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1.
This study was based on the analysis of isotopic compositions of hydrogen and oxygen in samples from precipitation, groundwater and stream water. In addition, parts of groundwater samples were dated by carbon-14 and tritium. These data are integrated to provide other views of the hydrologic cycle in the Hsinchu-Miaoli groundwater district. The groundwater district is principally composed of Pleistocene and Holocene aquifers. The Pleistocene aquifers are highly deformed by folding and faults into small sub-districts with areas of only tens of square kilometers. These aquifers are exclusively recharged by local precipitation. The Holocene aquifers cover narrow creek valleys, only tens of meters in thickness. The local meteoric water line (LMWL), constructed from rainfall samples in the Hsinchu Science Park, is described by the equation δD=8.02δ18O+10.16, which agrees with the global meteoric water line. In addition, the precipitation isotopic compositions can be categorized into two distinct end members: typhoon type and monsoon type. The groundwater isotopic compositions are perfectly located on an LMWL and can be considered a mixture of precipitations. Based on the mass balance of isotopic compositions of oxygen and hydrogen, infiltration is more active in the rainy season with depleted isotopic compositions. The amount of infiltration during May–September is roughly estimated to comprise at least 55% of the whole year’s recharge. The isotopic compositions of stream water are expressed by a regression equation: δD=7.61δ18O+9.62, which is similar to the LMWL. Although precipitation isotopic compositions are depleted during summer time, the isotopic compositions contrarily show an enriched trend in the upstream area. This is explained by the opposite altitude effect on isotopic compositions for typhoon-related precipitations.  相似文献   

2.
An investigation using environmental isotopes (δ18O and δD) was conducted to gain insight into the hydrological processes of the Ganga Alluvial Plain, northern India. River-water, shallow-groundwater and lake-water samples from the Gomati River Basin were analyzed. During the winter season, the δ18O and δD compositions of the Gomati River water ranged from ?1.67 to ?7.62 ‰ and ?25.08 to ?61.50 ‰, respectively. Deuterium excess values in the river water (+0.3 to ?13 ‰) and the lake water (?20 ‰) indicate the significance of evaporation processes. Monthly variation of δ18O and δD values of the Gomati River water and the shallow groundwater follows a similar trend, with isotope-depleted peaks for δ18O and δD synchronized during the monsoon season. The isotopically depleted peak values of the river water (δ18O?=??8.30 ‰ and δD?=??57.10 ‰) can be used as a proxy record for the isotopic signature of the monsoon precipitation in the Ganga Alluvial Plain.  相似文献   

3.
【研究目的】揭示武汉北部新城地表水、地下水的氢氧稳定同位素特征及其相互作用。【研究方法】2019年，采集、测定了降水样7件、河水样6件、水库样14件、民井样98件、泉水样3件和钻孔样11件，并收集到武汉站1986—1998年的监测数据50件，以空间分析和流域分析为基础，氢氧稳定同位素分析为手段。【研究结果】（1）武汉降水氢氧同位素随季节变化，并表现出“降雨效应”明显、“温度效应”不明显的特点；（2）地表水在枯水期受到强烈的蒸散发，表现出一定的“地貌效应”与“干支流效应”的特征；（3）民井、泉和钻孔等地下水均源于大气降水，表现出“含水层埋深效应”与“山区平原效应”的特点；（4）枯水期，界河流域中界河获得了上游水库和地下水的补给，夏家寺水库流域中夏家寺水库得到了地下水补给。【结论】氢氧同位素能显著提高武汉北部新城地表水-地下水相互转换规律的认识。创新点：利用各类水体氢氧同位素组成及空间分布特征，揭示了武汉北部新城降水、地表水和地下水相互转换的规律  相似文献   

4.
在第四纪的末次冰期、新冰期和小冰期期间,位于大峡谷入口处的则隆弄跃动冰川发生多次的快速前进,多次发生阻塞雅鲁藏布江事件,在大峡谷以上河段形成4期(Ⅳ~Ⅰ)的林芝古堰塞湖。14 C测年结果指示第2次、第3次和第4次堰塞湖分别发生在9760~11300aB.P.,1220±40~1660±40aB.P.和287±93~394±83aB.P.。估计Ⅳ~Ⅱ期堰塞湖库容量约2150km3,835km3和81km3。冰川阻塞湖坝的溃决释放突发性洪水,对下游的雅鲁藏布大峡谷河段及下游地区的环境产生巨大的影响。  相似文献   

5.
Hundreds of precipitation samples collected from meteorological stations in the Ordos Basin from January 1988 to December 2005 were used to set up a local meteoric water line and to calculate weighted average isotopic compositions of modern precipitation. Oxygen and hydrogen isotopes, with averages of ?7.8‰ and ?53.0‰ for δ18O and δD, respectively, are depleted in winter and rich in spring, and gradually decrease in summer and fall, illustrating that the seasonal effect is considerable. They also show that the isotopic difference between south portion and north portion of the Ordos Basin are not obvious, and the isotope in the middle portion is normally depleted. The isotope compositions of 32 samples collected from shallow groundwater (less than a depth of 150 m) in desert plateau range from ?10.6‰ to ?6.0‰ with an average of ?8.4‰ for δ18O and from ?85‰ to ?46‰ with an average of ?63‰ for δD. Most of them are identical with modern precipitation. The isotope compositions of 22 middle and deep groundwaters (greater than a depth of 275 m) fall in ranges from ?11.6‰ to ?8.8‰ with an average of ?10.2‰ for δ18O and from ?89‰ to ?63‰ with an average of ?76‰ for δD. The average values are significantly less than those of modern precipitation, illustrating that the middle and deep groundwaters were recharged at comparatively lower air temperatures. Primary analysis of 14C shows that the recharge of the middle and deep groundwaters started at late Pleistocene. The isotopes of 13 lake water samples collected from eight lakes define a local evaporation trend, with a relatively flat slope of 3.77, and show that the lake waters were mainly fed by modern precipitation and shallow groundwater.  相似文献   

6.
Paleo-groundwaters of 6000?years BP from the Liwa water-table sand dune aquifer in the Rub al Khali and the Gachsaran artesian carbonate aquifer, on the coast of the Emirate of Abu Dhabi (UAE), exhibit normal ??2H/??18O slopes, modest ??18O increases, and large negative deuterium excess ??d?? (Liwa aquifer: 2.19?? VSMOW and d?=??C15; Gachsaran aquifer: 3.16?? VSMOW and d?=??C28) compared to local Shamal precipitation (0.05?? VSMOW and d?=?7). This unusual isotopic signature is hypothesized to result from re-evaporation of continental runoff to the Red Sea catchment basin. It is postulated that this continental water flowed onto the surface of the Indian Ocean providing a moisture source for the monsoon that dominated precipitation during this, the last wet period in the area from 5000 to 9000 BP. Carbonate precipitation, forming speleothems, travertines, tufas, lacustrine, and capillary-zone deposits, subsequently record this ??18O isotopic signature. This rock record is thus dominated by the water source, rather than environmental conditions of deposition normally assumed to control the rock ??18O isotopic signature. As a consequence, re-evaluation of paleo-climate??18O data from the rock record may be necessary for this time period in southern Arabia.  相似文献   

7.
Recent (<50 years old) freshwater cyanobacterial carbonates from diverse environments (streams, lakes, waterfalls) throughout Britain and Ireland were analysed for their stable carbon and oxygen isotope compositions. The mean δ18O value of ?5–9‰ PDB for river and stream data represents calcite precipitation in equilibrium with the mean oxygen isotopic composition of precipitation in central Britain (?7–5‰SMOW) assuming a mean water temperature of 9°C. The mean δ18O of lake data, ?4–5‰ PDB, is statistically different, reflecting the effects of residence time and/or variations in the oxygen isotopic composition of rainfall. Carbon isotopes have wide variations in both fluviatile and lake data sets (+ 3 to ?12‰ PDB). These variations are principally controlled in the fluviatile samples by contribution of isotopically light ‘soil zone’ carbon relative to isotopically heavier carbon from limestone aquifer rock dissolution. Lake samples have the heaviest carbon isotope values, reflecting a trend toward isotopic equilibrium between atmospheric CO2 and aqueous HCO?3. We infer that isotopic compositions of ancient cyanobacterial carbonates should also record environmental information, although the effects of stabilization and diagenesis on primary δ18O values will need careful consideration. Primary carbon isotope compositions should be well preserved, although in marine samples values will be buffered by the isotopic composition of aqueous marine bicarbonate.  相似文献   

8.
Humidity is one of the fundamental variables controlling the energy balance of the climate, and thus its reconstruction represents a significant aspect of paleoclimate studies. We here report a study of oxygen and hydrogen isotopic compositions of tree-ring cellulose along a precipitation gradient in the Olympic Mountains of Washington, USA, to examine whether and how the relative humidity is recorded in the cellulose. According to the physically-based model described in this paper, the relationship between δD and δ18O of cellulose should have the same slope as that in the relationship between δD and δ18O in the source water (∼8.8 for the local meteoric water) if there is no systematic variation in the mean relative humidity among study sites and no physiologic differences among trees. However, our isotopic analyses of cellulose yielded a slope of 17.4, significantly greater than the slope of the Local Meteoric Water Line. We show that to produce such a slope, a positive covariation between the relative humidity and the δD and δ18O in the source water is required across the precipitation gradient. This work suggests that the δD vs. δ18O relationship in tree rings can be a useful tool for paleohumidity reconstruction.  相似文献   

9.
The Ganges River water and riverbank shallow groundwater were studied during a single wet season using the hydrochemical and isotopic composition of its dissolved load. The dissolved concentrations of major ions (Cl?, SO4 2?, NO3 ?, HCO3 ?, Ca2+, Na+, Mg2+, and K+), trace elements (barium (Ba) and strontium (Sr)) and stable isotopes (O and D) were determined on samples collected from the Ganges River and its riverbank shallow aquifers. In the present study, the shallow groundwater differs significantly from the Ganges River water; it shows distinct high concentrations of Ca2+, Mg2+, HCO3 ?, Ba, and Sr due to water–rock interaction and this in particular suggests that the Ganges River may not contribute significantly to the riverbank shallow aquifers during wet season. Besides, the sum of the total cationic charge (∑+, in milliequivalents per liter) in the groundwater shows high values (2.48 to 13.91 meq/L, average 9.12 meq/L), which is much higher than the sum of the cations observed in the Ganges water (1.36 to 3.10 meq/L, average 1.94 meq/L). Finally, the more depleted stable isotopic (δ 18O and δ 2H) compositions of the Ganges River water are in contrast to those of the riverbank aquifer having enriched stable isotopic values during the wet season and the riverbank groundwater thus has a purely local origin from precipitation.  相似文献   

10.
The clay fractions of sedimentary kaolin deposits representing different ages (Carboniferous and Cretaceous), types (pisolitic flint and plastic), and localities (Sinai and Aswan) from Egypt were analyzed for their H and O isotopic compositions to examine the paleoclimate conditions during their formation. The δD values of the Carboniferous deposits in Sinai range between −67‰ and −88‰, while the values for the Cretaceous deposits in Sinai range between −59‰ and −75‰. The δ18O values of the Carboniferous deposits range from 17.9‰ to 19.4‰ and the values for the Cretaceous deposits range between 19.2‰ and 20.4‰. The relatively low δD and δ18O values of the Carboniferous deposit at the Abu Natash area (−67‰ and 17.9‰, respectively) compared to other Carboniferous deposits (averages of −83.3‰, and 18.8‰ for δD and δ18O, respectively) could be due to isotopic exchange between this deposit and the adjacent dolomite and/or the enclosed hydrothermally-formed Mn ores of the Carboniferous Um Bogma Formation. The δD and δ18O values of the Cretaceous pisolitic flint kaolin deposit from Aswan (averages of −65‰ and 20.3‰, respectively) and plastic kaolin from the same area (averages of −66‰ and 19.5‰, respectively) are almost identical. The differences in the δ18O values between the clay fractions of the pisolitic flint kaolin (20.3‰) and the previously analyzed bulk kaolin of the same deposit (average of 17.5‰) suggest a significant effect of non-clay minerals on the isotopic compositions of the kaolin deposits.The H and O isotopic compositions plot close to the kaolinite line that marks the isotopic composition of kaolinite in equilibrium with meteoric water at 20 °C. This indicates that the kaolinite from both the Carboniferous and Cretaceous deposits in Egypt formed by meteoric water weathering of the source rock(s). The δD and δ18O values also suggest that kaolinite of these deposits formed under warm-temperate to tropical conditions. The slight deviations of some samples from the kaolinite line suggest post-depositional modifications of the isotopic compositions of studied deposits probably due to the interaction between earlier-formed kaolinite and downward percolating meteoric water.The δD and δ18O values of the Cretaceous and Carboniferous deposits from all localities suggest that both deposits formed under similar climatic conditions due to the location of Egypt at almost the same distance from the equator either to the south during the Carboniferous or to the north during the Cretaceous.  相似文献   

11.
Many cities around the world are developed at alluvial fans. With economic and industrial development and increase in population, quality and quantity of groundwater are often damaged by over-exploitation in these areas. In order to realistically assess these groundwater resources and their sustainability, it is vital to understand the recharge sources and hydrogeochemical evolution of groundwater in alluvial fans. In March 2006, groundwater and surface water were sampled for major element analysis and stable isotope (oxygen-18 and deuterium) compositions in Xinxiang, which is located at a complex alluvial fan system composed of a mountainous area, Taihang Mt. alluvial fan and Yellow River alluvial fan. In the Taihang mountainous area, the groundwater was recharged by precipitation and was characterized by Ca–HCO3 type water with depleted δ18O and δD (mean value of −8.8‰ δ18O). Along the flow path from the mountainous area to Taihang Mt. alluvial fan, the groundwater became geochemically complex (Ca–Na–Mg–HCO3–Cl–SO4 type), and heavier δ18O and δD were observed (around −8‰ δ18O). Before the surface water with mean δ18O of −8.7‰ recharged to groundwater, it underwent isotopic enrichment in Taihang Mt. alluvial fan. Chemical mixture and ion exchange are expected to be responsible for the chemical evolution of groundwater in Yellow River alluvial fan. Transferred water from the Yellow River is the main source of the groundwater in the Yellow River alluvial fan in the south of the study area, and stable isotopic compositions of the groundwater (mean value of −8.8‰ δ18O) were similar to those of transferred water (−8.9‰), increasing from the southern boundary of the study area to the distal end of the fan. The groundwater underwent chemical evolution from Ca–HCO3, Na–HCO3, to Na–SO4. A conceptual model, integrating stiff diagrams, is used to describe the spatial variation of recharge sources, chemical evolution, and groundwater flow paths in the complex alluvial fan aquifer system.  相似文献   

12.
As part of the AIRMoN program, daily precipitation samples have been collected since the early 1990s throughout the eastern and central United States. Using precipitation stable isotope (δ18O and δD) and HYSPLIT back trajectory analysis of 591 samples collected by the AIRMoN program from Florida, Illinois, Pennsylvania, Tennessee, Vermont, and West Virginia, amount weighted seasonal average isotopic compositions were calculated for precipitation from Continental, Pacific, Gulf of Mexico, Arctic, North Atlantic, and Mid Atlantic sources. Our results suggest that these sources are isotopically distinct and variable at and among most sites during most seasons. However, in many instances, the isotopic differences of the sources require dramatic changes in precipitation amounts from these sources to modify the seasonal average isotopic composition at a particular site. The relative importance of each source type to the seasonal average isotopic composition is highly variable among and within sites. The largest differences in the isotopic compositions of different sources are in winter and spring precipitation from the high latitude sites. At the Vermont location, the seasonal average isotopic composition is potentially quite sensitive to the relative amounts of precipitation from Arctic and Gulf of Mexico sources.  相似文献   

13.
采用1961-2010年雅鲁藏布江流域6个气象站近50 a降水量的实测数据,统计降水量的年、干季、湿季平均序列;结合流域6个水文站近50 a年径流序列资料,分析雅鲁藏布江流域降水变化特征及其对径流量的影响. 研究表明： 雅鲁藏布江流域1961-2010年近50 a年平均降水量表现为不显著增加,增加速率为3.3 mm·（10a）-1,其中干季、湿季分别为1.9 mm·（10a）-1 和1.4 mm·（10a）-1,均为增加趋势;降水量的年代际变化在20世纪60年代相对偏多,70年代较平稳,而80年代为最少,到90年代有所回升,21世纪前10 a降水量处于不显著的增多态势. 雅鲁藏布江径流的变差系数CV值在0.15~0.40之间,年际变化较小. 径流的年代际变化总体上存在一定的周期性波动,20世纪60年代是一个相对的丰水期,70年代减少,80年代达到最小值,之后径流有所回升,进入21世纪前10 a呈不显著增加趋势. 年、湿季尺度上径流量和降水量的相关显著,湿季作为径流主要形成期,其降水量的多寡直接影响流域径流量的丰枯,湿季降水量的增减影响着流域径流量的增减. 由此可见,降水变化是雅鲁藏布江天然径流最主要影响因子,最终也决定了雅鲁藏布江流域年径流量的丰枯.  相似文献   

14.
Meteoric sphaerosiderite lines (MSLs), defined by invariant δ18O and variable δ13C values, are obtained from ancient wetland palaeosol sphaerosiderites (millimetre‐scale FeCO3 nodules), and are a stable isotope proxy record of terrestrial meteoric isotopic compositions. The palaeoclimatic utility of sphaerosiderite has been well tested; however, diagenetically altered horizons that do not yield simple MSLs have been encountered. Well‐preserved sphaerosiderites typically exhibit smooth exteriors, spherulitic crystalline microstructures and relatively pure (> 95 mol% FeCO3) compositions. Diagenetically altered sphaerosiderites typically exhibit corroded margins, replacement textures and increased crystal lattice substitution of Ca2+, Mg2+ and Mn2+ for Fe2+. Examples of diagenetically altered Cretaceous sphaerosiderite‐bearing palaeosols from the Dakota Formation (Kansas), the Swan River Formation (Saskatchewan) and the Success S2 Formation (Saskatchewan) were examined in this study to determine the extent to which original, early diagenetic δ18O and δ13C values are preserved. All three units contain poikilotopic calcite cements with significantly different δ18O and δ13C values from the co‐occurring sphaerosiderites. The complete isolation of all carbonate phases is necessary to ensure that inadvertent physical mixing does not affect the isotopic analyses. The Dakota and Swan River samples ultimately yield distinct MSLs for the sphaerosiderites, and MCLs (meteoric calcite lines) for the calcite cements. The Success S2 sample yields a covariant δ18O vs. δ13C trend resulting from precipitation in pore fluids that were mixtures between meteoric and modified marine phreatic waters. The calcite cements in the Success S2 Formation yield meteoric δ18O and δ13C values. A stable isotope mass balance model was used to produce hyperbolic fluid mixing trends between meteoric and modified marine end‐member compositions. Modelled hyperbolic fluid mixing curves for the Success S2 Formation suggest precipitation from fluids that were < 25% sea water.  相似文献   

15.
The geochemical and isotopic compositions of river water are controlled by different factors. The seasonal and spatial variations in the geochemical composition, δD, δ18O, and δ15N–NO3 of the Kumho River were investigated to reveal the geochemical processes occurring at different seasons. The Kumho River, which runs through different geologic terrains with different land use characteristics, is the largest tributary of the Nakdong River, the longest river in South Korea. The data varied significantly according to the land use and the season. Each monitoring station showed the lowest concentrations of various ions during July, the rainy season, due to the increase of precipitation rate. The ionic concentrations gradually increased downstream by the mineral weathering and anthropogenic activity. At the upper regions of the river, Ca and HCO3, which are closely associated with mineral weathering, were the most dominant cation and anion, respectively. The relatively high Si concentration of the headwater samples, caused by the weathering of volcanic rocks, also showed the importance of weathering in the upper regions mainly composed of volcanic rocks. The downstream regions of the Kumho River are mainly influenced by sedimentary rocks. At the lower reaches of the river, especially near the industrial complexes in Daegu, the third largest city in Korea, Na, Cl, and SO4 became the dominant ions, indicating that the anthropogenic pollution became more important in regulating the chemical composition of the river. The increasing (Ca + Mg + Na + K)/HCO3 ratio downstream also indicates that the anthropogenic effects became more important as the river flows downstream. The isotopic compositions of δD and δ18O indicate that the river waters were significantly affected by evaporation during May and July, but the evaporation effect was relatively low during October. The isotopic composition of δ15N–NO3 increased downstream, also confirming that anthropogenic effects became more significant at the lower reach of the river and near Daegu.  相似文献   

16.
The present work was conducted in the Sinai Peninsula (1) to identify the recharge and flow characteristics and to evaluate the continuity of the Lower Cretaceous Nubian Sandstone aquifer; and (2) to provide information for the aquifer's rational appraisal. Isotopic and hydrochemical compositions combined with the geological and hydrogeological settings were used for this purpose. A considerable depletion in isotopic content (oxygen-18 and deuterium) and low d-excess values exist in the studied groundwater, reflecting the contribution of old meteoric water that recharged the aquifer in pluvial times. Modern recharge also occurs from precipitation that falls on the aquifer outcrops. The wide scatter of the data points around the two meteoric lines, the global meteoric water line (GMWL) and Mediterranean meteoric water line (MMWL), in the δ18O–δD diagram indicates considerable variation in recharge conditions (amount, altitude, temperature, air masses, distances from catchment, overland flow, etc.). The isotopic composition in the El-Bruk area is minimum (18O=–9.53‰), very close to the average value of the Western Desert Nubian Sandstone (18O=–10‰), where the local structural and lithologic conditions retard groundwater flow and the main bulk of water becomes noncyclic. The continuity of the aquifer in northern and central Sinai is evidenced by the isotopic similarity between samples taken from above and below the central Sinai Ragabet El-Naam fault, the distribution of potentiometric head, and hydrogeological cross sections. The combination of isotopic composition in terms of 18O and chemical composition in terms of TDS and salt contents is the basis for separating the studied groundwater into groups that reflect the recharge sources and isotopic and chemical modifications during flow. Electronic Publication  相似文献   

17.
In the spring of 1995, 24 samples were collected from a widely distributed system of municipal water wells in Albuquerque, N.M., and analyzed for hydrogen (δD) and oxygen (δ18O) isotopic compositions. δD values for 15 of these samples are largely similar to those reported by Yapp in 1985, but have locally become more negative by as much as 5 per mil (ö). δD–δ18O data define two endmembers that are well aligned along the familiar meteoric water line (MWL): (1) the eastern domain (mountain precipitation runoff), having δD>–86ö (similar to the criteria of Yapp) and δ18O>–12.1ö (this work); and (2) a central basin domain, which may be in part derived from water seepage from the Rio Grande, having δD<–95ö and δ18O<–13.2ö. Only a few wells across the basin have δD values near the "baseline" value of the Rio Grande, defined by Yapp as –92ö. The proximity of these wells to the Rio Grande is consistent with recharge by seepage from the river bed under baseline conditions. Extensive pumping in the eastern domain and West Mesa areas may be partly responsible for an apparent expansion of the central-basin regime of water more depleted in δD, much as a plume migrating in response to transient perturbations in original hydraulic gradients. Vertically stacked groundwater occurrences having limited interconnection are inferred from the significant differences in isotopic compositions of samples from two wells screened at multiple depths. The central and western parts of the basin are little influenced by contributions from the eastern domain. Some groundwaters from the western part of the basin plot below the MWL and clearly cannot be mixtures solely of the eastern domain and central basin endmembers. The origins of these western groundwaters and the most depleted central basin groundwaters are as yet unknown, but we speculate they may have received recharge under climatic conditions different from the present.  相似文献   

18.
笔者测定了稚鲁藏布江地区蛇绿岩的氦、氩同位素组成。白朗的玄武岩He同位素组成比较均一，^3He/^4He平均值为5.359Ra；与之伴生的变橄岩的^3He／^4He比值范围为1.104～3.384Ra，平均为2.383Ra。从东部的仁布和大竹到西部的下鲁和白朗，辉绿岩的^3He／^4He由低变高。吉定的辉绿岩样品^3He／^4He比值平均高达31.57Ra，该值与夏威夷发现的高比值样品接近。分步加热法结果显示，该样品高比值的He是在低温区段释放的，这种高^3He／^4He比值He的捕获表明稚鲁藏布江蛇绿岩  相似文献   

19.
Spatial variations of δD and δ18O among seven tributaries and their water sources were investigated in the Heishui Valley of the Yangtze River, China during the dry-season in 2004. A one-way ANOVA (analysis of variation) test showed that both δD (p?18O (p?=?0.045) spatially varied among the seven tributaries. The plot of δ18O versus δD for the river water collected at different locations showed that isotopic fractionation occurred during the snow and glacial melting process. The depleted δ18O and δD in the tributary waters distributed above the local meteoric water line (LMWL) suggested that the glacial and early snowpack meltwater largely recharged these streams during the early spring. The meltwater was isotopically distinguishable from the precipitation and river water, which had been evaporated during warmer and drier times. If glaciers and snow accumulation diminish with future climate warming, the recharge of these tributaries’ baseflow will decline and the security of the water resource in this watershed will be threatened.  相似文献   

20.
应用氢氧同位素研究矿床成因的一些问题探讨   总被引：10，自引：1，他引：10       下载免费PDF全文
翟建平  胡凯 《地质科学》1996,31(3):229-237
成矿热液的氢、氧同位素组成与其水的类型、水/岩交换的岩石成分和同位素组成、水/岩交换时的温度及水/岩交换程度(W/R比值大小)等诸多因素有关,微生物和有机质也对其有一定的影响。因此,仅通过简单投影的方法将成矿热液的氢、氧同位素值与一些所谓的标准值进行类比,由此就推断出热液中水的来源,这种方法是不可取的;尤其当成矿热液的氢、氧同位素值介于大气降水和岩浆水的值之间时,切忌滥用两种水混合成矿模式,因为实际情况往往并不是这样。本文以胶东乳山金矿床为例,展开了这方面的讨论。  相似文献   

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