δD Values Of Precipitation Research Articles

Unexpected hydrogen isotope variation in oceanic pelagic seabirds.

Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism's tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred up the food web from an isotopically homogeneous water source. We report a 142‰ range in the δD values of flight feathers from the Hawaiian petrel (Pterodroma sandwichensis), an oceanic pelagic North Pacific species, and inquire about the source of that variation. We show δD variation between and within four other oceanic pelagic species: Newell's shearwater (Puffinus auricularis newellii), Black-footed albatross (Phoebastria nigripes), Laysan albatross (Phoebastria immutabilis) and Buller's shearwater (Puffinus bulleri). The similarity between muscle δD values of hatch-year Hawaiian petrels and their prey suggests that trophic fractionation does not influence δD values of muscle. We hypothesize that isotopic discrimination is associated with water loss during salt excretion through salt glands. Salt load differs between seabirds that consume isosmotic squid and crustaceans and those that feed on hyposmotic teleost fish. In support of the salt gland hypothesis, we show an inverse relationship between δD and percent teleost fish in diet for three seabird species. Our results demonstrate the utility of δD in the study of oceanic consumers, while also contributing to a better understanding of δD systematics, the basis for one of the most commonly utilized isotope tools in avian ecology.

The “inverse altitude effect” of leaf wax-derived n-alkane δD on the northeastern Tibetan Plateau

The response of soil wax derived n-alkane hydrogen isotope values (δDwax, the abundance weighted average δD values of the C29 and C31n-alkanes) and isotopic lapse rates (the average change in δDwax with elevation) to factors other than elevation change should be assessed and taken into account for quantitative elevation reconstructions. To shed more light on how plant wax derived n-alkanes may be used for this purpose, soil and Gramineae samples analyzed for δDwax values. Those were derived from the foreland basin, the mountain vegetation zone and glacier catchment areas along the Beida River (a tributary in the Heihe River Basin; up to the headwaters of the Qiyi glacier), and the Xiying River catchment (up to the headwaters and glaciated areas of the Lenglong Range), located on the northeastern Tibetan Plateau. For comparison, this study analyzed surface soils from the Maxian Mountains for δDwax. As a whole, the trend in δDwax in the study regions seems to primarily reflect δDrw (δD values of river water) and/or δDp (δD values of precipitation). These data show good inverse linear relationships between Gramineae and soil δDwax values and elevation (altitude effect) in the mountain vegetation zone of the Xiying River catchment (2200–3500m) and Maxian Mountains (2800–3700m), where the elevation effect becomes the main control factor even in the dry Qilian Mountains. However, at the low elevation sites, soil and Gramineae δDwax values from the Xiying River (1750–2200m) and Maxian Mountains (2060–2800m) show the “inverse altitude effect”. The recycled fraction and trajectory of water vapor may result in these positive δDwax elevation gradients in dry continental settings. The “inverse altitude effect” has also been observed in periglacial regions below the Qiyi glacier and from the Lenglong Range. We interpret this effect as evidence of stronger fractionation processes occurring in the freeze–thaw mass exchange between the solid and liquid phases at high elevations. Thus, the “inverse altitude effect” can be attributed to the decrease of precipitation amount in the upper valley and to marked fractionation in soil water and the residual or melting snow in periglacial regions, which may complicate the isotope thermometry. When interpreting changes of long term δD and δ18O records for determining elevation change, one must consider all possible influences on the lapse rate of δDwax values with elevation, including the patterns of atmospheric circulation in the past, topography, recycling of moisture in dry continental settings, and strong fractionation processes effecting soil and glacier melt water in the periglacial regions.

Constraints on the salinity–oxygen isotope relationship in the central tropical Pacific Ocean

Uncertainties surround the relationship between salinity and the stable isotopic composition of seawater, largely due to a dearth of modern seawater isotope data. Here we report 191 new, paired measurements of salinity and seawater oxygen isotopes (δ18Osw) taken from the central tropical Pacific in May 2012, from the surface to 4600m depth. We observe significant correlations between δ18Osw and salinity across the study region, with slopes ranging from 0.23 to 0.31‰/psu for the mixed layer, and 0.35–0.42‰/psu for waters between the mixed layer and 500m depth. When considering δ18Osw–salinity across averages of individual water masses in the region, slopes range from 0.21 to 0.40‰/psu, albeit with appreciable scatter. Surface salinity and δ18Osw data corresponding to the North Equatorial Countercurrent are significantly higher than previously observed, which we attribute to a weak westerly current and dry conditions in the region during the May 2012 cruise. Subsurface (80–500m) salinity values from 2012 are significantly lower than corresponding values from pre-existing regional data, highlighting a different latitudinal sampling distribution, while subsurface δ18Osw is not significantly different. Thus, in May 2012, δ18Osw in this region could not be used to distinguish between subsurface water masses of different salinities. Unlike other regions where the surface ‘freshwater endmember’ is close to the δ18O value of regional precipitation, the freshwater endmember implied by our dataset (−10.38‰) is consistent with a strong evaporative influence. Paired δ18O–δD values of precipitation and surface seawaters have similar slopes (5.0, 5.1), and relatively low intercepts (1.4, 0.8) indicating isotopic variability in both reservoirs is also partly controlled by evaporation.

Spatial variability in stable isotope values of surface waters of Eastern Canada and New England

• We map distribution of δ 18 O and δD values of surface waters in Eastern Canada/USA. • We assess spatial/temporal variability in δ 18 O and δD of precipitation in E Canada. • Significant agreement between precipitation and surface water δ 18 O/δD values exist. • Winter precipitation dominates recharge, evaporation is important in inland Labrador. • We provide basis/calibration for future paleoenvironmental research in this area. A total of 294 surface water samples were collected in Eastern Canada and the New England states of the USA in 2007, 2009, 2011, and 2013 and analyzed for δ 18 O and δD values to investigate climatic controls on hydrology and to test whether isotope values of surface waters can provide a suitable calibration for evaluation of paleoenvironmental proxy data in this region. Results demonstrate that surface waters in this region exhibit latitudinal gradients, with some overprinting by regional trends. Surface water δ 18 O and δD values range from −2.8‰ to −16.0‰, and from −23.8‰ to −118.5‰, respectively. Regression of all δ 18 O and δD values yields a surface water line (SWL) (δD = 7.53(±0.11)δ 18 O + 3.81(±1.12); r 2 = 0.95; n = 294), similar to slopes of 7.63(±0.06) and 7.96(±0.1) based on monthly and annual precipitation amount-weighted means for GNIP/CNIP stations in this study area. At smaller spatial scales evaporation and greater water residence time generate lake SWL with lower slope (7.50) than river SWL (7.80). At greater spatial scales, δ 18 O and δD values of lakes and rivers show a more uniform distribution, thus reflecting the prevalence of regional over local hydrological effects. Contour maps of surface water δ 18 O and δD values exhibit more detail than existing global precipitation models and suggest (a) a progressive decrease in δ 18 O H2O and δD H2O values towards higher latitudes via Rayleigh distillation and (b) generally higher δ 18 O H2O and δD H2O values in Western Newfoundland likely due to its proximity to the ocean. Contour maps predict the average annual-amount weighted δ 18 O and δD values of precipitation provided by GNIP/CNIP networks fairly well. It was also determined that recycled moisture supplies a significant proportion of precipitation in the southern/western parts of our study area, while evaporation could be a more dominant factor for interior Labrador. In addition, a strong agreement is observed between temperature and precipitation/surface water δ 18 O and δD values, suggesting that δ 18 O and δD values of surface waters can provide a suitable template and aid for ongoing paleoenvironmental research in this region.

Hydrogen and oxygen isotopic records in monthly scales variations of hydrological characteristics in the different landscape zones of alpine cold regions

Monthly scale variations in stable isotopic composition in precipitation and various water bodies were analyzed in this study using data collected from a field station. Experimental observation was performed to analyze processes in the glacier-snow zone, alpine cold desert zone, marsh meadow zone, alpine shrub zone, and mountain grassland zone based on the isotopic and hydrochemical analyses of glacier, snow, frozen soil, groundwater, and other water sources in the headwater catchment of the alpine cold region. δ18O and δD values of precipitation and various water bodies in Mafengou River Basin exhibited strong seasonal variations. Precipitation and various water bodies were rich in δ18O and δD during the wet season and relatively negative in δ18O and δD during the dry season. The isotopic content of various water bodies in Mafengou River Basin was dependent on temperature, elevation of the recharge area, and amount of precipitation. Lower temperatures were typically associated with lower δ18O and δD values and are believed to be mainly responsible for the seasonal patterns observed in the isotopic values of various water bodies in Mafengou River Basin in the alpine cold region. Seasonal variations were larger in streams where recent precipitation is the main source of the flow and smaller in streams where groundwater is the dominant source of water.

Water, plants, and early human habitats in eastern Africa

Water and its influence on plants likely exerted strong adaptive pressures in human evolution. Understanding relationships among water, plants, and early humans is limited both by incomplete terrestrial records of environmental change and by indirect proxy data for water availability. Here we present a continuous record of stable hydrogen-isotope compositions (expressed as δD values) for lipid biomarkers preserved in lake sediments from an early Pleistocene archaeological site in eastern Africa--Olduvai Gorge. We convert sedimentary leaf- and algal-lipid δD values into estimates for ancient source-water δD values by accounting for biochemical, physiological, and environmental influences on isotopic fractionation via published water-lipid enrichment factors for living plants, algae, and recent sediments. Reconstructed precipitation and lake-water δD values, respectively, are consistent with modern isotopic hydrology and reveal that dramatic fluctuations in water availability accompanied ecosystem changes. Drier conditions, indicated by less negative δD values, occur in association with stable carbon-isotopic evidence for open, C(4)-dominated grassland ecosystems. Wetter conditions, indicated by lower δD values, are associated with expanded woody cover across the ancient landscape. Estimates for ancient precipitation amounts, based on reconstructed precipitation δD values, range between approximately 250 and 700 mm · y(-1) and are consistent with modern precipitation data for eastern Africa. We conclude that freshwater availability exerted a substantial influence on eastern African ecosystems and, by extension, was central to early human proliferation during periods of rapid climate change.

Environmental control on eastern broadleaf forest species’ leaf wax distributions and D/H ratios

Local climate and environment broadly affect the deuterium/hydrogen (D/H) ratios of plant materials, however the degree to which an individual plant’s leaf waxes D/H ratios are affected by these parameters remains in question. Understanding these issues is particularly important in order to reconstruct past floral transitions and changes in the paleohydrologic cycle. For this study, we sampled five co-occurring tree species, Acer rubrum, Platanus occidentalis, Juniperus virginiana, Pinus taeda, and Pinus strobus and soils at forty sites along the East Coast of the US, from Florida to Maine. Hydrogen isotopic compositions of leaf wax n-alkanes, stem and surface waters were analyzed and compared against high-resolution temperature, precipitation, relative humidity, and vapor pressure deficit data to determine environmental controls on isotopic composition.Our results demonstrate that each tree species produce a unique distribution of n-alkanes with distinct chain length pattern. Average n-alkane chain lengths recovered from soils, A. rubrum, and J. virginiana leaves show significant correlations with mean annual temperature. δD values of A. rubrum leaf n-alkanes were strongly correlated to modeled mean annual precipitation δD values and other climate parameters related to latitude (i.e. temperature, relative humidity, vapor pressure deficit), while the δD values of J. virginiana n-alkanes were not. Differences in correspondence may reflect the timing of leaf wax synthesis between the two species. Further, soil n-alkane D/H compositions were strongly correlated to modeled mean annual precipitation δD values, while the apparent hydrogen isotopic fractionation was not. These findings indicate that the isotope ratio of n-alkanes from soils in Eastern North American forests and similar ecosystems likely represents a time-averaged value that smooth out the environmental influence any one plant experiences.

Leaf water deuterium enrichment shapes leaf wax n-alkane δD values of angiosperm plants II: Observational evidence and global implications

Leaf wax n-alkanes are long-chain hydrocarbons that can persist in sedimentary records over geological timescales. Since their hydrogen isotopic composition (expressed as a δD value) can be correlated to the δD values of precipitation, leaf wax n-alkane δD values have been advocated as new and powerful proxies for paleohydrological research. The exact type of hydrological information that is recorded in the δD values of leaf wax n-alkanes remains, however, unclear. In a companion paper we provide experimental evidence showing that the δD values of leaf wax n-alkanes of angiosperm plants grown under controlled environmental conditions not only reflect δD values of precipitation – as has often been assumed – but that evaporative deuterium (D)-enrichment of leaf water has an additional critical effect on their δD values. Here we present a detailed observational study that illustrates that evaporative D-enrichment of leaf water also affects the δD values of leaf wax n-alkanes in plants from natural ecosystems along a 1500km climate gradient in Northern Australia. Based on global simulations of leaf water D-enrichment we show that the effects of evaporative D-enrichment of leaf water on leaf wax n-alkane δD values is relevant in all biomes but that it is particularly important in arid environments. Given the combined influence of precipitation δD values and leaf water D-enrichment we argue that leaf wax n-alkane δD values contain an integrated signal that can provide general hydrological information, e.g. on the aridity of a catchment area. We also suggest that more specific hydrological information and even plant physiological information can be obtained from leaf wax n-alkanes if additional indicators are available to constrain the plant- and precipitation-derived influences on their δD values. As such, our findings have important implications for the interpretation of leaf wax n-alkane δD values from paleohydrological records. In addition, our investigations open the door to employ δD values of leaf wax n-alkanes as new ecohydrological proxies in contemporary plant and ecosystem sciences.

Using the deuterium isotope composition of permafrost meltwater to constrain thermokarst lake contributions to atmospheric CH4 during the last deglaciation

Thermokarst lakes are thought to have been an important source of methane (CH4) during the last deglaciation when atmospheric CH4 concentrations increased rapidly. Here we demonstrate that meltwater from permafrost ice serves as an H source to CH4production in thermokarst lakes, allowing for region‐specific reconstructions ofδDCH4 emissions from Siberian and North American lakes. δDCH4 reflects regionally varying δD values of precipitation incorporated into ground ice at the time of its formation. Late Pleistocene‐aged permafrost ground ice was the dominant H source to CH4production in primary thermokarst lakes, whereas Holocene‐aged permafrost ground ice contributed H to CH4 production in later generation lakes. We found that Alaskan thermokarst lake δDCH4 was higher (−334 ± 17‰) than Siberian lake δDCH4 (−381 ± 18‰). Weighted mean δDCH4values for Beringian lakes ranged from −385‰ to −382‰ over the deglacial period. Bottom‐up estimates suggest that Beringian thermokarst lakes contributed 15 ± 4 Tg CH4 yr−1 to the atmosphere during the Younger Dryas and 25 ± 5 Tg CH4 yr−1during the Preboreal period. These estimates are supported by independent, top‐down isotope mass balance calculations based on ice coreδDCH4 and δ13CCH4 records. Both approaches suggest that thermokarst lakes and boreal wetlands together were important sources of deglacial CH4.

Controls on the D/H ratios of plant leaf waxes in an arid ecosystem

The extent to which leaf water D-enrichment (transpiration) and soil water D-enrichment (evaporation) affect the D/H ratio of plant leaf waxes remains a contentious issue, with important implications for paleohydrologic reconstructions. In this study we measure δD values of precipitation (δD_p), groundwater (δD_(gw)), plant xylem water (δD_(xw)) and leaf water (δD_(lw)) to understand their impact on the δD values of plant leaf wax n-alkanes (δD_(wax)) in an arid ecosystem. Our survey includes multiple species at four sites across an aridity gradient (80–30% relative humidity) in southern California. We find that many species take up groundwater or precipitation without significant fractionation. D-enriched soil water is a minor source even in species known to perform and utilize waters from hydraulic lift, such as Larrea tridentata (+10‰). Measurements of leaf water isotopic composition demonstrate that transpiration is an important mechanism for D-enrichment of leaf waters (+74 ± 20‰, 1σ), resulting in the smallest net fractionation yet reported between source water and leaf waxes (L. tridentata −41‰; multi-species mean value is −94 ± 21‰, 1σ). We find little change in leaf water D-enrichment or net fractionation across the climatic gradient sampled by our study, suggesting that a net fractionation of ca. −90‰ may be appropriate for paleohydrologic reconstructions in semi-arid to arid environments. Large interspecies offsets in net fractionations (1σ = 21‰) are potentially troublesome, given the observed floristic diversity and the likelihood of species assemblage changes with climate shifts.

Multiple controls for the variability of hydrogen isotopic compositions in higher plant n‐alkanes from modern ecosystems

AbstractWe performed a global scale analysis of available leaf wax n‐alkane δD data compiled from our new results, as well as from the literature and expressed as average values of D/H ratios from three common lipids of n‐alkanes with odd carbon numbers (n‐C27, n‐C29, and n‐C31) from living higher plants. Our results clearly indicate multiple controls of hydrogen isotope composition and its variability in plants leaf wax. (1) At the global scale, precipitation δD values play a dominating factor that exercises the first order of control for hydrogen isotopic compositions in plant leaf wax. The hydrogen isotopic composition of plant leaf wax tracks the decreasing trend of precipitation δD with increasing latitude. (2) Because of different water acquisition systems, plant life form influences the hydrogen isotopic composition of leaf wax n‐alkanes with woody plants and grasses having different responses to the change of global precipitation δD. (3) Physiological difference, due to different photosynthesis pathways or different water usage strategies, can leave an imprint on δD patterns of plant leaf waxes, causing δD variations among plants using the same source water. While these results better explain the variability of hydrogen isotope composition in leaf wax, they also have important implications for the interpretation of n‐alkane δD data from fossils and ancient sediments.

Spatial and seasonal variations in δ18O and δD values in the River Sava in Slovenia

Stable isotope measurements of oxygen and hydrogen (δ18O and δD) in stream waters and precipitation were used to investigate hydrological pathways and residence times in the River Sava catchment in Slovenia. δ18O and δD values of precipitation exhibited strong seasonal variations. Precipitation is of mixed Atlantic–Mediterranean origin which is also reflected in the isotopic composition of River Sava surface waters. The isotopic content of the river water is dependent on temperature, elevation of the recharge area and amount of precipitation. Spatially, rivers water is 16O-enriched in the high mountain areas due to higher amount of precipitation, lower temperature and higher elevation of the recharge area, while in the lower part of the River Sava catchments the δ18O values are higher. It is also observed that the River Sava responds quickly to precipitation which is reflected in its δ18O and δD values and the low residence time estimated in the river. Using an exponential flow model it was calculated that mean stream water residence times varied between 0.4 and 2.1 years. The shortest residence time determined at Savica is connected mainly to the higher amount of precipitation in the upper Sava watershed and the mountains carbonate karst terrain characterized by a higher runoff. The mean residence time in the main stream water of the River Sava was estimated to be 1.32 years and is in a good agreement with the residence time determined using 3H measurements. These data extend our knowledge in understanding the hydrological cycle of the River Sava, the interactions between precipitation, surface water and groundwater and, at the same time, demonstrate the utility of isotope tracers in determining catchments characteristics.

δD values of individual n-alkanes from terrestrial plants along a climatic gradient – Implications for the sedimentary biomarker record

The compound-specific hydrogen isotope composition ( δD) of sedimentary n-alkanes is increasingly used as a palaeoclimate proxy. To explore the origin of the hydrogen isotope signal of n-alkanes from higher terrestrial plant biomass in sedimentary organic matter of small lakes we have analysed the n-alkane composition and δD values of 31 plant biomass samples (Birch ( Betula), Beech ( Fagus), Oak ( Quercus), Alder ( Alnus), Hornbeam ( Carpinus) and Myrtle ( Myrtus) as well as non-stomata containing Sphagnum, Cladonia and moss) from 14 sites along a climatic gradient from Northern Finland to Southern Italy. Eleven of the sites were previously investigated for the n-alkane δD values in adjacent lake sediments and are compared to the leaf wax n-alkane δD values. The distribution of terrestrial n-alkanes in lake sediments was not found to be characteristic of the dominant vegetation around the lake. Evidently, n-alkane distributions within the same species at different sites were found to be variable. These findings complicate the use of certain n-alkane distributions in sediments as a palaeoenvironmental indicator. δD values of plant biomass n-alkanes show a significant positive correlation with the precipitation δD values. Biomass n-alkane δD values are in general less negative than the associated sedimentary n-alkanes of terrestrial origin, possibly due to the stronger evapotranspiration during the summer, when sampling took place. This suggests, that n-alkanes in leaves show seasonal variations and the sedimentary organic matter receives the lighter isotope signal of the autumn, when most leaves are incorporated into the sediment. The variability of the δD values from non-stomata containing plants is much higher than for broadleaf trees, since stomata can regulate water loss through evapotranspiration. The average chain length (ACL) of n-alkanes from deciduous tree leaves increases from North to South. With increasing ACL the hydrogen isotopic fractionation ( ε) between source water and n-alkanes also increases. Our results prove that terrestrial n-alkane δD values record the δD value of precipitation, modified by the amount of isotope enrichment in the leaf water due to plant anatomy (stomata vs. no stomata) and site specific meteorological conditions, such as evapotranspiration, relative humidity and soil moisture. Therefore, terrestrial n-alkanes in lake sediments can deliver information on changes in these parameters over geological timescales. In lake sediments where aquatic n-alkanes, such as n-C 17 record the lake water δD value, the isotopic difference between terrestrial and aquatic n-alkanes could therefore be used to reconstruct changes in evapotranspiration.

Influence of physiology and climate on δD of leaf wax n-alkanes from C 3 and C 4 grasses

We measured hydrogen isotope compositions ( δD) of high-molecular-weight n-alkanes (C 27–C 33) from grasses grown in greenhouses and collected from the US Great Plains. In both cases, n-alkanes from C 4 grasses are enriched in D by more than 20‰ relative to those from C 3 grasses. The apparent enrichment factor ( ε C 29 - GW ) between C 29 n-alkane and greenhouse water is −165 ± 12‰ for C 3 grasses and −140 ± 15‰ for C 4 grasses. For samples from the Great Plains, δD values of C 29 n-alkanes range from −280 to −136‰, with values for C 4 grasses ca. 21‰ more positive than those for C 3 grasses from the same site. Differences in C 3 and C 4 grass n-alkane δD values are consistent with the shorter interveinal distance in C 4 grass leaves, and greater back-diffusion of enriched water from stomata to veins, than in C 3 grass leaves. Great Plains’ grass n-alkane isotopic ratios largely reflect precipitation δD values. However, the offset or apparent fractionation between n-alkanes and precipitation is not uniform and varies with annual precipitation and relative humidity, suggesting climatic controls on lipid δD values. The dryer sites exhibit smaller absolute apparent fractionation indicative of D-enrichment of source waters through transpiration and/or soil evaporation. To explore the relationship between climate and n-alkane δD values, we develop three models. (1) The ‘direct analog’ model estimates δ D C 29 values simply by applying the apparent enrichment factors, ε C 29 - GW , observed in greenhouse grasses to precipitation δD values from the Great Plains. (2) The ‘leaf-water’ model uses a Craig–Gordon model to estimate transpirational D-enrichment for both greenhouse and field sites. The transpiration-corrected enrichment factors between C 29 and bulk leaf-water, ε C 29 - GW , calculated from the greenhouse samples (−181‰ for C 3 and −157‰ for C 4) are applied to estimate δ D C 29 values relative to modeled bulk leaf-water δD values. (3) The ‘soil- and leaf-water’ model estimates the combined effects of soil evaporation, modeled by analogy with a flow-through lake, and transpiration on δ D C 29 values. Predictions improve with the addition of the explicit consideration of transpiration and soil evaporation, indicating that they are both important processes in determining plant lipid δD values. D-enrichment caused by these evaporative processes is controlled by relative humidity, suggesting that important climatic information is recorded in leaf wax n-alkane δD values. Calibration studies such as this one provide a baseline for future studies of plant-water–deuterium systematics and form the foundation for interpretation of plant wax hydrogen isotope ratios as a paleo-aridity proxy.

Regional and seasonal trends in the oxygen and hydrogen isotope ratios of Finnish groundwaters: a key for mean annual precipitation

The isotopic composition of oxygen and hydrogen in Finnish groundwaters was studied as part of two hydrogeological research programs during 1995–2001. A groundwater data set of 983 samples with good geographical coverage and a long-term groundwater data set from 19 study sites were included. The isotopic composition of oxygen and hydrogen in groundwaters shows a systematic shift from higher δ 18 O and δD values in the south to lower values in the north, the difference being approximately 4‰ for oxygen and 34‰ for hydrogen. The δ 18 O values are correlated with the mean annual surface temperature and the slope is close to that reported for the precipitation in European stations. In order to evaluate the relationship between the δ 18 O and δD values in precipitation and those in local groundwater, precipitation was collected at one site in southern Finland. No precipitation isotope records have been published in northern Finland, and those from groundwaters were therefore compared to published precipitation data from northern Sweden. No significant differences were observed between the mean annual δ 18 O and δD values in precipitation and those in local groundwaters. These groundwater data provide the first approximation of regional trends in the isotopic composition of precipitation in Finland.

Climatic controls on the stable isotopic composition of precipitation in Northeast Asia

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 23:137-148 (2003) - doi:10.3354/cr023137 Climatic controls on the stable isotopic composition of precipitation in Northeast Asia Kwang-Sik Lee1,*, Andrew J. Grundstein2, David B. Wenner3, Man-Sik Choi1, Nam-Chil Woo4, Dae-Ha Lee5 1Korea Basic Science Institute, Eoeun-dong 52, Yusung-gu, Daejeon 305-333, Korea 2Department of Geography, and 3Department of Geology, University of Georgia, Athens, Georgia 30602, USA 4Department of Earth System Sciences, Yonsei University, Seoul 120-749, Korea 5Korea Institute of Geoscience and Mineral Resources, Gajeong-dong 30, Yusung-gu, Daejeon 305-350, Korea *Email: kslee@kbsi.re.kr ABSTRACT: An examination of oxygen and hydrogen isotopic compositions of precipitation in NE Asia from the IAEA/WMO data set reveals that many sites have a distinct winter-summer seasonal pattern in deuterium excess (d-) values that appears to reflect different climatic conditions. To further understand this pattern, stable isotopic data were obtained for individual rainfall events over a 2 yr period at Jeju Island, Korea. The δ18O- and δD-values of precipitation at Jeju Island are not dependent upon temperature. However, the deuterium excess values, which range from 3.0 to 40.6‰, show a distinct seasonal variation with higher d-values in winter (>~15‰) and lower values in summer (~10‰). Such a seasonal variation is closely related to different air masses affecting the island during different seasons: a cold-dry continental polar air mass in winter and a hot-humid maritime tropical air mass in summer. KEY WORDS: Oxygen · Hydrogen · Isotopic composition · Precipitation · Deuterium excess values · Northeast Asia · Jeju Island · Korea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 23, No. 2. Online publication date: January 31, 2003 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2003 Inter-Research.

Influence of precipitation seasonality on piñon pine cellulose δD values

SummaryThe influence of seasonal to interannual climate variations on cellulose hydrogen isotopic composition (δD) was assessed by analysing tree rings and needles of piñon pine (Pinus edulis and P. monophylla). Sites spanned a gradient of decreasing summer precipitation, from New Mexico to Arizona to Nevada. Tree rings were divided into earlywood, latewood and whole‐year increments, and annual cohorts of needles were collected. The study period (1989–96) included two La Niña events (1989, 1996) and a prolonged El Niño event (1991–95). Winter and spring moisture conditions were strongly related to October–March Southern Oscillation Index (SOI) in New Mexico and Arizona, with above‐average precipitation occurring in El Niño years. Wood δD values at these sites were correlated with winter and spring moisture conditions. Needle δD values were correlated with summer moisture conditions in New Mexico and with winter moisture and SOI in Arizona. Low cellulose δD values observed from 1991 to 1993 in both wood and needles occurred during wet El Niño years, whereas high δD values in needles were present during the dry, La Niña years of 1989 and 1996. North‐eastern Nevada does not receive precipitation anomalies related to ENSO, and thus cellulose δD values did not reflect the ENSO pattern observed at the other sites. Cellulose δD values were strongly, inversely correlated with relative humidity variations at all sites, as predicted by a mechanistic model. Contrary to predictions from the same model and observations from more mesic areas, time series of cellulose δD values were not directly correlated with interannual or seasonal variations in precipitation δD values or temperature at any of the sites. On a regional basis, however, mean δD values in needles and wood were correlated with mean annual temperature and δD values of precipitation. This suggests that temporal averaging may bias relationships between biological systems and climate.

Tracing origins and migration of wildlife using stable isotopes: a review.

To understand the ecology of migratory animals it is important to link geographic regions used by individuals including breeding, wintering, and intermediate stopover sites. Previous conventional approaches used to track animal movements have relied on extrinsic markers and typically the subsequent recovery of individuals. This approach has generally been inappropriate for most small, or non-game animals. The use of intrinsic markers such as fatty acid profiles, molecular DNA analyses, and the measurement of naturally occurring stable isotopes in animal tissues offer alternative approaches. This paper reviews the use of stable isotope analyses (primarily δ13C, δ15N, δ34S, δD, δ87Sr) to trace nutritional origin and migration in animals. This approach relies on the fact that foodweb isotopic signatures are reflected in the tissues of organisms and that such signatures can vary spatially based on a variety of biogeochemical processes. Organisms moving between isotopically distinct foodwebs can carry with them information on the location of previous feeding. Such an approach has been used to track animal use of inshore versus offshore, marine versus freshwater, terrestrial C3 versus marine, terrestrial mesic versus xeric, and C3 versus C4 or Crassulacean acid metabolism foodwebs. More recently, the use of stable hydrogen isotope analyses (δD) to link organisms to broad geographic origin in North America is based on large-scale isotopic contours of growing-season average δD values in precipitation. This technique, especially when combined with the assay of other stable isotopes, will be extremely useful in helping to track migration and movement of a wide range of animals from insects to birds and mammals. Future research to refine our understanding of natural and anthropogenic-induced isotopic gradients in nature, and to explore the use of stable isotopes of other elements, is recommended.

Geothermal‐Water Characteristics in the Surdulica Aquifer

AbstractThe Surdulica‐Bujanovac geothermal region of southeastern Serbia, with granodiorite (Surdulica) and granite (Bujanovac) aquifers (water temperatures of 125°C and 46°C, respectively) was hydrogeologically and geochemically studied using environmental isotopes from 1986 to 1990. In the Surdulica system, water, rock, and vegetation samples from 35 locations (springs, rivers, and boreholes) representing all parts of the hydrogeological system (recharge area, transition zone, and terminus with hot deep‐circulated waters) were collected for geochemical and isotope analyses (D, 18O,3H, 13C, 14C). From the recharge area to the terminus of the system, ground‐water temperatures and ionic concentrations increase two to three orders of magnitude: temperature from 3–126°C, Na+ 2.3–1127 mg/1; HCO3− 30.5–2989 mg/1; SO42− 4.8–480 mg/1; SiO2 3–90 mg/1. The hot waters, appearing at the terminus of the system (Vranjska and Bujanovac Spas locations) are the oldest, based on 14C and 3H. The δ13C attains the low negative value of −0.4‰ for hot waters, approaching those in the aquifer matrix, which are in the range between −8.4 and + 2 ‰. The δ18O and δD values in precipitation and ground water indicate that recharge takes place predominantly at the higher elevations (more than 500 m asl) and in the cold seasons. A dual‐porosity system comprised of fissures and intergranular storage controls fluid transport. The deepest flows are hydraulically isolated from fresh waters. Low 14C contents (1–6 pMC) and the absence of3 H suggest the mean residence times for the older water up to 20,000 years. A 18O shift and chemical geothermometers suggest that their base temperatures of more than 200°C are not likely.

Stable isotope composition of waters in southeastern California: 2. Groundwaters and their relation to modern precipitation

We compare isotopic data on modern groundwater recharge, estimated from a 7‐year collection of precipitation samples, with the isotopic compositions of 82 samples from wells and perennial springs collected in southeastern California. Over half the samples represent recharge that is considerably more depleted in deuterium (δD) than the lightest (winter) precipitation δD values now precipitating in nearby areas. Wells in the vicinity of irrigation canals fed from the Colorado River contain water whose δD resembles that of the irrigation canals, and wells adjacent to the Mojave River are recharged by Mojave River water. The remainder of the samples from the 17 hydrologic units discussed in this paper include one or more whose δD values are depleted in deuterium by at least 10‰ compared to recharge estimated from modern winter precipitation. A plot of δ18O versus δD for 56 wells and 22 springs shows substantial scatter (R2=0.66) and defines a slope of 4.9, which is lower than the slope of the Meteoric Water Line. This slope and the scatter of the data suggest these diverse waters were evaporated to different degrees before recharge, and they may also have exchanged oxygen with solid mineral phases. We interpret the fact that many groundwaters in this region have lower δD values than modem precipitation to indicate that recharge of many of the groundwater basins occurred during an earlier period, probably the late Pleistocene, when winters were colder, evaporation rates were lower, and precipitation was quantitatively greater and isotopically lighter.