El "status" hidrico en eco-agrosistemas es de gran importancia para un manejo sustentable. Entre las tecnologias para monitorear el agua del suelo las basadas en procesos nucleares juegan un papel importante, debido principalmente a la propiedad de penetrar en el material bajo estudio sin causar interferencia importante. Se discute el uso de sondas de neutrones y de rayos gamma para la determinacion de la propiedad del suelo de retener y transmitir agua, y lograr establecer balances hidricos del suelo, y para la caracterizacion de las particulas del suelo y su arreglo como un medio poroso. Esto se hace principalmente analizando la investigacion llevada a cabo en Latinoamerica

En este trabajo se ha estudiado la influencia del portainjerto sobre la composicion isotopica del mosto de vid (Vitis vinifera, L.). Las plantas de Cabernet Sauvignon injertadas sobre 101-14, 420A y 41B fueron cultivadas al aire libre y sometidas a tres regimenes hidricos. El portainjerto modifico de forma estadisticamente significativa el contenido de oxigeno-18 en el agua del mosto. Se observo que el enriquecimiento en oxigeno-18 estaba correlacionado positivamente con la diferencia de temperatura entre la canopy y el aire. Probablemente, la reduccion del factor de fraccionamiento de equilibrio no fue suficiente para compensar el enriquecimiento a traves del aumento del factor de fraccionamiento cinetico, debido al aumento del VPD en condiciones de baja disponibilidad hidrica. El 41B indujo el mayor enriquecimiento a pesar de evidenciar la mas elevada transpiracion foliar. Las diferencias observadas en la composicion isotopica del mosto podrian ser debidas a la influencia del portainjerto sobre la conductancia estomatica foliar y sobre la transpiracion de las bayas. Los resultados obtenidos pueden contribuir a aclarar ciertos aspectos en los estudios sobre la caracterizacion y autenticacion de vinos y otros productos agroalimentarios.

The correlation between water use efficiency (WUE) and carbon isotope descrimination (delta) was studied in winter wheat. A weak negative correlation (r=0.51, P=0.11) was found. Significant canopy effects were observed for (delta). Genotype effects were significant for (delta), WUE, and total biomass. No genotype by environment interaction was detected.

Stable isotopes (δ¹⁸O, δD), dissolved silica (DSi) concentration and major ion composition were used to indicate groundwater/surface-water interaction between the aquifers, the rivers and a lake in the high-latitude Lake Pyhäjärvi catchment in Finland. Significant differences were recorded in water chemistry between the groundwater and surface waters, especially in the stable isotope composition and DSi concentrations, which could thus be used as tracers. The baseline data on isotopic patterns and hydrogeochemistry in the hydrological cycle were provided by a 1-year monitoring survey in this snow-type catchment area. The proportions of groundwater in the rivers, the lake inshore area and in a groundwater abstraction plant were calculated using stable isotopes and DSi. Two inflowing rivers had distinct differences in their water chemistry. DSi has potential as a tracer in the river environment, whereas stable isotopes were more applicable in the lake environment. Locally, near the shoreline, the effect of discharging groundwater on the lake-water quality could clearly be observed. Furthermore, infiltration of the lake water into the aquifer could be observed near the pumping wells onshore. This infiltration presents a potential risk for the water quality of water supply (intake) wells. Frequent sampling is needed as part of the evaluation of the level of groundwater/surface-water interaction in snow-type catchments in order to estimate the magnitude of seasonal variation. In groundwater/surface-water interaction studies, spring thaw and high-precipitation events could be problematic, in terms of both sampling and interpreting results.

A study in eastern Taiwan evaluated the importance of montane water contribution (MC) to adjacent valley-plain groundwater (VPG) in a tectonic suture zone. The evaluation used a ternary natural-tracer-based end-member mixing analysis (EMMA). With this purpose, VPG and three end-member water samples of plain precipitation (PP), mountain-front recharge (MFR), and mountain-block recharge (MBR) were collected and analyzed for stable isotopic compositions (δ²H and δ¹⁸O) and chemical concentrations (electrical conductivity (EC) and Cl⁻). After evaluation, Cl⁻ is deemed unsuitable for EMMA in this study, and the contribution fractions of respective end members derived by the δ¹⁸O–EC pair are similar to those derived by the δ²H–EC pair. EMMA results indicate that the MC, including MFR and MBR, contributes at least 70% (679 × 10⁶ m³ water volume) of the VPG, significantly greater than the approximately 30% of PP contribution, and greater than the 20–50% in equivalent humid regions worldwide. The large MC is attributable to highly fractured strata and the steep topography of studied catchments caused by active tectonism. Furthermore, the contribution fractions derived by EMMA reflect the unique hydrogeological conditions in the respective study sub-regions. A region with a large MBR fraction is indicative of active lateral groundwater flow as a result of highly fractured strata in montane catchments. On the other hand, a region characterized by a large MFR fraction may possess high-permeability stream beds or high stream gradients. Those hydrogeological implications are helpful for water resource management and protection authorities of the studied regions.

The impacts of wastewater on Indigenous drinking water sources is an issue of concern across Canada. This study investigated the wastewater impacts on groundwater resources at a First Nations reserve located on a vulnerable fractured sedimentary bedrock aquifer in southern Ontario. The objectives were to examine the spatiotemporal variability of a variety of tracers of wastewater and their movement to groundwater. The tracers included nitrate, E. coli, total coliforms, and the artificial sweeteners sucralose, acesulfame, and cyclamate. Isotopes in the groundwater were also examined, including tritium and the isotopes of oxygen and nitrogen in dissolved inorganic nitrate. Three multilevel monitoring systems (seven-channel continuous multi-channel tubing) were retrofitted in unused drinking-water wells on the reserve and monitored from December 2015 to November 2016. Results indicate that groundwater at various depths has been impacted by the septic systems on the reserve. The fractures intersected by the three retrofitted wells contain a mix of newly recharged and older water, and contaminant peaks do not always correspond with ports aligned with higher hydraulic conductivity, showing variable travel times for the constituents. The selection of wastewater management systems that are appropriate for the particular hydrogeological setting on the reserves is critical to providing safe, clean drinking water to Indigenous communities. In particular, special consideration should be made for communities situated on fractured sedimentary bedrock aquifers with thin overburden.

A two-dimensional numerical groundwater flow model was established and calibrated for the hyperarid Najd region in southern Oman. The results indicate that recent recharge rates are required to sustain the observed groundwater heads in the Najd. The model was also used to estimate possible ranges of past recharge rates and the effective porosity of the main aquifer unit. Recharge rates during past humid periods were estimated to be no more than 1–3 times modern rates. The effective porosity was estimated to be between 0.06 and 0.093. Insight into the nature of the long-term transport within the aquifer was gained by using transient model runs over the last 350 ka and (1) varying the recharge intensity (from 0.1 to 2.5 times modern), and (2) the timing and duration of humid and dry periods. Finally, results indicate that although recharge rates and the flow conditions have likely changed over time, a steady-state model is capable of reproducing the observed groundwater residence times in the Najd based on carbon-14, helium and chlorine-36 dating.

The Eocene deposits of Kazan Basin in Turkey contain a rare trona mineral which is planned to be extracted by solution mining. The complex flow dynamics and mixing mechanisms as noted from previous hydraulic and hydrochemical data need to be augmented with environmental tracer and noble gas data to develop a conceptual model of the system for the assessment of the impacts of the mining and to develop sustainable groundwater management policies throughout the area. The tracers used include the stable isotopes of water (δ²H, δ¹⁸O), δ¹³C and¹⁴C of dissolved inorganic carbon (DIC), tritium (³H), the chlorofluorocarbons CFC-11 and CFC-12, and the noble gases He and Ne. The system studied consists of three aquifers: shallow, middle, and deep. CFC data indicate modern recharge in the shallow system. The estimates of ages through¹⁴C dating for the deeper aquifer system are up to 34,000 years. Helium concentrations cover a wide range of values from 5 × 10⁻⁸to 1.5 × 10⁻⁵ cm³STP/g.³He/⁴He ratios vary from 0.09RAto 1.29RA(where RAis the atmospheric³He/⁴He ratio of 1.384 × 10⁻⁶), the highest found in water from the shallow aquifer. Mantle-derived³He is present in some of the samples indicating upward groundwater movement, possibly along a NE–SW-striking fault-like feature in the basin.

Environmental tracers (noble gases, tritium, industrial gases, stable isotopes, and radio-carbon) and hydrogeology were interpreted to determine groundwater transit-time distribution and calculate mean transit time (MTT) with lumped parameter modeling at 19 large springs distributed throughout the Upper Colorado River Basin (UCRB), USA. The predictive value of the MTT to evaluate the pattern and timing of groundwater response to hydraulic stress (i.e., vulnerability) is examined by a statistical analysis of MTT, historical spring discharge records, and the Palmer Hydrological Drought Index. MTTs of the springs range from 10 to 15,000 years and 90 % of the cumulative discharge-weighted travel-time distribution falls within the range of 2−10,000 years. Historical variability in discharge was assessed as the ratio of 10–90 % flow-exceedance (R ₁₀/₉₀%) and ranged from 2.8 to 1.1 for select springs with available discharge data. The lag-time (i.e., delay in discharge response to drought conditions) was determined by cross-correlation analysis and ranged from 0.5 to 6 years for the same select springs. Springs with shorter MTTs (<80 years) statistically correlate with larger discharge variations and faster responses to drought, indicating MTT can be used for estimating the relative magnitude and timing of groundwater response. Results indicate that groundwater discharge to streams in the UCRB will likely respond on the order of years to climate variation and increasing groundwater withdrawals.

A prerequisite for minimizing contamination risk whilst conducting managed aquifer recharge (MAR) with recycled water is estimating the residence time in the zone where pathogen inactivation and biodegradation processes occur. MAR in Western Australia’s coastal aquifers is a potential major water source. As MAR with recycled water becomes increasingly considered in this region, better knowledge of applied and incidental tracer-based options from case studies is needed. Tracer data were collected at a MAR site in Floreat, Western Australia, under a controlled pumping regime over a distance of 50 m. Travel times for bromide-spiked groundwater were compared with two incidental tracers in recycled water: chloride and water temperature. The average travel time using bromide was 87 ± 6 days, whereas the estimates were longer based on water temperature (102 ± 17 days) and chloride (98 ± 60 days). The estimate of average flow velocity based on water temperature data was identical to the estimate based on bromide within a 25-m section of the aquifer (0.57 ± 0.04 m day⁻¹). This case study offers insights into the advantages, challenges and limitations of using incidental tracers in recycled water as a supplement to a controlled tracer test for estimating aquifer residence times.