采煤活动影响下娘子关岩溶水系统演化研究

发布时间：2018-04-04 14:25

本文选题：娘子关岩溶水系统　切入点：采矿活动　出处：《中国地质大学》2017年博士论文

【摘要】：岩溶地下水历来是岩溶地区重要的供水水源,近年来由于受城乡经济的发展及全球气候变化的影响,对地下水的需求量急剧增加。特别是在我国北方碳酸盐岩分布地区,地表水资源分布严重不均,污染日趋严重,岩溶水资源的开发利用和合理保护也就显得日益重要。娘子关泉是我国北方最大的岩溶泉之一,也是阳泉市工农业生产和人民生活的重要供水水源,对地方经济的可持续发展具有至关重要的作用。然而,自从20世纪80年代以来,随着社会经济的快速发展,由于降雨量周期性变化、过度开采地下水和受采煤疏干影响,使得地下水水位持续下降。更为严重的是在气候变化和人类活动影响下,岩溶水水质恶化现象显著,硬度和硫酸盐等指标严重超标,同时伴随着其它致毒性组分含量升高,生态环境恶化。由于地下水水质下降导致的可利用水资源量减少,已严重影响了城市工农业的健康发展。在整个研究区内,由采煤活动引起的酸性矿坑排水会对地表水和地下水水质造成影响。煤系地层富含各种有机、无机成分,在煤矿采掘与空气接触后,硫铁矿等被氧化,使得矿坑水酸化并极大地增强其溶解能力,地层中矿物以及采掘设备损耗的金属成分被溶入水中而导致水质恶化。矿坑水水质总体上有如下特征:(1)pH值偏低,(2)硫酸根离子含量偏高,(3)硬度偏大,(4)溶解性总固体高,(5)铁离子含量高。本文通过水文地球化学、锶同位素以及室内水岩相互作用实验等方法来探究人类采矿活动影响下娘子关泉域岩溶水的水质演化特征以及矿坑水对研究区内碳酸盐岩物理性质的影响。文章内容可分为以下三个部分:1.娘子关岩溶系统水文地球化学特征以及采煤活动对岩溶水水质的影响本文运用水文地球化学分析,多元统计分析,以及地球化学模拟等方法对娘子关泉域采矿活动对岩溶水水质的影响进行了评估。娘子关泉是中国北方最大的岩溶泉之一,沿着地下水流动的方向出现了严重的水质恶化现象,比如岩溶水中硫酸盐、硝酸盐和TDS均被检测到有明显的上升。在泉域补给区,所采集的水样主要为Ca-Mg-HCO3型水,在煤矿开采区域的水样以Ca-Mg-HCO3-SO4为主,在排泄区域则以Ca-Mg-SO4-HCO3/HCO3-SO4为主。运用主成分分析法(PCA)将所采集的水样提出4个主成分,能够解释大于82.9%的总变化量。其中,所占的比例最大的因子1为45.33%,说明煤矿开采活动和自然水-岩相互作用是作为最主要的控制喀斯特水质量的影响因素。人类活动影响被当做因子2提出来,其NO3-和Cl-的因子载荷都很高并且偏正。其他两个因子分别可以解释共沉淀去除微量元素以及硅酸盐矿物溶解,占总变化量的20.96%。由于用硫同位素来估算矿坑水与岩溶水的混合比会导致结果偏高,本文根据硫酸盐含量建立一个双端元混合模型来估算矿坑废水在岩溶水中所占的混合比例。模拟结果表示,矿坑水对地下岩溶水的贡献在1.11-27.05%之间,这比用硫同位素方法得到的结果要低将近3倍。2.基于D,18O,~(87)Sr/~(86)Sr以及Sr/Ca特征对娘子关岩溶地下水污染物来源再认识本文对娘子关泉域所采集的样品进行了水化学分析和同位素(D,18O和~(87)Sr/~(86)Sr)分析。联合研究区水样中主要离子的水化学特征和稳定同位素特征可以确定(1)地表水和地下水的化学组分来源,(2)岩溶地下水可能经历的水化学过程,以及(3)采矿活动对岩溶地下水的影响。就岩溶水、裂隙水和泉水而言,他们的水化学类型从Ca-HCO3演变为接近地表水和矿坑水的Ca-SO4,表明沿着地下水流动方向从补给区到煤矿开采区,地下水经历了一个混合过程。lgCa和lgSr的线性关系表明在大多数水样中锶的一个可能性来源为碳酸盐岩的溶解。根据水样中Sr/Ca和Sr/Mg的比例可以确定两个端元水体。端元MW3的特征为Sr/Ca和Sr/Mg的比例都很高,但是端元RW1则具有相当低的Sr/Ca比值。像水样KW8和Sf8都比较靠近MW3端元,这可以解释为它们与矿坑水发生了混合作用。像水样Sf6、KW17和FW2都很靠近端元RW1,这些水样可以归因于大气降水的输入。岩溶地下水水样的稳定氢氧同位素组成都分布比较广,δ18O的分布范围是-9.93到-6.85,δD的范围是-69到-50.2。泉水是岩溶地下水的主要排泄方式,其氢氧同位素的分布范围分别为-69到-50.2和-9.93到-6.85,这比岩溶水的分布范围要低很多,并接近于雨水样品的分布范围。根据18O和D的分布情况,大部分水样都分布在全球大气降水线附近(GMWL,δD=8δ18O+10),表明这些水样都受大气降水补给。其中,岩溶水样的同位素组成分布范围比较广并且有轻微的偏离大气降水线,这反应了岩溶水中同位素分布受到蒸发作用的影响。高~(87)Sr/~(86)Sr以及低Sr/Na比值表明了一些岩溶水样和矿坑水样都来自硅酸盐矿物的溶解,比如水样KW21和MW3。低~(87)Sr/~(86)Sr以及高Sr/Na比值则表示岩溶水是碳酸盐岩来源的,比如水样KW8。由于硅酸盐来源的水和矿坑水对岩溶水有共同影响的作用,因此本文建立了一个三端元混合计算模型。岩溶地下水主要分布在矿坑水混合比例小于10%的区域,说明采矿活动的影响不是很显著。其中矿坑水混合比例最高的是岩溶水样KW8,高达20%。3.酸性矿坑水-碳酸岩含水介质水岩作用行为实验研究碳酸盐岩矿物的溶解控制着娘子关岩溶地下水系统中的主要离子组分。由反应溶液穿透孔隙介质引起的矿物溶解或沉淀经常会使孔隙体积和孔隙比表面积发生改变,并影响孔内流体和运移参数,比如饱和/相对渗透率、孔隙度、反应比表面积、毛细管压力曲线以及孔径分布特征。在3组岩心穿透实验中,Ca、Mg和碱度的升高表明是来源于白云石和方解石的溶解。在对岩心RD2进行的穿透实验中,在流出溶液中检测到Na+和Si有轻微的上升,表明可能是钠长石的溶解。值得注意的是,初始溶液S1中的Fe3+和S2中的Fe2+在穿透实验后基本下降到仪器检测线附近,表明溶液经历了铁水合物的沉淀过程。在岩心RD2中,铁离子浓度的峰形曲线表明经过13天的穿透实验出现了虫孔,导致流体在岩心中的驻留时间变短。然而,优势流通道不会一直存在,因为铁水合物的沉淀会堵塞通道,这可以从铁浓度在后5天中的浓度又逐渐减少得到印证。对于粗粒白云岩岩心RD1,初始穿透溶液pH为3.27,主要重金属离子为Fe3+,在15天的穿透实验后总孔隙度从3.1%减小到1.7%,渗透率只是轻微的从0.7751×10-3μm2减少到0.7469×10-3μm2。对于白云岩岩心RD2,初始穿透溶液pH为2.3,主要重金属离子为Fe2+,在20天的穿透实验后,其总孔隙度从4%减小到2.7%,渗透率从0.~(86)51×10-3μm2下降到0.8471×10-3μm2。这表明当实验室制备的酸性矿坑水与白云岩岩心接触后,有矿物沉淀在孔隙表面积并且堆积起来从而导致有效反应表面积的减少。除此之外,我们还对这些穿透实验前后的岩心进行氮气吸附实验。其热力学曲线属于类型I和IV的结合。在相对压力较低的区域,热力学曲线表现出较高的吸附性,说明岩石中主要存在微孔(类型I),在相对压力较高的区域(P/P00.45),其热力学曲线呈现一个滞回环,说明在介孔中存在毛细管冷凝(类型IV)。主要涉及碳酸盐岩中孔径分布变化的过程为为以下两个:(1)酸性流体穿透碳酸盐岩可以刺激微孔裂隙的形成,增加介孔数量;(2)由于pH的升高而导致铁水合物的纳米颗粒形成,这些纳米颗粒可以附着在孔隙表面并减小平均孔径。
[Abstract]:Karst groundwater is always an important water source in karst area in recent years, due to the impact of urban and rural economic development and global climate change, the demand for groundwater increased rapidly. Especially in the distribution area of Northern Rock carbonate in China, the distribution of surface water resources is extremely uneven, serious pollution, water resources development and utilization of the karst reasonable protection will become increasingly important. The Niangziguan Spring is the largest karst spring in North China, Yangquan city is also the important water resource for industrial and agricultural production and people's life, has the vital role in the sustainable development of the local economy. However, since 1980s, with the rapid development of social economy, due to periodic rainfall change, over exploitation of groundwater and coal mining drainage effect, the groundwater level continued to decline. The more serious is the climate change and human activities. Ring, the karst water quality deteriorated significantly, the hardness and sulphate index accompanied by serious exceed the standard, other toxic components content increased, the deterioration of the ecological environment. The groundwater quality decline caused by the reduction of water resources, has seriously affected the healthy development of city industry and agriculture. In the study area, cause by mining activities of acid mine drainage will affect the surface water and groundwater quality. Coal strata rich in organic and inorganic components in coal mine mining and air contact, pyrite is oxidized, the mine water acidification and greatly enhance its ability to dissolve, formation of minerals and mining equipment loss metal components are dissolved in the water due to the deterioration of water quality. The mine has the following characteristics: the overall water quality (1) pH (2) value is low, high sulfate content, (3) greater hardness, total dissolved solids (4), (5) Iron content is high. The hydro geochemistry, strontium isotope and indoor water rock interaction experiment and other methods to explore the impact of human activities under water mining in Niangziguan karst water affect the evolution of characteristics and mine water on the physical properties of the carbonate rocks in the area. The contents of the article can be divided into the following three parts: 1. lady close the karst system hydrogeochemical characteristics and influence of mining activities on karst water quality based on hydrogeochemical, multivariate statistical analysis, and geochemical simulation methods of mining activities off spring snake effect on karst water quality was evaluated. The Niangziguan Spring is the largest karst spring in North Chinese, along the groundwater flow direction appeared serious deterioration of water quality, such as karst water sulfate, nitrate and TDS were significantly increased in spring. Domain recharge area, collected water samples for Ca-Mg-HCO3 water, mainly Ca-Mg-HCO3-SO4 in the coal mining area of water, the discharge area is dominated by Ca-Mg-SO4-HCO3/HCO3-SO4. By using principal component analysis (PCA) collected water samples presented 4 main components, can explain more than 82.9% of the total variation. The factor the largest proportion of the 1 was 45.33%, that of coal mining activities and natural water rock interaction is as the main factors affecting the quality of water control in Karst. The impact of human activities was proposed as the 2 factor, the factor loadings NO3- and Cl- are very high and partial. The other two factors respectively. Explain the removal of trace elements and silicate mineral dissolution precipitation, the total changes in the amount of 20.96%. due to estimate mixed mine water and karst water ratio will lead to the results with high sulfur isotope, according to sulfate The content of building a two endmember mixing model to estimate the mine wastewater for karst water mixing ratio. The results showed that the mine water of underground karst water contribution between 1.11-27.05%, than with sulfur isotope results to low nearly 3 times of.2. based on D, 18O, ~ (87) Sr/~ (86) Sr and Sr/Ca characteristics of Niangziguan karst groundwater pollution source recognition based on Niangziguan water samples were collected for chemical analysis and isotope (D, 18O and ~ (87) Sr/~ (86) Sr) analysis. The main research area in water samples with water chemical characteristics and stable isotope characteristics (1) to determine the chemical composition of groundwater and surface water source, (2) water chemical process of karst groundwater may experience, and (3) the effect of mining activities on the karst groundwater. Karst fissure water and water, water, water chemical type from their Ca-HCO3 Is close to the surface water and mine water Ca-SO4, that along the flow direction of the groundwater from recharge area to coal mining area, groundwater has undergone a mixing process of.LgCa and lgSr showed a linear relationship between the source of the possibility in most samples for strontium carbonate rock dissolution. According to Sr/Ca and Sr/Mg in water ratio can be determined two end water. The characteristics of end member MW3 for Sr/Ca and Sr/Mg were high, but the end is Sr/Ca yuan RW1 ratio is quite low. Like water KW8 and Sf8 are relatively close to the end of MW3 yuan, which may explain the mixing effect for their students with mine water. As the water Sf6, and KW17 FW2 is very close to the end of RW1, these samples can be attributed to the precipitation inputs. Groups of stable hydrogen and oxygen isotope of groundwater in the Chengdu karst distribution is wide, -9.93 to the -6.85 distribution range of delta 18O, -69 to -50.2. range is 5 D Spring is the main discharge of karst groundwater, the distribution range of the hydrogen and oxygen isotopes were -69 to -50.2 and -9.93 to -6.85, the ratio of the distribution range of karst water is much lower, the distribution range and close to the water samples. According to the distribution of 18O and D, the majority of water are located in the vicinity of the global meteoric water line (GMWL, Delta D=8 Delta 18O+10), indicating that these samples are recharged by rain. The karst water isotope composition distribution range is relatively wide and slightly deviate from the atmospheric precipitation, the reaction of karst water isotope distribution affected by evaporation. High ~ (87) Sr/~ (86) Sr and low Sr/Na ratio show some karst water and mine water dissolved from silicate minerals, such as water KW21 and low MW3. (87) Sr/~ ~ (86) Sr and high Sr/Na ratio indicates that karst water is carbonate sources, such as water samples by KW8. In silicate sources of water and the mine water has the common influence on karst water effect, so we set up a three endmember mixing calculation model. The karst groundwater is mainly distributed in the mine water mixing ratio is less than 10% of the area, illustrates the influence of mining activities is not very significant. The ore pit water mixing ratio is the highest in karst water KW8, up to 20%.3. of acid mine water - dissolved carbonate rock aquifer water rock interaction behavior experimental study of carbonate minerals in control of the main ion group Niangziguan karst groundwater system in the reaction solution. The penetration of mineral dissolution and precipitation in porous media which often makes the pore volume and pore specific surface area changed. And the influence of hole and fluid transport parameters, such as saturation / relative permeability, porosity, reaction surface area, pore size distribution and capillary pressure curve characteristics. In 3 groups of core penetration In the experiment, Ca, elevated Mg and alkalinity is dissolved from dolomite and calcite. The penetration experiment was carried out on the core of RD2, the effluent solution was detected in Na+ and Si increased slightly, which may indicate albite dissolution. It is worth noting that the initial solution in S1 and Fe3+ S2 Fe2+ in the experiment after the fall to near penetration instrument detection line, show that the solution subjected to precipitation process of iron hydrate. In the core RD2, peak curves of iron ion concentration showed that after 13 days of the experiment through the wormhole, resulting in Yan Xinzhong's fluid residence time becomes shorter. However, the dominant flow channel not always exist, because of the iron precipitation hydrate will block the channel, it can concentration from iron concentration in 5 days and decreased gradually confirmed. For coarse grained dolomite rock RD1, initial penetration solution pH is 3.27, the main heavy metal ions For Fe3+, the total porosity in the penetration experiment after 15 days decreased from 3.1% to 1.7%, the permeability only slightly from 0.7751 * 10-3 M2 reduced to 0.7469 * 10-3 m2. to dolomite rock RD2, initial penetration solution pH is 2.3, the main heavy metal ions is Fe2+, in the breakthrough experiment after 20 days, the total the porosity decreased from 4% to 2.7%, the permeability from 0.~ (86) 51 * 10-3 M2 down to 0.8471 * 10-3 m2. suggesting that the laboratory preparation of acid mine water and dolomite cores after contact with mineral deposits in the pore surface area and piled up resulting in effective reaction surface area decrease. In addition we have to penetrate these, before and after the experiment of core nitrogen adsorption experiment. The thermodynamic curve belongs to the type I and IV. At a relatively low pressure region, the thermodynamic curve shows better adsorption properties, rock existed in micro hole (type I), In the relatively high pressure region (P/P00.45), the thermodynamic curves show a hysteresis loop, indicating the presence of capillary condensation in mesoporous (type IV). The process mainly involves the change of pore distribution in carbonate rocks as the following two aspects: (1) the formation of acid fluid penetrating carbonate can stimulate the micropore fracture, increase mesoporous number; (2) due to the increase of pH and lead to the formation of hydrate iron nanoparticles, the nanoparticles can be attached to the pore surface and average pore size decreased.

【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P641.134

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