Stable Hydrogen Isotope Ratios Research Articles

The movement ecology of the straw-colored fruit bat, Eidolon helvum, in sub-Saharan Africa assessed by stable isotope ratios.

Flying foxes (Pteropodidae) are key seed dispersers on the African continent, yet their migratory behavior is largely unknown. Here, we studied the movement ecology of the straw-colored fruit bat, Eidolon helvum, and other fruit bats by analyzing stable isotope ratios in fur collected from museum specimens. In a triple-isotope approach based on samples of two ecologically similar non-migratory pteropodids, we first confirmed that a stable isotope approach is capable of delineating between geographically distinct locations in Sub-Saharan Africa. A discriminant function analysis assigned 84% of individuals correctly to their capture site. Further, we assessed how well hydrogen stable isotope ratios (δ2H) of fur keratin collected from non-migratory species (n = 191 individuals) records variation in δ2H of precipitation water in sub-Saharan Africa. Overall, we found positive, negative and no correlations within the six studied species. We then developed a reduced major axis regression equation based on individual data of non-migratory species to predict where potentially migratory E. helvum (n = 88) would come from based on their keratin δ2H. Across non-migratory species, δ2H of keratin and local water correlated positively. Based on the isoscape origin model, 22% of E. helvum were migratory, i.e. individuals had migrated over at least 250 km prior to their capture. Migratory individuals came from locations at a median distance of about 860 km from the collection site, four even from distances of at least 2,000 km. Ground-truthing of our isoscape origin model based on keratin δ2H of extant E. helvum (n = 76) supported a high predictive power of assigning the provenance of African flying foxes. Our study highlights that stable isotope ratios can be used to explain the migratory behavior of flying foxes, even on the isotopically relatively homogenous African continent, and with material collected by museums many decades or more than a century ago.

Compound‐specific carbon, nitrogen, and hydrogen isotopic ratios for amino acids in CM and CR chondrites and their use in evaluating potential formation pathways

Abstract– Stable hydrogen, carbon, and nitrogen isotopic ratios (δD, δ13C, and δ15N) of organic compounds can reveal information about their origin and formation pathways. Several formation mechanisms and environments have been postulated for the amino acids detected in carbonaceous chondrites. As each proposed mechanism utilizes different precursor molecules, the isotopic signatures of the resulting amino acids may indicate the most likely of these pathways. We have applied gas chromatography with mass spectrometry and combustion isotope ratio mass spectrometry to measure the compound‐specific C, N, and H stable isotopic ratios of amino acids from seven CM and CR carbonaceous chondrites: CM1/2 Allan Hills (ALH) 83100, CM2 Murchison, CM2 Lewis Cliff (LEW) 90500, CM2 Lonewolf Nunataks (LON) 94101, CR2 Graves Nunataks (GRA) 95229, CR2 Elephant Moraine (EET) 92042, and CR3 Queen Alexandra Range (QUE) 99177. We compare the isotopic compositions of amino acids in these meteorites with predictions of expected isotopic enrichments from potential formation pathways. We observe trends of decreasing δ13C and increasing δD with increasing carbon number in the α‐H, α‐NH2 amino acids that correspond to predictions made for formation via Strecker‐cyanohydrin synthesis. We also observe light δ13C signatures for β‐alanine, which may indicate either formation via Michael addition or via a pathway that forms primarily small, straight‐chain, amine‐terminal amino acids (n‐ω‐amino acids). Higher deuterium enrichments are observed in α‐methyl amino acids, indicating formation of these amino acids or their precursors in cold interstellar or nebular environments. Finally, individual amino acids are more enriched in deuterium in CR chondrites than in CM chondrites, reflecting different parent‐body chemistry.

Atmospheric moisture residence time affects rainwater isotope ratios

The water cycle is expected to respond to rising air temperature, which redistributes moisture in the lowest part of the atmosphere, known as the boundary layer. To understand how boundary layer processes redistribute rainfall across different climate settings, climatologists use stable isotope ratios of oxygen and hydrogen in rainwater. A process known as Rayleigh fractionation—which depends on air temperature and amount of rainfall among other factors—controls the stable isotope makeup of rainwater. For example, in the tropics the isotope ratio depends on the amount of rainfall, whereas in high‐latitude continents it depends on the air temperature.

Enrichment in <sup>13</sup>C of atmospheric CH<sub>4</sub> during the Younger Dryas termination

Abstract. The abrupt warming across the Younger Dryas termination (~11 600 yr before present) was marked by a large increase in the global atmospheric methane mixing ratio. The debate over sources responsible for the rise in methane centers on the roles of global wetlands, marine gas hydrates, and thermokarst lakes. We present a new, higher-precision methane stable carbon isotope ratio (δ13CH4) dataset from ice sampled at Påkitsoq, Greenland that shows distinct 13C-enrichment associated with this rise. We investigate the validity of this finding in face of known anomalous methane concentrations that occur at Påkitsoq. Comparison with previously published datasets to determine the robustness of our results indicates a similar trend in ice from both an Antarctic ice core and previously published Påkitsoq data measured using four different extraction and analytical techniques. The δ13CH4 trend suggests that 13C-enriched CH4 sources played an important role in the concentration increase. In a first attempt at quantifying the various contributions from our data, we apply a methane triple mass balance of stable carbon and hydrogen isotope ratios and radiocarbon. The mass balance results suggest biomass burning (42–66% of total methane flux increase) and thermokarst lakes (27–59%) as the dominant contributing sources. Given the high uncertainty and low temporal resolution of the 14CH4 dataset used in the triple mass balance, we also performed a mass balance test using just δ13C and δD. These results further support biomass burning as a dominant source, but do not allow distinguishing of thermokarst lake contributions from boreal wetlands, aerobic plant methane, or termites. Our results in both mass balance tests do not suggest as large a role for tropical wetlands or marine gas hydrates as commonly proposed.

Assessing dispersal in threatened migratory birds using stable hydrogen isotope (δD) analysis of feathers

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 16:17-29 (2012) - DOI: https://doi.org/10.3354/esr00383 Assessing dispersal in threatened migratory birds using stable hydrogen isotope (δD) analysis of feathers Steven L. Van Wilgenburg1,*, Keith A. Hobson1,2, Katherine R. Brewster2, Jeffrey M. Welker3 1Environment Canada, Saskatoon, Saskatchewan S7N 3H5, Canada 2Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada 3Environment and Natural Resources Institute, University of Alaska Anchorage, Alaska 99508, USA *Email: steve.vanwilgenburg@ec.gc.ca ABSTRACT: Management decisions involving species at risk are typically made in the face of substantial biological uncertainty. Incorporating uncertainty into decision-making allows managers to perform risk/benefit analysis. Stable hydrogen isotope ratios (δD) provide a tool for studying large-scale movements of migratory organisms and can contribute to the management of migratory species at risk. However, this analytical approach is based on predicted precipitation amount-weighted average deuterium (δD p) values, and individual years of interest can involve substantial departures from long-term averages. Local growing-season δD p at locations within the Great Plains of North America deviates from that described by GIS-based models of δD p derived from long-term estimates based on the Global Network of Isotopes in Precipitation (GNIP). We augmented the GNIP dataset with information from the US Network for Isotopes in Precipitation database for sites in the Great Plains, refining a previously published isoscape for inferring origins of migratory wildlife. Accounting for longitude and the coefficient of variation within precipitation in a single year at specific locations allowed us to determine year- and site-specific estimates of δD p and estimated rates of long-distance dispersal for 3 species of grassland songbirds based upon δD values of feathers (δDf). Using a likelihood-based approach to classify individuals as ‘local’ or ‘immigrant,’ we incorporated uncertainty in making these designations. This approach provides a convenient tool to effectively communicate research results to policy makers, who must make decisions at the level of risk which they are willing to assume when determining ­management strategies. KEY WORDS: Species at risk · Stable isotopes · Global Network of Isotopes in Precipitation · Isoscape Full text in pdf format PreviousNextCite this article as: Van Wilgenburg SL, Hobson KA, Brewster KR, Welker JM (2012) Assessing dispersal in threatened migratory birds using stable hydrogen isotope (δD) analysis of feathers. Endang Species Res 16:17-29. https://doi.org/10.3354/esr00383 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 16, No. 1. Online publication date: January 09, 2012 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2012 Inter-Research.

Potential and Limits in Detecting Altitudinal Movements of Bats using Stable Hydrogen Isotope Ratios of Fur Keratin

Despite their small size, bats are exceptionally mobile. But where and when bats move seasonally often remains enigmatic, particularly for altitudinal movements. Recently, stable hydrogen isotope ratios (δD) of metabolically inert material like hair keratin have been utilized to track altitudinal movements of animals. Here, we measured δD in hair keratin of seven bat species captured in the Merendon Mountain Range in Honduras: three species were captured only at the low elevation site (≈ 1,100 m above sea level), one species only at the high elevation site (≈ 1,500 m a.s.l.) and three species at both sites. Based on information from the literature, we categorized two out of the seven species as sedentary (obligate fruit-eating Artibeus toltecus and insect-feeding Micronycteris microtis). All others were categorized as potentially migratory species (obligate fruit-eating Artibeus jamaicensis, Sturnira ludovici and Sturnira lilium and insect-feeding Myotis keaysi and Molossus ater). Hair keratin of insectivorous species was enriched in deuterium by about 40‰ relative to that of co-existing fruit-eating species, irrespective of whether they were sedentary or potentially migratory, suggesting that δD of consumer tissue increases markedly with increasing trophic level. Hair keratin of sedentary A. toltecus and potentially migratory S. ludovici did not differ between populations of the two elevations indicating that the altitudinal gradient in δD may be too small and/or that variation in hair keratin δD too large to unravel altitudinal movements of less than 400 m in bats based on keratin δD alone.

Tritium Concentration in River Water and Groundwater Collected in Rokkasho, Aomori, Japan

In order to study the effect of 3H released from the commercial spent nuclear fuel reprocessing plant on 3H concentration in the local fresh water environment, river water and well water samples were collected at seventeen and nine points, respectively, around the plant. Concentrations of 3H were measured in the samples collected during the period of the final testing using actual spent fuel in the plant. The stable isotope ratios of hydrogen and oxygen in water samples were also measured for a hydrological study around the plant area. Concentrations of 3H in the river water samples were in the background level, and their variation among sampling locations was small. Although well water samples also did not have significantly high 3H concentrations originating from the 3H released from the plant, the variation in 3H concentration among sampling locations was larger than that in the river water samples. Comparison of ΔD and Δ18O data with a local meteoric water line suggested that groundwater around the plant area is mainly recharged by precipitation in winter.

Effects of size and diet on stable hydrogen isotope values (δD) in fish: implications for tracing origins of individuals and their food sources

Recent studies suggest that stable hydrogen isotope ratios (δD) of fish can be used to track their watershed origin and the relative contributions of source material. Both applications assume that there is no metabolic or trophic effect on tissue δD. We studied the local variation of δD values in four fish species of contrasting size and feeding habits in an isotopically homogenous reservoir (Flix, Spain). Other isotopic values (δ15N, δ13C) and trace metal content were measured as indicators of trophic and bioaccumulation patterns. In addition, isotopic values (δD, δ15N, δ13C) of other food web components were measured for comparison. Muscle δD values differed greatly among fish species: European catfish, Silurus glanis (–131‰); common carp, Cyprinus carpio (–141‰); rudd, Scardinius erythrophthalmus (–158‰); and roach, Rutilus rutilus (–163‰). The influence of fish size and trophic position affected the fish δD values. Possible mechanisms that drive δD variation among fish might be a metabolic effect and (or) the compounding effect of ambient water δD on exchangeable H at each trophic stage. Our findings showed that size and feeding habits are factors that should be controlled when tracing origins of fish or their dependence on nutrient inputs using δD measurements.

Causes of bimodal stable isotope signatures in the feathers of a molt-migrant songbird

Stable isotope ratios of hydrogen (δD) and carbon (δ13C) in feathers collected from Painted Buntings ( Passerina ciris (L., 1758)) breeding in the midwestern United States revealed a surprising degree of variation in δD, as well as a clear bimodal signal in δ13C in the innermost primary feather. Because this population does not molt on the breeding grounds, we reasoned that these observations could be due (i) to birds migrating to two (or possibly more) distinct molting areas or (ii) to differences in the timing of molt (as opposed to molt location) relative to arrival at the stopover site. To evaluate these hypotheses, we collected feathers at a molting location in northwestern Mexico, which revealed patterns similar to those from the birds in the US (favoring the second hypothesis above). We suspect that some birds arrive at stopover sites and begin molting before their body tissues equilibrate to the new isoscape so that the first feathers grown represent a blend of materials from the breeding and stopover locations. Other birds may delay molt after arriving at the molting site, allowing them to equilibrate with the local isoscape and produce feathers with isotope signatures of the molting location.

Perennial ponds are not an important source of water or dissolved organic matter to groundwaters with high arsenic concentrations in West Bengal, India

[1] Arsenic (As) concentrations and stable hydrogen (δ2H) and oxygen (δ18O) isotope ratios of surface and groundwaters from a representative site in West Bengal, India, are reported. Shallow groundwaters (≤35 m) from the study site have among the highest As concentrations measured in the entire Bengal Basin, reaching values in excess of 4600 μg kg−1. Stable isotope ratios of waters from constructed, perennial ponds indicate the ponds are chiefly recharged during the summer monsoon, and subsequently undergo extensive evaporation during the dry (winter) season. In contrast, groundwaters with high As concentrations plot along the local meteoric water line (LMWL) near where the annual, volume-weighted mean precipitation values for δ2H and δ18O would plot. The stable isotope data demonstrate that groundwaters are directly recharged by local precipitation without significant evaporation, and thus are not recharged by, nor mixed with, the pond waters. Furthermore, reactive transport modeling indicates that dissolved organic matter (DOM) derived from pond waters does not fuel microbial respiration and As mobilization at depth in the underlying aquifer because travel times for pond-derived DOM exceed groundwater ages by thousands of years. Instead, organic matter within the aquifer sediments must drive dissimilatory iron reduction and As release to groundwaters.

Stable hydrogen isotope ratios of n-alkanes in atmospheric aerosols from Okinawa, Japan

Molecular compositions of n-alkanes and their stable hydrogen isotope ratios (δD) were studied in atmospheric aerosols collected from Cape Hedo, Okinawa, Japan, to better understand the long-range atmospheric transport of organic aerosols from the Asian continent. The δD values of the C22– C33 n-alkanes range from –201 to –115‰, being similar to those of typical fossil fuels and contemporary higher plant leaf waxes in Far East Asia. A correlation between the δD values and the carbon preference index (CPI) suggests that these n-alkanes originated from fossil fuel combustion residues and/or terrestrial higher plant waxes. The concentrations of fossil fuel-derived n-alkanes increased from mid-November 2009 to February 2010, which is consistent with the enhanced emission of coalburning aerosols during the winter in China. δD values of the fossil fuel-derived n-alkanes (–174 ± 7‰) in the atmospheric aerosols from Okinawa are much lower (by up to 95‰) than those from Tokyo and Sapporo, Japan, suggesting that they are derived from multiple sources in East Asia and are delivered by complex transport processes.

How do Robins Erithacus rubecula resident in Iberia respond to seasonal flooding by conspecific migrants?

Capsule The majority of Robins in Iberia are sedentary and stay in their nesting areas despite the presumed increased competition that results from the seasonal flooding of the area by conspecific migrants. Aims To evaluate if Robins in Iberia are displaced from their nesting areas by the presence of large numbers of competitors originating from higher latitudes. Methods Data from constant effort ringing sites were used to estimate the proportion of Robins that are strictly sedentary and the seasonal variation in Robin numbers. Hydrogen stable isotope ratios (δ2H) in feathers, and sex ratios determined through molecular techniques, allowed an insight into the numerical importance of invading Robins from higher latitudes. Results Robins were more numerous outside the breeding season, with clear influxes in autumn. Around half of the locally nesting Robins were captured during winter, indicating they are truly sedentary. δ2H in feathers suggests that a wide mixture of Robins from all European latitudes were present in winter, and these data, together with sex ratios, suggest that there may be similar numbers of local and foreign individuals in winter at the main study site. Conclusion Despite the occupation of their range by migrants, local birds are largely sedentary.

ISOTOPES MARK THE SPOT

WHEN IRISH criminal investigators couldn’t identify a dismembered body, parts of which they found around a canal near Dublin in the spring of 2005, Wolfram Meier-Augenstein got a phone call. An analytical chemist at James Hutton Institute, in Dundee, Scotland, Meier-Augenstein has pioneered a way to help determine where unidentified victims like this one lived or traveled. To do so, he measures the stable isotope ratios of carbon, oxygen, hydrogen, nitrogen, and sulfur found in samples of the victim’s hair, teeth, nail, and bone. Checking these elements’ isotope ratios against databases that contain global isotope abundances can provide investigators with the victim’s probable trajectory during his or her last weeks, months, and years. In the case of the Dublin body, “the Irish investigators had several leads, but they were all equally probable,” Meier-Augenstein says. But his isotope data pointed to a likely home area for the victim. Following that lead, the police eventually identified the ...

Leaf wax n‐alkane δD values are determined early in the ontogeny of Populus trichocarpa leaves when grown under controlled environmental conditions

The stable hydrogen isotope ratios (δD) of leaf wax n-alkanes record valuable information on plant and ecosystem water relations. It remains, however, unknown if leaf wax n-alkane δD values record only environmental variation during the brief period of time of leaf growth or if leaf wax n-alkane δD values are affected by environmental variability throughout the entire lifespan of a leaf. To resolve these uncertainties, we irrigated Populus trichocarpa trees with a pulse of deuterium-enriched water and used compound-specific stable hydrogen isotope analyses to test if the applied tracer could be recovered from leaf wax n-alkanes of leaves that were at different stages of their development during the tracer application. Our experiment revealed that only leaf wax n-alkanes from leaves that had developed during the time of the tracer application were affected, while leaves that were already fully matured at the time of the tracer application were not. We conclude from our study that under controlled environmental conditions, leaf wax n-alkanes are synthesized only early in the ontogeny of a leaf. Our experiment has implications for the interpretation of leaf wax n-alkane δD values in an environmental context, as it suggests that these compounds record only a brief period of the environmental variability that a leaf experiences throughout its life.

Winter Habitat Influences the Number of Feather Mites of Two Species Living on European RobinsErithacus rubecula

Winter habitat influences the number of feather mites of two species living on European robins Erithacus rubecula.Plumicolous feather mites are a little-known but diverse and abundant group of symbionts of birds. The nature of the feather mite versus bird relationship is controversial, with reports ranging from suggestions of parasitism to evidence supporting commensalism or even mutualism. In addition, little is known as to why enormous inter-individual variation in mite loads is observed within bird species. In this study we show that migrant European robins Erithacus rubecula differ in their load of Proctophyllodes rubeculinus and Trouessartia c.f. rubecula by a factor of 2 to 3 depending on the winter habitat that they occupy. Such variation cannot be explained as being due to robins from different geographic origins wintering in different habitats, as wing shape and stable hydrogen isotope ratios (inferring breeding origin) in feathers of those robins did not explain variation in mite loads. Furthermore, there were no age or sex effects on the number of mites, but abundance increased as winter progressed. Robins wintering in the best putative habitat had higher mite numbers and the fact that there was no correlation between mite infestation levels and either muscle or fat scores indicates minimal costs to the host and hints at a commensal or mutualistic relationship. More research is needed to better understand the factors underlying differences between habitats. Meanwhile, habitat must be taken into consideration in future studies of the relationships between feather mites and birds.

Long-range atmospheric transport of terrestrial biomarkers by the Asian winter monsoon: Evidence from fresh snow from Sapporo, northern Japan

Molecular distributions of terrestrial biomarkers were investigated in fresh snow samples from Sapporo, northern Japan, to better understand the long-range atmospheric transport of terrestrial organic matter by the Asian winter monsoon. Stable carbon (δ13C) and hydrogen (δD) isotope ratios of C22–C28 n-alkanoic acids were also measured to decipher their source regions. The snow samples are found to contain higher plant-derived n-alkanes, n-alkanols and n-alkanoic acids as major components. Relative abundances of these three biomarker classes suggest that they are likely derived from higher plants in the Asian continent. The C27/C31 ratios of terrestrial n-alkanes in the snow samples range from 1.3 to 5.5, being similar to those of the plants growing in the latitudes >40°N of East Asia. The δ13C values of the n-alkanoic acids in the snow samples (−33.4 to −27.6‰) are similar to those of typical C3 gymnosperm from Sapporo (−34.9 to −29.3‰). However, the δD values of the n-alkanoic acids (−208 to −148‰) are found to be significantly depleted with deuterium (by ∼72‰) than those of plant leaves from Sapporo. Such depletion can be most likely interpreted by the long-range atmospheric transport of the n-alkanoic acids from vegetation in the latitudes further north of Sapporo because the δD values of terrestrial higher plants tend to decrease northward in East Asia reflecting the δD of precipitation. Together with the results of backward trajectory analyses, this study suggests that the terrestrial biomarkers in the Sapporo snow samples are likely transported from Siberia, Russian Far East and northeast China to northern Japan by the Asian winter monsoon.

Carbon and hydrogen isotope ratio characterization of methane dynamics for Fluxnet Peatland Ecosystems

Methane concentration [CH 4] and stable isotope ratio values (δ 13C) characterize methanogenic and methanotrophic processes within two contrasting peatland ecosystems of the Fluxnet Canada Research Network: (i) a western Canada peatland fen in northern Alberta (Fen) and (ii) an eastern Canada peatland bog in southeastern Ontario (Bog). We use carbon isotope ratio discrimination of produced methane (δ 13C CH4) from the precursor carbon compounds (δ 13C preC) to estimate the relative proportions of archaebacterial acetoclastic methanogenesis (AM) and hydrogenotrophic carbonate reduction methanogenesis (HM) in these terrestrial ecosystems. The [CH 4] and δ 13C CH4 signatures describe contrasts in the methanogenic and methanotrophic processes between the Fen and the Bog. The differences are substantiated by stable hydrogen isotope ratio (δD) separation between the dissolved δD CH4 and co-existing δD H2O. Methanogenesis at the Fen is dominated by AM, in contrast to the Bog, which is essentially HM. We suggest that this is potentially a result of differences in type/quality of organic substrates. The trajectory of 13C enrichment in δ 13C CH4 values with depth at the Bog reflects a closed system, substrate depletion effect. Our Rayleigh distillation model estimates 58–76% depletion in the source dissolved inorganic carbon (DIC).

Isotopic evidence for the moisture origin and composition of surface runoff in the headwaters of the Heihe River basin

We investigated the moisture origin and contribution of different water sources to surface runoff entering the headwaters of the Heihe River basin on the basis of NECP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) re-analysis data and variations in the stable hydrogen and oxygen isotope ratios (δ D and δ18O) of precipitation, spring, river, and melt water. The similar seasonality in precipitation δ18O at different sites reveals the same moisture origin for water entering the headwaters of the Heihe River basin. The similarity in the seasonality of δ18O and d-excess for precipitation at Yeniugou and Urumchi, which showed more positive δ18O and lower d-excess values in summer and more negative δ18O and higher d-excess values in winter, indicates a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter. Higher d-excess values throughout the year for Yeniugou suggest that in arid inland areas of northwestern China, water is intensively recycled. Temporal changes in δ18O, δD, and d-excess reveal distinct contributions of different bodies of water to surface runoff. For example, there were similar trends for δ D, δ18O, and d-excess of precipitation and river water from June to September, similar δ18O trends for river and spring water from December to February, and similar trends for precipitation and runoff volumes. However, there were significant differences in δ18O between melt water and river water in September. Our results show that the recharge of surface runoff by precipitation occurred mainly from June to mid-September, whereas the supply of surface runoff in winter was from base flow (as spring water), mostly with a lower runoff amount.

Water Origins over Central and Southern Japan during the Early Summer Rainy Season as Simulated with an Isotope Circulation Model

By applying the Japanese long-term Re-Analysis project (JRA-25) and the Japan Meteorological Agency Climate Data Assimilation System (JCDAS) data to a Rayleigh-type global one-layer isotope circulation model, we performed a long-term simulation and examined how water vapor is remotely transported to the vicinity of Japan from water source regions during the early summer rainy (Baiu) season. We validated the model outputs, comparing them with the stable hydrogen and oxygen isotope ratios (δD and δ18O) of precipitation observed at two in situ sites in southern and central Japan during the 2010 Baiu, and determined that the correlations between the simulation and observation are comparable to those in precipitation in Thailand from August to October when the Asian summer monsoon withdraws. The model results demonstrate that the Baiu is characterized by relatively low values of δD and that the δD values over central Japan are lower than those over southern Japan. When the Baiu commences, Indian Ocean water increases rapidly and then contributes substantially to the total precipitable water until the withdrawal of the Baiu, which is partially responsible for the low values of δD. Once the Baiu withdraws, alternatively, Pacific Ocean water occupies most of the total precipitable water. Another signature of its withdrawal is the decrease in land water of the Eurasian continent. It is also clear that the intrusion of the Indian Ocean water into central Japan remained until the end of August in the extremely cool summers of 1993 and 2003, which is interpreted as an extraordinary persistence of the Baiu period.

Application of compound specific stable carbon and hydrogen isotope ratios for paleoclimate study

Application of compound specific stable carbon and hydrogen isotope ratios for paleoclimate study