Hydrochemical investigation on the clastic and carbonate aquifers of Kuwait

The field pH and contents of basic cations, anions, total alkalinity and other aqueous species have been measured in 89 groundwater samples collected from clastic sediments and carbonate aquifers of Kuwait. The mean molar ratio of Mg²⁺/Ca²⁺ is 0.63 and 0.48 for the carbonate and clastic aquifers respectively, indicating that the groundwater of the carbonate aquifer is in equilibrium with calcite and dolomite, the calculated mean PCO₂ of the clastic and carbonate aquifers suggesting a deep closed environment system. The clastic aquifer is supersaturated with respect to calcite, aragonite, quartz and chalcedony, undersaturated to near-saturated with dolomite and undersaturated with respect to gypsum, anhydrite and halite, whereas the carbonate aquifer is supersaturated with respect to dolomite, calcite, aragonite and quartz but undersaturated with anhydrite, gypsum and halite. The salinity of both aquifers increases in the direction of flow. The water types are dominantly NaCl and Na₂SO₄ in the clastic aquifer and Na₂SO₄, CaSO₄ and NaCl in the carbonate aquifer. Electronic Publication     

Hydrogeological and Hydrochemical Study of the Al-Shagaya Field-F, Kuwait

The study area, Al-Shagaya Field-F, is located at the south western part of Kuwait and includes twenty-seven production water wells, tapping the Kuwait Group aquifer. The main objectives of this study were to identify the aquifer type, determine its properties, outline the geological factors and the hydrochemical processes that control the quality of the groundwater of the study area, and to assess the water quality of the Kuwait Group aquifer. Analyses of aquifer test data revealed that the Kuwait Group aquifer acts as a semi-confined to confined aquifer, with a range of transmissivity values between 103 and 1,198 m²/day. The initial water level ranges from 70 to 146 m (M.S.L). The estimated quantity of groundwater entering the study area is about 12,950 m³/day. The chemical analyses show that the groundwater of the study area is a brackish water type, with total dissolved solids ranging from 3,586 to 5,334 mg/l. The aquifer salinity increases in the direction of regional flow towards the NE. The average pH value is 7.7 and the average electrical conductivity is 5,349 s/cm. Groundwater is highly concentrated with Na⁺, Ca²⁺, Cl^- and SO₄^2- and is depleted in HCO₃^- and Mg²⁺ ions. It is characterized by secondary salinity, where the alkaline earths exceed the alkalies and strong acids exceed weak acids. Three groundwater chemical types are recognized: NaCl, Na₂SO₄ and CaCl₂. The NaCl water type is the most abundant in the study area. The main genetic types of water are: MgCl₂ and Na₂SO₄. It is found that the groundwater is oversaturated with respect to aragonite and calcite and undersaturated with respect to anhydrite, gypsum, halite and dolomite. A comparison of the hydrochemical coefficients of Na⁺/Cl^-, SO₄^2-/Cl^- and Ca²⁺/Mg²⁺ in the study area with those of seawater and river water shows that the groundwater of the study area is a mixture of marine and continental water.     

Nitrate and chloride concentrations in the high plains aquifer,Texas

Groundwater nitrate and chloride concentrations were compiled for 122 wells in a rural, three‐county area of northwest Texas. The counties are located on the High Plains aquifer, a major source of groundwater in the region. Cropland/pasture is the predominant land use in the study area. The area also contains numerous cattle feedlots. Fertilizer and manure associated with those land uses are potential sources of ground‐water contamination. Although locally elevated above background levels, none of the chemical concentrations exceeded the primary drinking water standard of 44.27 mg/L for nitrate (10mg/L for NO₃ — N) or secondary standard of 250mg/L for chloride. Rank correlations between nitrate and chloride were statistically significant in two of the three counties, where the solutes may have originated from a common surface source. Denitrification and scant precipitation recharge may account for an absence of nitrate levels above the drinking water standard.     

Hydrogeochemistry along the flow path of a confined aquifer,Düzce plain,north western Turkey

The Düzce plain is formed of Quaternary deposits derived from the surrounding hills, which feed water to three aquifers. The groundwater flow direction in the first confined aquifer is towards Efteni Lake and the Büyük Melen River. Generally the waters have a low concentration of minerals adjacent to the hills from which they are recharged while the groundwater increases in mineral content as it passes through the confined aquifer. Although Ca²⁺, HCO₃ ⁻, total hardness, TDS-EC and Na⁺ values increase along the groundwater flow path, they remain within the limits specified by standards related to drinkability and industrial/agricultural usages.      

天津潜水含水层介质有效孔隙度的渗透试验研究

有效孔隙度是地下水运移及污染物迁移扩散分析中重要的水文地质参数,为获取天津地区潜水含水层有效孔隙度的参考值,利用改进的室内一维土柱示踪渗透装置进行了含水层介质有效孔隙度的测试与探究。结果表明:利用土柱示踪渗透试验测试天津地区粉土、粉砂介质的有效孔隙度是可行的。受介质平均粒径d₅₀、不均匀系数C_u及颗粒级配等因素的影响,测得的不同含水层介质和不同场地相同含水层介质的有效孔隙度存在一定的差异。通过土柱示踪渗透试验,可得天津地区粉土、粉砂介质有效孔隙度的参考值范围分别为18.99%~24.12%和28.66%~33.26%。在实际应用过程中,可在考虑介质颗粒大小及颗粒不均匀程度等因素的基础上,结合此次试验结果在合理范围内进行取值。     

Shallow aquifer resources in the federal capital territory of Nigeria

Public water supply to the Federal Capital Territory (FCT) of Nigeria is inadequate and an alternative source of water includes streams, hand-dug wells and boreholes. A survey showed that 41% of the territory uses hand-dug wells, while 23% depends on boreholes and 16% depends on streams. Measurements were taken from 84 wells in 2002 and 2003 to assess the contribution of hand-dug wells. The parameters considered include ground surface elevation, water level, permeability and well yield. The well diameter ranged between 0.7 and 1.2 m, while the depth ranged between 4.5 and 16 m. The permeability ranged between 0.000518 and 0.002541 cm/s. The source of recharge to the aquifer is rain, and well productivity ranged between 211 and 1806 L/day. Wells located in seven out of nine groups considered cannot meet the water demand of an average household (20 people) in the territory.     

补给区温度季节性周期波动对承压含水层温度影响的解析研究

本文介绍了补给区温度季节性周期波动对承压含水层温度的影响,建立了相应的数学模型,并导出了其解析解。通过对该解析解的分析表明:补给区温度的季节性波动会导致含水层中温度的周期性波动,其波动幅度随与补给区距离的增加而减小,并具有一定的时间滞后性,且含水层中温度的波动情况与含水层的热容量和地下水的流速有关。还发现当含水层自身的热容量发生改变时,含水层中温度波动始终围绕着同一个均值进行波动,只有振幅和相位上发生相应变化,而当含水层中地下水的流速发生改变时,含水层中温度波动的均值也发生相应改变。对于含水层中没有温度波动的区域,温度随距补给区水平距离的变化率与含水层的热容量和地下水流速无关。     

Modflow软件在矿山地质环境保护与恢复治理方案中的应用——以鄂尔多斯盆地某油田为例

含水层预测评估及地下水监测点布设是矿山地质环境保护与土地复垦方案中的重要部分,鉴于目前矿山地质环境保护与土地复垦方案中含水层预测评估多采用定性评估,很难有针对性地提出地下水防治与监测措施。文章以甘肃鄂尔多斯盆地某油田为例,利用Modflow软件建立地下水数值模型,通过数值模型的建立与校正,预测油田建设、施工对地下水环境影响,使含水层预测评估从定性评估趋于定量评估。     

地源热泵系统工作井优化布设地下水热量运移模拟

针对地源热泵空调系统工作井优化布设问题,通过建立理想的＂对井抽-灌＂概念及数学模型,模拟拟建地下水源热泵系统特定水流及热源条件下抽水、回灌井不同间距夏季运行期间地下水热量运移过程,为抽、灌井合理间距确定等实际应用提供理论参考和依据。根据数值模拟结果,抽、灌井不同井间距对该热泵系统夏季运行期间地下水热量运移过程影响显著;...     

基于承压含水层水力响应的溪洛渡水电工程区谷幅收缩变形预测研究

溪洛渡高拱坝位于一个向斜盆地内,区域水文地质的一个典型特征是盆地内下覆有一个完整延伸的阳新灰岩承压含水层。水库蓄水以来上下游库岸边坡发生了明显的谷幅收缩变形,主要是由于水库蓄水引起承压含水层孔隙水压力增加,从而引起灰岩地层因有效应力减小而产生膨胀,以及相对隔水层底板扬压力增加所引起的。基于承压含水层水力响应规律,建立了谷幅收缩变形反演及预测的解析模型,分别预测了在变形速率小于0.01,0.001mm/d两个收敛准则下的谷幅收缩变形收敛时间以及收敛值。所建立的反演预测模型能够较好地重现谷幅收缩变形历时曲线,反映出谷幅收缩变形与库水位变化具有高度的相关性。模型预测结果显示,溪洛渡水电工程的谷幅收缩变形已趋于收敛。     

Evaluation of a pressure pulse in a fractured‐rock aquifer to reduce uncertainty of hydraulic conductivity measurements,Rio Grande Rift,New Mexico,United States

Fractured‐rock aquifers are inherently difficult for determining flow dynamics because of variability in fracture orientation and extension. A confined, fractured‐rock aquifer in a semi‐arid mountainous area of the Rio Grande Rift Zone was analysed for its response to recharge events that produced a pressure pulse within its potentiometric surface. The pulse was evaluated at the well scale and subaquifer level to evaluate flowpaths, travel times and dispersion and compare the bulk‐scale aquifer response to possible velocities from slug test hydraulic conductivity measurements. Travel time and dispersion from the pulse proved comparable to probable travel times based on hydraulic conductivity measurements. Evaluation of the pressure pulse and the hydraulic conductivity measurements allowed for a holistic interpretation of the fractured‐rock aquifer through analysis of two distinct data sets that provided corroborative evidence of flow dynamics and fracture connectivity. This holistic approach reduced uncertainty regarding the individual hydraulic conductivity values.     

俄罗斯远东地区铜成矿作用及资源潜力

俄罗斯远东地区铜矿资源潜力巨大,且开发程度低,是我国未来重要的资源潜在来源地。文章通过对远东地区铜矿床的成矿特征进行系统的总结,将其分为4个主要的铜成矿类型,分别为沉积型、块状硫化物型、铜镍硫化物型和斑岩型,并总结了每个成矿类型的铜成矿作用特征,分析了远东地区的铜资源潜力。认为铜镍硫化物型和斑岩型铜矿是俄罗斯远东地区最具潜力的铜矿成因类型,是未来远东地区铜矿开发与利用的重点。     

The role of organic matter in the removal of emerging trace organic chemicals during managed aquifer recharge

This study explored the effect of different bulk organic carbon matrices on the fate of trace organic chemicals (TOrC) during managed aquifer recharge (MAR). Infiltration through porous media was simulated in biologically active column experiments under aerobic and anoxic recharge conditions. Wastewater effluent derived organic carbon types, differing in hydrophobicity and biodegradability (i. e., hydrophobic acids, hydrophilic carbon, organic colloids), were used as feed substrates in the column experiments. These carbon substrates while fed at the same concentration differed in their ability to support soil biomass growth during porous media infiltration. Removal of degradable TOrC (with the exception of diclofenac and propyphenazone) was equal or better under aerobic versus anoxic porous media infiltration conditions. During the initial phase of infiltration, the presence of biodegradable organic carbon (BDOC) enhanced the decay of degradable TOrC by promoting soil biomass growth, suggesting that BDOC served as a co-substrate in a co-metabolic transformation of these contaminants. However, unexpected high removal efficiencies were observed for all degradable TOrC in the presence of low BDOC concentrations under well adopted oligotrophic conditions. It is hypothesized that removal under these conditions is caused by a specialized microbial community growing on refractory carbon substrates such as hydrophobic acids. Findings of this study reveal that the concentration and character of bulk organic carbon present in effluents affect the degradation efficiency for TOrC during recharge operation. Specifically aerobic, oligotrophic microbiological soil environments present favorable conditions for the transformation of TOrC, including rather recalcitrant compounds such as chlorinated flame retardants.     

A decision support system for water quality issues in the Manzanares River (Madrid, Spain)

The Manzanares River, located in Madrid (Spain), is the main water supplier of a highly populated region, and it also receives wastewater from the same area. The effluents of eight Waste Water Treatment Plants (WWTPs) downstream of the river, which represent 90% of the flow in the middle and lower parts of the river, are the primary sources of water pollution. Although the situation has improved slightly in the last two years, the water in the river is highly polluted, making it uninhabitable for aquatic life. Water quality modelling is typically used to assess the effect of treatment improvements in water bodies. In this work, the GESCAL module of the Aquatool Decision Support System Shell was used to simulate water quality in the Manzanares River. GESCAL is appropriate for modelling in an integrated way water quality for whole water resources systems, including reservoirs and rivers. A model was built that simulates conductivity, phosphorous, carbonaceous organic matter, dissolved oxygen, organic nitrogen, ammonia, and nitrates. The period from October 2006 to September 2008 was selected for calibration due to the many treatment modifications that occurred during this time. An earlier and longer period, from October 2000 to September 2006, was used for validation. In addition, a daily model was used to analyse the robustness of the GESCAL model. Once the GESCAL model was validated, different scenarios were considered and simulated. First, different combinations of nutrient elimination among the different WWTPs were simulated, leading to the conclusion that investments have to focus on three of the proposed WWTPs. Moreover, these treatments will not be sufficient to maintain fish habitat conditions at all times. Additional measures, such as the increment of the flow in the river or oxygen injection, were simulated. Incrementing the flow of the Manzanares River has been shown to be an efficient means of increasing water quality, but this implies an increment in the risk of water scarcity situations in the Madrid water supply system.     

Role of biodegradation in the removal of pharmaceutically active compounds with different bulk organic matter characteristics through managed aquifer recharge: batch and column studies

Natural water treatment systems such as bank filtration have been recognized as providing effective barriers in the multi-barrier approach for attenuation of organic micropollutants for safe drinking water supply. In this study, the role of biodegradation in the removal of selected pharmaceutically active compounds (PhACs) during soil passage was investigated. Batch studies were conducted to investigate the removal of 13 selected PhACs from different water sources with respect to different sources of biodegradable organic matter. Neutral PhACs (phenacetine, paracetamol, and caffeine) and acidic PhACs (ibuprofen, fenoprofen, bezafibrate, and naproxen) were removed with efficiencies greater than 88% from different organic matter water matrices during batch studies (hydraulic retention time (HRT): 60 days). Column experiments were then performed to differentiate between biodegradation and sorption with regard to the removal of selected PhACs. In column studies, removal efficiencies of acidic PhACs (e.g., analgesics) decreased under conditions of limited biodegradable carbon. The removal efficiencies of acidic PhACs were found to be less than 21% under abiotic conditions. These observations were attributed to sorption under abiotic conditions established by a biocide (20 mM sodium azide), which suppresses microbial activity/biodegradation. However, under biotic conditions, the removal efficiencies of these acidic PhACs were found to be greater than 59%. This is mainly attributed to biodegradation. Moreover, the average removal efficiencies of hydrophilic (polar) neutral PhACs (paracetamol, pentoxifylline, and caffeine) with low octanol/water partition coefficients (log K_ow less than 1) were low (11%) under abiotic conditions. However, under biotic conditions, removal efficiencies of the neutral PhACs were greater than 98%. In contrast, carbamazepine persisted and was not easily removed under either biotic or abiotic conditions. This study indicates that biodegradation represents an important mechanism for the removal of PhACs during soil passage.     

印度尼西亚苏拉威西岛北部Buol县砂金矿地质特征及成因浅析

苏拉威西岛位于印度尼西亚群岛的中心,在其北部分布大量砂金矿。通过对Boul县砂金源区的矿体规模、矿化特征、成矿类型和剥蚀淋滤程度调查,结合河谷砂金现场淘洗和试生产情况,认为砂金主要富集于河流中游地区,其次为上游地区,具体可归结为富集于河流拐弯处凸岸的“胃口袋”阶地、河流由窄变宽或两条河流汇合呈“Y”型的外侧以及河床坡度由陡变缓地区。该区砂金矿具有“金源丰富”,“成矿时代新”、“离矿源近”、“成矿过程短”的特点。按砂金矿产出位置认为砂金矿成因类型主要是冲积型,其次为洪积型和残坡积型。原生金矿可能是该地区砂金的主要物质来源,原生金矿先后经历风化带中金的次生加大和富集过程(化学成因)→机械搬运和沉积分异作用(机械成因)→形成砂金矿。此认识可为该地区寻找砂金提供一定借鉴意义。     

江西武蛟地热田成因及资源量评价

通过对武蛟地热田已有钻孔及区域地热地质资料,结合前人勘查资料,分析了武蛟乡地热田区域地质特征、地温场分布特征、地热水水化学特征及补径排条件,说明武蛟地热属深循环途中正常大气热流加热火山型地热系统,地热成因模式为断裂岩溶复合型,地热田的热储模型为断裂对流型带状热储。采用热储法计算出研究区内控制级的允许放热量为6. 40×10~5Kca L·h~(-1),推断级的允许放热量为9. 08×10~5Kca L·h~(-1);研究区内年可开采水量为63. 02×10~4m~3。初步摸清武蛟地热田分布规律及资源量,为武蛟地热田地热资源的合理开发利用提供科学依据。     

Application of RANS and LES field simulations to predict the critical ventilation velocity in longitudinally ventilated horizontal tunnels

Field modelling results are presented for well-ventilated horizontal tunnel fires. Both the Reynolds-Averaged Navier–Stokes (RANS) and Large-Eddy Simulations (LES) approaches are applied to model turbulence. Experimental tunnel fires are simulated on a computational tunnel of reduced length. It is shown that this is possible due to the fact that the flow downstream of the fire source becomes essentially one-dimensional. Based on the integral turbulent length scale, obtained from the RANS calculations, a criterion for the local mesh size is provided in order to obtain reliable results with LES simulations. It is illustrated that the accuracy of the LES results strongly depends on the mesh quality. We also show that there is more turbulent thermal diffusion in the LES simulations than in the RANS simulations. The RANS simulations are performed with FLUENT. The realizable k–ε model is used in combination with a buoyancy model based on the generalized gradient diffusion hypothesis. The LES calculations are performed with the Fire Dynamics Simulator of NIST. Predictions of the critical ventilation velocity obtained by RANS and LES are compared.