[en] Study of water exchange between atmosphere and biosphere was initiated to understand the ties between these two spheres. Main objective of this study is to acquire sufficient environmental isotopic data for the exploration of water cycle dynamics in selected areas of Pakistan, in order to contribute to the IAEA global network for the development of regional scale model on ecosystems. Isotope investigations (¹⁸O, ²H) help evaluate the major processes such as photosynthesis, respiration and evapotranspiration. From January 2005 to April 2005 non woody plants (wheat, grass) and soil samples from wheat and grass fields (from the surface and 7cm below the surface) were collected. Moisture contents from these samples were extracted using the vacuum distillation method and analysed for hydrogen and oxygen isotope contents. Air moisture was also collected in the field. Woody plants consisting of eucalyptus, pine, delbergia sisso, melia azedarch were sampled from Islamabad. Seventeen more species of woody plants are included in the study, from another site, located near Lahore. Data depicts that the leaves of the wheat plant are more enriched in ¹⁸O and ²H than other parts of the same plant and grass. It may be due to the process of evapotranspiration which is more rapid from the wider leaves as compared to the small ones. Rain effect was also observed on δ¹⁸O and δ²H of the samples collected just two days after the rain event. Isotopic values of this rainwater were more negative as compared to other rain events that took place during this season. This depletion may be due to the 'continental effect' in precipitation. More than 200 samples from woody plants of different species and soil were collected. Isotopic data of the moisture extracted from leaves and stems of the plants of different species indicate that leaves of all the plants are more enriched in ²H and ¹⁸O than that of the respective stems. There also seem some considerable species-specific effects transforming the isotope ratios of hydrogen and oxygen available for incorporation into plant metabolites relative to the water available for growth. (author)

[en] Stream water quality and quantity depend on discharge rates of water and nutrients from soils. However, soil-water storage is very dynamic and strongly influenced by plants. Stable isotopes of oxygen and hydrogen were analyzed to quantify spatial and temporal changes in evaporation, transpiration and stream discharge in a gauged watershed with dry summers and wet winters. The isotope data indicate that plant and soil water have been affected by evaporation. In contrast, stream water is not evaporated, though discharge rates show diurnal cycles driven by transpiration. It is concluded that two separate pools of water are held within the soil. One is a faster moving pool held at relatively weak matric potentials, making it more subject to gravitational transport to streams. The other pool is held more tightly by matric forces, has a longer residence time within the soil, and will more likely be evaporated or taken up by plants. (author)

[en] During the years 2004-2005 an investigation was carried out by CDTN and UFMG in the northwestern border of the state of Minas Gerais, Brazil, to assess the water resources related to the Guarani Aquifer System in the region of Araguari. The project was supported by the Fund of Universities (BNPPW/OAS) and was designed to cover a whole hydrological year. Main water supply for domestic, industrial and agricultural consumption derives from groundwater, and the system is under permanent stress. Among other classical tools, isotopic techniques were used to study groundwater origin, recharge processes and transit times. Environmental isotopic compositions (¹⁸O, ²H and ³H) of 51 water samples were analyzed. The overall results show that the local waters fit fairly well to the GMWL, with a shift in the deuterium excess due to some evaporation; also, the groundwater is locally recharged. The exponential model was used to estimate groundwater transit time, and the results show that most of the waters (84%) are young waters with renewal time less than 30 years. (author)

[en] In recent years, the rapid increase of the population in the region of Dakar, especially in suburban settlements, together with the lack of policies for urban waste management, has become a source of concern for water supply, needs, and quality control. Approximately 80% of water resources in the region come from groundwater reservoirs. In order to identify the origin of groundwater pollution a survey on 26 piezometers and wells was conducted in March 2006. In this study, both major and trace elements were measured as well as the stable isotopic signature of water molecules and dissolved compounds. Nitrates often exceed drinking water limits and are associated with microbiological pollutants, while sea water intrusion represents the major threat to rapidly declining groundwater quality. Stable isotopes of dissolved nitrates allow for the identification of urban sewage and fertilizers as a major source of contamination, and the ability to define the distribution of their impacts. The occurrence of denitrification processes, although limited, suggests the potential for auto-purification of the contaminated water, if the source of the pollution were to cease. (author)

[en] Better assessment of carbon isotopes cycle in the Unsaturated Zone (UZ) is a key point for estimating the ¹⁴C residence time of relatively young groundwater. In order to approach the UZ carbon cycle and to quantify C-fluxes, the distribution of the isotopic composition (¹³C-¹⁴C) of each carbon phase (Dissolved Inorganic Carbon, CO₂, carbonates) have been investigated on two experimental sites i.e. respectively the carbonate-free Fontainebleau sands (Paris Basin, France) and the carbonate Astian sands (South France). Similar matrix properties on both sites allowed identical in situ sampling protocols based on water-gas permanent samplers specifically developed for this work. In a carbonate-free UZ, the isotopic composition of water depends essentially on CO₂ diffusion. While, in a carbonated UZ, the carbonates force the isotopic composition of dissolved inorganic carbon and CO₂. These carbon exchanges lead to a depletion of matrix carbonates by precipitation of secondary calcite. (author)

[en] This study aims to identify the groundwater recharge systems of Kathmandu Valley using isotopic compositions of water (δ¹⁸O and δ²H) along with other hydrochemistry data. The preliminary study consisted of 15 deep groundwater and 5 shallow groundwater samples that were collected from northern and central part of the valley. Three types of the deep groundwater isotope compositions were observed while δ¹⁸O is plotted against δ²H. The results indicate that the deep groundwater has two main aquifers: north part and central part aquifers. In addition, the oxygen isotopic values of all samples when plotted against chloride indicate that deep groundwater is not being recharged by the shallow groundwater of the sampled area. It was also observed that the third type of groundwater is formed by the mixing of first and second types of groundwater. The next study will be focused on detailed investigation in finding source and recharge of this groundwater. (author)

[en] Observations of the isotopic composition of atmospheric water vapour are important for four main reasons: 1) It is not limited only to rainy days. 2) Isotopic information contained in newly formed raindrops is lost during rainout. 3) It is the principal tracer of water vapour sources, critical for eco-hydrology. 4) It is a key parameter in estimating the isotopic enrichment in leaf water, and therefore in the application the oxygen isotopic composition of CO₂ and O₂ as a tracer of land vegetation activities. More investigations are needed however into the controls over variations in the isotopic composition of water vapour across spatial and temporal scales. Here we address the effects of local air turbulence, wind direction and changes in mixing patterns over the daily and seasonal cycles on the isotope composition of water vapour by the admixture of evapotranspiration (ET) in vegetated areas, deviations from isotopic steady state in leaf transpiration and evaporation from water bodies. (author)

[en] Investigations were conducted to establish benchmark isotopic characteristics of water sources and baseline concentrations of trace elements related to contamination from the Montalban landfill. Water samples were collected from the production wells and surface water in Rodriguez and in San Mateo, both in the province of Rizal. These municipalities are nearest to the Montalban landfill. Stable isotope characterization of the deep groundwater and rivers shows isotopic values clustering along the LMWL with δ¹⁸O ranging from -7.5 per mille to -6.5 per mille and δ²H ranging from -53.59 per mille to -42.91. The shallow groundwater are more isotopically enriched trending towards the evaporation line, with mean δ¹⁸O and δD values of -6.46 per mille and -44.14 per mille, respectively. The mean isotopic signatures of surface water, with mean δ¹⁸O of -7.19 per mille, and deep groundwater, with mean δ¹⁸O of -6.67 per mile, in Rodriguez are significantly distinct. San Mateo groundwater appear to be more isotopically enriched, indicating recharge different from that of Rodriguez groundwater. Leachate from the landfill exhibits a distinct isotopic composition from the freshwaters, with most enriched δD values of +5.84 per mille for the leachate run-off and +16.55 per mille in the leachate pond. The significant differences in the isotopic signatures of the different water sources in the study area facilitates detection of contamination from leachate run-off to the surface water, and eventually, to the groundwater. Trace metals in the water samples collected, generally, were below the regulatory limits for drinking water and surface water. (author)

[en] The investigations at the Frankenthal site are performed as a part of the German funding priority KORA (TV 3.6) of the BMBF (Federal Ministry of Education and Research). The aim of KORA is to develop technical and legal instruments, which will facilitate the evaluation and customised use of Natural Attenuation (NA) processes in the risk assessment and remediation of contaminated sites. The investigations show that by using compound specific isotope analysis (GC-IRMS, Gas Chromatograph Isotope Ratio Mass Spectrometry) evidence of NA processes on chlorinated hydrocarbons (CHC) can be provided. The amount of microbial degradation was quantified by using a Rayleigh-type-model approach with the weighted mean ¹³C-CHC-signature, the derived starting ¹³C-signature and the sum of site specific ¹³C-enrichment factors ε that were determined in laboratory experiments. The results indicate an ongoing degradation process, which is shown in diagrams under minimum criteria, which is the basis of the used quantification method. The diagram shows that the state of degradation is increasing with time (sampling campaign 2000-2004-2005-2006) and distance from the source. The methods will be implemented into guidelines for the use of Monitored Natural Attenuation processes in the risk assessment and remediation of contaminated water resources. (author)

[en] Konya region (Turkey) has three important geothermal subregion. These are Cihanbeyli, Beysehir-Seydisehir-Ilgin and Ismil-Eregli subregions. Geothermal waters in the region have temperature between 19.8-51 deg. C, discharge between 0.1-130 L/s and total mineralization range from 852 to 5110 mg/L. The isotopic analysis evaluated according to ¹⁸O/²H, ¹⁸O/TU, Cl/TU, pH/EC and Giggenbach diagrams. The geothermal water aquifers are recharged from higher altitudes and they are hardly affected by recent precipitations and these waters reveal meteoric origin. They have more negative δ¹⁸O and δ²H values and lower ³H contents compared to cold waters. The reservoir rock temperature is 250 deg. C, and water depths are ranging from 500 to 1000 m. The waters heat from volcanism and geothermal gradient. (author)