Explore the vast range of titles available.

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.

Oxygen and deuterium isotopic values of meteoric waters from Ethiopia are unusually high when compared to waters from other high‐elevation settings in Africa and worldwide. These high values are well documented; however, the climatic processes responsible for the isotopic anomalies in Ethiopian waters have not been thoroughly investigated. We use isotopic data from waters and remote data products to demonstrate how different moisture sources affect the distribution of stable isotopes in waters from eastern Africa. Oxygen and deuterium stable isotopic data from 349 surface and near‐surface groundwaters indicate isotopic distinctions between waters in Ethiopia and Kenya and confirm the anomalous nature of Ethiopian waters. Remote data products from the Tropical Rainfall Measuring Mission (TRMM) and National Centers for Environmental Prediction (NCEP) reanalysis project show strong westerly and southwesterly components to low‐level winds during precipitation events in western and central Ethiopia. This is in contrast to the easterly and southeasterly winds that bring rainfall to Kenya and southeastern Ethiopia. Large regions of high equivalent potential temperatures (θe) at low levels over the Sudd and the Congo Basin demonstrate the potential for these areas as sources of moisture and convective instability. The combination of wind direction data from Ethiopia and θe distribution in Africa indicates that transpired moisture from the Sudd and the Congo Basin is likely responsible for the high isotopic values of rainfall in Ethiopia.

The time and geographic sources of streamwater in low-relief watersheds are poorly understood. This is partly due to the difficult combination of low runoff coefficients and often damped streamwater isotopic signals precluding traditional hydrograph separation and convolution integral approaches. Here we present a dual-isotope approach involving 18O and 2H of water in a low-angle forested watershed to determine streamwater source components and then build a conceptual model of streamflow generation. We focus on three headwater lowland sub-catchments draining the Savannah River Site in South Carolina, USA. Our results for a 3-year sampling period show that the slopes of the meteoric water lines/evaporation water lines (MWLs/EWLs) of the catchment water sources can be used to extract information on runoff sources in ways not considered before. Our dual-isotope approach was able to identify unique hillslope, riparian and deep groundwater, and streamflow compositions. The streams showed strong evaporative enrichment compared to the local meteoric water line (δ2H = 7.15 · δ18O +9.28‰) with slopes of 2.52, 2.84, and 2.86. Based on the unique and unambiguous slopes of the EWLs of the different water cycle components and the isotopic time series of the individual components, we were able to show how the riparian zone controls baseflow in this system and how the riparian zone \"resets\" the stable isotope composition of the observed streams in our low-angle, forested watersheds. Although this approach is limited in terms of quantifying mixing percentages between different end-members, our dual-isotope approach enabled the extraction of hydrologically useful information in a region with little change in individual isotope time series.

Climate change west of the Antarctic Peninsula is the most rapid of anywhere in the Southern Hemisphere, with associated changes in the rates and distributions of freshwater inputs to the ocean. Here, results from the first comprehensive survey of oxygen isotopes in seawater in this region are used to quantify spatial patterns of meteoric water (glacial discharge and precipitation) separately from sea ice melt. High levels of meteoric water are found close to the coast, due to orographic effects on precipitation and strong glacial discharge. Concentrations decrease offshore, driving significant southward geostrophic flows (up to ∼30 cm s−1). These produce high meteoric water concentrations at the southern end of the sampling grid, where collapse of the Wilkins Ice Shelf may also have contributed. Sea ice melt concentrations are lower than meteoric water and patchier because of the mobile nature of the sea ice itself. Nonetheless, net sea ice production in the northern part of the sampling grid is inferred; combined with net sea ice melt in the south, this indicates an overall southward ice motion. The survey is contextualized temporally using a decade-long series of isotope data from a coastal Antarctic Peninsula site. This shows a temporal decline in meteoric water in the upper ocean, contrary to expectations based on increasing precipitation and accelerating deglaciation. This is driven by the increasing occurrence of deeper winter mixed layers and has potential implications for concentrations of trace metals supplied to the euphotic zone by glacial discharge. As the regional freshwater system evolves, the continuing isotope monitoring described here will elucidate the ongoing impacts on climate and the ecosystem.

This paper presents research on the degradation processes of the fresco painting in the cave church of Corbii de Piatră Hermitage under the influence of meteoric infiltration water and environmental factors. The medieval fresco dates from the end of the 13th century and the beginning of the 14th century, being painted on a sandstone wall. The infiltration of meteoric water through this wall, the temperature variations, the environment and the repeated wetting/drying processes determined the degradation of the fresco, resulting in its detachment from large surfaces. This research established correlations between the processes that take place, the structural transformations, the changes in composition and the adhesion of the fresco to the sandstone wall. The results have been made available to conservation and restoration specialists, in order to choose appropriate materials and technologies. This paper presents findings regarding the pictorial material and introduces new analysis techniques in research on the degradation processes of the fresco painting in the cave church of Corbii de Piatră Hermitage under the influence of meteoric infiltration water and environmental factors.

The stable isotopic compositions of hydrogen (δ 2 H) and oxygen (δ 18 O) in precipitation serve as valuable indicators for perceptive the characteristics of precipitation, the mechanisms of groundwater replenishment, and for conducting climatological investigation. Environment isotope monitoring in Iraq, was conducted, with the assistance of the International Atomic Energy Agency IAEA and the World Meteorological Organization WMO as a part of the worldwide activity entitled Global Network of Isotopes in Precipitation GNIP. Precipitation samples were collected from main station sites in Iraq during the period (2023-2024), represented 154 samples .Rain samples were collected with the support of the Iraqi Meteorological Organization and Seismology, under the supervision of authorities from meteorological stations across various governorates in Iraq. The isotopic measurements of (δ 2 H) and (δ 18 O) were obtained from WISER website. The linear regression analysis was employed to regulate the relationship between δ 18 O and δ 2 H in rainfall. This work aimed to generate Local Meteoric Water Lines LMWL in three main regions across Iraq (Western, Northern, and Central/Southern) and compare them with the LMWLs for the neighboring countries. The results showed that Northern region, NMWL (δ2H= 7.9171δ 18 O + 15.011) exhibit depletion in precipitation isotope δ 18 O and δ 2 H values reflecting moisture contributions from the Mediterranean and black sea. While, western region with, WMWL (δ 2 H =5.7526 δ 18 O + 7.3653); appear to be dominated by evaporation enrichment of δ 18 O and δ 2 H. And central and Southern region, CSMWL (δ 2 H = 6.6102 δ 18 O + 10.412) experience relatively enriched δ 18 O and δ 2 H values, likely due to evaporation effects and moisture contributions from the Arabian Gulf. The fluctuation in δ 1 ⁸O throughout longitudinal transect related to the air mass trajectories and moisture origin, effecting isotopic composition of precipitation.Furthermore, a depletion in isotope levels was seen in the northern region based on the spatial distribution of precipitation isotopes. Conversely, the western region displayed relatively enriched isotope levels. Additionally, there is greater isotope value enrichment in the central and southern regions.These findings contribute to to identify locations with high and low precipitation, support in water project management, agricultural improvement, and drought and flood prediction.

The dolomite aquifer in Witwatersrand is one of the most important water resources in South Africa. The present paper aims to evaluate the hydrochemical and isotope (δ2H and δ18O) signature of water (n = 36) (groundwaters, surface waters, dams, springs, canal, cave and pipeline) of the Wonderfonteinspruit (WFS). These samples were analysed for the first time in the Centre for Water Sciences and Management (South Africa). The dominant anions are SO42− and Cl−, while the dominant cations are Ca2+ followed by Mg+, Na+ and K+. A Piper diagram showed that there are two principal hydrochemical facies (1) Ca–Mg–Cl–SO4; (2) Ca–Mg–HCO3 in the study area. Bivariate plots revealed that the main hydrogeochemical processes influencing the water are water–rock interaction, mineral precipitation/dissolution, ions exchange and anthropogenic activities. The local meteoric water line (LMWL) was plotted for the first time for the WFS catchment based on precipitation data during six periods (November 2018 until June 2019) with the following equation δ2H = 7.39 * δ18O + 7.9‰ (R2 = 0.85). The results of stable isotopes (δ2H and δ18O) indicated that the water points from local precipitation and recent water, and the groundwater recharge is influenced by rapid infiltration river flow and return irrigation flow.

Mixing is a dominant hydrogeological process in the hydrothermal spring system in the Cappadocia region of Turkey. All springs emerge along faults, which have the potential to transmit waters rapidly from great depths. However, mixing with shallow meteoric waters within the flow system results in uncertainty in the interpretation of geochemical results. The chemical compositions of cold and warm springs and geothermal waters are varied, but overall there is a trend from Ca–HCO 3 dominated to Na–Cl dominated. There is little difference in the seasonal ionic compositions of the hot springs, suggesting the waters are sourced from a well-mixed reservoir. Based on δ 18 O and δ 2 H concentrations, all waters are of meteoric origin with evidence of temperature equilibration with carbonate rocks and evaporation. Seasonal isotopic variability indicates that only a small proportion of late spring and summer precipitation forms recharge and that fresh meteoric waters move rapidly into the flow system and mix with thermal waters at depth. 3 H and percent modern carbon (pmC) values reflect progressively longer groundwater pathways from cold to geothermal waters; however, mixing processes and the very high dissolved inorganic carbon (DIC) of the water samples preclude the use of either isotope to gain any insight on actual groundwater ages.

In this study, main characteristics controlling the evolution of groundwater chemistry were assessed by employing hydrochemical methods along with environmental stable isotope (δ18O, δ2H, and δ13C) techniques in major and complex karstic resources in Paveh–Javanrud (PV─JR) area, northwest (NW) of Iran. Thirty-four water samples from caves, springs, and wells were collected during two seasons for major ions (cations and anions) as well as stable isotope investigations on December 2014 (wet season) and October 2015 (dry season). Additionally, nine samples were also acquired from monthly precipitation (January 2015 till November 2015) for isotopic analyses from PV climatology station. Determining meteoric water line of Paveh (PMWL, δ2H = 6.9 δ18O + 11.9, R2 = 0.97) indicates that the origination of air masses of the region was found to be Mediterranean Sea. Hydrogeochemical investigations, on the other hand, indicated that three major formations including a pure limestone, Bistoun formation (JKb), and two limestones with some sort of impurities, i.e., Ilam–Sarvak (KIl-KSv) and Goru (Gr.) affected the water resources of the region. Regarding δ18O and δ2H results, most of karstic resources are plotted near PMWL and represent depleted isotopic values due to recharging from high altitudes. Finally, carbon isotope investigation was also utilized to determine the main source of carbon which was found to be carbonate dissolution and C4 plants. Furthermore, the karst development type (less-, moderate-, and well-developed) of all formations were identified. Providing that isotopic findings are complementary to hydrochemical features, this study gives an in-depth understanding of vulnerable karstic terrains in NW Iran, which are highly important frameworks for effective water management.

The Jiuquan Basin, with area of 6,800 square kilometers, located in the arid northwest of China, is a vital part of the Hexi Corridor. Investigating its groundwater circulation model is essential for understanding regional hydrogeological processes, sustainable water resource management, and ecological protection. This study, building upon previous research, utilizes hydrogeological surveys, hydrogeochemical analysis, isotope tracing (δD and δ 18 O) with sample size of 439, and radiocarbon dating ( 14 C) with sample size of 45 to evaluate the groundwater flow systems and groundwater age distribution. Results reveal that groundwater primarily originates from meltwater from the Qilian Mountains and atmospheric precipitation, flowing from south to north. The central basin exhibits slower circulation and older groundwater, while the groundwater in the Heihe River mainstream and the Beida River Basin was relatively young due to the favorable conditions for recharge and discharge. The local meteoric water line (LMWL) is defined as δD = 6.02 × δ 18 O- 2.5. Based on isotopic and age data, the basin is divided into several secondary groundwater flow systems (SGFS). This work contributes valuable insight into arid-zone hydrodynamics and supports ecological and water management strategies in the Jiuquan Basin.