指示娘子关泉群水动力环境的水化学—同位素信息分析

本文依据宏量组分、微量元素和氢氧同位氧组成监测资料，分析了娘子关泉群水动力环境及其水文地质演化趋势。除国家和城西泉主要排泄局部流动系统的地下水外，其它各泉均为不同空间尺度流动系统地下水混合、排泄之产物。在人类活动影响下，娘子关泉群水质恶化，流量衰减，水帘洞、程家泉断流，城西、坡底泉也面临断流之危险。目前抽取的水帘洞泉的水资源量组成已与五龙泉和苇泽关泉相似，以区域和中间流动系统地下水为主。     

Degradation of carbon tetrachloride in a reducing groundwater environment: implications for natural attenuation

Several laboratory experiments have demonstrated degradation of carbon tetrachloride (CT) in groundwater, but there appear to have been no corroborating long-term field studies. Investigations conducted in 1989 and 1999 at an industrial site constructed on an infilled estuarine environment in France provide data over a decade for which CT degradation could be evaluated. A Dense Non-Aqueous Phase Liquid (DNAPL) containing oil and >90% CT that was present in 1989 was absent in the extremely reducing site groundwater in both 1999 and 2000 (average Eh=−170 mV at pH 7, sulfide up to 21 mg l⁻¹, and Fe⁺² up to 3.2 mg l⁻¹). These conditions facilitated dechlorination of CT to chloroform (CF) present at up to 46 mg l⁻¹, and methylene chloride (up to 75 mg l⁻¹). Carbon disulfide (CS₂), a terminal degradation product in reducing environments in laboratory experiments, was present at a mass ratio averaging 2.4:1 CF:CS₂, indicative of abiotic degradation. The lack of detection of the separate phase CT, the ratio of CF:CS₂, the presence of low molecular weight organic acids (i.e., acetate ∼900 mg l⁻¹; citrate 360 mg l⁻¹; and propionate, up to 111 mg l⁻¹) and pyrite in conjunction with excess inorganic Cl in groundwater are all indicators of ongoing degradation of the chlorinated compounds. However, while natural attenuation of chloromethanes may be a viable adjunct to strategies designed to remediate CT in reducing groundwater, its efficacy is hard to quantify in complex field environments where upgradient sources are still present.     

山西太原晋祠—平泉水力联系及对晋祠泉复流的贡献

晋祠泉出露于山西太原西山悬瓮山下,由难老泉、圣母泉、善利泉组成。1954—1958年实测泉水平均流量为l.94 m³/s。与晋祠泉同处山前断裂带的平泉于1978年成为特大岩溶水自流井水源地,自流量最大达到1.56 m³/s。由于这些自流井的开采,使晋祠泉的流量急剧下降,1994年4月30日断流。研究山西太原晋祠泉—平泉水力联系对晋祠泉复流方案制定具有重要意义。本文以晋祠泉、平泉为研究对象,通过样品采集、水质监测,综合运用水化学（离子比例、硫同位素、氢氧同位素）方法。揭示晋祠泉—平泉水文地球化学特征和环境同位素特征,反映地下水流系统的特征、水力联系特征。得出1980—1992年,晋祠泉地下水水位的变化呈稳定下降趋势,主要原因是有太原化学工业公司、开化沟、淸徐县平泉村和梁泉村等水源地大量开采岩溶地下水,导致地下水水位下降。晋祠—平泉一带岩溶地下水氢氧同位素值较接近,说明这一带岩溶地下水补给来源与补给途径相近。水质监测分析得出晋祠泉与平泉各个离子变化趋势基本一致。说明晋祠与平泉存在紧密的水力联系,因此晋祠泉与平泉必然存在一个比较强的导水通道。可以通过在晋祠泉下游导水通道上帷幕灌浆,提高晋祠泉水水位,使晋祠泉出流。     

Large-diameter,non-pumped wells filled with reactive media for groundwater remediation

A groundwater flow and contaminant transport model was used to simulate arrays of non-pumped wells with reactive media for remediating contaminated groundwater. Each array featured a minimum number of wells, with identical diameter, capable of removing a contaminant plume within a hypothetical site. Simulated well diameters ranged from 0.25 m (similar to typical remediation wells) to 1.25 m (similar to large-diameter, bucket-augered wells). Both arrays occupied a linear transect located approximately 5 m downgradient of the front of a polluted enclave and oriented 90° to the hydraulic gradient. The minimum smallest diameter array contained 23 wells, whereas the minimum largest diameter array contained only four wells. Results of this study suggest that bucket-augering technology, adapted to install non-pumped wells with reactive media, may be an effective alternative for remediating contaminated groundwater in some environments.     

非均质介质中重非水相污染物运移受泄漏速率影响数值分析

重非水相污染物(DNAPL)在地下介质中运移和分布受多种因素控制,包括DNAPL本身的物理化学性质,土的性质,泄漏条件等等。由于介质的非均质性,使得多相流运移行为更为复杂。基于地下水随机理论构建渗透率随机场,采用蒙特卡罗方法探讨泄漏速率对非均质饱和介质中DNAPL运移的影响。数值结果表明,在泄漏总量一定的情况下,泄漏速率越低,介质非均质性对DNAPL运移的影响程度越高。反之,DNAPL的渗漏速率越高,小尺度地层的非均质性影响越低。由于DNAPL运移过程中在垂直方向受重力的影响,污染羽在空间上的质心位置(一阶矩)以及展布范围(二阶矩)在垂直方向上的变异程度要高于水平方向。     

Recovery of groundwater in the Sanriku region contaminated by the tsunami inundation from the 2011 Tohoku earthquake

Many wells in the Sanriku region used as sources for water supply systems were heavily contaminated by the tsunami of the 2011 great Tohoku earthquake on March 11 in 2011. To better understand the nature of the groundwater contamination by the tsunami inundation and to clarify the recovery process of contaminated groundwater at the study wells, groundwater monitoring has been conducted once or twice yearly since early summer in 2011. High and abnormal values of electric conductivity (EC), chloride ion concentration (CIC), Na⁺, Ca⁺, heavy metal ions, and heavier isotopes of the contaminated groundwater were also obtained in April and June 2011. The chemical elements have rapidly and exponentially decreased as a result of effective pumping of the contaminated groundwater from the study wells and because of abundant rainfall in 2011. In April 2015 (about 4 years after the tsunami inundation), the CIC and EC of the contaminated groundwater of two study wells in Minamisanriku town had reached pre-inundation values. The estimated residence times of groundwater of the two study wells were 105–118 days in the full-day pumping stage and 910–1000 days in the daytime-only pumping stage.     

Using solver to determine vertical groundwater velocities by temperature variations, Purdue University, Indiana, USA

Vertical groundwater velocities can be estimated based on directions of groundwater thermal gradients. Temperature-depth profiles were obtained from 12 monitoring wells at 3 different times of the year (Fall, Winter, and Spring) in West Lafayette, Indiana (USA) mainly on the Purdue University campus. Microsoft Excel Solver was used to match plots of groundwater temperature distribution in the wells with published type curves in order to find a dimensionless parameter β, from which vertical groundwater velocities were obtained. The vertical groundwater velocities found in the monitoring wells ranged from 0.92 to 4.53 cm/yr. Clay-rich aquitards presented greater vertical groundwater velocities than outwash aquifers. The highest groundwater velocities occurred in the Spring while the lowest were during the Winter. This method was found to be especially useful in glacially-derived materials with varying hydraulic conductivities for estimating vertical groundwater velocities in-situ.     

Application of Visual MODFLOW to simulation of migration in Cr6+ contaminated site

On the basis of site investigation and data collection of a certain electro plating factory, the groundwater flow and solute transport coupled models were established by applying Visual MODFLOW 4.1 software, which was used to conduct a numerical simulation that forecast the transport process of Cr6+ in groundwater. The results show that contamination plume of Cr6+ transports with groundwater flow direction. Without control measures, in 3 650 days, 19 wells for drinking would be contaminated, and the range of transport would be 52 172 m2, the maximum contamination would be 35.8 mg/L     

Application of Numerical Modeling for Groundwater Flow System Analysis in the Akaki Catchment,Central Ethiopia

A three dimensional steady-state finite difference groundwater flow model is used to quantify the groundwater fluxes and analyze the subsurface hydrodynamics in the Akaki catchment by giving particular emphasis to the well field that supplies water to the city of Addis Ababa. The area is characterized by Tertiary volcanics covered with thick residual and alluvial soils. The model is calibrated using head observations from 131 wells. The simulation is made in a two layer unconfined aquifer with spatially variable recharge and hydraulic conductivities under well-defined boundary conditions. The calibrated model is used to forecast groundwater flow pattern, the interaction of groundwater and surface water, and the effect of pumping on the well field under different scenarios. The result indicates that the groundwater flows regionally to the south converging to the major well field. Reservoirs and rivers play an important role in recharging the aquifer. Simulations made under different pumping rate indicate that an increase in pumping rate results in substantial regional groundwater level decline, which will lead to the drying of springs and shallow hand dug wells. Also, it has implications of reversal of flow from contaminated rivers into productive aquifers close to main river courses. The scenario analysis shows that the groundwater potential is not enough to sustain the ever-growing water demand of the city of Addis Ababa. The sensitivity and scenario analysis provided important information on the data gaps and the specific sites to be selected for monitoring, and may be of great help for transient model development. This study has laid the foundation for developing detailed predictive groundwater model, which can be readily used for groundwater management practices.     

开封市垃圾场污染物运移模拟与控制

在对开封市某典型垃圾场进行野外调查的基础上,应用Visual Modflow建立了该垃圾场污染场地的水流和溶质运移耦合模型并进行数值模拟预测,预测了20年后该污染场地垃圾渗滤液污染羽运移范围、途径及方式等特点。模拟了应用防渗墙和抽水井两种方式控制地下水污染的措施和方案,并利用计算机模型对污染控制的效果进行了模拟分析。模拟结果表明,模拟初期污染羽覆盖了3个抽水井,污染羽前缘距离村庄688 m。模拟20年后污染羽已经覆盖了7个抽水井,其中浓度超标井有3口,污染羽前缘距离村庄605 m。建议在加强污染物监测的同时协助开展其他的污染控制措施,进一步控制污染羽的扩散。     

某氨氮污染地下水体抽出 -处理系统优化模拟研究

抽出 -处理系统设计多侧重于考虑修复初期的效率,在修复后期通常效率低下,产生拖尾现象,其优化的关键在于布设的井群系统能否高效抽出受污染的地下水体。利用溶质运移数值模拟可为井群布设和抽水方案优化提供依据。本研究旨在优化我国北方某化肥厂高浓度氨氮污染的地下水体的抽出 -处理修复系统,节约时间和成本。在水文地质调查及氨氮浓度监测的基础上,综合考虑井数、抽水天数和总抽水量三个变量,采用中轴线法与三角形法结合的布井方法,利用GMS软件反复试算,筛选出三种较优抽水方案并进一步模拟优化,最终从中选出最优抽水方案。结果,相比最初方案（方案1）,最优方案（方案3）将修复周期缩短了23个月,抽水总量减少了约31.9×104 m3,而抽水井数量仅增加了1口。该模型进行了稳定流水位拟合验证和4期非稳定流实测溶质浓度验证,较符合实际。结果表明,针对抽水井数量不足引起的拖尾问题,关键因素在于合理的井位布设与分阶段的抽水模式。在修复过程中,及时对地下水中污染物进行监测,并随着污染羽变化过程及时调整抽水方案,保证高浓度区一直有抽水井进行较大流量抽水,可有效提高修复效率并缩短修复周期。     

水位波动下包气带透镜体影响LNAPL迁移的数值模拟研究

轻质非水相液体（LNAPLs）在土壤包气带中具有多相态特征,非均质性、地下水位波动等因素将显著增加包气带内LNAPLs污染的复杂程度。已有研究多关注于揭示包气带内自由相LNAPLs的污染过程,少有更为深入地探究水位波动时非均质结构对LNAPLs迁移及各相态分布规律的影响。基于TOUGH2程序构建包气带多相流数值模型,以揭示透镜体结构与地下水位波动共同作用下LNAPLs迁移过程及相态分布。研究结果表明:（1）含水率变化是LNAPLs迁移分布的主要控制因素,包气带内受透镜体介质岩性、水位波动影响所呈现的含水率变化直接控制LNAPLs迁移规律及分布特征;（2）水位恒定时,细砂透镜体使LNAPL呈“蓄积穿透-横向扩展-绕流”迁移,粗砂透镜体则是LNAPL垂向迁移的“优势通道”,水位波动引起的细砂透镜体含水率变化使“绕流”显著增强,粗砂透镜体则进一步呈现“优势空间”作用;（3）水位恒定时,细砂透镜体模型中LNAPL滞留于透镜体内部,粗砂模型中LNAPL则集中于透镜体下方,水位波动下透镜体附近LNAPL分布范围扩展,两模型LNAPL分布面积较水位恒定时分别增大51%、63%;（4）两模型中LNAPL挥发通量均呈“先减小-后增大”规律,并受LNAPL-气体接触条件及LNAPL分布状况共同作用,水位波动打破三相平衡状态,主要表现为水位抬升阶段LNAPL挥发增强,此时两模型中平均挥发量较水位恒定时增大124%～126%。研究为非均质石油污染场地中的LNAPL污染过程认识提供了科学的理论依据。     

Hydrogeological investigation of a groundwater contamination site in southern Taiwan

 Groundwater samples taken from wells adjacent to a food machinery manufacturing plant in southern Taiwan indicate that there is a serious phenolic contamination. To understand the hydrogeological properties, and to prepare for remedial action, a series of hydrogeological investigations were conducted. Investigative work included collecting background information, analyzing existing data, measuring the groundwater, and conducting a slug test, pumping and recovery test, aerial photography analysis and electrical resistivity survey. Results from these investigations show that the local groundwater aquifer may be classified as an unconfined or confined formation, depending on the thickness of the interbedded clay layer. The direction of local groundwater flow is from southwest to northeast, with high transmissivity. The contaminant moves much more slowly than the average groundwater velocity, and it is limited to an area centered around the plant. The local geology of the contaminated area exhibits significant heterogeneity; it is not likely to have been formed by natural sedimentation. Data from the field aerial photography analysis and electrical resistivity survey also suggest that this shallow formation may result from artificial back-filling. Received: 1 September 1994 · Accepted: 28 December 1995     

Characteristics of karst groundwater system in the northern basin of Laiyuan Spring area

Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs (e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and 18O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.     

利用GPR天线-目标极化的瞬时属性分析方法探测LNAPL污染土壤

轻非水相流体(LNAPL)泄漏后会对土壤和地下水造成严重污染,为了准确探测出LNAPL泄漏范围,本文将GPR天线-目标极化的瞬时属性分析方法应用于轻非水相流体污染土壤探测的研究中。采用注入柴油的石英砂砂箱在实验室建立污染土壤模型,利用探地雷达对该污染土壤分别进行天线方位为0°、90°的测量。LNAPL土壤污染物形状、大小、结构并不规则,因此可以通过0°和90°方位天线测量来分析天线-目标极化特征,了解目标物的走向、形状等地下介质信息。通过对预处理后的包含天线-目标极化特征的信息进行瞬时属性分析,LNAPL污染范围可以被清晰地识别,提高了GPR探测能力。     

Geoenvironmental site investigation using different techniques in a municipal solid waste disposal site in Brazil

Different geoenvironmental site investigation techniques to assess contamination from a municipal solid waste disposal site in Brazil are presented here. Superficial geophysical investigation (geoelectrical survey), resistivity piezocone penetration tests (RCPTU), soil samples collected with direct-push samplers and water samples collected from monitoring wells were applied in this study. The application of the geoelectrical method was indispensable to identify the presence and flow direction of contamination plumes (leachate) as well as to indicate the most suitable locations for RCPTU tests and soil and water sampling. Chemical analyses of groundwater samples contributed to a better understanding of the flow of the contaminated plume. The piezocone presented some limitations for tropical soils, since the groundwater level is sometimes deeper than the layer which is impenetrable to the cone, and the soil genesis and unsaturated conditions affect soil behavior. The combined interpretation of geoelectrical measurements and soil and water samplings underpinned the interpretation of RCPTU tests. The interpretation of all the test results indicates that the contamination plume has already overreached the landfill’s west-northwest borders. Geoenvironmental laboratory test results suggest that contamination from the solid waste disposal site has been developing gradually, indicating the need for continuous monitoring of the groundwater.     

区域地下水位监测网优化设计方法

区域地下水位监测提供了定量评价含水层地下水位持续下降及其对环境影响必不可少的信息。历史上的地下水位监测网是为了评价地下水资源或监测水源地降落漏斗而设立的,目前它们已经不能适应为流域水资源综合管理提供必需的信息。本文在综述国际地下水位监测现状的基础上,介绍了区域地下水位监测网优化设计的方法。采用地理信息系统编制的地下水动态类型图为地下水位监测井位置的选择提供了坚实的水文地质基础;克里金插值法能定量评价监测网观测值绘制的地下水位等高线的精度,因而可以用来定量设计地下水位监测网;时间序列分析和统计检验提供了优化地下水位监测频率的定量标准。这些方法已被应用于北京平原、乌鲁木齐河流域和济南岩溶泉域,其成果将在本刊分期发表。     

Impact of liquid waste disposal on potable groundwater resources near Perth,Western Australia

 Drilling of 15 boreholes at a disused liquid waste disposal site near Perth, Western Australia, has indicated that a contamination plume extends about 1000 m in a southerly direction from the site in the direction of groundwater flow. The plume is up to 600 m wide and 5–40 m thick. Chemical and microbiological analyses have indicated that contaminated groundwater contains high concentrations of ammonia, iron, and bacteria at levels that commonly exceed national drinking water guidelines. It is likely that a proposed water supply production well in the path of the contamination plume will have to be abandoned, and additional wells may have to be abandoned if the plume continues to extend in the direction of groundwater flow. There is currently insufficient information to indicate whether the plume is continuing to expand, but studies on similar plumes in the Perth metropolitan area have indicated that contaminated groundwater can move at rates up to 100 m yr^–1. Several other liquid waste disposal sites are now located in residential areas of Perth where wells are used for garden irrigation. Further work is required to ensure that there is no potential impact of groundwater contamination on public health in these areas. Received: 31 July 1995 · Accepted: 18 September 1995     

Protection of groundwater from oil pollution in the vicinity of airports

Airports are potential, and quite frequently also actual, sources of serious groundwater pollution. This is due to the large amounts of liquid fuel being handled all the time, to the physicochemical properties of oil hydrocarbons, and often to technical errors in the transport and storage of fuels. The environment is further affected by liquid and gaseous emissions escaping during the take-off and landing of aircraft Snow in the vicinity of runways has been found to contain oil hydrocarbons in concentrations of tenths to units of milligrams per liter Moreover, soil tends to accumulate carcinogenous benzopyrenes. In rock formations, oil hydrocarbons spread as a separate layer as well as in solution in porous permeable formations, pollution by a free product affects areas on the order of tens of meters, while hydrocarbons in solution penetrate to distances of hundreds of meters or even kilometers. More complex conditions for the spreading of oil-based substances arise in fissured rocks. Aviation kerosene as a separate phase was found to migrate over 700 meters within 5 months through fissure systems in sandstones Prevention is the most efficient way of protecting groundwater from oil pollution. Preventive surveys are based on the drilling of observation wells at suitable points of the potentially endangered areas. Monitoring of these wells provides timely detection of possible leaks of oil products into the aquifer In the case of an emergency, it is necessary to remove, as soon as possible, the oil substances from the surface or to remove the contaminated soil. When the contaminant has penetrated into the aquifer, the reparatory measures are usually based on hydraulic protection which consists of a system of boreholes. The respective hydrocarbon product is removed from the formation by pumping, the process being speeded up by the change in groundwater flow caused by the creation of depression cones The example of Prague Airport is suitable for describing a successful, although complex and expensive, purification of a Chalk aquiter polluted among other things by a leak amounting to 300 m³ of aviation kerosene. Vapex filters have proven very satisfactory for purifying the contaminated water Preventive protection of groundwater and mineral waters using monitoring devices is being carried out at Karlovy Vary Airport No groundwater pollution has so far been observed in this instance. However, a seasonal variation in the content of hydrocarbons dissolved in groundwater has been established. The highest content occurs in the spring months. Observation wells situated in the tectonic zone can also be utilized for reparative pumping     

Effects of rainwater-harvesting-induced artificial recharge on the groundwater of wells in Rajasthan, India

In light of the increasing deterioration of groundwater supplies in Rajasthan, India, rainwater harvesting practices in southern Rajasthan were studied to determine the effects of artificially recharged groundwater on the supply and quality of local groundwater. A physical and geochemical investigation utilizing environmental tracers (δ¹⁸O and Cl^–), groundwater level and groundwater quality measurements, and geological surveys was conducted with two objectives: (1) to quantify the proportion of artificially recharged groundwater in wells located near rainwater harvesting structures and (2) to examine potential effects of artificial recharge on the quality of groundwater in these wells. A geochemical mixing model revealed that the proportion of artificial recharge in these wells ranged from 0 to 75%. Groundwater tracer, water table, and geological data provided evidence of complex groundwater flow and were used to explain the spatial distribution of artificial recharge. Furthermore, wells receiving artificial recharge had improved groundwater quality. Statistical analysis revealed a significant difference between the water quality in these wells and wells determined not to receive artificial recharge, for electrical conductivity and SO ₄ ^– . The findings from this study provide quantitative evidence that rainwater harvesting structures in southern Rajasthan influence the groundwater supply and quality of nearby wells by artificially recharging local groundwater.