jianfeng, WU Jichun

2025, 31(01):  14-23.  DOI: 10.16108/j.issn1006-7493.2024089

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Reactive transport simulation in fractured media is a prominent and challenging research area in the fields of geosciences and environmental engineering. Traditional equivalent porous media models and discrete fracture networks have certain limitations in accurately characterizing groundwater flow and solute transport processes within complex fracture networks.
This paper presents the development of FracRTM, a numerical simulation software for groundwater flow and reactive transport in the fractured media. FracRTM, based on Discrete Fracture Network (DFN) modeling, employs the Upscaled Discrete Fracture Matrix Model (UDFM) to construct continuum meshes and calculate equivalent permeability and porosity. The software integrates open-source reactive transport simulation programs to model the physical and chemical processes of groundwater flow, solute transport, and chemical reactions within fractured-matrix systems. This paper describes the overall design and functional modules of FracRTM , followed by a numerical simulation case study of acid mine drainage migration, which is used to validate the software’s effectiveness.


Cluster Analysis of Acid Mine Drainage Pollution Characteristics Based on Self-Organizing Map Technology: A Case Study of Linkeng Coal Mine in Longyan, Fujian Province

JIA Wenhui, YE Shujun, CHE Qiaohui, XU Wanqiang, ZHENG Wenming, WANG Bangtuan

2025, 31(01):  24-33.  DOI: 10.16108/j.issn1006-7493.2024088

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Acid Mine Drainage (AMD) is one of the major environmental issues arising from coal mining, posing serious threats to ecosystems and human health. This study selected the Linkeng Coal Mine area in Longyan, Fujian as a case study and employed Self-Organizing Maps (SOM) technology to systematically analyze the pollution characteristics of AMD, aiming to accurately assess the current AMD pollution status and effectively identify the main pollution sources. The study comprehensively analyzed four water quality indicators including pH, Fe, Mn, and SO₄^2- of 37 water samples using the SOM method, and finally divided the samples into four clusters with varying degrees of pollution, clearly revealing the spatial distribution characteristics of water bodies with different levels of pollution. The clusters, in order from the highest to the lowest pollution levels, are Cluster IV, Cluster III, Cluster II, and Cluster I. Samples in clusters III and IV show severe pollution characteristics, mainly located near coal mine water inrush points and coal waste stone stacking areas, which are key areas for future remediation efforts. Samples in cluster II are primarily affected by the influx of polluted water; cluster I contains the most samples, indicating that most of the water bodies in the area are minimally affected by AMD. The SOM method offers an effective tool for assessing AMD pollution characteristics and has the potential to be applied in other coal mine areas. Future studies need to increase monitoring frequency to capture the impact of seasonal changes on water quality. As the monitoring data continues to increase, the application potential of the SOM method will become more evident.


A Review of Research on Optimal Design of Groundwater Pollution Monitoring Networks

LIU Mingli, LUO Qiankun, WU Jianfeng, SONG Jian, YANG Yun, SUN Xiaomin

2025, 31(01):  34-47.  DOI: 10.16108/j.issn1006-7493.2024090

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Groundwater can be contaminated by mining activities, landfill operations and chemical production processes. Both the tracing of pollution sources and the monitoring of pollutant transport trends demand the establishment of appropriate monitoring networks. The long-term operation of poorly designed groundwater pollution monitoring networks is inevitably accompanied by high monitoring costs. Thus, it is indispensable to undertake research on the optimal design of groundwater pollution monitoring networks, with the aim of acquiring data regarding changes in pollutant concentrations with utmost precision and at minimal monitoring costs. The primary optimizations of the groundwater pollution monitoring network encompass the optimization of the spatial monitoring positions of the monitoring wells and that of the monitoring frequency over time. At present, a variety of qualitative (such as hydrogeological analysis method) and quantitative (such as simulation-optimisation model method and kriging method) optimisation approaches have been put forward to address the optimal design issue of the groundwater pollution monitoring network, and numerous outcomes have been attained. Nevertheless, each method possesses its specific applicable scenarios, along with its respective advantages and disadvantages. The paper initially compiles the research findings on the optimal design of groundwater pollution monitoring networks over the past four decades. Subsequently, seven methods for the optimal design of groundwater pollution monitoring networks, which are currently employed in numerous domestic and international applications, are presented, evaluated, and contrasted. Finally, the paper concludes with a perspective on the primary research directions for the optimal design of groundwater pollution monitoring networks in the future. 

Screening of Characteristic Pollutants in Groundwater of High-sulfur Coal Mines in China

DING Haoran, CHENG Tianhang, HUANG Yanchang, YIN Ziyue, LU Ping

2025, 31(01):  48-57.  DOI: 10.16108/j.issn1006-7493.2024086

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China has abundant coal reserves, and some mining areas contain a large amount of sulfur-containing minerals in coal and gangue. After coal seam mining, the redox conditions change, and chemical components are released and enter the water environment, causing groundwater or surface water pollution. This article is based on field testing and research data on
the chemical composition of groundwater in high sulfur coal mines in China. The potential hazard index method, comprehensive scoring method, and Hasse graphical method are combined and improved to screen for characteristic pollutants in groundwater in coal mining areas in China. The screening results show that the characteristic pollutants in acidic groundwater are Mn, Ni, Fe, Se, SO₄^2-, Al, Co, Cd, and As; The characteristic pollutants of non acidic groundwater are SO₄^2-, Mn, Ni, Fe, Pb, Co, and Cd.Among them, sulfate shows two peaks under strong acidic conditions and weak alkaline environments, especially under strong acidic conditions, with a generally high content of up to 17870 mg/L. Fe, Mn, Al, Co, Zn, and Ni are generally higher in acidic environments and gradually decrease with increasing pH, indicating that alkaline conditions are not conducive to the enrichment of these heavy metal elements in groundwater. There is a certain degree of positive correlation between the concentration of SO₄^2- in the groundwater of the mining area and the concentrations of Fe, Mn, Al, and Zn ions, indicating that some SO₄^2- and Fe, Mn, Al, and Zn ions may jointly originate from the oxidation of sulfide minerals.

Identification of Subsurface Water Flowing Channels in Metal Mines Based on Comprehensive Geophysical Prospecting

FANG Yunhai, QIAN Jiazhong, MA Lei, DIN Dan, XIE Wei

2025, 31(01):  58-66.  DOI: 10.16108/j.issn1006-7493.2024087

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Detailed depiction of subsurface water flowing channels is very important for the safe mining and multi-echnical collaborative treatment of mining discharge. Abandoned goafs and water conducted faults are buried deep underground, and their complex spatial structures are difficult to characterize at low cost and quickly. In this study, transient electromagnetic method and high-frequency electromagnetic method were combined to identify the evolution of subsurface water flowing channels in the sulfurgold mining area of Tianma Mountain. The results indicated that there were three main water flowing channels in the mining area to receive atmospheric precipitation recharge, located in the west tailings backfill zone, the gully terrain zone south of Line 40, and the fault fracture zone on the southwest side of the gully zone. The largest was the gully zone, where surface water converged due to the low terrain and formed a seepage channel for downward recharge. Under the Quaternary loose overburden, elongated fracture zones developed locally, generating a water flowing channel extending from the surface to -700 m. The entire seepage zone was distributed in a north-west direction along the trend of the gully topography. There were continuous minimum resistance anomalies at -400 m and -600 m elevations, which were speculated to be local water-rich areas for karst development. The above results suggested that the application of high-frequency electromagnetic method to preliminarily identify the local water-rich areas and stratum structure characteristics, combination with the transient electromagnetic method to carry out fine detection of the main water flowing channels, is an effective way to achieve low-cost, fast, and accurate identification of subsurface water flowing channels in metal mines.

Research on Monitoring and In-situ Chemical Remediation of Heavy Metal Contamination in Aquifers Using ERT Methods

ZHANG Yong, LUO Qiankun, LIU Xing, LI Yingchun, DENG Yaping, MA Lei, QIAN Jiazhong

2025, 31(01):  67-83.  DOI: 10.16108/j.issn1006-7493.2024093

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The remediation of heavy metal contamination in aquifers requires cost-effective dynamic monitoring methods as support. However, traditional monitoring methods have issues such as being time-consuming, costly, producing delayed data, and causing significant disturbances to the site. This paper uses copper ions as an example and employs Electrical Resistivity  Tomography (ERT)，a method offering rapid, low-cost, real-time dynamic monitoring with in-situ, non-invasive advantages. Through one-dimensional and two-dimensional sandbox experiments, the feasibility of using ERT to monitor heavy metal contamination in aquifers and the process of in-situ chemical remediation is validated, while factors affecting monitoring accuracy are also explored. The study results show that in the one-dimensional sand column experiment, the correlation coefficient (R²) between ERT monitoring data and sampling data exceeds 0.96 during the contamination phase, with a relative error (δ) below 4.04%; during the remediation phase, R² exceeds 0.94, and δ is below 6.43%. In the two-dimensional sandbox experiment, a quantitative analysis of ERT monitoring results was conducted using the spatial moment method of the contaminant plume combined with sampling data. The first moment error of copper ion migration is below 9%, and the second moment error is below 14% during the contamination phase; during the remediation phase, the first moment error is below 11%, and the second moment error is below 19%. Furthermore, the accuracy of information capture by the ERT device is influenced by the migration and reaction rates of copper ions. The slower the migration and reaction rates of copper ions, the higher the accuracy of information capture by the ERT device. This study validates the feasibility and accuracy of the ERT method in monitoring heavy metal contamination and the remediation process in groundwater, providing important data support for practical applications.

Evaluation of Groundwater Quality in High-sulfur Mining Zone Based on Variable Fuzzy Set Theory

XIE Wei, QIAN Jiazhong, MA Lei, FANG Yunhai, DIN Dan

2025, 31(01):  84-91.  DOI: 10.16108/j.issn1006-7493.2024092

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Water quality assessment of high-sulfur mining zones and the comprehensive understanding of groundwater environment are the prerequisites for the treatment and prevention of acid mining discharge. The contamination of groundwater in water quality assessment is a vague idea that stems from the inherent uncertainty of water quality classification standards and  their thresholds. To solve the problems of mismatch of evaluation criteria and absolutization of membership degree in groundwater quality evaluation by fuzzy mathematical methods, this study introduced the variable fuzzy set theory to establish a comprehensive evaluation model of groundwater quality in the high-sulfur mining area of Tongguanshan, and the ambiguity of water quality categories was dynamically identified. The results showed that the relative membership degree quantitatively characterized the subordination between the evaluation index and the evaluation standard. When the concentration of the evaluation index was within the standard range of a certain grade, the membership degrees of this grade and the grades on the adjacent sides were greater than 0. Most of groundwater quality in the study area was evaluated as grade IV and V., accounting for 89%, and the overall water quality was poor. The monitoring points M3-M7 were the position of water bursting in mine shaft with obvious characteristics of acid mining discharge, and the concentration of sulfate, iron, manganese, total dissolved solids, total hardness, and acidity exceeded the standard. Although the risk of ecological environment pollution can be reduced after the ex-situ end treatment of mine drainage, the disposal cost was high, and it is suggested that the subsequent collaborative treatment should improve the comprehensive benefits in terms of “source control” and “process blocking”.

Numerical Modeling of Groundwater Dynamic Response to Agricultural Irrigation in a Typical Arid Area

WANG Beida, SONG Jian, YIN Ziyue, LIN Jin, WU Jianfeng

2025, 31(01):  92-103.  DOI: 10.16108/j.issn1006-7493.2024010

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Researching the impact of agricultural irrigation on the groundwater dynamic under different crop growth conditions in arid and semi-arid area holds significant practical importance for the rational development and utilization of regional groundwater. Using the MODFLOW-NWT program and unsaturated zone simulation subroutine package UZF1 in GMS software, a numerical model was established for the northern bank of the Kaidu River in the Yanqi Basin. The model was calibrated using daily groundwater level data. Water balance analysis was also conducted. Water requirement for five typical crops (peppers, tomatoes, wheat, sugar beets, and corn) was computed using the crop coefficient method. The calibrated groundwater model was used to simulate the effects of agricultural irrigation on the groundwater depth dynamic under different planting scenarios. The results show that planting the high-water-consumption sugar beets corresponds to the greatest average groundwater depth, while planting wheat results in the smallest average groundwater depth. Average Groundwater depth are similar when planting tomatoes, peppers, and maize. During sugar beets cultivation, the average groundwater depth is 0.85 meters greater than during wheat cultivation. With a 100-millimeter-increase in water demand, the average groundwater depth increases by 0.31 meters during the growing season. It indicates that crop water requirement is a crucial factor affecting groundwater level fluctuation in study area. The finding can provide a scientific guidance for the sustainable management of water resources and the formulation of agricultural planting strategy of arid and semi-arid area. 

Impact of Climate Warming on Potential Groundwater Recharge in Typical Semi-arid Regions

QIANG Yucheng, XIE Yueqing, LU Shiang, DAI Xin

2025, 31(01):  104-112.  DOI: 10.16108/j.issn1006-7493.2024038

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In arid and semi-arid regions, rainfall infiltration is the main source of groundwater recharge, and studying its recharge
mechanism is of great significance for the rational development and utilization of groundwater resources in the regions. Nowadays, the global climate warming is increasingly intensifying, causing changes in the spatiotemporal variability of rainfall and therefore groundwater recharge. However, the impact of climate warming on groundwater recharge in arid and semi-arid regions is still unclear. This study chose Yulin City, Shaanxi Province as the study area. An observation station was constructed to record meteorological data and soil moisture data at several depths. A one-dimensional unsaturated water flow model was established using HYDRUS-1D to simulate infiltration process and calculate potential groundwater recharge. The model was calibrated and validated with the observed soil moisture data. Based on the validated model, the mechanism of groundwater recharge in the study area under four climate warming scenarios, ssp1-2.6, ssp2-4.5, ssp3-7.0, ssp5-8.5, was systematically studied, and the potential groundwater recharge trend was predicted. Results show that, (1) The impact of climate warming on rainfall in the study area is relatively minor, but its impact on air temperature is more significant. The rainfall in the study area will slowly increase, and the trend of air temperature changes will vary with different climate warming scenarios; (2) The potential groundwater recharge will reduce in all scenarios except ssp1-2.6, the weakest climate warming scenario; (3) The potential groundwater recharge in the study area is less affected by the change in the rainfall, and more affected by the change in evapotranspiration intensity.

Estimating Watershed Groundwater Runoff Using Water Balance Analysis and Memory Curve Model

CHEN Ziang, ZENG Xiankui, WU Jichun

2025, 31(01):  113-122.  DOI: 10.16108/j.issn1006-7493.2024043

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Groundwater circulation is a crucial component of the global terrestrial water cycle, and accurately describing basin  groundwater runoff is essential for understanding the groundwater circulation process within a basin. Using hydrometeorological remote sensing data, this study estimates the groundwater runoff released by precipitation in a basin by constructing memory curve models for evaporation and surface runoff, integrating them with the water balance equation, and conducting parameter uncertainty analysis. Taking the Jequitinhonha River basin in Brazil as the study area, the results indicate that the memory curve model can effectively simulate the processes of evaporation, surface runoff, and terrestrial water storage change in the study area. The simulated evaporation values fit well with GLEAM-based evaporation observations, with R² values of 0.74 and 0.81 for the calibration and validation periods, respectively. The simulated surface runoff values had R² values of 0.69 for the calibration period and 0.63 for the validation period when compared to observations. The simulated total water storage change (TWSC) values had R² values of 0.73 and 0.6 for the calibration and validation periods, respectively, when compared to the GRACE TWSC series. Furthermore, based on the groundwater runoff memory curve model, the estimated monthly cumulative groundwater runoff released by precipitation in the study area fluctuated between 50 and 350 m³/s, showing a clear intra-annual variation pattern. This study provides a new approach for estimating basin groundwater runoff in large-scale areas lacking groundwater observation data.