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We present ∼1300 new isotopic measurements (δ 18 O and δ 2 H) from a network of snowpack sites in the Rocky Mountains that have been sampled since 1993. The network includes 177 locations where depth-integrated snow samples are collected each spring near peak accumulation. At 57 of these locations snowpack samples were obtained for 10–21 years and their isotopic measurements provide unprecedented spatial and temporal documentation of snowpack isotope values at mid-latitudes. For environments where snowfall accounts for the majority of annual precipitation, snowmelt is likely to have the strongest influence on isotope values retained in proxy archives. In this first presentation of the dataset we (1) describe the basic features of the isotope values in relation to the Global Meteoric Water Line (GMWL), (2) evaluate space for time substitutions traditionally used to establish δ 18 O-temperature relations, (3) evaluate site-to-site similarities across the network and identify those that are the most regionally representative, (4) examine atmospheric circulation patterns for several years with spatially coherent isotope patterns, and (5) provide examples of the implications this new dataset has for interpreting paleoclimate records (Bison Lake, Colorado and Minnetonka Cave, Idaho). Results indicate that snowpack δ 18 O is rarely a simple proxy of temperature. Instead, it exhibits a high degree of spatial heterogeneity and temporal variance that reflect additional processes such as vapor transport and post-depositional modification. Despite these complexities we identify consistent climate-isotope patterns and regionally representative locations that serve to better define Holocene hydroclimate estimates and their uncertainty. Climate change has and will affect western U.S. snowpack and we suggest these changes can be better understood and anticipated by oxygen and hydrogen isotope-based reconstructions of Holocene hydroclimate using a process-based understanding of the controls on snowpack isotope ratios.

Isotopic compositions of ice and meltwater play a very crucial role in paleoclimate studies based on ice cores and water resources research conducted in alpine hydrogeology. Better understanding of variations in the stable isotopic compositions of water is required since changes from ice to liquid water are gaining more attention due to recent climate change. In this work, a melting experiment was designed and conducted to investigate how the isotopic compositions of ice vary with time by heat sources, such as solar radiation. We conducted the melting experiment for 22 hours. The discharge rate rose to a maximum value after 258 minutes and gradually declined because we fixed the heat source. The isotopic compositions of meltwater increased linearly or to a second degree polynomial. The linear relationship between oxygen and hydrogen has a slope of 6.8, which is less than that of the Global Meteoric Water Line (8) and higher than a theoretical value (6.3). The deuterium excess decreased when δD or δ 18 O increases or vise versa since the slope of the relationship for ice-liquid exchange is less than 8. These findings and the apparatus of the melting experiments will make a helpful contribution to the studies of stable isotopes and the melting process in temperate and polar regions.

Hydrogeological and geochemical approaches were combined to investigate the impact of a short-term artificial flooding event on arsenic and associated hydrogeochemisty at a field monitoring site of high arsenic aquifers in Datong Basin, northern China. The groundwater levels fluctuated in response to the flooding (the surface water level and groundwater level fluctuated with time in a range of over 80 cm and 30 cm, respectively), indicating groundwater–surface water interaction. Redox indices, major ions, trace element concentrations, O, H and Sr isotope compositions for surface water and groundwater were determined before and after the flooding. δ 2 H and δ 18 O values for all water samples plot close to the global meteoric water line (GMWL); a subset of the samples (shallow wells) averagely increased from − 11.78 to − 11.26 for δ 18 O and from − 86.59 to − 83.49 for δ 2 H, commensurate with mixing with ~ 10% surface water. The relationship between compositions of strontium isotope 87 Sr/ 86 Sr ratios and Mg concentration also clearly indicates the effect of mixing between groundwater and surface water. Before and after the flooding, there were obvious variations in water chemistry, including arsenic concentrations. Increases and positive correlations between Cl − and Na + , Mg 2 + , Ca 2 + and SO 4 2 − following flooding revealed surface water infiltration into groundwater, plus additional input from dissolution of evaporate minerals and/or evaporated pore-water. Organic matter and oxygen are carried into groundwater together with surface water; oxidation of organic matter leads to exhaustion of oxygen and consumption of terminal electron acceptors (e.g. ferric iron, sulfate, nitrate) inducing a more reducing groundwater environment (indicated by decreased ORP values). Consequently, reductive dissolution of iron oxides/hydroxides resulted in an observed elevation of HS, NH 4 -N, Fe(II), with the concentrations increasing from 5 μg/L to 10 μg/L, from 0.19 mg/L to 0.68 mg/L and from 0.06 mg/L to 1.86 mg/L, respectively. This may explain that the As concentrations were enhanced after surface water flooding (from mean value of 22.6 μg/L to 31 μg/L). However, a positive correlation was observed between enhance values of As and Cl in the groundwater after flooding is interpreted as reflecting re-dissolution of evaporate crusts and/or saline pore water during infiltration, and this may alone explain the increase in As observed in the groundwater. Surface water As concentration increased to a minor degree following flooding also (from 14 μg/L to 15.1 μg/L), possibly reflecting return flow of the high As groundwater during a temporary switch to gaining conditions.

Stable (H,O,N,C) and radiogenic isotope (Sr) data for cheese, milk, animal feed and soil from six artisanal cheese producers in Quebec, Canada, demonstrated the potential of isotope geochemistry in linking land/terroir to agricultural produce. The hydrogen and oxygen isotope compositions of the water, milk and cheese samples showed good general alignment with the Global Meteoric Water Line, with small off-sets in the milk and cheese samples related to cheese production. Carbon and nitrogen isotope data for the cheese and milk reflect the diet of the cattle and fertilization of the cattle grazing pastures. The strontium isotope compositions of the soils, milk and cheese are similar for a given farm/cheese producer, but vary widely between producers due to differences in geology. Combining the climate-sensitive δ 18 O and geology-sensitive 87 Sr/ 86 Sr proxies shows potential for discriminating between Quebec artisanal cheeses, commercial Canadian cheeses and European cheeses.

Based on the variations in stable hydrogen and oxygen isotope ratios (δD and δ18O) of precipitation and NCEP/NCAR (National Centers of Environmental Prediction/National Center for Atmospheric Research) re-analysis data, we investigated the characteristics of the precipitation isotopes and the moisture origin during spring and summer seasons (from May to August) in the Yushugou River basin, East Tianshan Mountains. The more negative δ18O and higher d-excess values in spring and more positive δ18O and lower d-excess values in summer indicated the different moisture sources and temperature effects on isotope variations. By studying the meteoric water line, we found that the slope and intercept of local meteoric water line (LMWL) were lower than the global meteoric water line (GMWL) and China LMWL, which indicated arid climate. The temperature effect of δD and δ18O in precipitation was obvious with correlation coefficients of 0.41 and 0.48, respectively, and there was no rainfall effect. The research of water vapor transfer showed that the moisture origin was predominantly from westerly air masses during the observation period. δ18O and d-excess values variations in precipitation and the HYSPLIT4.0 air mass trajectory model suggested that there were accidental events, and sometimes the moisture was from drier polar air masses during the spring.

Snow albedo can be decreased if there are any impurities on the snow surface other than the snow itself. Due to the decrease of snow albedo, melting rates of surface snow can increase, which is very crucial in climate change and hydrogeology in many parts of the world. Anthropogenic black carbons caused by the incomplete combustion of fossil fuel affect snow and tephra particles generated by geologic volcanic activities reduce snow albedo. In this study, we investigated isotopic compositions for snow covered by tephra particles and compared with this with clean snow. Isotopic compositions of snow with tephra statistically show more enriched than those of clean snow (p 18 O or D relative to meltwater as melting rates are increased. In addition, the slopes of the linear regression between oxygen and hydrogen for snow with tephra and clean snow are 6.7 and 8, respectively, and the latter is similar to that of the global meteoric water line of 8. Therefore, we can conclude that snow impurities control the isotopic compositions of snow, which is very crucial in the study of climate change and hydrogeology. To quantitatively explain these observations, melting experiments and numerical approaches are required.

The isotopic composition of near surface (or planetary boundary layer) water vapor on the south coast of Iceland (63.83°N, 21.47°W) has been monitored in situ between November 2011 and April 2013. The calibrated data set documents seasonal variations in the relationship between δ18O and local humidity (ppmv) and between deuterium excess and δ18O. These seasonal variations are attributed to seasonal changes in atmospheric transport. A strong linear relationship is observed between deuterium excess and atmospheric relative humidity calculated at regional sea surface temperature. Surprisingly, we find a similar relationship between deuterium excess and relative humidity as observed in the Bermuda Islands. During days with low amount of isotopic depletion (more enriched values), our data significantly deviate from the global meteoric water line. This feature can be explained by a supply of an evaporative flux into the planetary boundary layer above the ocean, which we show using a 1-d box model. Based on the close relationship identified between moisture origin and deuterium excess, we combine deuterium excess measurements performed in Iceland and south Greenland with moisture source diagnostics based on back trajectory calculations to establish the distribution of d-excess moisture uptake values across the North Atlantic. We map high deuterium excess in the Arctic and low deuterium excess for vapor in the subtropics and midlatitudes. This confirms the role of North Atlantic water vapor isotopes as moisture origin tracers.

Isotopic signatures of δD-H2O, δ18O-H2O, δ15N-NO3−, δ18O-NO3− and δ15NFertilizer isotopes were used in order to evaluate the impact of agricultural inputs (fertilizers and calcium nitrate) and sewage effluents on the water of tributaries of the Faxinal Dam, which supply the city of Caxias do Sul in Southern Brazil. δ2H and δ18O were identified by spectroscopy laser absorption tunable diode-type cavity ring-down spectroscopy, while the isotopic ratios of 15N and 18O in nitrate were determined by isotopic ratio mass spectrometry, applying the chemical denitrification method. The results showed that most of the analyzed samples are compatible with the Global Meteoric Water Line, Local Meteoric Water Line and Carlos Barbosa Wells and Fountains Tendency Line, except for the Fx-07 sample that presented greater similarity to δ18O values for groundwater. The isotopic signatures of δ15N-NO3− versus δ18O-NO3−, in the great majority of the samples, pointed out the influence and the contribution of the fertilizers. In a monitored affluent, the results show the impact of the direct discharge of domestic sewage, while in the sewage treatment plant there is clear evidence of denitrification. This study demonstrated that isotope application of δ15N-NO3− and δ18O-NO3− is efficient tools for identification of N-NO3− of synthetic fertilizers and domestic sewage.

The environmental isotopes such as deuterium and oxygen-18 and the deuterium excess values have been used to assess groundwater recharge sources and their dynamics in Khan Younis City in the Gaza Strip in Palestine. Three isotopic lines for the relationship between δ2H and δ18O were used in the assessment. These lines are the global meteoric water line, the local meteoric water line and the groundwater evaporation line. The δ2H, δ18O and D-excess values indicate that deuterium and oxygen-18 isotopes originated in the groundwater from groundwater mixing with rainfall and other water sources; the groundwater in the area recharged from rainfall from a distant source that came from the Mediterranean Sea and from other sources such as wastewater, irrigation return flow and saline water.

The current study was focused on the characterization of recharge, weathering processes and to check the aptness of groundwater for household and agriculture utility in the Chhaprola industrial area located in Gautam Buddha Nagar district of Uttar Pradesh, India. Groundwater samples (n = 33) were analyzed for major cations and anions from which (n = 22) were analyzed for stable isotopic records (δ2H and δ18O). Solute chemistry revealed neutral to moderately basic nature (pH ranged 6.4–8.8) and showed a higher (ranged 552–3130 µS/cm) of electrical conductivity. Isotopic signals ranged from − 8.7 to − 3.3‰ for δ18O and − 60.1 to − 37‰ for δ2 H. Bivariate plot of stable isotopes (δ 18O and δ2 H) showed that majority of the samples fell below the global meteoric water line (GMWL) and local meteoric water line (LMWL) of New Delhi, indicating enrichment of heavier isotopes in the aquifers, which explain that recharging water, has undergone evaporation before recharging the aquifer. Monsoonal precipitation was observed as the major source of aquifer recharge in the surveyed area. Vertical hydraulic connectivity of the aquifer layers was traced with the help of isotopic record which exhibited a more negative intercept for shallow depth tube well than the middle depth tube well. About 76% of the samples exhibited negative Schoeller index thereby indicated cation-anion exchange reactions while the remaining samples depicted the Base Exchange Reactions. Sodium-normalized Ca versus Na-normalized Mg and HCO 3, indicated an equal contribution of silicate and carbonate type weathering on global-average weathering system. About 52% of the groundwater samples fell into the Ca-HCO3- water type while remaining samples fell into 33% and 15% of Na-HCO3 and Mg-HCO3 type, respectively. Water quality indices (viz. residual sodium carbonate, Kelly index, permeability index, magnesium hazard, and Chloroalkaline indices) revealed unsuitability of the groundwater for drinking and irrigation purpose at few locations.

The 8 water samples of rain in Jinan were collected in the summer. A local meteoric line (LMWL) was got. And the derived equation is that δD = 8.19δ18O+ 8.89, which represents the local precipitation line. The precipitation water in Jinan is characterized by the high mean deuterium excess (d=10.9‰). The isotopic compositions in Xi’an were also be collected. And the local meteoric line in Xi’an is that δD=6.97δ18O+3.01, with a low slope The slopes of the meteoric line were different for the two sites, which can reveals some evaporation information about the precipitation.

In an effort to establish a clear relation between stable isotopes and altitude in the Pamir region, as well as to improve the understanding of stable isotope spatial variations found along the routes taken by the westerlies, surface river water samples were collected along a roughly west–east profile in Tajikistan. Here we present the spatial changes in modern surface water δ 18 O and deuterium excess ( d -excess), and their links with snow melt, glacier melt and seasonal precipitation patterns in Tajikistan. The results show a close relation between river water δ 18 O and δD above the GMWL (Global Meteoric Water Line), implying that surface evaporation exerts a weaker influence. Spatially, river water δ 18 O is gradually depleted from west to east due mainly to the effect of altitude, yielding a river water δ 18 O vertical lapse rate of 0.09‰/100 m. River water d -excess shows a decreasing trend from west to east in Tajikistan. This spatial d -excess pattern in surface water is explained by the different moistures influenced by the Mediterranean and other in-land seas with higher d -excess in west, and no-Mediterranean moisture in east. Another possible reason is the differences in precipitation seasonality between the west and east of Tajikistan.

This study presents a dataset, derived from the analysis of 162 bottled and canned beers from around the globe, which may be used for comparison with suspected counterfeit or substitute products. The data comprise δ2H and δ18O compositions of the whole beer and δ13C compositions of the dry residue (mostly sugar) together with the concentrations of five anions (F, Cl, NO3, SO4, PO4) and seven cations (Ca, K, Mg, SiO2, V, Mn, Sr). A strong correlation, consistent with natural waters but offset from the Global Meteoric Water Line, was observed between the δ2H/δ18O composition of the beers. The extent of the offset could be explained by the brewing process and the alcohol and sugars present in the beers. Correlations between inorganic analytes were consistent with the addition of salts in the brewing process. Beers were classified as follows: ale, lager, stout or wheat-beer and the chemical composition was found to be characteristic of the assigned type, with lagers being the most readily classified. A combination of chemical and isotopic data was found to be characteristic of the geographical origin (on a continental scale) and could most easily identify beers from Australasia or Europe. A global map of δ18O data revealed a geo-spatial distribution that mirrored existing maps of the isotopic composition of annual precipitation. This confirmed a commonsense view that local precipitation will be the primary source for the water used in brewing. Using this isoscape (or alcoscape) it may be possible to assess the geographical origins of samples for which genuine comparative samples cannot be obtained.

During the last decades, a decrease in precipitation and an increase in air temperature are observed from arid and semi-arid areas. Therefore, changes in the water resource balance are expected. In this context, this study aimed to identify the climate change effects on groundwater from the Essaouira basin (southwestern Morocco). The average precipitation is about 300 mm/year and the temperatures oscillate around 20 °C. The climate study showed that the precipitation and the air temperatures show a general downward trend (~12%) and an upward trend (~1.5 °C), respectively. The decrease in recharge and recurrent drought episodes caused a continuous decrease in groundwater level. The hydrogeochemical approach indicates that (i) the groundwater facies was mainly of the Na–Cl type from 1990 to 2009, and Mg–Ca–Cl for 2015, (ii) a degradation of groundwater quality with an increase in salinity (80–3500 mg/L) that resulted from the dissolution of evaporate minerals and seawater intrusion. The concentration of 18O, 2H are determined, the local meteoric water line (LMWL) close to the global meteoric water line (GMWL) characterizing ocean precipitations is determined. The ground waters of Essaouira basin are very sensitive to any variation in the natural recharge, this makes them very vulnerable faced with the climate change. The results of this study should be taken in consideration for the future water management in this region.

Spatial and temporal variability in stable isotopic compositions (δ18O and δD) in river water of the Yarlungzangbo was investigated to identify major hydrological processes along the river channel and evaluate the isotopic response to discharge variation. The results show geographic, distinct isotopic evolutions in the Yarlungzangbo system. Along the main stem, river δ18O exhibits a decreasing trend from the headwaters to the middle reach but an increasing one from the middle to the lower reaches, and main flows demonstrate much greater δ18O-δD slope and intercept compared to the global meteoric water line (GMWL) and reported local meteoric water lines (LMWLs) for sites within the basin. These results are found to be consistent with the isotopic characteristics of stream and river waters collected across the entire drainage basin. Water mixing appears to be the dominant hydrological process along the Yarlungzangbo, and the pattern of isotopic change in individual river reaches closely reflects that of precipitation in corresponding part of the river basin. The isotopic variability along the main stem observed during the synoptic survey is evidenced to hold through time by a time-series investigation at three key hydrological stations. River water at such three stations shows a strong isotopic response to discharge variability. In general, river δ18O tends to be negatively correlated with discharge, highlighting a typical monsoon precipitation-driven isotope-discharge pattern. Specifically, we found their individual discharge-weighted average δ18O values likely vary in a similar rate with the ratio of mean discharge in monsoon season (JAS) to that in pre-monsoon season (MJ) on a yearly basis, indicating a specific relationship between average river isotopic composition and discharge seasonality throughout their drainage areas (i.e. the middle-lower Yarlungzangbo basin). This study thus demonstrates the usefulness of isotopic data for assessing hydrodynamics over a less explored, complex and high-altitude large river catchment.

The 18O/16O and 2H/1H ratios of 18 water brands representing the most popular bottled water brands in the Saudi market were measured using a system based on the latest advancements in tunable off-axis integrated cavity output diode laser spectroscopy (OA-ICOS) in the near-infrared spectral region. Utilizing δ18O and the δ2H values of locally produced water samples, a meteoric water line (δ2H = 7.84 δ18O + 2.11) was extracted and found to be consistent with the slope of the global meteoric water line (GMWL) and the geographic location of Saudi Arabia.

It is important to have qualitative as well as quantitative understanding of the hydraulic exchange between lake and groundwater for effective water resource management. Dal, a famous urban fresh water lake, plays a fundamental role in social, cultural and economic dynamics of the Kashmir Valley. In this paper geochemical, isotopic and hydrological mass balance approaches are used to constrain the lake water–groundwater interaction of Dal Lake and to identify the sources of lake water. Water samples of precipitation (n = 27), lake water (n = 18) and groundwater (n = 32) were collected across the lake and its catchment for the analysis of δ18O and δ2H. A total of 444 lake water samples and 440 groundwater samples (springs, tube wells and dug wells) were collected for the analysis of Ca2+, Mg2+, HCO3 −, SO4 2−, Cl−, NO3 −, Na+ and K+. Water table and lake water level were monitored at 40 observation locations in the catchment. Water table map including pH and EC values corroborate and verify the gaining nature of the Dal Lake. Stable isotopes of lake water in Boddal and Gagribal basins showed more deviation from the global meteoric water line than Hazratbal and Nigeen basins, indicating the evaporation of lake water. The isotopic and geochemical mass balance suggested that groundwater contributes a significant proportion (23–40%) to Dal Lake. The estimated average groundwater contribution to Dal Lake ranged from 31.2 × 103 to 674 × 103 m3 day−1 with an average of 276 × 103 m3 day−1. The study will be useful to delineate the possible sources of nutrients and pollutants entering the lake and for the management of lake water resources for sustainable development.

Coal mining, as one of the key drivers of land degradation worldwide, caused land subsidence problems. In this study, we conducted experimental research to explore the reclaimed mine soil (RMS) water dynamics and its sources in relation to reclaimed land use types using stable water isotopes in the Longdong coal mining area with high groundwater level in east China. We collected water samples seven times in 2017 from all of these water bodies (precipitation, surface waters (river water and water from subsidence pits (WSP)), groundwater and soil water). Our main findings are three fold: (1) the values of slope and intercept of the local meteoric water line of Craig (LMWL) of precipitation for the study area are higher than the global meteoric water line of Craig (GMWL) because of the humid monsoon climate zoon, and the values of &delta, D and &delta, 18O of surface waters and soil water and groundwater deviated from LMWL to some extent with a range of 5%&ndash, 30%, and the D and 18O of precipitation and the surface waters have higher seasonal variation than groundwater, (2) the values of &delta, 18O of RMS for the whole soil profile (0&ndash, 100 cm) are lower than that of precipitation and have obvious seasonal variations and great fluctuation in the topsoil (0&ndash, 30/40 cm) and decrease at depth (30/40&ndash, 70 cm) and stable in deep soil layers (below 70 cm deep), (3) the RMS with forest and crop enhanced water infiltration capacity and soil water mixing strength compared with the waste RMS, so establishment of forest and crops should be encouraged in the RMS, (4) the main sources of topsoil (0&ndash, 30 cm for crop and 0&ndash, 40 cm for forest) of RMS are precipitation through infiltration, the main supply for deep soil water (below 70 cm deep) is groundwater, and the soil water for the middle deep soil layers (30/40&ndash, 70 cm) is mainly from mixing sources of precipitation, groundwater, and river water through pant root water absorbing and groundwater upshifting.

Hydrology of forested wetlands is critical to the ecosystem functions and services of the forests. Our understanding of the hydrology of those wetlands, however, is very limited most likely due to the tediousness and costs of monitoring those scattered small wetlands by the traditional methods. Stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in water may provide us a much simpler alternative to study the hydrology of those wetlands. We investigated the sensitivity and resolution of using natural stable water isotopes to quantify the hydrology of those isolated wetlands in the forests of North Florida. The observed Local Meteoric Water Line (LMWL) [δ2H = 7.7*δ18O + 9.2 (r2 = 0.97, n = 202)] followed closely to the Global Meteoric Water Line (GMWL), indicating the local rains were formed following a general isotopic equilibrium condition. Using data collected between 2014 and 2017, we observed a negative linear correlation between monthly total rain and the weight of its isotopic signature. There was no significant effect of temperature or humidity on the isotopic signatures of the rains. The water isotopes of the ephemeral ponds and sinks, on the other hand, were significantly enriched relative to the precipitation. The local evaporation lines (LEL) of the studied ephemeral ponds and sinks indicated significant evaporation. The isotope data indicated that the ephemeral Pond 55 and Pond 12 were rain fed while the water source to Blue Sink was a mixture of precipitation and groundwater. We showed that the significant differences in stable water isotopic signatures among the precipitation (especially during tropical storms and hurricanes), surface water and ground water can be used to trace the hydrological budgets and processes of forested wetlands in North Florida.

The chemo-isotopic characteristics, geothermal activity and water origin of the 5 thermal and 7 non-thermal springs have been investigated in Damavand volcanic region, northern Iran. The Damavand thermal waters are characterized by outlet temperature values of 23 to 65 °C and the Ca–Cl or Ca-SO4 water types. Stable isotope values of 49 monthly precipitation samples from 5 stations at 2500 to 3200 m elevations were also measured in the study area and Damavand meteoric water line (DMWL) was drawn as δD = 7.64 × δ18O + 8.93 (R2 = 0.98, n = 49). It has a lower slope and intercept than the global meteoric water line (GMWL) due to isotope kinetic fractionation effects during precipitation. The δ18O = (−0.0018 × H(m.a.s.l.) − 3.12) equation was derived based on precipitation data. The reservoir temperature was estimated to be 110–135 °C based on different geothermometers. Damavand volcano can be considered as the main heat source for the thermal springs in the region. The conductive process along with the mixing of thermal waters with shallow cold groundwaters is the main cooling mechanisms. Almost, all the thermal waters fall near the LMWL and within prediction interval area, indicating meteoric origin and no significant effect of water-rock interaction. The Damavand geothermal reservoir is fed by local meteoric water from altitudes of 2500 to 4100 m and circulates at least 500 m deep, near the magma chamber.

Due to the significance of karst groundwater for water supply in arid and semi-arid regions, the characteristics of the karst groundwater flow system in the Liulin spring area, North China, are analysed through isotopic tracing (δ(2)H, δ(18)O, δ(13)C and (3)H) and dating approaches ((14)C). The results show that the primary recharge source of karst groundwater is precipitation. Evaporation during dropping and infiltration of rainfall results in a certain offset in the values of δ(2)H and δ(18)O in groundwater samples from the global meteoric water line (GMWL) and the local meteoric water line (LMWL). The altitudes of the recharge region calculated by δ(18)O range from 1280 to 2020 m above sea level, which is consistent with the altitudes of the recharge area. The Liulin spring groups could be regarded as the mixing of groundwater with long and short flow paths at a ratio of 4:1. In the upgradient of the Liulin spring, the groundwater represents modern groundwater features and its [Formula: see text] is mainly derived from dissolution of soil CO(2), while in the downgradient of the Liulin spring, the (14)C age of dissolved inorganic carbon (DIC) in groundwater shows an apparent increase and [Formula: see text] is mainly derived from the dissolution of carbonate rocks. The mean flow rate calculated by (14)C ages of DIC between IS10 and IS12 is 1.23 m/year.

The stable isotopic composition of meteoric precipitation is an important component of global and regional water cycle research. Stable isotope data can help reconstruct paleoclimate related to ice cores, lake sediments, and stalagmites. We investigated the daily variation in isotopic composition of meteoric precipitation from 2008 to 2012 in the Guilin region of China. δ18O of meteoric precipitation ranged from −14.21 to +2.38 ‰, with an average value of −5.78 ‰ (Vienna Standard Mean Ocean Water; VSMOW). Meteoric precipitation in the summer half-year (May through October) increased, with a relatively low δ18O value of −8.04 ‰ (VSMOW; average of 261 groups) and −56.03 ‰ (VSMOW) of average δD, accounting for 67.6 % of the total annual meteoric precipitation. Meteoric precipitation in the winter half-year (November through April) decreased, with a relatively high δ18O value of −2.89 ‰ (average of 210 groups) and −9.23 ‰ of average δD, accounting for 32.4 % of total meteoric precipitation. The local meteoric water line (LMWL) equation in Guilin area has local climate characteristics. By combining environmental isotope data of precipitation using a backwards trajectory, water vapor sources of the meteoric precipitation in Guilin area are inferred and traced. Our results show that the isotopic composition of meteoric water vapor sources in Guilin area are related to monsoon type, source of precipitation cloud masses, and precipitation properties. The isotopic composition of meteoric precipitation in the summer half-year (May through October) was mainly affected by the summer monsoon or summer typhoons, namely controlled by water vapor source from the Bay of Bengal and the South China sea, and the second the West Pacific, and the δ18O value of meteoric precipitation was strongly negative. There was a significant negative correlation between the δ18O values of meteoric precipitation and the amount of precipitation and temperature in the summer half-year. The amount effect of the meteoric precipitation often concealed the temperature effect. The isotopic composition of meteoric precipitation in the winter season or winter half-year was affected by the water vapor source of the warm moist air masses from the West Pacific and continental cold air masses from the Siberia–Mongolia/winter monsoon or local evaporation vapor circulation, and the δ18O value of meteoric precipitation was relatively positive, and indicated that the water vapor of meteoric precipitation along the water vapor trajectory was affected by the evaporation as well as the local water vapor evaporation. The research results have showed that different sources of water vapor has a significant influence on the δ18O variation of meteoric precipitation, therefore, analysis of δ18O in the meteoric precipitation, especially its seasonal variation characteristics of analysis, can conversely reveal the water vapor sources of local meteoric precipitation.

Based on the precipitation samples obtained at Lanzhou City (36°06′N, 103°44′E, 1,548 m a.s.l.) in western China and its surrounding counties (Yongdeng, Gaolan, and Yuzhong) from April 2011 to February 2013, the characteristics of stable isotopes in precipitation and the correlations between δ 18O and meteorological factors were analyzed. The LMWL (local meteoric water line) of Lanzhou City and its surrounding areas was calculated, and the order of LMWL slopes in the four stations is Yuzhong (7.70) > Lanzhou (7.57) > Yongdeng (7.24) > Gaolan (6.80). Both the slope and intercept of the LMWLs for each station are less than those of the global meteoric water line. There is a weakly positive correlation between δ 18O and air temperature, and the correlation between δ 18O and precipitation amount is weakly negative. Evidenced from the slope and intercept of LMWL and the relationship between δ 18O and relative humidity, there is secondary evaporation when the precipitation falls from clouds to the ground.

Due to the ability of stable water isotopes to characterize the origin of water and connected processes of groundwater recharge, we used the isotope variations of hydrogen and oxygen in different water sources for assessing the recharge process in the Dhofar region. δ(18)O and δ(2)H of precipitation, spring water, and groundwater cover a range from -10 to +2 and from -70 to +7 ‰ (vs Vienna Standard Mean Ocean Water), respectively, and correlate in a linear relationship close to the Global Meteoric Water Line. No obvious evaporation processes are detected. A clear signal of the recent precipitation is given by the annual monsoon. The monsoon signal is confirmed by several springs existing in the south at the foot of the Dhofar mountains and sources at Gogub above 450 m and Tawi Atir at 650 m above sea level. They occur here first in the form of water intercepted by trees as stemflow and throughflow. The isotope signature of groundwater in the Dhofar mountains reflects the climatic conditions at the time of recharge and the lithological features of the limestone matrix. To the north, the isotope patterns of the groundwater are continuously depleted from the monsoon signal along the outcropping aquifer D (Lower Umm Er Radhuma). Here, a more negative signature towards the wells in the Najd desert region was observed. Cyclone water that flooded wadis in the Dhofar region occasionally, as observed in November 2011, falls isotopically into the same range as we observed in the fossil groundwater. Taking into account the different sources of precipitation and groundwater and thus a clear distinction of the isotopic composition of the water sources, we conclude a recharge process divided into a southward and a northward component in the Dhofar region.

This paper presents an overview of the geothermal systems on the island of Bali, Indonesia. Physicochemical data of hot springs and shallow geothermal wells were collected from four geothermal locations: Penebel, Batur, Banjar and Banyuwedang. The concentrations for the three main anions varied significantly indicating a different geothermal history. The values for Cl− ranged from 0.1 to 1000 mg/L, for HCO3− from 20 to 2200 mg/L and for SO42 − from 0.1 to 500 mg/L. Although the island of Bali is underlain by carbonate rocks, a carbonate host rock for the geothermal reservoirs could not be confirmed, because the (Ca2 + + Mg2 +)/HCO3− molar ratios were approximately 0.4, well below 1.0 and the K/Mg ratios were approaching those of a calc-alkaline rock reservoir. The HCO3− of the thermal waters correlated with Ca2 +, Mg2 +, Sr2 + and K+ indicating water–rock interaction in the presence of carbonic acid. Phase separation was inferred for the Bedugul and Banjar geothermal systems, because of relatively high B/Cl ratios. Boron isotopes were determined for selected samples with values ranging from δ11B of 1.3 to 22.5‰ (NBS 951). The heavy δ11B of + 22.5‰ together with a low B/Cl ratio indicated seawater input in the Banyuwedang geothermal system. The hydrogen and oxygen isotopic composition of the thermal water plotted along the global meteoric water line (GMWL) and close to the mean annual value for precipitation in Jakarta indicating a meteoric origin of the geothermal water. Comparison of the Si, Na/K, Na/K/Ca and Na/Li geothermometers with actual reservoir temperature measurements and physicochemical considerations led to the conclusion that the Na/Li thermometer provided most reliable results for the determination of geothermal reservoir temperatures on Bali. Using this thermometer, the following reservoir temperatures were calculated: (1) Penebel (Bedugul) from 235 to 254 °C, (2) Batur 240 °C and (3) Banjar 255 °C. Due to seawater input this thermometer could not be applied to the Banyuwedang geothermal system. There application of a SiO2 thermometer indicated a reservoir temperature below 100 °C.

Knowledge of stable isotopes and chemical tracers in meteoric water has been used as a valuable tool in various environmental studies. A systematic monthly sampling of precipitation, in the Ndop plain, was carried out to generate basic data on δ18, δD and Cl−, determine their seasonal variations and controlling factors to be used as baseline data in hydrological and climatological studies. The δ18O–δD relationship of rainfall gives a regression line: δD = 7.93 δ18O + 13.26 (R2 = 0.99), which represents the Ndop Meteoric Water Line (NMWL). The slope is similar to the Global Meteoric Water Line (GMWL), but, with a high d-excess, which suggests a contribution of continental recycled moisture to precipitation. Precipitation shows a wide variation, throughout the year (2012) in δ18O and δD, from +3.86 to +38.62‰ in January to −7.98 and −53.18‰ in September, respectively. The volume-weighted mean of precipitation, which plots close to June rainfall, is −5.61‰ and −31.93‰ for δ18O and δD, respectively. Light convective pre-monsoon and post-monsoon showers, under low relative humidity conditions, are isotopically more enriched than heavy orographic monsoon rain, under high relative humidity conditions. Chloride varies from 1.56 mg/l in the pre-monsoon to 0.06 mg/l during the monsoon rains; like δ18O and δD, it shows high values in early and late rains. Apart from January, all d-excess values in monthly rains are >10‰. The high d-excess values at the beginning and end of the rainy season suggest the contribution of recycled moisture to precipitation during these periods, under low relative humidity conditions. Assuming a constant condensation temperature, the observed seasonal variation in isotopic composition of precipitation is probably as a result of the (1) rain out of Atlantic moisture, (2) monthly rainfall amounts, (3) addition of inland recycled moisture, (4) rain formation mechanism, and (5) varied relative humidity. The varied Cl− concentrations are due to anthropogenic and oceanic sources, and rainfall amounts.

Madeira is a volcanic island whose economy is highly dependent on groundwater. Previous studies suggest that, besides precipitation, cloud water interception contributes to groundwater recharge. As such, the isotopic characterization of the sources of recharge is useful for the hydrogeological framework of the island. The δ 18O and δ 2H content of rain and cloud water was analyzed during three campaigns. Rain plots over a local meteoric water line (LMWL) whose equation is δ 2H = 7.92 δ 18O + 10.49 (R 2 = 0.97, n = 43). The volume-weighted average meteoric line (WLMWL) is given by δ 2H = 7.97 δ 18O + 10.57 (R 2 = 0.98, n = 20). Both are similar to the global meteoric water line which indicates, along with the d-excess values (10.8 and 11 ‰ for the LMWL and WLMWL, respectively), that rain originates, essentially in the Atlantic. Seasonal variations were also observed and rain in Campaign II was isotopically enriched and had a higher d-excess (δ 18Omean −3.63 ‰; δ 2Hmean −16.3 ‰; d-excess 12.7 ‰), than rain in Campaign III (δ 18Omean −7.01 ‰; δ 2Hmean −46.5 ‰; d-excess 9.5 ‰). Campaign I stood in between. These variations were probably the result of differences in temperature, water vapor source areas and rain forming processes. Rain was found to become increasingly depleted with altitude (δ 18O), at a rate of −0.15 ‰/100 m and −0.11 ‰/100 m in the windward and leeward sides, respectively. Cloud water was always isotopically enriched when compared with rain at the same altitude. This was related to constant water vapor replenishment of orographic clouds, to the fact that it usually represents an early stage condensation from air moisture and to the smaller size of cloud water droplets when compared to rain droplets. These results will be useful to refine Madeira’s hydrogeological conceptual model. Future extended sampling during more years, with smaller sampling periods and single rainfall events should be useful to support the conclusions of this study.

In the present study, the stable isotope compositions of water samples collected from Sana’a basin were investigated. The obtained data indicate that the recharge from direct infiltration of precipitation is divided into two groups: groundwater recharged from evaporated meteoric origin; and water that was barely affected by evaporation before recharge. The δ-values (δ18O and δ2H) of the water samples collected from the alluvium and sandstone aquifer plot are close to the Global Meteoric Water Line and Sana’a Meteoric Water Line (SMWL) indicating a recharge from non-evaporated meteoric water. While the samples collected from the volcanic and limestone aquifer plot below are both meteoric water lines, which indicate an evaporation process took place before recharge. The water samples collected from volcanic and sandstone aquifers are more depleted in their heavy isotopes δ18O and δ2H than the rainwater falls in the region. This indicates old groundwater occurrences within both aquifers and non-modern recharges, from direct infiltration occurred in the last few decades. However, a small contribution of modern groundwater could be observed in the alluvium and limestone aquifers. The δ18O and δ2H of the rainwater samples vary in a wide range; δ18O ranges between −8.02 and +4.50 ‰, while δ2H varies from −53.60 to + 14.90 ‰ with an average of−0.21 and +7.02 ‰, respectively. The final dataset of 52 rainwater samples was used to construct the so-called SMWL which defined by the equation δ2H = 7.4*δ18O + 8.6 ‰.

The first ever systematic study on spatio-temporal variation of the chemo-isotopic compositions of the precipitation in Iran was carried out in a hydrological year (2016–2017) at 7 sites located in Bojnourd area, northeast of Iran. The main aims were to determine the moisture and air mass sources and, in particular, to evaluate the effect of atmospheric conditions on isotope compositions. The isotopic value of the precipitation fluctuates seasonally with higher values in summer and lower values in winter at the all sites. Stable isotope values of the precipitation samples within the local scale resulted a Bojnourd meteoric water line (BMWL): δD = 6.4 × δ18O+1.2 (R2 = 0.93, n = 75), with a lower slope and intercept than the global meteoric water line (GMWL) due to isotope kinetic fractionation effects during precipitation in semi-arid region with lower humidity. The air temperature can be suggested as the main controlling factor that impacts the stable isotope compositions of precipitation in the study area. The large rainfall events totally displayed the highest slope, intercept and d-excess values nearly similar to the snowfall samples, indicating the re-evaporation effects on the low rainfall amounts. Precipitations during summer season (Jun–August) with higher isotopes and lower d-excess values mainly originated from the polar and Caspian Sea air moistures. While, moisture contributing to high d-excess and low isotope precipitation during January was mainly transported by the Mediterranean air moisture. The air-mass trajectories that affect the precipitation in autumn (September–December) and spring (March–May) displayed multiple sources, originating from the polar, Mediterranean and Caspian Sea air moistures. Trajectory analysis by HYSPLIT modeling allowed the association of moisture sources with the isotopic compositions of the precipitation. Based on the sea salt contribution for Na+ and Cl−, a sea effect is recognized especially from Caspian Sea and Mediterranean region, despite the long distance at the present study. The correlation between EC and the ions indicate that ion compositions in the precipitation and atmosphere of the study area are mainly effected by dust of soil and sea salt and to some extent from secondary evaporation during rainfall. The hydrochemical investigations confirmed the air masses trajectories which resulted from the isotopic characteristics.

High arsenic concentration in groundwater is influenced by redox reactions in As-bearing iron (oxy)hydroxide minerals and elevated total organic carbon, resulting in arsenic contamination and enrichment in groundwater after introduction of seawater into an aquifer. In this study, hydrochemical and isotopic (S, O and C) techniques were used to relate arsenic contamination and seawater flooding/intrusion in groundwater aquifers in the Chianan Plain, southwestern Taiwan. Thirty-three samples (30 from groundwater and 3 from river water) were collected from April–June of 2014. Most of the groundwater samples collected from the Chianan Plain were dominated by As(III), indicating that reducing conditions prevailed within the aquifers. The δ18O-δD plots of most of the groundwater samples from the Chianan Plain are generally lined on the global meteoric water line (GMWL), but the δ18O and δD isotopic compositions of the river water samples show enriched signals. Salinity and sulfate concentrations of river water and shallow groundwater have been found to increase after seawater flooding/intrusion. The δ18O and δD isotopic compositions of the river water showed a gradual trend toward those of seawater. The trend in the isotopic compositions of the river and groundwater samples indicated a mixing of seawater and meteoric water. Up to the present, the groundwater levels in the coastal areas of the Chianan Plain have dropped to zero meters in elevation parallel to sea level due to excessive groundwater withdrawal, resulting in seawater intrusion into the aquifers in Budai, Yichu, and Beimen in the Plain. Moreover, high salinity (48.1‰) occurred only in the Beimen 2B shallow groundwater at a depth of 60 m is a result of seawater flooding infiltration from the nearby salinized Pachang River. The δ34S[SO4]/δ18O[SO4] isotopic ratios (2.63–2.82) of low-As (concentration

Stable isotope ratios of precipitation are useful tracers of climatic and hydrological processes. To better understand the isotope hydro-climatology of a high-elevation Rocky Mountain valley we collected meteoric water samples from Gunnison, Colorado, USA and determined stable isotope values for 239 individual precipitation events over a nine year period. Annual precipitation in Gunnison is moderately bi-modal with significant winter snowfall and convective summer thunderstorms associated with the North American Monsoon. Stable isotope values of precipitation span a large range, with summer rains as high as δ2H = +19‰ and δ18O = +4.8‰ (relative to V-SMOW) and winter snowfall as low as δ2H = -286‰ and δ18O = -36.7‰. These data define a local meteoric water line for Gunnison of δ2H = 7.2 δ18O – 4.2. Monthly meteoric water lines have slopes similar to the Global Meteoric Water Line (∼8) for winter months and more evaporated slopes (∼6) during the summer. Monthly mean temperature most strongly controls the monthly isotopic composition of precipitation (m = 0.61–0.64 ‰/°C); the slope of the isotope/temperature relationship is steeper in summer than winter.

Water samples were collected from cold and warm karst springs for stable isotopes (δ18O and δD) and 3H from SE of Kashmir valley (western Himalayas) to distinguish the sources of recharge and infer their recharge areas. The spring water samples were most depleted in heavier isotopes in May (average δ18O: −8.87‰ and δD: −50.3‰) and enriched in September (average δ18O: −7.58‰ and δD: −48.1‰). The depleted 18O and 2H of spring waters bear the signatures of winter precipitation while as the enriched 18O and 2H of spring waters bear the signature of summer rainfall. D-excess and 3H corroborate with the stable isotope results that the spring flow in spring season (May) and autumn (September) is dominantly controlled by the melting of winter snowmelt and summer rainfall, respectively. The results showed that unlike δD, the δ18O value in the karst spring waters decreases in January suggesting δ18O shift. The spring water samples also fall above the Local Meteoric Water Line and Global Meteoric Water Line indicating the δ18O shift due to interaction of groundwater with the host carbonate rocks during its traverse. The mean elevation of the recharge areas of the springs using δ18O and δD tracers was also estimated. Copyright © 2014 John Wiley & Sons, Ltd.

We present a case study of physical and chemical indicators and isotope characteristics of Lake Nuoertu, one of the largest and deepest lakes of the Badain Jaran Desert. We analyze the concentrations of eight ions, total dissolved solids, and stable isotope composition of the lake and groundwater, as well as radioactive isotope tritium concentration in groundwater. The results show that annual and seasonal variations of the physical and chemical characteristics of Lake Nuoertu water are significantly greater than those of groundwater. The lake is uniformly mixed in the horizontal and vertical directions, and the hydrochemical types of the lake at different depths are consistent for Na–Cl–CO3–(SO4). Stable isotope composition of the lake and groundwater at Nuoertu is distributed along the local evaporation line (EL) slope, which is less than the slope of the global meteoric water line. The comparatively small slope shows the characteristic strong evaporation in the study area. Lake water isotopes are mostly in the upper right corner of the EL, whereas groundwater is mostly in the lower left corner. The main recharge source of Nuoertu lake water is groundwater, in combination with lake water and groundwater level change. The age of tufa springs around Nuoertu is about 75–80 a, which shows that the initial recharge source of the lake is a mix between modern and 1952 or older; however, further research is required.

Deuterium and oxygen-18 are common environmental tracers in water used to investigate hydrological processes such as evaporation and groundwater recharge, and to trace moisture source. In this study, we collected event precipitation from 01 January 2010 to 28 February 2011 at a site in Changsha, Yangtze River Basin to estimate the influence of moisture source and atmospheric conditions on stable isotope compositions. The local meteoric water line, established as δD = (8.45 ± 0.13) δ18O + (17.7 ± 0.9) (r2 = 0.97, n = 189), had a higher slope and intercept than global meteoric water line. Temperature–δ18O exhibited complex correlations, with positive correlations during Nov.–Apr. superior to during Jun.–Sep., which was attributed to distinctive moisture sources, but vague the overall period; amount effect examined throughout the year. Linear regressions between δ18O and δD value in different precipitation event size classes revealed progressively decreasing slope and intercept values with decreasing precipitation amount and increasing vapour pressure deficit, indicating that small rainfall events (0–5 mm) were subject to secondary evaporation effects during rainwater descent. In contrast, snowfall and heavy precipitation events exhibited high slope and intercepts for the regression equation between δ18O and δD. High concentrations of heavy isotopes were associated with precipitation events sourced from remote westerly air masses, degenerated tropical marine air masses from the Bay of Bengal (BoB), and inland moisture in the pre-monsoon period, as determined from backward trajectories assessed in the HYSPLIT model. Meanwhile, low concentrations of heavy isotopes were found to correspond with remote maritime moisture from BoB, the South China Sea, and the west Pacific at three different air pressures in summer monsoon and post-monsoon using HYSPLIT and records of typhoon paths. These findings suggest that stable isotope compositions in precipitation events are closely associated with the meteorological conditions and respond sensitively to moisture source in subtropical monsoon climates. Copyright © 2013 John Wiley & Sons, Ltd.

Hydrochemical and stable isotopes (18O and 2H) analyses of groundwater samples were employed to establish the origin of major dissolved ions in groundwater within the Lower Pra Basin. Results showed that, the major processes responsible for chemical evolution of groundwater include: silicate (SiO4)4− dissolutions, ion exchange reactions, sea aerosol spray and pyrite (FeS2) and arsenopyrite (FeAsS) oxidations. The groundwater is strongly acidic to neutral, with pH generally range from 3.5 to 7.0 pH units and mean 5.9 (±0.5). Approximately 89 % of boreholes had pH values outside the World Heath Organization (WHO, Guidelines for drinking water quality, 2004) guideline value for drinking water due principally to natural biogeochemical processes and therefore, not suitable for potable purposes. Electrical conductivity (EC) range from 57.6 to 1,201 μS/cm with mean 279.3 (±198.8) μS/cm. Total dissolved solids (TDS) range from 32 to 661 mg/L with mean 151.7 (±106.8) mg/L, with 98.6 % of groundwater as fresh (TDS Ca2+> Mg2+ > K+ and HCO3 − > Cl− > SO4 2−, respectively. A plot of ∂18O ‰ against 2H ‰ showed that, ground and surface waters clustered on or closely along the Global Meteoric Water Line, suggesting that, the waters emanated principally from meteoric source with evaporation playing an insignificant role on the infiltrating water.

Here we report temporal changes of As concentrations in shallow groundwater of the Bengal Delta Plain (BDP). Observed fluctuations are primarily induced by seasonally occurring groundwater movement, but can also be connected to anthropogenic groundwater extraction. Between December 2009 and July 2010, pronounced variations in the groundwater hydrochemistry were recorded in groundwater samples of a shallow monitoring well tapping the aquifer in 22-25 m depth, where Astot concentrations increased within weeks from 100 to 315 μg L(-1). These trends are attributed to a vertically shift of the hydrochemically stratified water column at the beginning of the monsoon season. This naturally occurring effect can be additionally superimposed by groundwater extraction, as demonstrated on a local scale by an in situ experiment simulating extensive groundwater withdrawal during the dry post-monsoon season. Results of this experiment suggest that groundwater extraction promoted an enduring change within the distribution of dissolved As in the local aquifer. Presented outcomes contribute to the discussion of anthropogenic pumping influences that endanger the limited and yet arsenic-free groundwater resources of the BDP.

Zhangye Basin, in arid northwestern China, has recently been repeatedly flooded by rising groundwater. Isotope signatures of sampled waters gained insight into the recharge source of the groundwater. The summer Heihe River water and most of the spring water in Zhangye and Yongchang basins plotted above the global meteoric water line (GMWL) on the δ18O-δD plot. The spring water had R/Ra ratio >1, low TDS and high tritium, which indicates origin from Qilian Mountain glacier meltwater. The groundwater of Qilian Mountains was transported to the Hexi Corridor (in which Zhangye Basin is located) through underground fault zones. Additionally, some of the groundwater in the alluvial plain, and all spring water surrounding Zhangye Basin, plotted below the GMWL on the δ18O-δD plot along an evaporation line, and had R/Ra ratio

RATIONALE The hydrogen and oxygen isotopic analyses (δ2H and δ18O values) of water trapped within speleothem carbonate (fluid inclusions) have traditionally been conducted utilizing dual-inlet isotope ratio mass spectrometry (IRMS) or continuous-flow (CF)-IRMS methods. The application of cavity ring-down spectroscopy (CRDS) to the δ2H and δ18O analysis of water in fluid inclusions has been investigated at the University of Miami as an alternative method to CF-IRMS. METHODS An extraction line was developed to recover water from the fluid inclusions consisting of a crusher, sample injection port and an expansion volume (either 100 or 50 cm3) directly connected to the CRDS instrument. Tests were conducted to determine the reproducibility of standard water injections and crushes. In order to compare results with conventional analytical methods, samples were analyzed both at the University of Miami (CRDS method) and at the Vrije Universiteit Amsterdam (CF-IRMS method). RESULTS The analytical reproducibility of speleothem samples crushed on the Miami Device demonstrates an average external standard deviation of 0.5 and 2.0 ‰ for δ18O and δ2H values, respectively. Sample data are shown to fall near the global meteoric water line, supporting the validity of the method. Three different samples were analyzed at Vrije Universiteit Amsterdam and the University of Miami in order to compare the performance of each laboratory. The average offset between the two laboratories is 0.7 ‰ for δ18O and 2.5 ‰ for δ2H. CONCLUSIONS The advantage of CRDS is that the system is a low-cost alternative to CF-IRMS for fluid inclusion isotope analysis. The CRDS method demonstrates acceptable precision and good agreement with results from the CF-IRMS method. These are promising results for the future application of CRDS to fluid inclusion isotope analysis. Copyright © 2013 John Wiley & Sons, Ltd.

Hydro-geochemistry and isotopes were used to understand the geochemical character and origin of the groundwater from coal bearing aquifer in Northern Anhui province, China. Twenty three groundwater samples were collected, and the isotopic composition δD, δ18O and major ions were analyzed, conventional graphical and multivariate statistical approach was completed and the result showed: three groups of groundwater could be divided form the rectangular field, the Ca-Mg-Cl, Na-Cl-SO4 and Na-HCO3 type water; the feldspar weathering is dominating weathering process, whereas, the sulfuric acid is the weathering agent along with the carbonic acid; the groundwater mainly supplied from the meteoric water for all the plots are below the local meteoric water line and global meteoric water line, the values of δD are drifted obviously, what could be caused by the exchange reaction of δD between groundwater and alkyl.

Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future.

The coal seams in the Permian Taiyuan Formation and the Carboniferous Shanxi Formation are the primary reservoirs for the coalbed methane (CBM) in the Hancheng region in the Ordos Basin. In this paper, the origin and evolution of waters associated with CBM production were studied on the basis of water chemistry and isotopes including the chloride and iodine compositions, oxygen and hydrogen stable isotopes, and radioactive isotope ratio of 129I/127I. The ratio of 129I/127I of water was determined by accelerator mass spectrometry (AMS). The result shows that the formation water is of NaHCO3 and NaCl types with the total dissolved solids (TDS) varying from 1532.29 mg/L to 7061.12 mg/L. The values of 129I and I/Cl ratio indicate that the formation waters were diluted by meteoric water. The 129I/127I ratios range from 6.6×10−13 to 1459.5×10−13. The 129I/127I ratios for most of the samples are between the 129I/127I initial value and that of recent anthropogenic water. This age of the formation water samples, obtained through the 129I decay curve method, ranges from 0 Ma to 18.5 Ma, suggesting that the waters from the Taiyuan Formation and the Shanxi Formation are very young. Two different origins of water are identified in the Hancheng region. One group is dominated by pre-anthropogenic meteoric water, and is characterized by 129I/127I ratios lower than the initial value of 15×10−13 and δD, δ 18O values of waters below the Global Meteoric Water Line. The other group is characterized by 129I/127I ratios in excess of 15×10−13, which has undergone variable degrees of dilution by recent anthropogenic water.

Precipitation water samples were collected at an urban site in Beijing in a hydrological cycle (July 2008-July 2009), and analyzed for TDS, total alkalinity, total hardness, free CO₂, soluble SiO₂, bromide, sulfide, phosphate, major ions (K(+), Na(+), Ca(2+), Mg(2+), NH₄(+), HCO₃(-), Cl(-), SO₄(2-), NO₃(-)), trace elements (CO₃(2-), Mn, Sr(2+), Fe(2+), Fe(3+), Al, F(-), NO₂(-)), stable isotopes ((2)H and (18)O), and radioactive isotope ((3)H). In addition, available published hydrochemical and isotopic data of precipitation of Beijing in the past were also collected and conjointly analyzed. Most of the parameters of samples tested varied considerably in the hydrological cycle. In general, HCO₃(-) and SO₄(2-), and Ca(2+) and NH₄(+) are the dominant anions and cations, respectively. Using Na(+) as an indicator of marine origin, and Al for the terrestrial inputs, the proportions of major elements from sea salt and terrestrial sources were estimated by using the combination of statistical analysis methods and analogy method. More than 70.1% of Cl(-), 98.1% of Ca(2+), and 93.6% of K(+) were non-sea-salt origin, while more than 98.4% of Na(+) was from marine sources. The LMWL (Local Meteoric Water Line) was obtained with an equation of δ(2)H=7.0181δ(18)O+3.5231 (‰, R(2)=0.86, n=36), which was similar to GMWL (Global Meteoric Water Line). δ(2)H, δ(18)O and Δ-excess changed radically with month and season, but had no apparent seasonal effect, precipitation amount effect, and temperature effect. The annual mean values of Δ-excess for 1979 (16.5‰) and 1980 (16.3‰) were much bigger than that for 2007 (7.2‰), 2008 (2.1‰) and 2009 (4.5‰). The composition of (2)H and (18)O was probably intrinsically determined by the sources of water vapor and the physical and chemical processes occurred along the migration paths of water vapor from sources to the aimed precipitation area. Temporal change of (3)H was only influenced by the nuclear testing in the early 1960s worldwide and the natural yield of (3)H in the upper atmosphere intrinsically. (3)H had nearly approached to the natural levels, which would bring difficulty if not invalidation to groundwater dating using (3)H technique.

Stable isotopes of water molecules in hydrology, the water cycle and Craig's global meteoric water line (GMWL) relating δ 18 O and δ 2 H are well established with a slope of around 8 and an intercept of around 10. However, in many situations the slope is less than 8 and the intercept is smaller or even negative. These observations need to be understood and a method is suggested to correlate with the global meteoric water line (GMWL). How to find the isotopic composition of water at a particular place is also suggested.

Altitude encompasses broad environmental gradients that influence the isotopic composition of lake water. We selected 55 lakes in the Eastern Alps along an altitudinal gradient [214–2,532 m above sea level (a.s.l.)] to model the isotopic signal of surface water dependent on intrinsic (lake geomorphometry) and extrinsic (air temperature, precipitation) factors. Ordinary and generalised least squared regression were used for statistical analysis. The isotope signal of lake water was lower in spring than in summer and decreased with altitude (−0.21 δ18O ‰/100 m; −1.5 δ2H ‰/100 m). This pattern largely depended on temperature and a pseudo-latitude effect. The isotopic signal in monthly precipitation (12 stations; altitudinal gradient 90–2,730 m a.s.l.) generally showed the expected pattern of less enriched values with altitude; however, unusual values were related to weather anomalies. The local meteoric water line was similar to the global meteoric water line as shown by overlapping confidence intervals. By discriminating different elevational bands, we could show that high elevation lakes (>1,500 m a.s.l.) experience different patterns of evaporation with respect to low elevation lakes (

Sulphur Springs is a vigorous, geothermal field associated with the active Soufriere Volcanic Centre in southern Saint Lucia, Lesser Antilles island arc. The ‘Sulphur Springs Park’ is an important tourist attraction (touted as the ‘world's only drive-through volcano’) with some of the hot pools being developed into recreational pools. Some 200,000 people visit the park each year. Since 2001, the hydrothermal fluids of Sulphur Springs have been sampled as part of an integrated volcanic monitoring programme for the island. Gas and water samples were analysed to characterise the geochemistry of the hydrothermal system, and to assess the equilibrium state and subsurface temperatures of the reservoir. This has also enabled us, for the first time, to establish baseline data for future geochemical monitoring. The gases are of typical arc-type composition, with N2 excess and low He and Ar content. The dry gas composition is dominated by CO2 (ranging from 601–993 mmol/mol), with deeper magmatic sourced H2S-rich vapour undergoing boiling and redox changes in the geothermal reservoir to emerge with a hydrothermal signature in the fumarolic gases. Fluid contributions from magmatic degassing are also evident, mainly from the moderate to high contents of HCl and deeply-sourced H2S gas, respectively. Sulphur Springs hydrothermal waters have acid-sulphate type compositions (SO4 = 78–4008 mg/L; pH = 3–7), and are of primarily meteoric origin which have been affected by evaporation processes based on the enrichment in both δ18O and δD (δ18O = − 1 to 15‰ and δD = − 9 to 14‰ respectively) in relation to the global meteoric water line (GMWL). These waters are steam-heated water typically formed by absorption of H2S-rich gases in the near surface oxygenated groundwaters. Reservoir temperatures calculated from the evaluation of gas equilibria in the CO2–CH4–H2 system reveal higher temperatures (190 to 300 °C) than those derived from quartz geothermometry (95 to 169 °C), which appeared to be affected by dilution with meteoric waters. Generally, no significant variations in fluid geochemistry of the hydrothermal system were observed between 2001 and 2006, and we propose that there were no changes in the state of volcanic activity during this period.

Dissolved O 2 (DO) and pH data provide a novel, inexpensive field method to detect open cave passages in karst spring systems that can be complemented by laboratory measurements of major elements and nutrients, total suspended solids (TSS), Escherichia coli ( E. coli ) levels, and stable isotopes. Karst springs in east-central Missouri that have no known air-filled passages (“phreatic” springs) typically have low DO and pH values ( 60% saturation and >7.7, respectively) that resemble surface waters due to the equilibration of DO with the overlying cave atmosphere and the simultaneous degassing of dissolved CO 2 . Traverses down phreatic spring branches show exchange with the atmosphere causes an increase in DO only a short distance downstream of the spring orifice, while the pH concurrently increases due to the degassing of CO 2 . Further downstream both parameters tend to level off reflecting a general approach to equilibrium under surface conditions, though this process is more rapid for DO than for pH. In contrast, the DO and pH along cave spring branches change little from values at the cave entrance. Additionally, (1) degassing processes affect the saturation state of calcite, with cave springs being the most saturated with respect to calcite, (2) phreatic springs typically have lower TSS and E. coli levels than open cave springs due to slower and less variable flow delivery, longer residence times, and less turbulent flow, and (3) phreatic springs tend to plot on the global meteoric water line (MWL), while waters from open cave systems tend to be enriched in 18 O and D and can plot below the line due to evaporation and exchange of the water with the overlying cave atmosphere.

Horizontal and vertical variations in the distribution of 14C, δ13C, δ18O, and δ2H in groundwater of Žitný Island (Rye Island) have been studied. Žitný Island, situated in the Danube River Basin, is the largest island in Europe that is formed by interconnected rivers. It is also the largest groundwater reservoir in central Europe (∼1010 m3 of drinking water). The δ2H vs. δ18O plot made from collected groundwater samples showed an agreement with the Global Meteoric Water Line. In the eastern part of the island, it was found that subsurface water profiles (below 10 m water depth) showed enriched δ18O levels, which were probably caused by large evaporation losses and the practice of irrigating the land for agriculture. The core of the subsurface 14C profile represents contemporary groundwater with 14C values >80 pMC, indicating that the Danube River during all its water levels feeds most of the groundwater of Žitný Island. However, on the eastern part of the island a small area was found where the δ13C and 14C data (down to ∼30 pMC) helped to identify a groundwater aquifer formed below the Neogene clay sediments. This is the first time that vertical distributions of isotopes in different groundwater horizons have been studied.

Hydrogen and oxygen stable isotope in water bodies is a widely used tracer in hydrological process studies. In order to provide a basis for stable isotopic characteristics in different water bodies at the high mountainous area of northwestern Tibetan Plateau, samples for river water, groundwater, soil water, and plant water were collected from 10 sites in the Qilian Mountains during July and August 2015, and then analyzed for δ18O and δD, respectively. Results indicated that the stable isotope values of soil water were mostly plotted below the global meteoric water line (GMWL), which suggested that evaporation made heavy isotope in soil water enriched. The stable isotope values of soil water were quite different in the top soil layer, but tended to be uniform in the deep soil layer. Furthermore, the stable isotope difference of plant water is related to climatic conditions, water isotopes utilized by plant, plant species, growing season, and so on. Additionally, the variation of δ18O values for river water and groundwater relatively coincided with each other, and this showed the recharge sources of above two water bodies may be consistent. The stable isotope values of river water and groundwater were mainly plotted on the upper left of GMWL, and the lower level of isotopic fractionation due to weak evaporation may accountable for this.

In this study, the isotopic properties of the water resources located in Kopruoren Basin ( are determined. δ 18 O and δD contents of the samples respectively ranged from -10.84‰ to -7.09 ‰ and from -73.6‰ to -53.3‰ in dry season and ranged from -10.81‰ to -4.71‰ and -73.3‰ to -41.5‰ in wet season. Majority of the samples plotted along Global Meteoric Water line although some of them show deviations from this line. The reason for the deviations are attributed to evaporative enrichment, modifying the original δ 18 O and δD signatures of the samples. δ 18 O content of the thermal samples are not modified as a result of water-rock interaction due to low wellhead and reservoir temperatures. Tritium concentrations for all samples range from ~0 TU to 6 TU in wet season and from ~0 to 8 TU in dry season. Accordingly, some of the groundwater samples are recharged from modern precipitation, their groundwater residence times are short and they have shallow circulation. Besides, samples with tritium concentrations close to detection limits (thermal water samples and two of the groundwater samples) were recharge before tritium from nuclear weapon tests and have relatively higher residence times. These samples were also analysed for δ 13 C and 14 C to get information about the residence times. δ 13 C ve percent modern carbon contents of five samples range from -5‰ to -14.6‰ and from 8.2 to 78 pmc, respectively. The corrected 14 C ages for these samples are upto 11500 years before present, thereby indicating the presence of paleowaters in the basin. δ 13 C data indicate that 14 C contents of the thermal waters were diluted as a result of water-rock interaction.