Showing papers in "Isotopes in Environmental and Health Studies in 2016"
TL;DR: The findings indicate that only minor net U isotope fractionation occurs during weathering and transport of material from the continental crust to the oceans, and provides additional constraints on the relative size of the diverse U sinks and respective net isotopes fractionation during U removal.
Abstract: In this study, the U isotope composition, n(238U)/n(235U), of major components of the upper continental crust, including granitic rocks of different age and post-Archaean shales, as well as that of rivers (the major U source to the oceans) was investigated. Furthermore, U isotope fractionation during the removal of U at mid-ocean ridges, an important sink for U from the oceans, was investigated by the analyses of hydrothermal water samples (including low- and high-temperature fluids), low-temperature altered basalts and calcium carbonate veins. All analysed rock samples from the continental crust fall into a limited range of δ238U between −0.45 and −0.21 ‰ (relative to NBL CRM 112-A), with an average of −0.30 ± 0.15 ‰ (2 SD, N = 11). Despite differences in catchment lithologies, all major rivers define a relatively narrow range between −0.31 and −0.13 ‰, with a weighted mean isotope composition of −0.27 ‰, which is indistinguishable from the estimate for the upper continental crust (−0.30 ‰). Only some tr...
53 citations
TL;DR: This research frontier is explored using the coupled natural–human landscape of the Salt Lake Valley, USA, with its greater than one million inhabitants to provide data on the stable isotope ratios of the hydrologic system’s primary components: precipitation, incoming surface waters, and terminus waters in this closed basin.
Abstract: Isotope hydrology has focused largely on landscapes away from densely inhabited regions. In coming decades, it will become increasingly more important to focus on water supplies and dynamics within urban systems. Stable isotope analyses provide important information to water managers within large cities, particularly in arid regions where evaporative histories of water sources, vulnerabilities, and reliabilities of the water supplies can be major issues. Here the spatial and vertical understanding of water supporting urban systems that comes from stable isotope analyses can serve as a useful management tool. We explore this research frontier using the coupled natural-human landscape of the Salt Lake Valley, USA, with its greater than one million inhabitants. We first provide data on the stable isotope ratios of the hydrologic system's primary components: precipitation, incoming surface waters, and terminus waters in this closed basin. We then explore the spatial and temporal patterns of drinking waters within the urban landscape and the new opportunities to better link isotope ratio data with short- and long-term management interests of water managers.
46 citations
TL;DR: It is found that groundwater is the main water source that discharges the entire basin although individual rivers vary, and higher d-excess values throughout the year in the Aksu river and the Tizinafu river suggest that water may be intensively recycled in the mountains of the TRB.
Abstract: By using 233 isotope samples, we investigated the spatial and temporal variations of δ(18)O and δ(2)H in precipitation and surface water, and the contribution of different water sources in the rivers within the Tarim River Basin (TRB), which receives snow/glacier meltwater, groundwater, and rainfall. Our study revealed a similar seasonal pattern of precipitation δ(18)O and δ(2)H at both the north and south edges of the basin, indicating the dominant effect of westerly air masses in the summer and the combined influence of westerly and polar air masses during the winter, although the southern part showed more complex precipitation processes in the summer. River water in the basin has relatively large temporal variations in both δ(18)O and δ(2)H showing a distinct seasonal pattern with lower isotope values in May than in September. Higher d-excess values throughout the year in the Aksu river and the Tizinafu river suggest that water may be intensively recycled in the mountains of the TRB. Based on isotopic hydrograph separation, we found that groundwater is the main water source that discharges the entire basin although individual rivers vary.
33 citations
TL;DR: Accuracy and precision of this correction are demonstrated by clumped isotope analysis of three internal carbonate standards by correcting the measured m/z 47 ion beam intensities of sample and reference gas for the contributions deriving from secondary electrons after scaling these contributions to the intensity of the corresponding m/Z 49 ion beams.
Abstract: It is well known that a subtle nonlinearity can occur during clumped isotope analysis of CO2 that – if remaining unaddressed – limits accuracy. The nonlinearity is induced by a negative background on the m/z 47 ion Faraday cup, whose magnitude is correlated with the intensity of the m/z 44 ion beam. The origin of the negative background remains unclear, but is possibly due to secondary electrons. Usually, CO2 gases of distinct bulk isotopic compositions are equilibrated at 1000 °C and measured along with the samples in order to be able to correct for this effect. Alternatively, measured m/z 47 beam intensities can be corrected for the contribution of secondary electrons after monitoring how the negative background on m/z 47 evolves with the intensity of the m/z 44 ion beam. The latter correction procedure seems to work well if the m/z 44 cup exhibits a wider slit width than the m/z 47 cup. Here we show that the negative m/z 47 background affects precision of dual inlet-based clumped isotope measurements o...
31 citations
TL;DR: It is suggested that the low δ44/40Cafaeces of −CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage, and also that fractionation during Ca absorption is also required for explaining δ 44/ 40CafaECes of Con and GIO.
Abstract: In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ44/40Ca = [(44Ca/40Ca)sample/(44Ca/40Ca)reference]−1) of diet, faeces, blood, bones and urine from Gottingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (−CaD). In contrast to Con and GIO whose average δ44/40Cafaeces values (0.39 ± 0.13‰ and 0.28 ± 0.08‰, respectively) tend to be lower than their diet (0.47 ± 0.02‰), δ44/40Cafaeces of −CaD (−0.27 ± 0.21‰) was significantly lower than their δ44/40Cadiet (0.37 ± 0.03‰), but also lower than δ44/40Cafaeces of Con and GIO. We suggest that the low δ44/40Cafaeces of −CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ44/40Cafaeces of Con and GIO. The δ44/40Caurine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Gottingen minipigs we found a Ca isotope fractionation between blood and bones (Δ44/40Cablood-bone) of 0.68 ± 0.15‰.
31 citations
TL;DR: The calculations suggest that the double carbonates of calcite structure are systematically enriched in 18O relative to those of aragonite and mixture structures, which provides insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning indouble carbonates.
Abstract: Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in 18O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0–1200 °C. The calculated fractionation factors for double carbonate–water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally deter...
26 citations
TL;DR: An evident regional and partly temporal variation of nitrate isotope signatures which are clearly different between main landscape types is observed and a shift towards heavier isotope values in stream water samples taken in July 2012 is significant.
Abstract: Interactions between hydrological characteristics and microbial activities affect the isotopic composition of dissolved nitrate in surface water. Nitrogen and oxygen isotopic signatures of riverine nitrate in 133 sampling locations distributed over the Bode River catchment in the Harz Mountains, Germany, were used to identify nitrate sources and transformation processes. An annual monitoring programme consisting of seasonal sampling campaigns in spring, summer and autumn was conducted. δ15N and δ18O of nitrate and corresponding concentrations were measured as well as δ2H and δ18O of water to determine the deuterium excess. In addition, precipitation on 25 sampling stations was sampled and considered as a potential input factor. The Bode River catchment is strongly influenced by agricultural land use which is about 70 % of the overall size of the catchment. Different nitrogen sources such as ammonia (NH4) fertilizer, soil nitrogen, organic fertilizer or nitrate in precipitation show partly clear nitrate is...
25 citations
TL;DR: Calculated precipitation-weighted monthly climate parameters using national 5-km-gridded daily climate data have substantial benefits for studies that require the isotope composition of precipitation during specific time intervals, and may be further improved by comparison to daily and event-based precipitation samples as well as the use of back-trajectory calculations.
Abstract: Predictive understanding of precipitation δ(2)H and δ(18)O in New Zealand faces unique challenges, including high spatial variability in precipitation amounts, alternation between subtropical and sub-Antarctic precipitation sources, and a compressed latitudinal range of 34 to 47 °S. To map the precipitation isotope ratios across New Zealand, three years of integrated monthly precipitation samples were acquired from >50 stations. Conventional mean-annual precipitation δ(2)H and δ(18)O maps were produced by regressions using geographic and annual climate variables. Incomplete data and short-term variation in climate and precipitation sources limited the utility of this approach. We overcome these difficulties by calculating precipitation-weighted monthly climate parameters using national 5-km-gridded daily climate data. This data plus geographic variables were regressed to predict δ(2)H, δ(18)O, and d-excess at all sites. The procedure yields statistically-valid predictions of the isotope composition of precipitation (long-term average root mean square error (RMSE) for δ(18)O = 0.6 ‰; δ(2)H = 5.5 ‰); and monthly RMSE δ(18)O = 1.9 ‰, δ(2)H = 16 ‰. This approach has substantial benefits for studies that require the isotope composition of precipitation during specific time intervals, and may be further improved by comparison to daily and event-based precipitation samples as well as the use of back-trajectory calculations.
23 citations
TL;DR: From the result of a multiple regression analysis, the empirical formula of annual mean δ18O in precipitation from latitude and altitude for all sites across Japan was determined to be δ 18 O’= −0.348 (LAT)”− 0.00307 (ALT) + 4.29 (R2 =0.59).
Abstract: Spatial distribution of annual mean stable isotopes in precipitation (δ(18)O, δ(2)H) was observed at 56 sites across Japan throughout 2013. Annual mean δ(18)O values showed a strong latitude effect, from -12.4 ‰ in the north to -5.1 ‰ in the south. Annual mean d-excess values ranged from 8 to 21 ‰, and values on the Sea of Japan side in Northern and Eastern Japan were relatively higher than those on the Pacific Ocean side. The local meteoric water line (LMWL) and isotope effects were based on the annual mean values from all sites across Japan as divided into distinct regions: the Sea of Japan side to the Pacific Ocean side and Northeastern to Southwestern Japan. Slopes and intercepts of LMWL ranged from 7.4 to 7.8 and 9.8 to 13.0, respectively. Slopes for latitude, altitude, and temperature effects ranged from -0.27 to -0.48 ‰/°N, -0.0034 to -0.0053 ‰/m, and 0.36 to 0.46 ‰/°C, respectively, with statistically significance at the 99 % level. However, there was no precipitation amount effect. From the result of a multiple regression analysis, the empirical formula of annual mean δ(18)O in precipitation from latitude and altitude for all sites across Japan was determined to be δ(18) O = -0.348 (LAT) - 0.00307 (ALT) + 4.29 (R(2) = 0.59). Slopes for latitude and altitude ranged from - 0.28 to - 0.51, and - 0.0019 to - 0.0045, respectively. Even though site distribution was uneven, these equations are the first trial estimation for annual mean stable isotopes in precipitation across Japan. Further research performed on the monthly basis is required to elucidate factors controlling the spatiotemporal variability of stable isotopes in precipitation across Japan.
22 citations
TL;DR: It is estimated that about 65 % of milk ALA is directly derived from maternal diet, but dietary ALA does not seem to contribute much as a precursor to milk n-3 long-chain polyunsaturated fatty acids within the studied time period.
Abstract: The origin of fatty acids in milk has not been elucidated in detail. We investigated the contribution of dietary α-linolenic acid (ALA) to human milk fat, its oxidation and endogenous conversion to long-chain polyunsaturated fatty acids. Ten lactating women were given 13C-ALA orally, and breath and milk samples were collected for a five-day period, while dietary intakes were assessed. 37.5 ± 2.7 % (M ± SE) of the tracer was recovered in breath-CO2, and 7.3 ± 1.1 % was directly transferred into milk. About 0.25 % of the tracer was found in milk long-chain polyunsaturated fatty acids. Combining intake and milk data, we estimate that about 65 % of milk ALA is directly derived from maternal diet. Thus, the major portion of milk ALA is directly derived from the diet, but dietary ALA does not seem to contribute much as a precursor to milk n-3 long-chain polyunsaturated fatty acids within the studied time period.
19 citations
TL;DR: The groundwater in the active and slow exchange zone is isotopically more depleted compared with the precipitation values observed, and the depletion increases with depth down to the level where strongly enriched brines are encountered.
Abstract: A new data set of δ2H and δ18O in the groundwater from the central part of the Baltic Artesian Basin is presented. The hydrogeological section is subdivided into stagnation, slow exchange and active exchange zones. Na–Ca–Cl brine found at the deepest part – the stagnation zone – is characterized by δ18O values above −5 ‰ and δ2H values approaching −40 ‰ with respect to Vienna Standard Mean Ocean Water. The slow exchange zone where waters of mostly intermediate salinity reside is characterized by δ18O values around −11.7 ‰ and δ2H values around −85.3 ‰. Mean δ18O and δ2H values of the fresh groundwater in the active water exchange zone are −11.1 and −79.9 ‰, respectively. Characteristically, the groundwater in the active and slow exchange zone is isotopically more depleted compared with the precipitation values observed, and the depletion increases with depth down to the level where strongly enriched brines are encountered.
TL;DR: The stable isotopic composition of two rivers in southern and southwestern Finland was studied to resolve the transit times and travel routes of the river water in the two different catchments, and the methods work for simple two component catchments.
Abstract: The stable isotopic composition of two rivers, the Vantaanjoki River and the Kokemaenjoki River, in southern and southwestern Finland was studied to resolve the transit times and travel routes of the river water in the two different catchments. The Kokemaenjoki River is dominated by great lake basins whereas the Vantaanjoki River has been reported having a significant groundwater component. The mean residence time of the young surface flow component could be resolved by sine function fitting onto the annual fluctuations of the isotopic signal, and the amount of base flow was estimated by using the isotopic composition of the river and groundwater. In this study, we found that the methods work for simple two component catchments. In more complex cases with three different components mixing, the solution becomes increasingly difficult and requires more study.
TL;DR: Investigation of isotopic time series recorded in the St. Lawrence River basin suggests that the recorded seasonal variations mainly respond to mixing processes within the Great Lakes and mixing with tributaries located downstream.
Abstract: Linkages between δ(18)O-δ(2)H and hydrological processes have been investigated from isotopic time series recorded in the St. Lawrence River basin. Three stations were monitored from 1997 to 2008. They include the Ottawa River, the St. Lawrence River main channel at Montreal and the fluvial estuary. All sites depict seasonal isotopic cycles characterized by heavy isotope depletions during the snowmelt period and heavy isotope enrichments throughout the ice-free period. The data define δ(2)H-δ(18)O regression lines falling below the meteoric water line. In the Ottawa River, calculations suggest that approximately 8 % of the total inflow to the basin is lost through evaporation. In the St. Lawrence River main channel, seasonal isotopic fluctuations most likely reflect hydrological processes occurring within the Great Lakes and mixing with tributaries located downstream. In the St. Lawrence River fluvial estuary, isotopic data allow partitioning streamflow components and suggest that the recorded seasonal variations mainly respond to mixing processes.
TL;DR: The associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO– 3 concentration, which implies that aquifer’ pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the Aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.
Abstract: Po is the main Italian river and the δ(18)O and δ(2)H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca-HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ(13)CDIC and δ(34)SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ(15)NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO(-) 3 concentration. This implies that aquifers' pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.
TL;DR: It is proposed that detailed spatial measurement of lake water isotopic compositions provides a good proxy for water movement and pollutant and alga transports, especially over big lakes.
Abstract: Stable isotopic compositions of lake water provide additional information on hydrological, meteorological and paleoclimate processes. In this study, lake water isotopic compositions were measured for more than three years in Lake Taihu, a large and shallow lake in southern China, to investigate the isotopic spatial and seasonal variations. The results indicated that (1) the whole-lake mean δ2H and δ18O values of the lake water varied seasonally from −48.4 ± 5.8 to −25.1 ± 3.2 ‰ and from −6.5 ± 0.9 to −3.5 ± 0.8 ‰, respectively, (2) the spatial pattern of the lake water isotopic compositions was controlled by the direction of water flow and not by local evaporation rate, and (3) using a one-site isotopic measurement to represent the whole-lake mean may result in unreasonable estimates of the isotopic composition of lake evaporation and the lake water residence time in poorly mixed lakes. The original data, documented here as an online supplement, provides a good reference for testing sensitivity of...
TL;DR: The isotopic data suggest that the surface water and shallow groundwaters are subjected to intensive evaporation and, as a result, increase in their salinity, and there is no evidence from isotope and hydrogeochemical evaluation for seawater intrusion into groundwater in the Puttalam area.
Abstract: Extensive extraction of groundwater has resulted in deterioration of the groundwater quality in the Puttalam area in the northwestern coastal zone of Sri Lanka. This situation led us to carry out the present comprehensive study based on environmental isotopic ((18)O, (2)H, (3)H) and geochemical evaluation to understand the root cause for water quality deterioration. The isotopic data suggest that the surface water and shallow groundwaters are subjected to intensive evaporation and, as a result, increase in their salinity. Deep groundwater of the area is mostly recharged by direct infiltration of rainwater and at few places by nearby surface water bodies. The salinity increase of deep groundwater depends on the specific hydrogeological zones and would be due to dissolution of salts which are precipitated in soil through the seawater spray over the time, dissolution of minerals in geological matrix and leaching of salts from salterns. The quality of the deep groundwater is relatively good in the granitic gneiss zone and nearby areas outside the sedimentary aquifer. There is no evidence from isotope and hydrogeochemical evaluation for seawater intrusion into groundwater in the Puttalam area.
TL;DR: Bobcats and pumas exhibited only a moderate δ18Op−δ18Ow correlation, which differed from canid carnivores and other placental mammals, which indicates a difference in oxygen isotope routing from body water to bioapatite and hair.
Abstract: Feline carnivores are threatened by illegal wildlife trade. Tracing the provenance of unknown felid tissues via stable isotope analysis could provide important information in wildlife crime investigations. The oxygen isotope composition of mammalian skeletal phosphate (δ(18)Op) is widely applied to trace the origin of animal remains and to reconstruct migratory patterns in palaeontological, archaeological, ecological and wildlife forensic applications. Teeth and bones of terrestrial mammals form at constant body temperature in isotope equilibrium with body water, which is predominantly controlled by ingested meteoric water (δ(18)Ow) that varies systematically with latitude, altitude and climate. Here we analysed δ(18)Op of 106 North American puma and bobcat bones of known geographic origin to establish the first δ(18)Op-δ(18)Ow regression for feline carnivores: δ(18)Op = 0.40(±0.04) * δ(18)Ow + 20.10(±0.40) (R(2) = 0.46, n = 106). This was compared with those from their respective prey species (deer and rabbit), a canid carnivore (fox) and other placental mammals. Effects of species, sex and relative humidity on the feline δ(18)Op-δ(18)Ow correlation were analysed and additional intra-individual tissue comparisons (hair δ(18)Oh vs. bone δ(18)Op) were performed for some bobcat individuals. Bobcats and pumas exhibited only a moderate δ(18)Op-δ(18)Ow correlation, which differed from canid carnivores and other placental mammals. However, feline δ(18)Op values revealed a moderate relation with δ(18)Ow, which lacks for the δ(18)Oh of hair from the same bobcat individuals. This indicates a difference in oxygen isotope routing from body water to bioapatite and hair. Most herbivores and omnivores track δ(18)Ow in their bioapatite δ(18)Op values much better, whereas δ(18)Op and especially δ(18)Oh values of feline carnivores are less precise proxies for meteoric water δ(18)Ow values and thus for provenance determination in wildlife forensics and palaeoclimate reconstructions. Oxygen isotope fingerprinting of bobcat and puma is biased by factors related to their diet, behaviour and metabolism that need to be better understood.
TL;DR: The contribution of Jochen Hoefs to the development of stable isotope (bio)geochemistry on the occasion of his 75th birthday is celebrated.
Abstract: We celebrate the contribution of Jochen Hoefs to the development of stable isotope (bio)geochemistry on the occasion of his 75th birthday.
TL;DR: Determining the domicile of humans using isotope ratios of hair can be confounded by differing variability in hair δ18O and δ2H between locations, differential incorporation of H and O into this protein and, in some cases, by tap water values that differ significantly from predicted precipitation values.
Abstract: We examined multiple natural abundance isotope ratios of human hair to assess biological variability within and between geographic locations and, further, to determine how well these isotope values predict location of origin. Sampling locations feature differing seasonality and mobile populations as a robust test of the method. Serially-sampled hair from Cambridge, MA, USA, shows lower δ2H and δ18O variability over a one-year time course than model-predicted precipitation isotope ratios, but exhibits considerable differences between individuals. Along a ∼13° north-south transect in the eastern USA (Brookline, MA, 42.3 ° N, College Park, MD, 39.0 ° N, and Gainesville, FL, 29.7 ° N) δ18O in human hair shows relatively greater differences and tracks changes in drinking water isotope ratios more sensitively than δ2H. Determining the domicile of humans using isotope ratios of hair can be confounded by differing variability in hair δ18O and δ2H between locations, differential incorporation of H and O in...
TL;DR: Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system.
Abstract: Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h–1. Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h–1. An isodose map of the area was produced using ArcGIS software version 9.3.
TL;DR: Analysis of the stable isotopic characteristics of individual rain events in southern India, which is influenced by dual monsoon rainfall, will aid in a better understanding of its mechanism.
Abstract: The stable isotopic compositions of all major daily rain fall samples (n = 113) collected from Kozhikode station in Kerala, India, for the year 2010 representing the pre-monsoon, southwest and northeast monsoon seasons are examined. The isotopic variations δ18O, δ2H and d-excess in daily rainfall ranged from δ18O: −4.4 to 2 ‰, δ2H: −25.3 to 13.8 ‰, and d-excess: −2.4 to 15.3 ‰; δ18O: −9.7 to −0.6 ‰, δ2H: −61.7 to 5.3 ‰, and d-excess 5.8 to 17.4 ‰; δ18O −11.3 to −1.4 ‰, δ2H: −75.3 to 0.9 ‰, and d-excess: 8.8 to 21.3 ‰ during the pre-, southwest and northeast monsoon periods, respectively. Thus, daily rainfall events during two monsoon periods had a distinct range of isotopic variations. The daily rain events within the two monsoon seasons also exhibited periodic variations. The isotopic composition of rain events during pre-monsoon and a few low-intensity events during the southwest monsoon period had imprints of secondary evaporation. This study analysing the stable isotopic characteristics of individual ...
TL;DR: Estimates of carbon and nitrogen isotope discrimination factors and turnover for the tree lizard (Urosaurus ornatus) using a diet-switch experiment are estimated and should be appropriate for use in trophic studies of U. ornatus, and possibly other related small-bodied insectivorous lizards.
Abstract: Laboratory experiments are useful for estimating the carbon and nitrogen isotope discrimination factors and turnover rates that are critical for drawing field-based inferences on consumer diets using stable isotopes. Although the utility of these discrimination factors is widely recognized, work in terrestrial systems has largely been limited to studies involving mammals and birds. In contrast, scant attention has been paid to the application of isotopic techniques to reptiles, despite their broad diversity in terms of numbers of species as well as their trophic roles. Here we estimate carbon and nitrogen isotope discrimination factors and turnover for the tree lizard (Urosaurus ornatus) using a diet-switch experiment. Lizards were collected from a C4-dominated grassland and then switched to C3-based diet (crickets) in the laboratory. We estimated discrimination by lizard claw tissue as Δ(13)C = 1.2 ± 0.1 ‰ for carbon and Δ(15)N = 0.7 ± 0.1 ‰ (mean ± 1 SE) for nitrogen, with 95 % turnover occurring after ∼15.5 days. These estimates should be appropriate for use in trophic studies of U. ornatus, and possibly other related small-bodied insectivorous lizards.
TL;DR: The activity concentrations of 238U and 234U have been determined in groundwater samples in the Thermi-Vasilika region, northern Greece by alpha spectrometry after pre-concentration and separation of uranium by cation exchange and finally its electrodeposition on stainless steel discs.
Abstract: The activity concentrations of (238)U and (234)U have been determined in groundwater samples in the Thermi-Vasilika region, northern Greece. The analysis was performed by alpha spectrometry after pre-concentration and separation of uranium by cation exchange and finally its electrodeposition on stainless steel discs. The obtained isotopic ratio (234)U/(238)U varies between 0.95 and 3.50 and is correlated with the different aquifer types and water flow paths in the study area. Lower values (up to 1.10) are located in the shallow porous aquifer indicating younger waters. Moderate values of the activity ratio characterise the deeper porous aquifer as well as the fissured rock aquifer (1.5-2.05). The geothermal spring illustrates the highest activity ratio (3.5) due to older water.
TL;DR: The high durability of calcite formed during carbonation of slaked lime within the matrix of the ancient mortar, and thus the excellent resistance of the hydraulic lime mortar against water, was documented.
Abstract: Ancient hydraulic lime mortar preserves chemical and isotopic signatures that provide important information about historical processing and its durability. The distribution and isotopic composition of calcite in a mortar of a well-preserved Punic–Roman cistern at Pantelleria Island (Italy) was used to trace the formation conditions, durability, and individual processing periods of the cistern mortar. The analyses of stable carbon and oxygen isotopes of calcite revealed four individual horizons, D, E, B-1 and B-2, of mortar from the top to the bottom of the cistern floor. Volcanic and ceramic aggregates were used for the production of the mortar of horizons E/D and B-1/B-2, respectively. All horizons comprise hydraulic lime mortar characterized by a mean cementation index of 1.5 ± 1, and a constant binder to aggregate ratio of 0.31 ± 0.01. This suggests standardized and highly effective processing of the cistern.The high durability of calcite formed during carbonation of slaked lime within the matrix of th...
TL;DR: The rapid change in the isotopic composition, spring discharge, water temperature, and turbidity in response to recharge events is related to fast water travel times and low storage capacity in the conduit system of the karst aquifer.
Abstract: The Tanour spring is one of the several karst springs located in the northern part of Jordan. Water samples from the Tanour spring and precipitation were collected in the area of Ajloun in NW Jordan for the analysis of stable oxygen and hydrogen isotopes to evaluate the spring response to precipitation events. Rainwater and snow samples were collected from different elevations during winters of 2013-2014 and 2014-2015. In addition, spring samples were collected between December 2014 and March 2015. δ(18)O values in rainwater vary from -3.26 to -17.34 ‰ (average: -7.84 ± 3.23 ‰), while δ(2)H values range between -4.4 and -110.4 ‰ (average: -35.7 ± 25.0 ‰). Deuterium excess ranges from 17.8 to 34.1 ‰ (average: 27.1 ± 4.0 ‰). The Local Meteoric Water Line for the study area was calculated to be δ(2)H = 7.66*δ(18)O + 24.43 (R(2) = 0.98). Pre-event spring discharge showed variation in δ(18)O (range -6.29 to -7.17 ‰; average -6.58 ± 0.19 ‰) and δ(2)H values (range -28.8 to -32.7 ‰; average: -30.5 ± 1.0 ‰). In contrast, δ(18)O and δ(2)H rapidly changed to more negative values during rainfall and snowmelt events and persisted for several days before returning to background values. Spring water temperature, spring discharge, and turbidity followed the trend in isotopic composition during and after the precipitation events. The rapid change in the isotopic composition, spring discharge, water temperature, and turbidity in response to recharge events is related to fast water travel times and low storage capacity in the conduit system of the karst aquifer. Based on the changes in the isotopic composition of spring water after the precipitation events, the water travel time in the aquifer is in the order of 5-11 days.
TL;DR: The results suggest that matching sample and standard media improves accuracy, but that isotopic values differ with the extraction method in ways that are not due to spectral interference from organics.
Abstract: Application of stable isotopes of water to studies of plant-soil interactions often requires a substantial preparatory step of extracting water from samples without fractionating isotopes. Online heating is an emerging approach for this need, but is relatively untested and major questions of how to best deliver standards and assess interference by organics have not been evaluated. We examined these issues in our application of measuring woody stem xylem of sagebrush using a Picarro laser spectrometer with online induction heating. We determined (1) effects of cryogenic compared to induction-heating extraction, (2) effects of delivery of standards on filter media compared to on woody stem sections, and (3) spectral interference from organic compounds for these approaches (and developed a technique to do so). Our results suggest that matching sample and standard media improves accuracy, but that isotopic values differ with the extraction method in ways that are not due to spectral interference from organics.
TL;DR: The differences in δ13C and δ18O between whole wood and resin-free whole wood vary within the analytical uncertainty of 0.3 and 0.5 ‰, indicating that resin extraction is not necessary for sapwood of P. uncinata.
Abstract: δ13C and δ18O values from sapwood of a single Pinus uncinata tree, from a high elevation site in the Spanish Pyrenees, were determined to evaluate the differences between whole wood and resin-free whole wood. This issue is addressed for the first time with P. uncinata over a 38-year long period. Results are also compared with published isotope values of α-cellulose samples from the same tree. The differences in δ13C and δ18O between whole wood and resin-free whole wood vary within the analytical uncertainty of 0.3 and 0.5 ‰, respectively, indicating that resin extraction is not necessary for sapwood of P. uncinata. Mean differences between cellulose and whole wood are 0.9 ‰ (δ13C) and 5.0 ‰ (δ18O), respectively. However, further analyses of different species and other sites are needed to evaluate whether the findings reported here are coherent more generally.
TL;DR: The IWBMIso can be used to assess the spatial and temporal variability of annual and monthly water balance components for input to water planning and management.
Abstract: The International Atomic Energy Agency (IAEA) Water Balance Model with Isotopes (IWBMIso) is a spatially distributed monthly water balance model that considers water fluxes and storages and their associated isotopic compositions. It is composed of a lake water balance model that is tightly coupled with a catchment water balance model. Measured isotope compositions of precipitation, rivers, lakes, and groundwater provide data that can be used to make an improved estimate of the magnitude of the fluxes among the model components. The model has been developed using the Object Modelling System (OMS). A variety of open source geographic information systems and web-based tools have been combined to provide user support for (1) basin delineation, characterization, and parameterization; (2) data pre-processing; (3) model calibration and application; and (4) visualization and analysis of model results. In regions where measured data are limited, the model can use freely available global data sets of climate, isotopic composition of precipitation, and soils and vegetation characteristics to create input data files and estimate spatially distributed model parameters. The OMS model engine and support functions, and the spatial and web-based tool set are integrated using the Colorado State University Environmental Risk Assessment and Management System (eRAMS) framework. The IWBMIso can be used to assess the spatial and temporal variability of annual and monthly water balance components for input to water planning and management.
TL;DR: A high resilience of the system to anthropogenic disturbances is suggested and the sediment potential for the reconstruction of the environmental evolution in time and for the anthropogenic impact assessment is demonstrated.
Abstract: A one-year hydrochemical and isotopic monitoring was conducted at the Inle Lake, the second largest lake in Myanmar, also considering sediment samples. Lake waters are characterised by low electrical conductivities (236–489 μS/cm), neutral to alkaline pH (7.36–9.26), oxidising Eh (329–457 mV) and Ca–Mg–HCO3 facies. Stable isotopes indicate that lake waters are only slightly affected by evaporation, are fully flushed yearly and are not stratified. Carbonate equilibria dominate the lake water hydrochemistry. In summer, photosynthetic activity and temperature increase induce calcite precipitation, as testified by its high content in the sediments, up to 97 %, and by its isotopic composition. The short residence time and endogenic calcite precipitation likely prevent the accumulation of contaminants and nutrients in lake waters. This study suggests a high resilience of the system to anthropogenic disturbances and demonstrates the sediment potential for the reconstruction of the environmental evolution...
TL;DR: Multiple sulphur (δ34S, Δ33S) isotopes support the identification of microbial sulphate reduction and sulphide oxidation in the subsurface, the latter is also evident through the presence of thick aggregates of sulphide-oxidizing Thiothrix bacteria.
Abstract: Highly mineralized springs in the Scuol-Tarasp area of the Lower Engadin and in the Albula Valley near Alvaneu, Switzerland, display distinct differences with respect to the source and fate of their dissolved sulphur species. High sulphate concentrations and positive sulphur (δ34S) and oxygen (δ18O) isotopic compositions argue for the subsurface dissolution of Mesozoic evaporitic sulphate. In contrast, low sulphate concentrations and less positive or even negative δ34S and δ18O values indicate a substantial contribution of sulphate sulphur from the oxidation of sulphides in the crystalline basement rocks or the Jurassic sedimentary cover rocks. Furthermore, multiple sulphur (δ34S, Δ33S) isotopes support the identification of microbial sulphate reduction and sulphide oxidation in the subsurface, the latter is also evident through the presence of thick aggregates of sulphide-oxidizing Thiothrix bacteria.