scholarly journals An Overview of Aquifer Physiognomies and the δ18O and δ2H Distribution in the South African Groundwaters

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 68
Author(s):  
Tamiru A. Abiye ◽  
Molla B. Demlie ◽  
Haile Mengistu
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
South African ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
Shallow Aquifer ◽  
Arid Zones ◽  
Mixing Effect ◽  
Groundwater Systems

A comprehensive assessment of the stable isotope distribution in the groundwater systems of South Africa was conducted in relation to the diversity in the aquifer lithology and corresponding hydraulic characteristics. The stable isotopes of oxygen (18O) and hydrogen (2H) in groundwater show distinct spatial variation owing to the recharge source and possibly mixing effect in the aquifers with the existing water, where aquifers are characterized by diverse hydraulic conductivity and transmissivity values. When the shallow aquifer that receives direct recharge from rainfall shows a similar isotopic signature, it implies less mixing effect, while in the case of deep groundwater interaction between recharging water and the resident water intensifies, which could change the isotope signature. As aquifer depth increases the effect of mixing tends to be minimal. In most cases, the isotopic composition of recharging water shows depletion in the interior areas and western arid zones which is attributed to the depleted isotopic composition of the moisture source. The variations in the stable isotope composition of groundwater in the region are primarily controlled by the isotope composition of the rainfall, which shows variable isotope composition as it was observed from the local meteoric water lines, in addition to the evaporation, recharge and mixing effects.

scholarly journals Storage Changes Stable Isotope Composition of Cucumbers

2021 ◽  
Vol 5 ◽  
Author(s):  
Micha Horacek ◽  
Wolfgang Papesch
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
Stable Isotope Composition ◽  
Vegetable Food ◽  
O Isotope ◽  
Linear Correlations ◽  
Special Relevance ◽  
Reference Samples

Vegetable food stuff produced under controlled and identical conditions from one farm of identical “age” (batch) has a similar isotopic composition. This fact can be used to control the origin of vegetables. This question is of special relevance when food-contaminations have to be traced back to the producer, or certain production claims have to be controlled. However, as vegetables are harvested, brought to whole-sale merchants and to retail shops, where they remain until being bought by the consumer, one has to consider possible changes in isotopic composition during this transfer period, when comparing vegetables of questioned origin with reference samples taken directly from the field/producer. We investigated changes in the isotope composition of vegetables during storage by studying as an example cucumbers from one batch. We stored the cucumbers in a vegetable storage under controlled conditions and removed one sample every day and analyzed its isotopic composition. We found changes in the δ15N and δ18O isotope values over the investigated period of 21 days, with both parameters showing positive linear correlations, and maximum enrichments with time of more than 1.5‰ for δ15N and more than 2‰ for δ18O. However, within the interval the samples remained in a saleable condition the isotope variations remained more or less within the variability of the sample batch. Our study demonstrates that changes in the isotopic signature in vegetables might occur after harvest during storage and have to be taken into account when (commercial) samples collected in a market are investigated.

scholarly journals Lake water based isoscape in central-south Chile reflects meteoric water

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wesley P. Scott ◽  
Sergio Contreras ◽  
Gabriel J. Bowen ◽  
T. Elliott Arnold ◽  
Ramón Bustamante-Ortega ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Global Network ◽  
Ancillary Data ◽  
Energy Agency ◽  
Significant Information ◽  
Field Equipment ◽  
Central South

AbstractWarming across the globe is expected to alter the strength and amount of regional precipitation, but there is uncertainty associated with the magnitude of these expected changes, and also how these changes in temperature and the hydrologic cycle will affect humans. For example, the climate in central-south Chile is projected to become significantly warmer and drier over the next several decades in response to anthropogenically driven warming, but these anthropogenic changes are superimposed on natural climate variability. The stable isotope composition of meteoric water provides significant information regarding the moisture source, pathways, and rain-out history of an air mass, but precipitation samples suitable for stable isotope measurements require long-term placement of field equipment making them difficult to obtain. The International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations generate isotopic and ancillary data of precipitation from many locations around the world, but remote areas of developing countries like Chile typically have sparse networks of meteorological stations, which inhibit our ability to accurately model regional precipitation. Central-south Chile, in particular, has a sparse network of GNIP stations and, as a result, the isotopic composition of meteoric water is underrepresented in the global database complicating efforts to constrain modern day hydroclimate variability as well as paleohydrologic reconstruction for southern South America. In this study, we measured the stable isotope compositions of hydrogen (δ2H) and oxygen (δ18O) in surface lacustrine waters of central-south Chile to determine what physical and/or climatic features are the dominant controls on lacustrine δ18O and δ2H composition, assess whether or not the isotopic composition of the lakes record time-averaged isotope composition of meteoric water, and determine whether an isoscape map based on lake surface waters could predict the H and O isotope compositions of precipitation at the few GNIP stations in the region.

scholarly journals Technical Note: Silica stable isotopes and silicification in a carnivorous sponge \\textit{Asbestopluma} sp.

2014 ◽  
Vol 11 (12) ◽  
pp. 16573-16597
Author(s):  
K. R. Hendry ◽  
G. E. A. Swann ◽  
M. J. Leng ◽  
H. J. Sloane ◽  
C. Goodwin ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
The Body ◽  
Oxygen Isotope Composition ◽  
Silicon Isotope ◽  
Deep Seawater ◽  
Differential Distribution ◽  
Sponge Spicule

Abstract. The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotopic composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the biological vital effects on silica silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that appear related to unusual spicule silicification. The largest variation in both isotope systems was associated to the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence of an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotopic signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotopic signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

scholarly journals Measurement report: Spatial variability of northern Iberian rainfall stable isotope values – investigating atmospheric controls on daily and monthly timescales

2021 ◽  
Vol 21 (13) ◽  
pp. 10159-10177
Author(s):  
Ana Moreno ◽  
Miguel Iglesias ◽  
Cesar Azorin-Molina ◽  
Carlos Pérez-Mejías ◽  
Miguel Bartolomé ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Air Temperature ◽  
Isotope Composition ◽  
Significant Negative Correlation ◽  
Relative Role ◽  
Northern Spain ◽  
Mass Source ◽  
Highly Correlated

Abstract. For the first time, this article presents a large dataset of precipitation isotopic measurements (δ18Op and δ2Hp) sampled every day or 2 d from seven sites on a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to (1) characterize the rainfall isotopic variability in northern Spain at daily and monthly timescales and (2) assess the principal factors influencing rainfall isotopic variability. The relative role of air temperature and rainfall in determining the stable isotope composition of precipitation changes along the west-to-east transect, with air temperature being highly correlated with δ18Op at daily and monthly timescales, while a few sites along the transect show a significant negative correlation with precipitation. The highest air temperature–δ18Op dependency is found for a station located in the Pyrenees. Frontal systems associated with North Atlantic cyclones are the dominant mechanism inducing precipitation in this region, particularly in winter. This study allows an exploration of the role of air mass source and trajectory in determining the isotopic composition of rainfall in northern Iberia by characterizing the moisture uptake for three of the seven stations. The importance of continental versus marine moisture sources is evident, with clear seasonal and spatial variations. In addition, the type of precipitation (convective versus frontal rainfall) plays a key role, with convective rainfall associated with higher δ18Op values. This comprehensive spatiotemporal approach to analyzing the rainfall isotopic composition represents another step forward towards developing a more detailed, mechanistic framework for interpreting stable isotopes in rainfall as a paleoclimate and hydrological tracer.

The Isotopic Composition of Cyprus Precipitation. A Tool of Isotope Hydrology.

2021 ◽  
Author(s):  
Christos Christofi ◽  
Adriana Bruggeman ◽  
Christoph Kuells
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Soil Column ◽  
Seasonal Effect ◽  
Isotope Hydrology ◽  
Fractured Aquifer ◽  
Air Masses ◽  
Northern European ◽  
D Values

<p>Monitoring and profiling the isotopic composition of soil water in combination with groundwater isotope hydrology are commonly used in studying flow and transport in soils as well as in estimating groundwater recharge. Establishing the isotopic composition of local precipitation is of essence. Towards this end and in facilitating the application of isotope hydrology in Troodos Fractured Aquifer (TFA), precipitation was monitored in 16 precipitation sampling stations, stretching from the shoreline up to 1725 m above m.s.l., from January of 2015 to December of 2017. A seasonal trend was discerned, with isotopically depleted rainfall occurring in December as opposed to the more enriched autumn and spring rainfall. Northern European air masses appear to prevail during the months of December to January during which d values tend to be on average above 25‰ whereas the more enriched rain with the lowest d values occurs in July. The averaged seasonal effect between 2015 and 2017 on δ18O, δ2H and d values are 4.53‰, 30.98‰ and 14.93‰, respectively. Cyprus’ Local Meteoric Water Line (LMWL) was found to be equal to δ2H = (6.58±0.13)*δ18O + (12.64±0.91) and a general decrease of 1.22‰ for δ2H and 0.20‰ for δ18O in precipitation was calculated per 100 m altitude.  Similar values have been found by other researchers for the region. These variations in the isotope composition of rainfall can be used to earmark seasonal input of recharge water and for deriving percolation rates from tracing their movement in the soil column.</p>

scholarly journals Multiple isotope tracers from Permian-Triassic hydrated sulfates: Implications for fluid-mineral interaction

2019 ◽  
Vol 190 ◽  
pp. 11 ◽  
Author(s):  
Ana-Voica Bojar ◽  
Stanislaw Hałas ◽  
Hans-Peter Bojar ◽  
Andrzej Trembaczowski
Keyword(s):  
Isotopic Composition ◽  
Isotope Composition ◽  
Eastern Alps ◽  
Isotopic Signature ◽  
Isotope Tracers ◽  
Anionic Group ◽  
Gypsum Formation ◽  
Subsequent Event ◽  
Thermal Overprint ◽  
Mineral Interaction

Isotopic compositions of water of crystallization and sulfate anionic group in gypsum and polyhalite were used as tracers for events related to their formation and subsequent evolution, as for example origin of crystallization water and extent of thermal overprint. For this purpose, gypsum and polyhalite from the Permo-Triassic evaporites of the Eastern Alps, were analysed for isotope composition of sulfate anionic group (δ34S and δ18OSO4) and water of crystallization (δD and δ18O). For comparison, water of crystallisation of polyhalite samples of similar age from New Mexico (USA), Kłodawa (Poland) and Hattberg, Hesse (Germany) were also investigated. Estimated δ18O and δD values of polyhalite formation brines vary from 14.4 to 3.4‰ and 42.5 to −6.1‰, respectively. Gypsum formation brines show different δ18O and δD values, from −5.7 to −15‰ and −30.9 to −88.8‰, respectively. The measured δ18OSO4 values of sulfate group are compatible with a thermal overprint at 100°–200°C for both minerals. The thermal overprint documented for the Eastern Alps led to gypsum but not to polyhalite dehydration. The isotopic composition of water of crystallization suggests that polyhalite is preserving the isotopic signature of an enriched brine. During a subsequent event, anhydrite rehydrated to gypsum, with the isotopic composition of water of crystallisation indicating lower (δD and δ18O) values than the present-day meteoric water ones. Due to their distinct mineral structure and, as a result, different temperature of dehydratation, gypsum and polyhalite record different histories following precipitation in an evaporative system.

scholarly journals Hydrogeology and origin of waters of the Panyam Volcanic Line springs, Jos Plateau, Nigeria

2021 ◽  
Vol 43 (2) ◽  
Author(s):  
Longpia C. B.
Keyword(s):  
Stable Isotope ◽  
Meteoric Water ◽  
Ph Value ◽  
Isotope Composition ◽  
Water Type ◽  
Water Composition ◽  
Piper Trilinear Diagram ◽  
Physico Chemical ◽  
Isotope Ratio Mass Spectrometer ◽  
Irrigation Quality

The PVL springs are used for both domestic and agricultural purposes. The seepage from the springs has resulted in producing a large expanse of wetlands and is therefore intensively use for dry season farming. The aim of this study was to determine the hydrogeological, hydrochemical characteristics, origin and their suitability for domestic and irrigation. The hydrogeology of the springs was determined by field mapping. The physico-chemical parameters were determined in the field and by laboratory methods. For the cation and anion analysis the ICP-MS and the wet methods were employed respectively. The stable isotope composition of oxygen (δ18O) and hydrogen (δ2H) were analyzed by Isotope Ratio Mass Spectrometer. The hydrochemical analysis revealed that the PVL springs waters are generally neutral with an average pH value of 7.3. The average TDS and EC values are 127.8mg/l and 246µs/cm respectively. These values fall within fresh water class. The average Mg2+,Ca2+, Na+ and K+ cation concentration values are 16.3mg/l, 15.8mg/l, 10.8mg/l and 5.58mg/l respectively. The average anions concentration of HCO3-, SO4 and Cl- are 140mg/l, 8.6mg/l and 3.4mg/l respectively. Piper trilinear diagram show that the spring waters is predominantly Mg-Ca-HCO3 water type with potable qualities based on WHO drinking water standards. The sodium Adsorption Ratio (SAR) and Sodium Soluble Percentage (SSP) values range between 0.44 to 0.84 and 26.4 to 54% respectively and falls within irrigation quality standards. Stable isotope compositions of δ18O and δ2H ranges from -3.60/00 to -4.90/00 and -200/00 to -280/00 respectively falls within the meteoric water composition. This is further affirmed by the δ2H versus δ18O plot on the correlation diagram with Standard Meteoric Water Line.

Stable isotope composition of fluid inclusions in quartz minerals : New method for paleoaltimetry

2021 ◽  
Author(s):  
Raphaël Melis ◽  
Véronique Gardien ◽  
Gweltaz Mahéo ◽  
Christophe Lécuyer ◽  
Philippe-Hervé Leloup ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotope Composition ◽  
Shear Zones ◽  
Isotopic Signature ◽  
Stable Isotope Ratio ◽  
New Method ◽  
Good Precision ◽  
Stable Isotope Composition ◽  
Geological Time ◽  
Quartz Veins

<p>Paleoaltimetry is a powerful tool to study tectonic, climate and surface processes interactions. Indeed, stable isotope composition of meteoric water can be correlated with the elevation of reliefs. The δ18O and δD of orogenic rainfall decrease while the elevation increase. Current paleoaltimetric methods based on stable isotope, including the study of pedogenic carbonates and micas associated with fault or shear zones, represent an indirect way to obtain stable isotope « paleometeoric fluid » composition. These methods do not provide simultaneously the δ18O and δD values implying the use of isotope exchange equation, source of signficant errors (up to +/- 1000m).</p><p>We have developed a new method which allow to directly acces at both the δ18O and δD of « paleometeoric » fluids with a good precision and margin of error less than +/- 200m . This method has been developed on the stable isotope composition of fluid inclusion trapped in quartz veins. The developed experimental protocol allows to extract small quantity of fluid (~10mL) and directly analyse both the δ18O and δD with a OA-ICOS Spectroscopy. Tested on 18 Miocene alpine quartz veins from the Mont-Blanc and the Chenaillet massifs the stable isotope composition of the fluids fit very well with meteoric isotopic signature and highlight the robustness of stable isotope ratio through geological time.</p><p>More over, our results indicate that Miocene precipitation was way more positive (-4,8 to -9 ‰ for δ18O and -38,2 to 68,8‰ for δD) in the Mont-Blanc massif area than modern precipitation (-12,9 to -18 ‰ for δ18O and -101,1 to -144,25‰ for δD) which indicate that the massif was still at low elevation at this time. In contrast the « paleoprecipitation » of the Chenaillet massif fall in the same range than modern precipitation (-83 to -120,3 ‰ for δD and -11,8 to -16,9 ‰ for δ18O) which indicate this massif has already reached his present altitude (~ 2500m).</p>

Stable isotope composition of walleye: 15N accumulation with age and area-specific differences in δ13C

2001 ◽  
Vol 58 (6) ◽  
pp. 1253-1260 ◽  
Author(s):  
Nathanael C Overman ◽  
Donna L Parrish
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Carbon Isotope ◽  
Trophic Position ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Isotopic Fractionation ◽  
Stomach Content Analysis ◽  
Metabolic Effects ◽  
N Accumulation

Stable nitrogen and carbon isotope ratios were measured for walleye (Stizostedion vitreum) collected across Lake Champlain, Vermont, to determine relationships between isotopic composition and diet, location of capture, length, weight, and age. Variation in δ13C values reflected area-specific differences in isotopic composition of organisms collected across the lake. A critical assumption in the application of isotope techniques is that a predictable relationship exists between the diet and isotopic composition of an organism. Our results indicate that isotopic fractionation factors may not be independent of age as has largely been assumed. By combining stable nitrogen and carbon isotope analysis with conventional stomach content analysis, we documented significant age effects in the δ15N composition of adult walleye that were not attributable to observed changes in diet. Age accounted for 81% of the variation in δ15N values of walleye (ages 2–27, N = 65, δ15N range = 15.3–19.2‰), providing evidence supporting 15N accumulation over the life span of walleye. Therefore, the risk of making faulty inferences of trophic position and food web interactions based on δ15N values may be increased when age is unknown. Our results indicate that metabolic effects associated with age require greater consideration in applications of stable isotope analysis.

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