皖北矿区煤层底板岩溶水水化学特征研究

分析了皖北矿区煤层底板岩溶水常规离子水化学特征,并采用常规离子水质浓度梯度和Ca2+水化学平衡两种分析方法,对皖北矿区岩溶系统水循环特征进行了研究,指出岩溶水系统在矿区内TDS和△[Ca2+]值由北向南呈逐渐增高的趋势,北部有一个低TDS与△[Ca2+]值带,南部有两高TDS与高△[Ca2+]值带。      

Environmental isotopic and hydrochemical characteristics of groundwater systems in Daying and Qicun geothermal fields,Xinzhou Basin,Shanxi, China

The conceptual hydrogeological model of the low to medium temperature Daying and Qicun geothermal fields has been proposed, based on hydrochemical characteristics and isotopic compositions. The two geothermal fields are located in the Xinzhou basin of Shanxi, China and exhibit similarities in their broad‐scale flow patterns. Geothermal water is derived from the regional groundwater flow system of the basin and is characterized by Cl·SO₄‐Na type. Thermal water is hydrochemically distinct from cold groundwater having higher total dissolved solids (TDS) (>0·8 g/l) and Sr contents, but relatively low Ca, Mg and HCO₃ contents. Most shallow groundwater belongs to local flow systems which are subject to evaporation and mixing with irrigation returns. The groundwater residence times estimated by tritium and ¹⁴C activities indicate that deep non‐thermal groundwater (130–160 m) in the Daying region range from modern (post‐1950s) in the piedmont area to more than 9·4 ka BP (Before Present) in the downriver area and imply that this water belong to an intermediate flow system. Thermal water in the two geothermal fields contains no detectable active ¹⁴C, indicating long residence times (>50 ka), consistent with this water being part of a large regional flow system. The mean recharge elevation estimated by using the obtained relationship Altitude (m) = ? 23·8 × δ²H (‰ ) ? 121·3, is 1980 and 1880 m for the Daying and Qicun geothermal fields, respectively. The annual infiltration rates in the Daying and Qicun geothermal fields can be estimated to be 9029 × 10³ and 4107 × 10³ m³/a, respectively. The variable ⁸⁶Sr/⁸⁷Sr values in the thermal and non‐thermal groundwater in the two fields reflect different lithologies encountered along the flow path(s) and possibly different extents of water‐rock interaction. Based on the analysis of groundwater flow systems in the two geothermal fields, hydrogeochemical inverse modelling was performed to indicate the possible water‐rock interaction processes that occur under different scenarios. Copyright © 2010 John Wiley & Sons, Ltd.     

Identification of groundwater recharge sources and processes in a heterogeneous alluvial aquifer: results from multi‐level monitoring of hydrochemistry and environmental isotopes in a riverside agricultural area in Korea

We evaluated sources and pathways of groundwater recharge for a heterogeneous alluvial aquifer beneath an agricultural field, based on multi‐level monitoring of hydrochemistry and environmental isotopes of a riverside groundwater system at Buyeo, Korea. Two distinct groundwater zones were identified with depth: (1) a shallow oxic groundwater zone, characterized by elevated concentrations of NO₃^? and (2) a deeper (>10–14 m from the ground surface) sub‐oxic groundwater zone with high concentrations of dissolved Fe, silica, and HCO₃^?, but little nitrate. The change of redox zones occurred at a depth where the aquifer sediments change from an upper sandy stratum to a silty stratum with mud caps. The δ¹⁸O and δ²H values of groundwater were also different between the two zones. Hydrochemical and δ¹⁸O? δ²H data of oxic groundwater are similar to those of soil water. This illustrates that recharge of oxic groundwater mainly occurs through direct infiltration of rain and irrigation water in the sandy soil area where vegetable cropping with abundant fertilizer use is predominant. Oxic groundwater is therefore severely contaminated by agrochemical pollutants such as nitrate. In contrast, deeper sub‐oxic groundwater contains only small amounts of dissolved oxygen (DO) and NO₃^?. The ³H contents and elevated silica concentrations in sub‐oxic groundwater indicate a somewhat longer mean residence time of groundwater within this part of the aquifer. Sub‐oxic groundwater was also characterized by higher δ¹⁸O and δ²H values and lower d‐excess values, indicating significant evaporation during recharge. We suggest that recharge of sub‐oxic groundwater occurs in the areas of paddy rice fields where standing irrigation and rain water are affected by strong evaporation, and that reducing conditions develop during subsequent sub‐surface infiltration. This study illustrates the existence of two groundwater bodies with different recharge processes within an alluvial aquifer. Copyright © 2009 John Wiley & Sons, Ltd.     

Hydrological and isotopic characterization of river water,groundwater, and groundwater recharge in the Heihe River basin,northwestern China

We used hydrochemistry and environmental isotope data (δ¹⁸O, δD, tritium, and ¹⁴C) to investigate the characteristics of river water, groundwater, and groundwater recharge in China's Heihe River basin. The river water and groundwater could be characterized as Ca²⁺? Mg²⁺? HCO₃^?? SO₄^2? and Na⁺? Mg²⁺? SO₄^2?? Cl^? types, respectively. Hydrogeochemical modelling using PHREEQC software revealed that the main hydrogeochemical processes are dissolution (except for gypsum and anhydrite) along groundwater flow paths from the upper to middle Heihe reaches. Towards the lower reaches, dolomite and calcite tend to precipitate. The isotopic data for most of the river water and groundwater lie on the global meteoric water line (GMWL) or between the GMWL and the meteoric water line in northwestern China, indicating weak evaporation. No direct relationship existed between recharge and discharge of groundwater in the middle and lower reaches based on the isotope ratios, d‐excess, and ¹⁴C values. On the basis of tritium in precipitation and by adopting an exponential piston‐flow model, we evaluated the mean residence time of shallow groundwater with high tritium activities, which was around 50 years (a). Furthermore, based on the several popular models, it is calculated that the deep groundwaters in piedmont alluvial fan zone of the middle reaches and in southern part of the lower reaches are modern water, whereas the deep groundwaters in the edge of the middle reaches and around Juyan Lake in the lower reaches of Heihe river basin are old water. Copyright © 2010 John Wiley & Sons, Ltd.     

Hydrological influences on hyporheic water quality: implications for salmon egg survival

The spatial and temporal variability of groundwater–surface‐water (GW–SW) interactions was investigated in an intensively utilized salmon spawning riffle. Hydrochemical tracers, were used along with high‐resolution hydraulic head and temperature data to assess hyporheic dynamics. Surface and subsurface hydrochemistry were monitored at three locations where salmon spawning had been observed in previous years. Temperature and hydraulic head were monitored in three nests of three piezometers located to characterize the head, the run and the tail‐out of the riffle feature. Hydrochemical gradients between surface and subsurface water indicated increasing GW influence with depth into the hyporheic zone. Surface water was characterized by high dissolved oxygen (DO) concentrations, low alkalinity and conductivity. Hyporheic water was generally characterized by high levels of alkalinity and conductivity indicative of longer residence times, and low DO, indicative of reducing conditions. Hydrochemical and temperature gradients varied spatially over the riffle in response to changes in local GW–SW interactions at the depths investigated. Groundwater inputs dominated the head and tail of the riffle. The influence of SW increased in the area of accelerating flow and decreasing water depth through the run of the riffle. Temporal GW–SW interactions also varied in response to changing hydrological conditions. Gross changes in hyporheic hydrochemistry were observed at the weekly scale in response to changing flow conditions and surface water inputs to the hyporheic zone. During low flows, caused by freezing or dry weather, hyporheic hydrochemistry was dominated by GW inputs. During higher flows hyporheic hydrochemistry indicated that SW contributions increased. In addition, high‐resolution hydraulic head data indicated that rapid changes in GW–SW interactions occurred during hydrological events. The spatial, and possibly the temporal, variability of GW–SW interactions had a marked effect on the survival of salmon ova. It is concluded that hyporheic dynamics and their effect on stream ecology should be given increased consideration by fisheries and water resource managers. Copyright © 2004 John Wiley & Sons, Ltd.     

The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes

Our understanding of Lake Vostok, the huge subglacial lake beneath the East Antarctic Ice Sheet, has improved recently through the identification of key physical and chemical interactions between the ice sheet and the lake. The north of the lake, where the overlying ice sheet is thickest, is characterized by subglacial melting, whereas freezing of lake water occurs in the south, resulting in ～210 m of ice accretion to the underside of the ice sheet. The accreted ice contains lower concentrations of the impurities normally found in glacier ice, suggesting a net transfer of material from meltwater into the lake. The small numbers of microbes found so far within the accreted ice have DNA profiles similar to those of contemporary surface microbes. Microbiologists expect, however, that Lake Vostok, and other subglacial lakes, will harbour unique species, particularly within the deeper waters and associated sediments. The extreme environments of subglacial lakes are characterized by high pressures, low temperatures, permanent darkness, limited nutrient availability, and oxygen concentrations that are derived from the ice that provides the meltwater. Copyright © 2002 John Wiley & Sons, Ltd.     

The impact of storm events on solute exports from a glaciated forested watershed in western New York,USA

This study analysed the importance of precipitation events from May 2003 to April 2004 on surface water chemistry and solute export from a 696 ha glaciated forested watershed in western New York State, USA. The specific objectives of the study were to determine: (a) the temporal patterns of solutes within individual storm events; (b) the impact of precipitation events on seasonal and annual export budgets; and (c) how solute concentrations and loads varied for precipitation events among seasons as functions of storm intensity and antecedent moisture conditions. Analysis of solute trajectories showed that NH₄⁺, total Al and dissolved organic nitrogen (DON) peaked on the hydrograph rising limb, whereas dissolved organic carbon (DOC) concentrations peaked following the discharge peak. Sulphate and base‐cations displayed a dilution pattern with a minimum around peak discharge. End‐member mixing analysis showed that throughfall contributions were highest on the rising limb, whereas valley‐bottom riparian waters peaked following the discharge peak. The trajectories of NO₃^? concentrations varied with season, indicating the influence of biotic processes on the generation, and hence flux, of this solute. Storm events had the greatest impact on the annual budgets for NH₄⁺, K⁺, total dissolved Al, DON and DOC. Storm events during summer had the greatest impact on seasonal solute budgets. Summer events had the highest hourly discharges and high concentrations of solutes. However, NO₃^? and DOC exports during a spring snowmelt event were considerably more than those observed for large events during other periods of the year. Comparisons among storms showed that season, precipitation amount, and antecedent moisture conditions affected solute concentrations and loads. Concentrations of solutes were elevated for storms that occurred after dry antecedent conditions. Seven of the largest storms accounted for only 15% of the annual discharge, but were responsible for 34%, 19%, 64%, 13%, 39% and 24% of the annual exports of NH₄⁺, K⁺, Al, NO₃^?, DON and DOC respectively. These results suggest that the intense and infrequent storms predicted for future climate‐change scenarios will likely increase the exports of solutes like DOC, DON, NH₄⁺, Al and K⁺ from watersheds. Copyright © 2006 John Wiley & Sons, Ltd.     

贵州省水热型地热资源分布及流体水化学特征

为分析总结贵州省水热型地热资源分布特征和水化学特征,对省内天然温泉和地热井流体进行调查和采样测试,在全面收集已有最新地热勘查资料的基础上,通过地热资源地质勘查、评价相关标准和规范以及流体水化学Piper三线图分析等,划分地热资源类型,分析资源分布、资源富集和热储特征,研究不同构造区、不同热储中流体水文地球化学、微量元素等特征。结果表明: 贵州省水热型地热资源主要分布于黔中及黔北地区,属低温地热资源,类型以隆起(褶皱)断裂型为主,以层状兼带状热储分布最广; 地热流体富集和出露受构造控制明显,在石阡、遵义、贵阳、息烽等地形成以震旦系、寒武系白云岩热储为主的4大地热资源富集区,动态较稳定; 相同构造区和热储中流体水化学特征基本相似,水化学类型总体以重碳酸盐型为主,具有矿化度低、富含锶、偏硅酸、氟、氡等对人体有益的微量元素和放射性成分等特征。     

四川盆地东部高褶带三叠系地层卤水和温泉的地球化学特征及成因

四川盆地是我国著名的大型沉积盆地,地下卤水资源丰富,在川东宣汉地区的川25井曾发现富钾卤水。本文对川东高陡褶皱带三叠系碳酸盐岩地下水的分布和富集进行分析,对川25井和卧57井深层卤水以及仙女山温泉和统景温泉的水化学特征进行总结并探讨其成因。认为当背斜核部的三叠系地层埋藏较深、封闭性较好时,有利于深层卤水的富集;在半开启-开启型背斜中,背斜核部受到强烈的风化侵蚀作用,三叠系地层裸露地表,接受大气降水入渗淋滤,不利于高TDS卤水保存。深层卤水的水化学类型均为Cl-Na型,富集Br-、Li-、Sr2-、I-、B3+等微量元素,是同生沉积卤水。其中川25井是少见的高TDS富钾卤水,其TDS达352.693g/L,已达到泻利盐沉积阶段,K+异常富集,达25.955g/L。仙女山温泉和统景温泉地下热水为SO4-Ca型,富集Sr2+、F-、偏硅酸等。稳定性同位素δ2 H、δ18 O数据显示川东深层卤水均起源于古海水,仙女山温泉和统景温泉地下热水补给来源为大气降水。地下水在背斜核部三叠系裸露区接受大气降水的入渗补给,经历深循环获得加热后在地形较低的河谷处呈温泉出露。地下(热)水为溶滤围岩形成TDS不高(2~3g/L)的地下水,其总体趋势是朝着淡化的方向发展。     

Condensation water in heritage touristic caves: Isotopic and hydrochemical data and a new approach for its quantification through image analysis

Condensation water is a major factor in the conservation of heritage caves. It can cause dissolution of the rock substrate (and the pigments of rock art drawn on it) or covering thereof with mineral components, depending on the chemical saturation degree of the condensation water. In show caves, visitors act as a source of CO₂ and thus modify the microclimate, favouring negative processes that affect the conservation of the caves. In spite of their interest, studies of the chemical composition of this type of water are scarce and not very detailed. In this work we present research on the condensation water in the Nerja Cave, one of the main heritage and tourist caves in Europe. The joint analysis of isotopic, hydrochemical, mineralogical and microbiological data and the use of image analysis have allowed us to advance in the knowledge of this risk factor for the conservation of heritage caves, and to demonstrate the usefulness of image analysis to quantify the scope of the possible corrosion condensation process that the condensation water could be producing on the bedrock, speleothem and rock art. To our knowledge, this application of image analysis (relative to the condensation water in caves) is the first one of this type that has been documented.