The coal mining areas spanning the Inner Mongolia-Shaanxi border represent both a quintessential ecologically vulnerable zone and a critically important coal production base in China. However, large-scale, high-intensity coal mining has generated vast amounts of mine water. Currently, investigating the hydrogeochemical genesis of mine water and advancing its resource utilization have become critical issues for the green transition of coal industry. This study systematically collected mine water samples from multiple active large-scale coal mines in the region. The hydrogeochemical characteristics and formation mechanisms of the mine water were revealed through laboratory testing and data analysis, and technical pathways for the classified utilization of mine water were proposed based on water quality characteristics. The results indicate that the mine water in the study area is generally weakly alkaline, with an average TDS value of 2 053.57 mg/L. The dominant cations are Na⁺ and Ca²⁺, while the dominant anions are SO₄²⁻ and HCO₃⁻. The hydrochemical types are primarily SO₄-Na, HCO₃-Na and HCO₃-Ca. The chemical composition of the mine water is jointly controlled by silicate weathering and dissolution, evaporative concentration, and cation exchange. The main exceeding indicators in the mine water include TDS, Na⁺, SO₄²⁻, total hardness (TH), Cl⁻,and F⁻. Among these, TDS and Na⁺ have the highest exceeding rates(65%), followed by SO₄²⁻(45%). Furthermore, the integrated weighted water quality index was employed to evaluate mine water quality: Class Ⅰ and Class Ⅱ water each accounted for 25%, Class Ⅲ for 10%, and Class Ⅳ and Class Ⅴ accounted for 5% and 35%, respectively. Class Ⅰ mine water meets the quality requirements for ecological and agricultural irrigation use, whereas water of other classes is unsuitable for direct utilization and requires targeted treatment measures based on its specific hydrochemical characteristics to prevent soil salinization and vegetation degradation.

The extraction of coal seam could induce a series of ecological environment problems in arid and semi-arid mining area of Northwest China. In order to clarify the driving factors of ecological environment in coal mining areas and form an ecological risk prediction method, Yushen mining area was taken as the research object, the relationships between meteorology, soil, groundwater, aquiclude, mining parameters and ecological environment elements were analyzed, the ecological risk prediction model of coal mine area was formed, and the distribution of ecological risk index under coal mining conditions was predicted. The results showed that NDVI increased with the increase of precipitation and potential evapotranspiration, vegetation water consumption decreased first and then remains stable with the increase of water table depth. Under the condition of coal mining, the groundwater loss of loose aquifer decreased with the increase of the thickness of the aquiclude, the development height of water-conducting fracture zone was positively correlated with mining thickness, width and depth, the maximum surface horizontal deformation was positively correlated with mining thickness and width, and negatively correlated with mining speed. On this basis, the ecological risk prediction index system of coal mine was constructed, which was composed of nine key factors, such as drought index, surface slope, soil type, water table depth, aquiclude thickness, development height of water-conducting fracture zone, ratio of mining depth to mining thickness, ratio of mining width to mining depth, mining speed, and the grade division and corresponding value of each index were given according to the quantitative and qualitative characteristics. Taking the typical water-rich coal mine of Yushen mining area as an example, the comprehensive weight of each index was determined by the game theory based on the subjective and objective weight, the weight of development height of water-conducting fracture zone, water table depth, aquiclude thickness, drought index, ratio of mining depth to mining thickness was relatively large, and the sum of five weights accounted for 99% of the total weight, which played a decisive role in ecological risk prediction. The prediction results show that the areas with medium ecological risk accounted for 58.95%, and the areas with high ecological risk accounted for 41.05%, and there was no low-risk area. It was necessary to reduce the ecological risk of mining by adjusting the mining parameters to inhibit the development of water-conductive fracture zone and surface cracks, carrying out the reconstruction of aquiclude to increase the thickness of aquiclude, and restoring the damaged ecological environment. The research results could provide reference for the ecological environment protection and restoration in arid and semi-arid coal mining area of Northwest China.

[Objective]The mine water associated with coal mining tends to be rich in fluoride ions.If discharged dir-ectly without effective treatment,such water will cause severe pollution to regional ecology,affecting the quality of wa-ter resources and the stability of the ecosystem.[Methods]This study focuses on the challenging treatment of the fluor-ide pollution caused by coal mining-associated mine water.To overcome the bottlenecks including low efficiency and weak anti-interference of traditional methods for fluoride removal,this study designed a setup for fluoride removal us-ing the nucleation crystallization pelleting(NCP)processing and proposed a novel fluoride removal method-NCP chemical precipitation.The fluoride pollution of mine water poses great environmental risks since the resulting fluoride mass concentration in surface water might exceed relevant standards by 8‒15 times.The deep fluoride removal in a com-plex water quality environment is challenging in the prevention and control of fluoride pollution.This study developed a coordinated regulating mechanism integrating multi-phase reactions:chemical precipitation,nucleation induction,and porous adsorption.Process optimization experiments on a laboratory scale were conducted using a continuous flow chemistry system with a hydraulic retention time(HRT)of 45 min and an upward flow rate of 1.8 m/h.Then,this study systematically determined the dynamic process of fluorine migration and transformation using advanced characteriza-tion techniques such as X-ray photoelectron spectroscopy(XPS)and in-situ Fourier transform infrared(FTIR)spectro-scopy.[Results and Conclusions]The results indicate that the mass concentration of fluoride dropped from 12.6 mg/L to 7.6 mg/L(removal rate:39.8%)after only a single stage of processing under the optimized conditions(i.e.,a nucle-ation inducer(CaCl2)dosage of 1 200 mg/L and a seed loading ratio of 1∶50),with efficiency being 2.3 times higher than that of conventional coagulating sedimentation.X-ray diffraction(XRD)corroborated that thermodynamically stable aragonite and vaterite crystals were generated from reactions between Ca2+and F-.Notably,coexisting carbonates enhanced fluoride removal by forming CaCO3·CaF2 composite precipitates(FTIR reveals a characteristic peak at 1 080 cm-1)or porous calcite carriers(SEM images indicate a porosity increase of 62.76%).This study revealed the regulation pattern of interfacial reactions in a carbonate system.Energy dispersive spectroscopy(EDS)confirmed the gradient dis-tribution of fluorine elements in the cross section of formed particles,revealing the progressive removal mechanism from surface adsorption to lattice fixation.The NCP technique can effectively remove fluoride ions in mine water with com-plex water quality and can deal with the complex chemical composition in mine water.The results of this study will lay a foundation for the engineering application of the fluoride removal technology based on the NCP process while also providing a feasible technical route for solving the environmental pollution caused by fluoride-bearing mine water.

The mining areas in arid and semi-arid region have become important coal production bases to ensure China’s energy strategic security, however, coal development by large-scale and high-intensity mining has triggered a series of water resources and ecological environment problems. The article analyzes ecological issues from a hydrological perspective, systematically reveals the hydrological and ecological effects caused by coal mining, and develops restoration technologies for damaged hydrological ecology in mining areas based on water. The research results are indicated by the follow. The subsidence caused by coal mining accelerates the infiltration and evaporation of precipitation, and the soil moisture near the soil fractures appears “funnel zone”. The water conducting fracture connects directly with the loose aquifer in typical coal areas, and the groundwater flow field and resource quantity have undergone significant changes. The maximum water level drop exceeds 14 m, the average water level drop exceeds 5m, and the amount of negative balance exceeds 2500×104 m3/a. The decrease in groundwater level leads to a gradual reduction in river flow, with a maximum of 172×104 m3/a. In areas where the groundwater level is less than 5 m, the decrease in groundwater level significantly reduces the ecological water consumption of vegetation. Base on the water resources and ecological environment problems, the hydrological and ecological restoration technologies have been developed, to response to the current situation of water resource shortage, ecological water level reduction, poor soil water retention, and low vegetation water use efficiency. Firstly, the moderate purification technology for mine water by nanofiltration has been developed. The technology has a wide range of desalination rates, and the treated mine water can provide high-quality water sources for hydrological and ecological restoration. Secondly, the ecological reinjection technology has been developed in soil, basing on the large amount of mine water inflow, good mine water quality, and considerable storage space in the Quaternary loose aquifer. The mine water recharge can lift the ecological water level in the mining area. Thirdly, the soil reconstruction technology has been developed, in which a water-resistant soil layer is placed underneath the vegetation root soil layer, which can significantly increase soil moisture and vegetation water consumption in the collapsed area. Fourthly, soil microbial inoculation technology has been developed, and appropriate inoculation treatment can expand the absorption range and area of soil moisture and nutrients by roots, regulate the expression of genes related to photosynthesis, sugar metabolism, glutathione metabolism, and calcium ion signal transduction, and improve the water efficiency and drought resistance of vegetation. The research results provide scientific basis for water resource protection and ecological environment restoration in arid and semi-arid mining areas in western China.

The border area between Mongolia and Shaanxi is the core area for China’s energy security. However, a large number of mine water produced in the process of coal mining contains a variety of pollution components. Only by finding out the sources and characteristics of pollution components can we deal with and utilize mine water resources more scientifically and reasonably, which is also in line with the requirements of high-quality de-velopment of the Yellow River region. Based on the investigation of the geological, hydrogeological and coal mining disturbance conditions in the border area between Mongolia and Shaanxi, the hydrogeochemical charac-teristics of coal seam roof aquifer and the characteristics of typical pollution components in mine water were studied, and the sources of these typical pollution components were analyzed. The results showed that the border area between Mongolia and Shaanxi was located in the Yishan slope. According to the coal seam buried depth conditions, it could be divided into shallow buried area, medium deep buried area and deep buried area. The mine water in the shallow buried area came from all aquifer water of the coal seam roof, and the mine water in the medium deep buried area came from aquifer water of the Yan’an formation and the Zhiluo Formation (divided into complete bedrock section and weathered bedrock section) of the coal seam roof. The concentration of TDS in the Quaternary and Jurassic groundwater in the shallow buried area and the medium deep buried area was lower than 1 000 mg/L. The mine water in the deep buried area came from the aquifer water of the Jurassic Yan’an Formation and Zhiluo Formation in the roof of the coal seam. The Jurassic aquifer was relatively closed and stagnant. The long-term water rock interaction led to the concentration of TDS in groundwater upper than 1 000 mg/L, and the main exceeding standard components were Na+, Ca2+ and \begin{document}${\rm{SO}}_4^{2-} $\end{document}. The pollution components in mine water included two categories: one was from the roof aquifer water, and the long-term water rock interaction led to the entry of ion components into mine water. The other came from the underground production activities of coal mines. The release of coal cuttings, dust and oil led to the dissolution of suspended solids, nitrogen, organic matter and other pollution into mine water. The concentration of TDS in mine water in the shallow and medium deep buried areas was lower than 1 000 mg/L, which is mainly weakly alkaline HCO3-Ca water, and the main cation and anion (including Na+, Ca2+, Cl−, \begin{document}${\rm{SO}}_4^{2-} $\end{document}) basically did not exceed the standard. The TDS concentration in the mine water in the deep buried area (including the Xiaojihan coal mine) was 1 824.00−3 684.00 mg/L, which was slightly higher than that in the roof water. The increase of Na+ and \begin{document}${\rm{SO}}_4^{2-} $\end{document} ion concentration accounted for the largest proportion, which was mainly due to the further water rock interaction in the goaf. The concentration of COD in mine water of most coal mines exceeded the standard, but the TOC concentration and UV254 value were low, it showed that the organic matter in the mine water was mainly suspended. The 3DEEM spectrum detection results showed that the dissolved organic matter was mainly natural amino acids and humus, the fluorescence intensity of all kinds of organic matter was low, and there were few organic pollutants in mine water.

为了探究寒旱露天煤矿区土壤水分运移规律及其生态效应,以位于蒙东草原的露天煤矿为研究区,开展了长时间段土壤水分观测原位试验.研究结果表明:非冻结期浅层土壤含水率主要受降水影响,冻结期土壤含水率受土壤温度影响明显;50 cm以上土壤饱和渗透系数大于 150 cm/d,50 cm以下土壤饱和渗透系数仅为 20 cm/d左右,表现为土壤饱和渗透系数随土壤深度的增加呈减小趋势,降水入渗形成的土壤水主要滞留在 50 cm以上的植被根系作用层;区内地下水位埋深(＞10 m)远超地下水补给植被的临界埋深(3.52 m),植被指数与年降水量呈正相关关系,表明土壤水是维持区内植被需水的最关键水源;冻融期土壤含水率可恢复甚至超过非冻结期的含水率水平,同时特殊的土层结构造成植被根系区的土壤持水性较好,以上 2个因素对植被生长具有积极意义.研究结果可为寒旱露天煤矿区的生态环境保护与修复提供借鉴.

针对旱区露天煤矿排土场土壤退化问题,采用高效放线菌菌剂接种及原位盆栽试验,探究了放线菌对新疆黑山露天煤矿排土场红豆草根系生长及根际土壤肥力的影响.结果表明:(1)干旱条件下,放线菌接种可显著促进红豆草根系形态发育及生长.与对照相比,接种放线菌红豆草总根长、平均根系直径、根表面积及根总体积较不接菌对照均显著增加(P<0.05);根鲜重、茎叶鲜重及总鲜重较对照分别增加了77.24％、130％及103.49％.(2)接种放线菌显著增强了红豆草的抗旱性.接菌根谷胱甘肽、脯氨酸含量和根系活力分别增加了35.36％、229.23％和363.75％,降低了丙二醛含量和根细胞质膜透性.(3)接种放线菌显著提高了红豆草根际土壤肥力.供试放线菌在红豆草根际土壤中定殖量为2.5×105 cfu/g,接种后红豆草根际土壤细菌和放线菌总数较对照分别增加了113.7％和563.64％;根际土壤多酚氧化酶、脲酶及碱性磷酸酶活性较对照均达显著性增加(P<0.05);进而显著提高了根际土壤全氮、有效磷和速效钾含量,其中土壤全氮增加量最大.(4)相关分析表明,红豆草根生物量与根际细菌和放线菌数量、土壤脲酶活性、碱性磷酸酶活性及全氮含量呈显著正相关(P<0.01).结果证实了土壤接种放线菌通过增强植物的抗旱性,提高根际土壤微生物数量、酶活性及肥力水平,显著促进植物根系发育及生长,为旱区煤矿植被恢复及退化土壤改良提供了科学依据.

Abstract: In the context of extensive high-intensity mining in open-pit coal mines, the temporal and spatial changes of the groundwater level and the range of disturbance caused by the mining activities remain unclear, and the traditional hydrological observation methods are insufficient in obtaining accurate and real-time groundwater monitoring data under the open-pit mining conditions. To address these challenges, the construction of an automatic groundwater observation network to obtain long-term groundwater level dynamic monitoring data via wireless remote transmission, integrated with hydrological background value survey, open-pit coal mine production and drainage data, meteorological data, and hydrogeological data, will reveal the temporal and spatial change characteristics of groundwater under open-pit coal mining conditions and disturbances radius and area of influence on groundwater. The results show: 1) The drainage operation during the open-pit mining caused the drop of groundwater level and forming of a cone of depression, with maximum drawdown of the central groundwater level at 60 m. The disturbance mainly occurred in the mining area where the maximum groundwater disturbance radius was 8 km, and the disturbance area accounted for 66.7% of the mining area. and 10% of the hydrogeological units; 2) The range of groundwater level drop within the disturbance radius is closely related to the distance from the open-pit coal mine and the drainage volume. The closer the distance to the open-pit coal mine and the greater the drainage volume led to the greater the groundwater level drop; 3) The change characteristics of dynamic curve of groundwater can be divided into 3 types (weather-affected, unaffected and mining-affected). Therefore it is of great significance for groundwater resources protection and ecological restoration in open-pit coal mines to conduct automatic monitoring of groundwater, and study the influence of open-pit coal mining on groundwater by establishing a three-dimensional observation network of groundwater in open-pit mines.

Abstract In order to understand the evolution law of groundwater quality during the artificial recharge process with mine water, the effluent from the mine water treatment plant of the Mindong No. 1 Mine was selected to artificially recharge the Quaternary aquifer of the study area. In this experiment, the spatial evolution of the groundwater quality of some wells around the recharge well was monitored during the artificial recharge process with reclaimed mine water. The factor analysis method was used to reveal the evolution law of groundwater quality during the recharge process. Although the reclaimed mine water met the standards for artificial recharge, the results showed that pH value as well as Cl−, TDS, NO3−, and F− concentrations in the reclaimed water were higher than those observed in the Quaternary aquifer, presenting a potential risk to groundwater quality. On the other hand, four organic components were identified in the groundwater after the artificial recharge, including fulvic-like acids (Ex/Em = 280/440, Ex/Em = 250/440) as the main component. Indeed, most of these components were caused by terrestrial origin and soil migration. In addition, the reclaimed mine water contained protein-like tryptophan (Ex/Em = 300/340), which was mainly derived from the discharge of point sources. The total fluorescence intensity of organic pollutants in the different wells tended to be uniform with the recharge time. However, if external pollution is introduced, it may significantly affect the types of organic pollutants and diffuse rapidly within 24 hours. Therefore, it is necessary to control effectively the concentration of trace organic matter in the influent water to ensure the safety of the artificial recharge with mine water.

Groundwater distribution influenced by mining activities is hard to be tracked due to the lack of accurate and real-time monitoring data. To address the groundwater dynamic change data under the mining conditions of open-pit coal mines, a three-dimensional automatic observation network of groundwater was constructed, and this observation network takes open-pit as the center, showing a radioactive distribution, based on hydrogeological conditions, and observes different aquifers. The data was analyzed by integrating hydrology, mining activity, and meteorological data. Analytic hierarchy process was adopted to reveal the underground disturbance influencing factors, and suggestions for groundwater protection were given. The results show that the dynamic variations of the groundwater with time can be divided into 3 types (precipitation affected, unaffected type, and mining affected types). The drainage operation during the open-pit mining triggered the drop of groundwater level, resulting in a cone of depression. The maximum drawdown of the central groundwater level was 60 m. And the disturbance mainly occurred in the mining area where the maximum groundwater disturbance radius was 8 km. Artificial drainage was the main disturbance factor of groundwater, and the range of groundwater level drop within the disturbance radius was closely related to the distance from the open-pit coal mine and the drainage volume. The closer the distance to the mines and the higher the drainage volume led to the deeper the groundwater level drop. This study shows the importance of the three-dimensional observation network of groundwater and provides a good reference for groundwater resources protection and ecological restoration in open-pit coal mines.

针对矿井水人工回灌过程中水质演化及介质堵塞两大现实问题,通过自主搭建的矿井水人工回灌试验平台,开展矿井水人工回灌地下水库模拟试验.采用单一变量的试验方法,改变矿井水入库前的预处理方式,结合回灌前后矿井水浊度、TDS、悬浮物粒径及SEM扫描电镜,分析了地下水库连续储水过程中的水质变化规律,厘定了地下水库进水水质要求,并总结了露天煤矿地下水库自净化的主要机制;在此基础上研究了不同浊度矿井水人工回灌过程中介质渗透性变化规律,探查了矿井水人工回灌堵塞发生位置及堵塞类型,提出了地下水库自净化与介质渗透性间的矛盾关系.研究结果表明:采用混凝法对入库矿井水进行预处理,可以通过吸附架桥作用有效增大矿井水中悬浮微粒的粒径,进而淤积在回灌介质表层,促进了悬浮物在此阶段的去除,实现了地下水库的自净化,在地下水库连续储水过程中,水中浊度及TDS会进一步降低;但是从介质渗透性变化的角度而言,水中悬浮颗粒在被去除的同时缩短了回灌系统达到堵塞的时间,主要由于回灌介质表层发生了悬浮物堵塞,且回灌介质渗透性变化存在周期性规律,可采用0～5 cm表层清淤和30 h周期性回扬的技术手段消除介质渗透性下降对回灌系统的影响.

Vegetation plays an active role in soil water dynamics and water balance in atmosphere-soil-vegetation-groundwater system. Therefore, we characterised soil water transportation at depths of 0-4.0 m, induced by root water uptake of groundwater-dependent Salix across a whole growth stage, as well as taking place in non-vegetated soil, in the semi-arid Ordos basin of China. The results show that: soil moisture content showed clear heterogeneity under the combined influence of evaporation, rainfall and root water uptake. Thus, the soil profile was divided into the climate impacted layer, the transitional layer, and groundwater supporting layer. Root water uptake increased the variability of soil water in the vadose zone and changed the classification structure. The impacts of different rainfall regimes on soil moisture and vegetation response at the individual plant scale were systematically analysed. The rainwater infiltration hysteresis as connected to rainfall intensity, soil depth and the roots-system preferential channel were confirmed, as was the canopy-shading effect. Further, an exponential-logarithmic normal composite root water uptake distribution was obtained, via an inverse method. Of the accumulated 356.3 precipitation in 2016, the annual soil water increase was 97.9 mm for bare site, increased by 10.2% in total, accounting for 25.5% of the precipitation of that year. Conversely, for vegetated site, annual soil water decrease registered at 254.40 mm, decreased by 28.3% in total. The contrastive experiment indicates that root water uptake processes change the soil water flow field and aggravate water scarcity, resulting in soil desiccation in the deep local soil layers and groundwater depletion. The dried soil layers blocked water interchange, which is extremely detrimental to ecohydrological processes. Our results provide a scientific basis within which the hydrodynamic processes of vegetation in semi-arid regions may better be understood and inspire research to find a balance between groundwater management and vegetation replanting.

Based on the theory of the hydrogeochemistry,the hydrochemistry and environmental isotope basic eigenvalues of different aquifers overlying the coal seam in the Yushen mining areas were established. On this basis,the mine water sources of shallow buried mines,mid-deep buried mines,and deep buried mines were identified combined with the hydrogeological structures and heights of water conducting fracture zone of typical mines. Results showed that,the hydrochemical types and environmental isotope values of different aquifers overlying the coal seam were obviously different affected by the water-rock reactions and hydrodynamic condition. With the increase of the buried depth of coal seam,the salinity of mine water showed a significant increasing trend,while the δD and δ18 O of mine water showed a decreasing trend. And then the source of mine water for coal mines of different buried depth coal seam was identified by applying comprehensive hydrochemistry and stable isotope. It was considered that the mine water for shallow buried coal mines was a mixture of the groundwater for the Jurassic sandstone aquifer and the Quaternary loose aquifer. And the mine water for deep and mid-deep buried coal mines mainly came from the Jurassic sandstone aquifer.

为进一步查明孟加拉国巴拉普库利亚煤矿水文地质特征及含水层间水力联系,为矿井水害防治提供理论依据,以19组水质化验数据为基础,结合含水层及隔水层空间展布特征、井田构造特征、水位历时曲线、水化学类型、氢氧同位素特征等,综合分析新近系UDT含水层、Ⅵ煤顶板含水层、Ⅵ煤含水层之间的水力联系.结果表明,井田北部LDT隔水层局部缺失,为UDT含水层水向含煤地层补给提供了条件;井田北翼煤层顶板含水层与UDT含水层水位变化规律密切相关,且水位相近,初步证明两者存在水力联系;各含水层水均为HCO3-Ca·Na·Mg型,均为低矿化度水,进一步证明各含水层间存在水力循环;聚类分析结果表明各含水层水质存在一定关联度,推演含水层间水力联系程度;氢(δD)氧(δ18O)同位素特征点分布于全球大气降水线附近,表明大气降水是各含水层共同的补给水源.研究成果可以指导孟加拉国巴拉普库利亚煤矿Ⅵ煤层开采时水害防治方向.

Vegetation plays an active role in soil water dynamics and water balance in groundwater-soil-plant-atmosphere continuum systems. Therefore, we characterized soil water transport at depths of 0-4.0 m induced by root water uptake (RWU) at a groundwater-dependent Sax site during the whole growth stage and compared the results with those from a non-vegetated soil site, in the semiarid Ordos basin of China. The results showed that: during the whole experimental period, evapotranspiration at the vegetated site was more than twice evaporation at the bare site, indicating that the transpiration exceeded the evaporation and was the main output of soil water. For the bare site, the increase of soil water storage in the lysimeter was 97.9 mm in total, accounting for 27.5% of the precipitation, with 16.8% of rainfall as retention in the shallow vadose zone and 10.7% of rainfall as seepage below 150 cm depth. Conversely, in the vegetated site, rainfall-driven soil water was mainly consumed by vegetation, and the decrease of soil water storage was 254.4 mm in total, with no seepage being observed. Although the root system as the preferred channel improved the soil infiltration capacity, it did not mean that the deep soil water recharge increased. The infiltrated rainfwater could not offset the water consumption of the mot system. An exponential normal composite RWU model obtained by the reverse method showed that the water deficit soil layers caused by RWU changed the soil water flow field and blocked soil water interchange. Consequently, deep soil water and groundwater could not be replenished by precipitation. Our results emphasize ascertaining the hydrodynamic processes of vegetation in semiarid regions and help to strike a balance between vegetation restoration and groundwater management.

黄土区是我国重要的煤炭生产区,古土壤层在黄土区包气带中广泛发育.煤炭开采和洗选过程中会产生大量煤矸石,其中露天堆放的煤矸石在长期降水淋滤作用下会释放出含有大量污染物的淋滤液,对矿区周围的地下水造成污染.黄土区煤矸石淋滤液在进入到地下含水层之前,必将流经过古土壤层.要准确评价煤矸石淋滤液对地下含水层的影响,必须确定古土壤层对煤矸石淋滤液中污染物的防污性能.通过开展室内渗透试验和批式吸附试验,研究了古土壤对煤矸石淋滤液中典型污染物Mn2+,Zn2+,Cu2+和SO2-的阻隔情况.渗透试验结果显示,煤矸石淋滤液作用下古土壤试样的渗透系数在0.852× 10-9～1.01×10-9 m/s,比使用蒸馏水渗透时得到的渗透系数降低了1.5倍以上.古土壤试样渗透系数之所以会降低,是因为煤矸石淋滤液与古土壤之间发生了化学反应,生成新的沉淀物淤堵了古土壤试样中的孔隙.批式吸附试验结果显示,古土壤能够吸附Mn2+,Zn2+,Cu2+,吸附过程符合非线性的Freundlich模型;古土壤层中黏土矿物与重金属之间的离子交换反应,是古土壤吸附重金属的主要途径.古土壤颗粒呈电负性,与SO42-之间存在相互排斥作用,几乎不吸附SO42-.使用POLLUTE V7软件模拟预测了煤矸石淋滤液中典型污染物击穿古土壤层的时间,结果显示,厚度为1.0m的古土壤层对污染物的有效阻隔时间可以达到10 a以上.总体而言,古土壤层具有较强的防污性能,能够限制污染物向含水层迁移,因此在进行黄土区煤矸石堆场地下水环境影响评价及污染防控时,有必要考虑古土壤层产生的影响.

浅埋煤层开采经常诱发一系列的生态环境问题,为研究浅埋煤层开采区地面塌陷影响下的土壤水分运移规律并提出相应的调控方法,以西部风沙区浅埋煤矿为研究对象,将采煤塌陷对包气带结构的影响分为3个阶段:开采前,包气带较薄,土壤颗粒相对均一;开采中,水位明显下降,包气带厚度急剧增加,裂缝发育且土壤颗粒均一性变差;开采后,风沙区大多数地裂缝自然弥合,但土壤中的黏性颗粒减少,砂性颗粒增多,出现明显的粗化现象.以此为物理背景,构建了不同裂缝宽度二维土壤水分运移模型,结果显示:无裂缝时湿润锋平行向下运移,同一深度的土壤含水率基本相同,裂缝存在时湿润锋沿着裂缝快速运移,优势渗流现象明显;土壤含水率随裂缝宽度的增加呈减小趋势,含水率影响范围随裂缝宽度增加呈增大趋势;当包气带厚度大于极限蒸发深度(300 cm)时,入渗补给量和包气带厚度基本无关,仅会延长土壤水分通过包气带运移到潜水面的时间,对地下水的潜在补给量影响较小.现场调查了塌陷区和非塌陷区沙蒿的生长状况:受塌陷区土壤水分匮缺(吸水水源不足,含水率小于0.1 cm3/cm3)和塌陷诱发的植被根系密度降低(吸水通道降低,根系总干质量减小21.7％)2种因素影响,塌陷区沙蒿平均地上生物量相对非塌陷区减小22.2％.提出了地面塌陷影响下的土壤水分运移调控方法:煤层开采中,通过调整工作面宽度和开采厚度,减小地面塌陷的发育程度,从而减小塌陷区土壤含水率的损失量;开采后,开展塌陷区土壤重构时,考虑不同植被的耗水特征,在植被根系土壤层下衬垫10～ 30 cm的黄土,可明显提升植被根系层的土壤含水率,加速矿区植被恢复进程.

煤矿区地下水水化学特征及其形成作用对矿井突水水源识别及水害防治具有重要的意义.本文采集伊敏矿区水样21组,综合利用Piper三线图、同位素、Schoeller图、Gibbs图及离子比例关系分析了地下水化学特征及其控制因素.结果 表明,矿区不同类型水样主要阳离子为Na+,阴离子主要为HCO3-,平均pH值为7.92,TDS平均值为420.59 mg·L-1;大气降水、地表水、第四系水以及Ⅰ含水层水化学类型均为HCO3-Ca型,它们之间联系密切,Ⅱ含水层水化学类型为HCO3-Ca型和HCO3-Na型,Ⅲ含水层水与矿井水水化学类型为HCO3-Na型,且Ⅲ含水层水与矿井水δD和δ18O平均值最接近,矿井水主要来源于Ⅲ含水层补给;伊敏矿区地下水及矿井水主要离子形成作用受岩石风化控制,主要离子来源于钾长石、钠长石、钙长石等硅酸盐矿物的溶解,并受到Ca2+、Mg2+、K+、Na+阳离子交换作用的影响.

为了查清敏东一矿矿井水水质特征和地下储存过程中典型污染组分去除规律,设计了一种“地表处理+含水层储存”的实验装置,结合现场取样检测、污染组分分析、室内模拟实验等手段开展了相关研究,结果表明,敏东一矿井下矿井水中污染组分来源于天然地下水和煤炭生产,其中来自地下水的Fe,F,Mn等离子超标1.0～3.0倍;煤炭开采造成的污染包括COD、浊度、氨氮、总大肠菌群,分别超标69.67～192.33倍、24.16～55.17倍、0.52～1.10倍和4.33～7.67倍;石油类组分超标则表明矿井水中出现了一定程度的有机污染.混凝沉淀实验中,20.0 mg/L PAC条件下,浊度和COD分别降至13.60 NTU和4.73 mg/L;在常规处理(混凝沉淀)去除悬浮物和COD的基础上,采用“地表处理和含水层储存”的实验模拟工艺,利用地表包气带孔隙介质过滤、氧化反应等作用,使浊度＜1.0 NTU,TOC含量=1.097～1.128 mg/L,UV254=0.026～0.037 cm-1,NH4质量浓度0.1 mg/L,地表处理段出水已经满足当地地下水条件;含水层储存过程中,还原环境还可以进一步去除矿井水中有机组分,使TOC含量和UV254进一步降至0.48～0.54 mg/L和0.005～0.008 cm-1.另外,利用三维荧光光谱指纹可以进一步查清矿井水中有机组分种类和去除过程,实验源水中主要出现了Ⅲ区的多环芳烃类有机物(荧光强度(fluorescence intensity,FI)=4 147)和Ⅴ区的腐殖质类有机物(FI=3 140);地表处理后,Ⅲ区和Ⅴ区的FI分别降至2 033～3 140和2 201～2 760,结合UV254的变化特征可以看出,好氧阶段优先去除大分子/多环芳烃类有机物,再经过含水层储存,Ⅲ区的FI进一步降至1 496～1 779,Ⅴ区的FI则≤1 638.采用“地表处理+含水层储存”的矿井水处理储存模式,可以有效去除煤炭开采产生的污染组分,保障矿井水地下储存的水质安全.

Soil water and groundwater are important water resources for vegetation survival and growth in arid and semiarid regions, and their contributions to water use over a whole growth period are difficult to quantify with limited observations. Additionally, the root water uptake (RWU) processes of groundwater-dependent xeric vegetation are specific and aggravate the complexity of these issues. In this paper, Salix is selected to study the interaction among atmosphere, soil water, groundwater, and RWU from the sprout to withered stage based on an observation within the 'In situ Monitoring Lysimeter System of the Atmosphere-Plant-Unsaturated Zone-Groundwater Continuum'. Two lysimeters with a diameter of 2 m and depths of 1.2 m and 4.2 m were implemented with Salix. The initial water table depth was 0.7 m in case 1 and 2.2 m in case 2. The results show that: Water use of Salix is the main contribution to actual evapotranspiration (ETa), no less than 80%. ETa was 462.75 mm in case 1 with a shallower soil layer and limited groundwater, during the entire growth period, 2016. Contrastively, it was 619.70 mm in case 2 with relatively abundant soil water and groundwater. The soil water and groundwater contribution were 89.6% and 10.4%, 74.3% and 25.7% for both cases. The selective water use by Salix in different soil layers was subject to temporal moisture availability. Salix extended to utilize groundwater in drought period and shifted back to wetter upper layers in case of rainfall. The access to groundwater significantly alleviates water stress, although rainfall replenishment can also play a part. Salix can not only intercept rainfall infiltration in the root zone, but also cause the decrease of water level, implying that the replanting of Salix should be carried out in a reasonable mode to ensure rainfall infiltration and reduce the ineffective loss of groundwater. Our results provide a practical reference for groundwater management and ecology restoration in semiarid desert regions.