China is the most widely distributed karst in Asia， widely distributed in southwest China. The karst groundwater resources in southwest China are about 1，847.8×10 8 m 3 /a， and there are 2，836 underground rivers in southwest China， with a total discharge of 479.7×10 8 m 3 /a in the dry season， making it the main water source for life， industry and agriculture in southwest China. However， in recent years， due to the unreasonable development and utilization of karst water resources， the phenomenon of water shortage often occurs. How to make scientific， reasonable and effective use of karst water resources has become a difficult problem to solve water resource crisis. In this paper ，we study the hydrological process and numerical simulation of groundwater in karst area from the perspective of groundwater science， which is of great significance to the accurate evaluation of karst water resources and its rational development and utilization. This paper takes Dajing basin in southern Guizhou province as the research area， which is a typical karst peak-cluster depression area. Water-bearing media in karst areas often have karst pipelines with high permeability and dissolved gaps with low permeability. The flow mechanism of groundwater in the two media is quite different. The groundwater in the gap mainly meets Darcy’s law and meets the laminar flow mechanism， while the groundwater in the karst pipeline is mostly in the turbulent state due to the large flow rate. In the actual situation， the two media are independent of each other， and there is an interrelated process of hydraulic exchange on the boundary. Based on this， this paper adopts FODFLOW-CFP coupling model to carry out numerical simulation of Dajing basin. FODFLOW-CFP is a dual-system coupling model based on dual structure theory. Modflow-cfp model contains three kinds of groundwater flow simulation methods. In this paper， CFPM1 as the most basic model is adopted. In this pattern， the traditional groundwater flowing model is coupled with a specific pipeline model. The main purpose is to depict caves， cracks in interstitial spaces and basaltic aquifer pipes in karst aquifers， where groundwater can be fully or partially filled and flow patterns can be laminar or turbulent. Therefore， it can fully and completely simulate the hydrological process of karst groundwater， so as to grasp the law of groundwater movement in Dajing basin， evaluate karst water resources accurately， and promote its rational development and utilization. The process of using Modflow-CFP to establish a mathematical model of groundwater in big well basin includes the establishment of porous media model in MODFLOW and pipeline model in CFP， and then the two models are combined together. Based on the coupling model， the identification of the model and water balance analysis are carried out. Finally， the water resources are evaluated and the mechanism of groundwater migration is studied. In this study， it is found that Dajing basin is a groundwater system with complete recharge， drainage and drainage conditions， and the North-South， Northease-Southwest trending structure controls the distribution of regional karst aquifer and the development of karst. According to the buried conditions of groundwater and the practical significance of water supply， the main source of recharge in the area is atmospheric rainfall recharge， and the main discharge item is the outflow from the southern well. Meanwhile， the simulation results show that， The exchange capacity between pipes and porous media is 6，719.1 m 3 /a， mainly in the upper and middle reaches of Dajing basin. The total recharge water in the study area is 10，977.3×10 4 m 3 /a， and the recharge module is 108.794 m 3 /km 2 ·a. The rainfall inflow and infiltration accounted for 81.35% of the total recharge， and the total excretion was 10，813.47×10 4 m 3 /a， which was mainly discharged from the outlet of the underground river. Based on this， the migration mechanism of groundwater in Dajing basin is clarified， and new development and utilization of water resources are put forward to solve the problem of local water resources shortage.

Dispersed karst water is an important water supply source, or even the only water supply source, for some districts and counties in Chongqing City. It is particularly necessary to understand the distribution characteristics of metal elements in karst water and the health risks exposed. In this study, the scattered karst water in the southeastern part of Chongqing was taken as the main research object, and the concentrations of Al, Cu, Pb, Zn, Cr, Cd, Ni, Mn, As, and Hg in 42 groups of karst spring water samples were determined. The spatial distribution of metal elements with a high detection rate was revealed using the ordinary kriging interpolation method, and the spatial distribution characteristics, sources, and health risks of metal elements were analyzed using multivariate statistical methods and health risk models. The results showed that the quality of dispersed karst water in southeastern Chongqing was generally good, and the spatial scale variability in the occurrence of metal elements in karst water was strong, especially for Ni and As. The sources of Cu, Pb, As, Zn, and Cr were mainly affected by the regional geological background; Al and Mn were mainly affected by human industrial, agricultural, and mining activities; and Ni was affected by both the natural background and human activities. The total health risk of exposure through the drinking route was higher than that of the skin infiltration route, which was the main exposure route of the human body. The total health risk of children exposed through the drinking route was higher than that of adults, and the total health risk of adults exposed through the skin infiltration route was higher than that of children. It is worth noting that Cr was the determinant of total health risk. From the perspective of drinking water safety, local residents need to pay certain attention to water quality when drinking distributed karst groundwater, in order to reduce the health risk of the population.

为研究青藏高原流域岩石风化机制及其对CO2消耗通量和气候变化的影响,于2019年11月至2020年10月对拉萨河流域控制断面进行一个完整水文年每月2次的监测和采样,结合水化学及δ13CDIC和834SSO4,探讨了流域水化学特征及其主要影响因素,基于化学计量平衡与正演模型方法定量计算了河流水体主要物质来源,并对流域岩石风化速率与大气CO2消耗通量进行了估算.结果表明:拉萨河流域水体中Ca2+和HCO3-为主要的阳离子和阴离子,水化学类型为HCO3-Ca型,大气输入、人为输入、硅酸盐岩和碳酸盐岩风化端员对河水阳离子的年平均贡献率分别为6％、4％、21％和70％;河水化学计量学、δ13CDIC(-8.78‰～-1.35‰)和δ34SSO4(-2.26‰～-1.10‰)变化均证明由煤系地层硫化物及矿床硫化物的氧化形成的硫酸(各占约50％)广泛参与了流域的化学侵蚀,硫酸对碳酸盐岩的风化作用旱季显著强于雨季.流域硅酸盐岩风化速率与大气CO2消耗通量的年平均值分别为5.20 t·km-2·a-1和118×103 mol·km-2·a-1;仅考虑碳酸风化作用时,流域碳酸盐岩风化速率与大气CO2消耗通量分别为22.5 t·km-2·a-1和202× 103 mol·km-2·a-1;硫酸参与作用下,流域碳酸盐岩风化速率估算结果提高了 31％(升至29.4 t·km-2·a-1),岩石(碳酸盐岩和硅酸盐岩)风化消耗大气CO2通量则降低了 35％(降至207×103 mol·km-2·a-1).硫酸参与流域碳酸盐岩的风化改变了区域碳循环,这是全球碳循环模型应该考虑的一个重要环节.

[研究目的]近年来,随着生活水平的不断提高,人们对健康饮水的要求也在不断提高,寻找与开发富含H2SiO3等矿物质优质地下水已成为关键.[研究方法]本文以昭觉地区水文地质调查工程、地下水污染调查工程所获取的地下水化学数据为基础,探讨了昭觉地区富H2SiO3地下水的分布特点、元素水文地球化学特征、形成条件及成因.[研究结果]结果显示:(1)全县富H2SiO3(≥25 mg/L)地下水均属于低矿化度偏碱性水,分布在基底岩石为玄武岩的6个片区,H2SiO3含量一般介于25.74～46.04 mg/L,pH含量一般介于7.4～8.58,TDS含量一般介于49.4～333 mg/L;(2)玄武岩地下水存在HCO3-Ca、HCO3-Ca·Mg、HCO3-Ca·Na、HCO3-Ca·Mg·Na、HCO3-Na等5种水化学类型,总体以HCO3-Ca·Mg为主,其次为HCO3-Ca,再次为HCO3-Ca·Na,三者分别占总采样点数的50.00％、25.76％、12.12％;(3)全县富H2SiO3地下水的形成受水岩相互作用、硅酸盐矿物的分布范围及其可溶性、围岩裂隙发育程度、水源涵养及补给条件等四方面因素影响,其中水岩相互作用占据主导作用;(4)在后续开发利用过程中,需进一步揭示影响地下水中H2SiO3分布与迁移的因素.[结论]研究结果可以为昭觉地区矿泉水产业的发展及城乡优质水源地的建设提供依据.

岩溶关键带处于岩石、水、土壤、大气、生物五圈交汇地带.正确认识岩溶关键带的结构、特点及其水文地球化学过程是当前地球关键带与岩溶水科学研究的重点问题.本文基于对国内外相关研究成果的归纳整理,剖析了岩溶关键带水文地球化学内涵、岩溶关键带水动力垂向分带、岩溶关键带框架下的水文地球化学过程与机制,探寻变化环境下岩溶关键带水文地球化学过程演变的规律与驱动机制.指出了当前研究中存在的薄弱环节:目前工作仅停留在传统岩溶地下水科学工作范畴,未从岩溶关键带框架体系的角度考虑植物冠层至岩溶含水层之间水文地球化学过程及其耦合关系,未考虑新污染物持续输入、地球大数据科学工程深入实施、全球碳排放路径逐渐改变等时代因素对岩溶水文地球化学研究的潜在影响.进一步的研究可以从以下方面开展:基于岩溶关键带框架体系的新污染物水文地球化学研究,基于大数据框架体系的岩溶水文地球化学研究,"双碳战略"下的岩溶水文地球化学研究,岩溶关键带水文地球化学驱动的物质转化与能量迁移过程及其耦合以及高分辨率监测、评估与模拟手段的综合应用.

岩溶地下水为全球约25％的人口提供饮用水源,地下河作为主要岩溶地下水类型,是中国西南岩溶区重要供水水源,掌握其水质污染状况及人体健康风险,对岩溶区水资源保护与安全用水具有重要意义.本文以广西桂林会仙狮子岩地下河系统为例,采集地下河水样品22组(无机和有机样品各11组),采用电感耦合等离子体质谱、离子色谱、气相色谱-质谱等方法测定11项无机离子、10项金属元素及41项有机指标的质量浓度,运用单指标污染标准指数法、健康风险评价模型揭示了研究区无机与有机指标分布、污染及健康风险.结果表明:①狮子岩地下河水中无机超标指标有NH4+(1.33倍)、Fe(1.2倍)、Al(1.5倍)和Mn(1.01倍),超标点多位于地下河排泄区;检出18项有机物,其中挥发性有机物(VOCs)、半挥发性有机物(SVOCs)和有机氯农药(OCPs)检出率分别为18.75％、30.77％和91.67％,研究区存在普遍的农药残留(49.14～109.83 ng/L).②与地下水对照值相比,研究区受到10项无机指标的轻度～中度污染、14项有机指标的轻度污染,个别采样点受到NO3-、Fe、Al和Mn的较严重～严重污染,一处采样点遭受苯并[a]芘的极严重污染.③经饮用水和皮肤接触两种途径暴露的非致癌健康风险(成人9.98×10-3a-1,儿童1.09×10-2a-1)和致癌健康风险(成人1.33×10-7a-1,儿童2.82×10-7a-1)均在可接受范围内.本文认为研究区存在不同程度的无机和有机污染,但污染物指标对人体暂不构成非致癌和致癌健康风险.

通过地面水文地质调查、水文地质钻探和地下水资源开发利用等综合研究手段,查明研究区地下水类型以基岩裂隙孔隙水为主,碳酸盐岩岩溶水和第四系松散岩类孔隙水为辅,总结出不同类型地下水的赋存特征;从断裂、皱褶和裂隙发育特征阐明地质构造对研究区地下水运移、存储、富集和排泄的影响规律,断裂破碎带通常具有阻水作用,而在断裂一侧或两侧某一段的影响带内往往充水,沿断裂带发育方向易形成地下水排泄带,次级断裂是控制研究区内深部热水活动通道的主要构造;向斜构造使得浅层裂隙水和下部层间水得以富集,形成向斜储水盆地;近东西向张性和"X"节理裂隙有利于地下水的富集.根据研究区内主要地形地貌和含水层特点,将研究区划分为山间盆地、丘陵山区和岩溶山区3种主要类型区,通过对各类型区地下水赋存特征及规律分析总结,结合开发利用可行性,归纳出3种地下水开发利用模式:山间盆地蓄水构造钻井抽水模式、丘陵山区表层泉水池调蓄模式和岩溶山区溶洼成库和地下河堵洞成库地表-地下联合模式.研究成果为提高乌蒙山区地下水开发利用效率,解决该地区用水困难提供科学依据.