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This hydrochemical study of the surface and groundwater in Khan AL-Baghdadi area, western Iraq, included the interpretation of physical, chemical, and biological properties. Water samples were collected from wells (14 samples) and surface water of Euphrates River (6 samples) for the dry and wet periods of October 2018 and April 2019, respectively. The stable isotopes analysis was performed for the dry period only. The surface water samples were characterized by slightly alkaline, fresh, excessively mineralized, Ca-chloride type, and hard to very hard water class. While the groundwater samples were characterized by slightly alkaline, brackish, excessively mineralized, Ca-chloride and Na-Chloride type, and hard to very hard water class. The stable isotopic analysis was used in studying the interaction between water resources of Euphrates River and groundwater. Stable isotopes (δD and δ18O) were used to study the hydrological aspects of water resources in the study area. The results showed that surface and groundwater samples have similar source with a correlation relationship between them, in addition to the clear effect of river recharge on groundwater. The variation in δ2H and δ18O signature of groundwater in the study area is caused mainly by variation in isotopic composition of recharge water zone and mixing water. Using the δ 2H and δ 18O diagram, all surface and groundwater samples were plotted below the global meteoric water line (GMWL) and Local Meteoric Water line (LMWL), indicating the influences of the evaporation processes and seasonal variation.

Study region: Robit-Bata watershed, Upper Blue Nile basin, Ethiopia. Study focus: Stable isotopes of water (Oxygen-18 and Deuterium) were used as tracers to estimate the contribution of groundwater in shallow hillslope aquifers to streamflow in the Robit-Bata watershed. To assess the spatiotemporal variability of shallow groundwater and develop a hydrograph separation technique, we collected rainfall, shallow groundwater, and streamflow samples and analyzed their δ18O and δ2H isotopic compositions. The local meteoric water line (LMWL) and local evaporative line (LEL) of the study area were determined and compared with the global meteoric water line (GMWL). A standard unweighted two-component isotope-based hydrograph separation model was used to determine the percentage contribution of shallow groundwater to streamflow. New hydrological insights for the region: The LMWL (δ2H = 8.63·δ18O + 18.2) mostly showed heavy isotopic enrichment relative to GMWL, and the LEL (δ2H = 5.45·δ18O + 6.96) indicated isotopic enrichment compared to Ethiopian lakes. Shallow groundwater responded rapidly to rainfall, with good spatial correlation depending on topographic positions of wells. Pre-event water contributed 90% when the watershed reached maximum storage. This finding gives insight towards the predominant runoff generation process and has significant implications for sustainable dry season irrigation expansion in the area as the sub-surface flow drains out of the watershed from October onwards reducing water tables in the shallow wells.

The first systematic research of the geo-hydrogeological and hydrogeochemical characteristics and isotopic signatures was carried out in the transboundary karstic aquifer in northeast of Iran, in order to investigate the groundwater origin, flow directions and karst development. The karstic springs of the area are characterized by discharge rate of 50–500 L/s, EC values of 370–1050 μS/cm and the Ca–Mg–HCO3 water type. Stable isotope values of the precipitations resulted in a LMWL (δ2H = 7.2 × δ18O+8.6, R2 = 0.96, n = 96) with a lower slope and a lower intercept than the global meteoric water line (GMWL) due to isotope kinetic fractionation effects during precipitation. The δ18O precipitation gradient is −0.32‰ per 100 m of altitude. Isotopes data reveals that recent Mediterranean meteoric water (rain and/or snow) is the main origin of groundwater in the study area. The depleted isotope composition of some of the springs can be attributed to their higher catchment area and more recharge by snow. Groundwater budget analysis reveals that a large amount of water migrates toward the neighboring country. Fold and fault zones can be important variables on groundwater local and regional flows in the karstic aquifer. In terms of karst development, the Sarani spring in transboundary karstic aquifer with lower δ18O, δ37Cl and EC values and higher δ13CDIC has conduit flow regime and more karst development in its catchment area. In comparison, the isotopic values as well as physic-chemical characteristics of the springs confirm larger residence times (>30 years) and lower karst development in the other karstic springs. Consequently, the geo-hydrogeological and tectonic settings as well as isotopic approaches enhances knowledge in both groundwater flow direction and karst development and, ultimately, to better evaluate and manage water resources in the study area, and also in other transboundary karstic regions.

The north-east of Iran is a semi-arid region and faces a water shortage crisis. Therefore, monitoring water resources using accurate methods such as stable isotopes technique is vitally important. In this study, precipitation events were sampled in 10 stations in the Mashhad basin and the Bojnourd region in 2008, 2009, 2011, and 2015, additional surface and groundwater. These samples were analysed at the Ottawa University for both oxygen and hydrogen isotopes. In addition, the moisture sources were determined using the backward trajectories of the HYSPLIT model. The backward trajectories showed that both high- and low-latitude water bodies provide moisture for the north-east of Iran. However, the role of high-latitude water bodies including the Caspian, the Black, and the Mediterranean Seas is stronger. On the other hand, the stable isotopes showed large variations and the developed meteoric water lines deviated in both slope and intercept from the global meteoric water line. This showed that the precipitation events of the north-east of Iran were provided by various air masses and moisture sources. Finally, plotting the isotope values of the surface water resources on high- and low-latitude meteoric water lines demonstrated that these water resources were dominantly recharged by precipitation events originating from high-latitude water bodies.

By surveying and evaluating the δD and δ18O values of the water in the source region of the Yangtze River and the Lancang River, the characteristics of the hydrogen and oxygen stable isotope composition have been analyzed. The results showed that the ranges of δD and δ18O values varied from −126.28‰ to −47.96‰ and −16.77‰ to −7.13‰. The standard deviation of δD and δ18O value are 18.58‰ and 2.34‰. The stability of δ18O value is better than δD. Atmospheric precipitation is the principal source of river water supply in the region. The Local Meteoric Water Line equation is δD = 7.73 δ18O + 4.81 (R2 = 0.96, n = 19). Due to strong evapotranspiration, its slope and intercept are smaller than the Global Meteoric Water Line. The strong evapotranspiration in the source regions causes most of the d-excess to be negative, and the ice-snow melt water replenishment feature causes some d-excess to be positive. δD and δ18O values in the source regions exhibited certain latitude effect and continental effect.

As a species for ecological restoration in northern China, Tamarix ramosissima plays an important role in river protection, flood control, regional climate regulation, and landscape construction with vegetation. Two sampling sites were selected in the hillside and floodplain habitats along the Lanzhou City, and the xylems of T. ramosissima and potential water sources were collected, respectively. The Bayesian mixture model (MixSIAR) and soil water excess (SW-excess) were applied to analyze the relationship on different water pools and the utilization ratios of T. ramosissima to potential water sources in two habitats. The results showed that the slope and intercept of local meteoric water line (LMWL) in two habitats were smaller compared with the global meteoric water line (GMWL), which indicated the existence of drier climate and strong evaporation in the study area, especially in the hillside habitat. Except for the three months in hillside, the SW-excess of T. ramosissima were negative, which indicated that xylems of T. ramosissima are more depleted in &delta, 2H than the soil water line. In growing seasons, the main water source in hillside habitat was deep soil water (80~150 cm) and the utilization ratio was 63 &plusmn, 17% for T. ramosissima, while the main water source in floodplain habitat was shallow soil water (0~30 cm), with a utilization ratio of 42.6 &plusmn, 19.2%, and the water sources were different in diverse months. T. ramosissima has a certain adaptation mechanism and water-use strategies in two habitats, and also an altered water uptake pattern in acquiring the more stable water. This study will provide a theoretical basis for plant water management in ecological environment protection in the Loess Plateau.

The water sources of the Sokoto Basin are mainly of interrelated origin. The groundwater is composed of old water recharged in different climate regimes and of recent meteoric water. The recharge source is influenced by both local and regional moisture circulation given the lower slope and intercept of the local meteoric water line (LMWL) relative to those of the global meteoric water line (GMWL) and distribution of the deuterium excess d from –20 to +14 ‰. The identified interrelated water sources were confirmed by variations in tritium measured between 4.9 and

This review concerns the knowledge of the isotopic composition of current precipitation and its association with climate, geography and orography, in the Central Andes (14–28°S and 75–63°W). This knowledge is required for the evaluation of other hydrological values, especially aquifer recharge and water resources, in environments varying from rainy to hyper-arid. Since the 1960s, oxygen (δ18O) and deuterium (δ2H) isotope composition of natural water have been used as tracers of the global hydrological cycle. In the present article, the goal is to identify the origin and trajectory of air masses that produce rainfall in the Central Andes and the isotopic composition of the precipitation, as a first step to evaluate recharge and groundwater resources. The isotopic composition of rainfall varies spatially and temporarily, depending on the climatic phenomena that originate the movement of air masses, their moisture content and the isotope fractionation processes that occur until precipitation falls. Most of the significant and recent literature on the mechanisms of δ18O and δ2H transport and fractionation in precipitation along the Central Andes has been collected and summarized in this review. Precipitation in the eastern and central Andes comes mainly from the humidity generated in the Atlantic Ocean. Although the processes involved in isotope content variability of precipitation are well known, the processes involved in isotopic variability in the Western Cordillera remain poorly understood. This is mostly due to mixing of different moisture sources: from the Atlantic Ocean in summer and from the Pacific Ocean in winter. In general, winter rainfall is more enriched in δ18O and δ2H than summer rainfall. Looking at existing data, their distribution is far from being homogeneous and well-distributed, so spatial accuracy is poor in some areas, especially in the Altiplano. Hydrological and hydrogeological research and water resources evaluation in the Central Andes would greatly benefit from initiatives to obtain broader spatial coverage of rainfall collection to get isotope data for more accurate and continuous assessment of the local weather patterns. Groundwater isotope composition is a future tool to help in increasing the coverage in data scarce areas., The authors acknowledge SQM (Chile) for their support and for sharing isotopes data of the Salar de Atacama, as well as Southern Copper (Peru) for providing isotopic information. We thank two anonymous reviewers for their valuable comments. Further to this, numerous researchers, professors and practitioners from Argentina and Chile (Daniel E. Martinez, Cristina Dapeña and Christian Herrera) have contributed published and unpublished information and their personal experience.

Increasingly, modern hydrological technologies are dynamically altering river water flow and drastically affecting river hydrogeochemical cycle regimes globally. The present study focused on the reservoir discharges of artificial floodwaters that influence spatiotemporal variations in the physicochemical and stable isotope compositions in the lower Yellow River (LYR) of China. The surface water samples were collected at the nine sites along the LYR during the pre-, inter-and post-flood periods. Then, the collected samples were analysed with the following standard method. The δD and δ18O slopes of the waterline clearly indicated that the prolonged reservoir water and different water flows impacted the hydrological cycle in the LYR regions compared to GMWL (global meteoric water line) and LMWL (local meteoric water line). The thermal stratification processes of the water in the largest reservoir slightly enriched the heavy isotopes, and physicochemical alteration was neglected. Statistical analysis of two-way ANOVA revealed that the p-values (p

We assessed environmental tracers in groundwater in two contrasting basins in Namibia; the Kuiseb Basin, which is a predominantly dry area and the Cuvelai-Etosha Basin, which is prone to alternating floods and droughts. We aimed to determine why the quality of groundwater was different in these two basins which occur in an arid environment. We analysed groundwater and surface water for the stable isotope ratios of hydrogen (δ2H) and oxygen (δ18O) by cavity ring-down spectroscopy and metals by inductively coupled plasma mass spectrometry. The δ2H and δ18O of surface water in the Cuvelai-Etosha Basin plot on an evaporation trend below the global meteoric water line (GMWL) and the local meteoric water line (LMWL). The δ2H and δ18O of some groundwater samples in the Cuvelai-Etosha Basin also plot on the evaporation trend, indicating recharge by evaporated rain or evaporated surface water. In contrast, the δ2H and δ18O of groundwater samples in the Kuiseb Basin plot mostly along the GMWL and the LMWL, indicating direct recharge from unevaporated rain or unevaporated surface water. Fifty percent of groundwater samples in the Cuvelai-Etosha Basin was potable (salinity  K > Ca > Mg vs. Na > Mg > Ca > K for the Cuvelai-Etosha Basin. For metals in the Kuiseb Basin the order of abundance is Fe > Al > V > As > Zn vs. Al > Fe > V> As > Zn for the Cuvelai-Etosha Basin. The relative abundance of cations and metals are attributed to the differences in geology of the basins and the extent of water-rock interaction. Our results show that the quality of groundwater in Cuvelai-Etosha Basin and Kuiseb Basin which vary in the extent of aridity, is controlled by the extent of water-rock interaction at the surface and in the groundwater aquifer.

Isotopic characterization of all identified hydrological units in Lake Toba such as precipitation, inflows, outflows, and lake water, as a first assessment of lake water balance study, has been conducted. The isotopic characterization was done through the interpretation of the relationship of d D and d 18 O values of collected samples from various water sources and their variations as a function of time and space. Rain water samples were collected from four rain collectors that were installed in the study area in a monthly sampling for a period of 12 months in 2014. Several samples from various water sources i.e ., inflow streams, outflows, springs, and lake water, were also collected 2-3 times during this sampling period. From monthly sampling of rain water, local meteoric water line ( LMWL ) and the equation of elevations versus d D values have been constructed. Due to the slightly higher temperature in the study area compared with the average temperature on the other parts of the world, the slope of the constructed LMWL is slightly less than the slope of global meteoric water line. Based on the equation of elevations versus d D values, the elevations of four springs around study area have been identified. From the linear relationship of d D and d 18 O values of collected samples from inflow streams, it was found that most of the samples have experienced evaporation process before entering the lake. Due to mixing with other surface water and longer transit time, the d D and d 18 O values of those samples from streams in the Sumatran side are more enriched than those samples from streams in the Samosir side. It was also found that lake water has experienced significant evaporation as indicated by the d D and d 18 O values that were more enriched than any other samples. The d D and d 18 O of Asahan River samples, the only output of Lake Toba, were found to be very close to the d D and d 18 O of the lake. This is because almost all water that flowed in Asahan River originated from the lake. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

Understanding the sources and compositional characteristics of waters and sediments in the Indus River system is extremely important as its water availability is one of the primary factors for sustenance of the irrigation activities and the socioeconomic status of a very densely populated region of the world. Here we used stable isotopic compositions (δD and δ18O) and strontium isotopic ratio (87Sr/86Sr) in the Indus River water, its tributaries and its small streams (nallahs) in the Indian territory to understand the regional hydrology, water sources, and catchment processes (evaporation, transpiration, recycling, and mixing). The δ18O values in the Indus River system (IRS) ranges from − 16.9‰ to − 12.5‰ and δD from − 122.8‰ to − 88.5‰. The Indus River and its major tributaries (such as the Zanskar, Nubra and Shyok rivers) are characterized by relatively lower δ18O values, whereas TangTse and other small streams contributing to the Indus are relatively enriched in 18O. The local meteoric water line for the IRS was found to be δD = 7.87 × δ18O + 11.41, which is similar to the Global Meteoric Water Line (GMWL) indicating meteoric origin of the water and insignificant secondary evaporation in the catchment. The Deuterium excess (d-excess) in the IRS varies between 6.5‰ and 14.9‰ with an average of 11.7‰, which is mostly higher than the long-term average for the Indian summer monsoon (~ 8‰). The higher d-excess value is because of the contribution of moisture from westerlies; a simple mass balance shows ~ 26% water in the main Indus channel is contributed by the westerlies originated from the Mediterranean Sea. The Sr isotope ratio in IRS varies between 0.70515 and 0.71291; wherein the Indus, and its tributary rivers Shyok and Nubra, are characterized by relatively high Sr isotope ratios (avg. 0.71086–0.71243) compared to the Zanskar and TangTse tributaries (Sr ~ 0.709) because of the variation in silicate rock weathering component and carbonate rock weathering component ratios respectively.

In this study, the characteristics of δ2H and δ18O in rainwater, groundwater and spring water have been used to understand the groundwater recharge dynamics in the Amedzofe area (one of the highest human habitation in Ghana). The local Meteoric Water Line (LMWL) using all the rainfall events gave an equation with the best fit line of δ2H = 7.32 δ18O + 8.20 (n = 113; r 2 = 0.94). Heavier rainfall events greater than 10, 20 and 30 mm further orient the slope closer to the Global Meteoric Water Line (GMWL). The data showed that the isotopic compositions of the rainwater in the area are mainly influenced by the rainfall amount with temperature having minimal effect. All the spring water and most of the groundwater plot around the GMWL, implying they are of meteoric origin. The Chloride Mass Balance (CMB) and δ18O shift methods suggest annual mean recharge rate of 160.43 and 125.79 mm/year representing 10.70 and 8.39% of annual rainfall, respectively. The estimated mean recharge rate for the spring was 317.51 mm/year and 300.68 mm/year representing 26.46 and 25.06% of annual rainfall for CMB and δ18O shift methods, respectively. Rainfall stable isotopes from Kpando and Amedzofe gave an altitude effect of 0.17/100 m and altitude of recharge of the springs from +724.00 to +788.61 m amsl. The stable isotopes data identified two distinct moisture sources, isotopically enriched local moisture (evaporated surface water bodies and evapo-transpiration water vapour flux from vegetation) and isotopically depleted moisture source from the Atlantic Ocean. The results further showed that significant groundwater recharge in the study area takes place in the months of March, June and August.

Wang, T., Xu, Z., Zhang, S., Zhang, L., & Zhao, Z. (MarchApril, 2017). Research on the hydrologic cycle characteristics using stable isotopes of oxygen and hydrogen in the Jinxiuchuan Basin. Water Technology and Sciences (in Spanish), 8(2), 105-115. Stable isotopes of oxygen (δ18O) and hydrogen (δD) in water were used as important indicators to research the hydrologic cycle or processes. To study the hydrologic cycle characteristics of the Jinxiuchuan basin, the isotope labelling and the industrial salt tracing method were used in this research. Sixty-seven samples of different water bodies were collected at different sampling sites from July 2011 to July 2012. The stable hydrogen and oxygen isotopes in water samples were measured by using Liquid Water Isotope Analyzer (LWIA-24d) to study the conversion relationship among precipitation, river water, soil water, and groundwater of the Jinxiuchuan basin in Jinan. The results show that δD and δ18O varied from 35.6 ‰ to 128.3 ‰ and from 5.3 ‰ to 17.5‰, respectively. A meteoric water line of δD = 7.16δ18O + 4.35‰, which was in accordance with the global meteoric water line and the meteoric water line of China, was established in the Jinxiuchuan basin. The deuterium excess values vary with time and space, ranging from 5.1 to 22.3‰, and increase gradually from the southeast to the northwest. In addition, the exchange of different water bodies was determined preliminarily, the rates of precipitation transforming into river water, soil water, and groundwater are 43.76%, 21.91% and 6.84%, and the remaining is 27.49% returned to the atmosphere. The results indicated the hydrologic cycle characteristics in the Jinxiuchuan basin. It may provide the references for precipitation isotopes research in semi-humid regions.

Climate changes and other human activities have substantially altered the hydrological cycle with respect to elevation. In this study, longitudinal patterns in the stable isotopic composition (&delta, 2H and &delta, 18O) of Lancang River water, originating from the Qinghai&ndash, Tibetan Plateau, are presented, and several controlling factors in the wet season are hypothesized. Lancang River water &delta, 2H (&minus, 145.2&permil, to &minus, 60.7&permil, ) and &delta, 18O (&minus, 18.51&permil, 8.49&permil, ) were low but close to those of the Global Meteoric Water Line. In the upper reaches of the river, &delta, 2H decreased longitudinally, potentially due to groundwater inputs and melting ground ice in the headwater zone and to an increasing proportion of glacier meltwater with decreasing elevation. In the middle reaches of the river, &delta, 2H values increased slowly moving downstream, likely due to shifts in precipitation inputs, as evidenced by the isotopic composition of tributaries to the main stream. In the lower reaches of the river, the isotopic composition was relatively invariant, potentially related to the presence of large artificial reservoirs that increase the water resident time. The results reveal different hydrological patterns along an alpine river in central Asia associated with both natural and anthropogenic processes. Understanding the degree and type of human interference with the water cycle in this region could improve water management and water security.

All soluble substances for coastal shallow well waters were higher than those for the inland well waters in the Kinokawa River catchment along the Median Tectonic Line in Wakayama Prefecture, Japan. Coastal areas were thought to have been contaminated by sewage wastewater due to a high population. Shallow groundwater is thought to have derived from precipitation because all shallow groundwater is on the Global Meteoric Water Line. There are many hot springs in the Kinokawa River catchment along the Median Tectonic Line in Wakayama. Most hot spring waters are thought to originate from mixing of shallow groundwater and Arima type deep thermal water because of their δ18O and δD values. High Li+ concentration water was found for Arima type deep thermal water. In particular, Li+ concentration of Nohan No.5 borehole, 1100m in depth, in the center of Kinokawa River catchment reached 100 mg/l and this value was the highest in Japan. However, both δ18O and δD values for hot spring waters did not always increase with Li+ and HCO3- concentrations although both δ18O and δD values increased with Na+ and Cl- concentrations. Li+ concentration for hot springs increased with HCO3- concentration. Therefore, the Li source was determined not to be different from Na+ and Cl- source.

Salinity increase in groundwater was investigated in the area between Al-Zubair and Safwan, and close to the Khor Al-Zubair Channel of southern Iraq. Thirty-nine groundwater samples from the shallow aquifer and one sample from the Khor Al-Zubair Channel were analyzed. The mean total dissolved solids are 7556 mg/L. The δ2H and δ18O plot in two groups are below the global meteoric water line. Group A indicates the evaporation effect of irrigation return-flow, while group B is characterized by depleted δ18O values due to recharge under colder climate. Deuterium excess values plot within the region of modern precipitation and dilution of groundwater by precipitating water. The groundwater residence time is between 1000 and 2000 years and combining 14C -age with SO42− shows a contrasting effect on groundwater on both sides of Khedr Almai Fault and the Zubair anticline, which indicates the role of these geological structures on the hydrochemical evolution in the western part. Jabal Sanam shows no clear effect in this regard. The ratio Cl−/Br− and sulfate in groundwater showed that the measured salinity in groundwater is the result of a mixing process between groundwater, seawater intruding from Khor Al-Zubair Channel, and water from septic tanks in addition to dry and wet sea spray, and irrigation return-flow.

Geothermal fields are common in the north-western part of the Himalaya encompassing Himachal Pradesh and Ladakh region, owing probably to their link to the northward migration of the Indian plate and due to under plating. Twenty geothermal springs along the Indus and Nubra valleys of Ladakh region, Sutlej, Beas, and Parbati valleys of Himachal region have been studied. The major & trace element characteristics and stable isotopic composition (δ 13 C DIC , δ 18 O & δD) of these springs were employed to trace their origin and process of metamorphic CO 2 degassing. Surface temperature of these springs varies from 21 to 95 °C, with an average of 56 °C, whereas pH ranges from slightly acidic to alkaline 6.2–8.9 with an average of 7. Hydro-chemically these springs fall under the categories of HCO 3 : Cl: SO 4 and Na + K: Mg: Ca types. Abundance of trace element in these spring waters, such as Fe, B, Li, Sr, Mn, Al, Mo, Zn, and As, were found in considerable amount, possibly due to the rock-water interaction. Springs of the study area contain high ratios of dissolved inorganic carbon (DIC) with concentrations of HCO 3 − ranging from 1300 to 13400, (average of 5297) μE. The δ 13 C DIC ratios of these springs vary from −8.4‰ to +1.7‰ VPDB , which points towards the deeper source of their origin. δ 18 O composition of these springs range from −16 to −7.3‰ vsmow with corresponding variation in δD varies from −123.5 to − 44.8‰ vsmow indicating mixing of thermal water with a meteoric dominated reservoir as most of these samples fall on the line defined by Global Meteoric Water Line (GMWL). In the present study we have estimated the metamorphic CO 2 flux using concentration of HCO 3 ≈ DIC of these springs and have found that the geothermal springs of the northwest Himalaya have potential to degas ∼2.9 × 10 7 mol CO 2 per year in the atmosphere. Further reservoir temperatures for these springs were also estimated applying standard dissolved silica geothermometers which varies from 42 to 107 °C indicating their application in space heating and to generate electricity in certain cases.

Vertical infiltration of precipitation has been examined in this study for the purpose of evaluating groundwater recharge processes in parts of the Nasia sub-catchment of the White Volta Basin. As recharge is an essential component in the detailed assessment of groundwater resources potential in a basin, evaluating its processes is vital in determining the spatial and temporal variability of the resource. Stable isotope data of precipitation, groundwater, surface water and porewater in the area suggest that the local precipitation is largely enriched compared to global meteoric water. This is consistent with the prevailing local conditions in the region and ties in with observations in other parts of the sub-region. The groundwater and porewater data indicate that prior to, and in the process of infiltration and final percolation into the saturated zone, rainwater undergoes evaporative enrichment such that the finally recharged water plots along an evaporation line with a much shallower gradient and intercept compared to the global meteoric water line and the local meteoric water line. The isotope data further suggest that through the shallow unsaturated zone, a significant fraction of the initial precipitation would have been evaporated by a depth of 3.0 m. Evaporation rates in the range of 38–49% have been estimated for the depth range of 0–3.0 m based on the porewater stable isotope data. Details of the procedures and implications of high evaporation rates within such shallower depths are presented and discussed. Groundwater recharge rates estimated from the chloride mass balance technique report values in the range of 73.26 mm/yr (390 Mm 3 /yr)–109.89 mm/yr (585.27 Mm 3 /yr), with an average of 94 mm/yr (500.6 Mm 3 /yr). These translate into 6.6–10.9% of annual precipitation. Based on the current population trends and per capita water demand of 50 L per capita per day, this study finds that the estimated recharge rates exceed the demand 59 times. This suggests significant promise for developing groundwater resources for climate-proof livelihood support projects in the terrain. However, much more detailed hydrogeological assessments are required to constrain the effects of lateral and vertical lithological variations on the availability of the recharged groundwater for immediate abstraction and use. The study also observes that since evaporation is one of the main dynamic processes influencing the fraction of the initial precipitation that finally reaches the saturated zone, projected increases in temperature during the next decade may increase evaporation rates of infiltrating rainwater leading to reduced groundwater rates.

Geomorphological and thermo-hydrological changes to tundra, caused by a wildfire in 2002 on the central Seward Peninsula of Alaska, were investigated as a case study for understanding the response from ice-rich permafrost terrain to surface disturbance. Frozen and unfrozen soil samples were collected at burned and unburned areas, and then water isotope geochemistry and cryostratigraphy of the active layer and near-surface permafrost were analyzed to investigate past hydrological and freeze/thaw conditions, and how this information could be recorded within the permafrost. The development of thermokarst subsidence due to ice-wedge melting after the fire was clear from analyses of historical sub-meter-resolution remote sensing imagery, long-term monitoring of thermo-hydrological conditions within the active layer, in-situ surveys of micro-relief, and geochemical signals recorded in the near-surface permafrost. The resulting polygonal relief coincided with depression lines along an underground ice-wedge network, and cumulative subsidence to 2013 was estimated as at least 10.1 to 12.1 cm (0.9-1.1 cm/year eleven-year average). Profiles of water geochemistry in the ground indicated mixing or replenishment of older permafrost water with newer meteoric water, as a consequence of the increase in active layer thickness due to wildfire or past thaw event. Our geocryological analysis of cores suggests that permafrost could be used to reconstruct the permafrost degradation history for the study site. Distinct hydrogen and oxygen isotopic compositions above the Global Meteoric Water Line were found for water from these sites where permafrost degradation with geomorphological change and prolonged surface inundation were suggested.

Summary The present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the Chakdaha block, West Bengal, in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and concomitant As release. A low-land flood plain and a natural levee have been selected for this purpose. Although the stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) are largely controlled by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, especially during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. Increase in mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge. Concomitant increase in AsT, Fe(II) and HCO3− highlights a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The subsequent sharp increase in the mean As(III) proportions (by 223%), particularly in the flood plain samples during the post-monsoon season, which is accompanied by a slight increase in mean AsT (7%) may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without triggering additional As release from the aquifer sediments.

Although groundwater is an important component of the water cycle in the polar regions, groundwater in Antarctica has rarely been studied. This study evaluated the physical and chemical characteristics of groundwater, surface water, and snow in two lakes on the Barton Peninsula, King George Island, Antarctica, with a particular focus on groundwater. Influxes/outfluxes of groundwater were measured using seepage meters, and hydraulic conductivities were calculated based on grain size analysis for the sediments. A total of 41 water samples were used to determine the chemical compositions and isotopic ratios of oxygen and hydrogen. The groundwater fluxes measured in one lake (referred to as “Lake A”) were −9.9 × 10−10 ~ 2.7 × 10−9 m/s (average of −9.1 × 10−10 ± 3.6 × 10−9 m/s) and in a second lake (referred to as “Lake B”) were 2.2 × 10−9 ~ 3.0 × 10−9 m/s (average of 2.6 × 10−9 ± 4.0 × 10−10 m/s). This indicates that groundwater flux is highly dynamic in Lake A, whereas groundwater influx in Lake B is relatively stable. Hydraulic conductivity for the lake sediments ranged between 1.7 × 10−6 m/s and 2.1 × 10−4 m/s. Oxygen and hydrogen isotopic compositions followed the global meteoric water line (GMWL) and local meteoric water line (LMWL), indicating that groundwater and surface water in the study area originate from the atmosphere. Evaporation may not be an influential factor probably due to the relatively humid climate during the summer season in the study area. Groundwater and surface water might partially experience isotopic exchange fractionation during and after the snow melting process. The chemical composition of groundwater was distinguished from that of surface water and snow by higher concentrations of major anions (Cl, SO4, and alkalinity), major cations (Ca, Mg, K, and Na), and trace elements (Si, Li, Sr, Mn, Zn, and Cu), resulting from water-rock interactions. To the best of our knowledge, this is the first study to directly measure groundwater fluxes in lake systems in Antarctica, and to evaluate the characteristics of groundwater in the Barton Peninsula. It may therefore serve as a basis for studying the role of groundwater in the water cycle of Antarctica.

The surface water and groundwater interaction in the Imphal River Basin in Northeast India using hydrogeology, hydrochemical and isotopic constituents has examined to elucidate hydrochemical evolution, surface water and groundwater mixing and recharge condition. Groundwater is characterized by Ca2+–Cl-–HCO3-facies while surface water exhibits Ca2+–Cl- type. Surface water prevailed the intermediate stage of chemical evolution while groundwater characterizes the late stage of chemical evolution. Analysis of flow net combined with hydrogeologic sections revealed significant relationship of surface water and groundwater in the basin. The upper and lower reaches are characterized by contour heads showing an upstream pointing curvature due to depression induced by groundwater discharge where contour lines cross a gaining stream. The middle reach is marked by contour curvature pointing downstream owing to mounding induced by groundwater recharge where it crosses a losing stream. Groundwater shows markedly depleted isotopic composition than surface water. Both surface water and groundwater fall below Global Meteoric Water Line and Local Meteoric Water Line indicating the source of water through infiltration of modern precipitation. The slope of the evaporation line and the original composition of water are identified as 4.92 and −6.58‰ and −42.17‰, respectively. Isotopic d-excess values revealed isotopic composition of semi-arid climate.

A local meteoric water line based on rainwater and snow core samples was developed for an area comprising parts of eastern Norrbotten and Vasterbotten in northern Sweden. The oxygen and hydrogen isotopic composition of groundwater and water from four pit lakes was compared to the local meteoric water line by line-conditioned excess. The isotopic mass balance method was used to estimate the evaporation over inflow ratio and the residence time of the lakes. The results show that the local meteoric water line for the study area is: δ2H = (7.80 ± 0.09) δ18O + (4.35 ± 1.35) ‰, which is close to the global meteoric water line. The surface water of the four pit lakes all have negative line-conditioned excess values which indicate that they have been affected by evaporation. The groundwater plots on the local meteoric water line making it hard to utilize in a mixing model for a lake where precipitation and groundwater are treated as two different sources. Two scenarios were used to estimate the starting composition of the lakes for the isotopic mass balance method. One was based on the intersection point of the local meteoric water line and the local evaporation line and gave evaporation over inflow ratios ranging from 0.23 to 0.74 and residence times ranging from 7.2 to 44.9 years. The second scenario was based on the weighted average composition of precipitation and gave evaporation over inflow ratios ranging from 0.07 to 0.32 and residence times ranging from 2.8 to 14.9 years.

Stable hydrogen and oxygen in different water bodies were investigated to understand the isotopic characteristics in the Lhasa River Basin. A total of 73 water samples were collected from the river, well and spring in this study. The stable isotopic compositions of different water bodies are influenced by evaporation, and the slope of the local meteoric water line deviates slightly from that of the global meteoric water line. The slopes of the surface water, groundwater and spring water lines are smaller than that of the global meteoric water line. The surface water originates from not only atmospheric precipitation but also glacial/snow meltwater, especially in the Dang River, the upper reaches of the Lhasa River and the Duilong River. The groundwater is derived from meteoric water, and there are certain differences between the source and the cyclic process of groundwater at different locations and depths. Spring water is conjunctively recharged by groundwater, surface water and precipitation, but groundwater is the main source of spring water. The altitude effect of hydrogen and oxygen isotopes in river water is not obvious in the whole basin, but it is noticeable in some areas due to the effect of climate and temperature. Surface water, groundwater and spring water have a relationship of reciprocal recharge, and the miscibility of groundwater is the strongest, with recharge from multiple water sources.

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.

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.

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.

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.

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.

Groundwater of Chapai Nawabganj town has been studied using hydrogeological, hydrochemical and environmental isotope (δ 18 O, δ 2 H, δ 13 C, 3 H and 14 C) data. Aquifer underneath the study area is divided into unconfined to semi-confined Holocene alluvial floodplain aquifer and confined Plio-Pleistocene Dupi Tila sandstone aquifer. Chemical composition of groundwater is characterized by high concentrations of Mg 2+ , Na + , Ca 2+ , HCO 3 - , Fe Total , and low concentrations of Mn 2+ , NO 3 - and PO 4 3- . Groundwater samples are mainly Mg-Ca-HCO 3 and Na-Mg-Ca-HCO 3 types and Na-Mg-Ca-Cl-HCO 3 type of water is also found at some places. Based on Cl - and SO 4 2- concentrations groundwater is normal chloride and normal sulphate water, respectively. In terms of SAR and EC values water is excellent for irrigation purpose. The isotopic composition also suggests some segregation of groundwater from the different aquifers and indicates different ages of recharge. DOI: http://dx.doi.org/10.3329/jbas.v38i2.21338 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 2, 131-142, 2014

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.

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.

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.

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.

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.

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

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.

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 (

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.