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The whitemouth croaker, Micropogonias furnieri, is a long-lived fish of high commercial importance in the western Atlantic Ocean. Here, we used stable isotope ratios of carbon, sulfur, and nitrogen and isotopic niche metrics (SIBER) to study feeding habits and track habitat use by whitemouth croakers in Guanabara Bay, an estuary in Rio de Janeiro state, Brazil. Our results highlighted size-related habitat segregation, with small juvenile fishes (60 cm) feeding mainly in Continental Shelf waters. Medium adult fishes (30-60 cm) appear to feed in multiple coastal and Continental Shelf habitats. Moreover, their feeding ecology showed strong temporal differences, linked with seasonal and, to a lesser extent, interannual variation in oceanographic features of the ecosystem in which they live. Overall, these differences in ecological features suggest that (1) adult and juvenile whitemouth croakers should be treated as different components of the food web and (2) the conservation of these habitats should be prioritized to better manage and sustain the coastal fisheries in Guanabara Bay. Le tambour raye, Micropogonias furnieri, est un poisson longevif de grande importance commerciale dans l'ocean Atlantique occidental. Nous avons utilise les rapports d'isotopes stables du carbone, du soufre et de l'azote et des parametres associes a la niche isotopique (SIBER) pour etudier les habitudes d'alimentation et suivre l'utilisation de l'habitat de tambours rayes dans la baie de Guanabara, un estuaire dans l'Etat de Rio de Janeiro (Bresil). Nos resultats font ressortir une segregation de l'habitat associee a la taille, les petits poissons juveniles (60 cm) s'alimentent principalement dans les eaux du plateau continental. Les poissons adultes de taille moyenne (30-60 cm) semblent s'alimenter dans divers habitats littoraux et du plateau continental. L'ecologie de leur alimentation montre en outre de fortes variations temporelles associees a des variations saisonnieres et, dans une moindre mesure, interannuelles de caracteristiques oceanographiques de l'ecosysteme dans lequel ils vivent. Dans l'ensemble, ces variations des caracteristiques ecologiques indiqueraient que (1) les tambours rayes adultes et juveniles devraient etre traites comme representant differentes composantes du reseau trophique et (2) la priorite devrait etre accordee a la conservation de ces habitats pour une meilleure gestion a long terme des peches cotieres dans la baie de Guanabara. [Traduit par la Redaction], Introduction The Sciaenidae, popularly known as croakers or drums due to the sound they produce using muscles associated with the swim bladder, are a widely distributed fish family throughout the [...]

Pinniped vibrissae provide information on changes in diet at seasonal and annual scales; however, species-specific growth patterns must first be determined in order to interpret these data. In this study, a simple linear model was used to estimate the growth rate of vibrissae from adult female California sea lions (Zalophus californianus) from San Esteban Island in the Gulf of California, Mexico. The δ15N and δ13C values do not display a marked oscillatory pattern that would permit direct determination of the time period contained in each vibrissa; thus, time (age) was calculated in two ways: 1) based on the correlation between the observed number of peaks (Fourier series) in the δ15N profile and the length of each vibrissa, and 2) through direct comparison with the observed number of peaks in the δ15N profile. Cross-correlation confirmed that the two peaks in the δ15N profile reflected the two peaks in the chlorophyll-a concentration recorded annually around the island. The mean growth rate obtained from the correlation was 0.08 ± 0.01 mm d-1, while that calculated based on the observed number of peaks was 0.10 ± 0.05 mm d-1. Both are consistent with the rates reported for adult females of other otariid species (0.07 to 0.11 mm d-1). Vibrissa growth rates vary by individual, age, sex, and species; moreover, small differences in the growth rate can result in significant differences over the time periods represented by the isotopic signal. Thus, it is important to assess this parameter on a species-by-species basis. [ABSTRACT FROM AUTHOR]

The characterisation of natural stream conditions is the first important step to analyse ecological quality of streams in the Euphrates basin. We found that the community indices correspond to very good ecological conditions in five natural streams of that region. The macroinvertebrates composition differed significantly between September and May. Number of taxa and Shannon index were significantly higher in autumn than in spring. FPOM and biofilm were the most relevant basal resources of benthic invertebrates. [ABSTRACT FROM AUTHOR]

Groundwater, which is renewable under current climatic conditions separately from other natural sources, in fact is a finite resource in terms of quality and fossil groundwater. Researchers have long emphasized the necessity of exploiting, operating, conserving and managing groundwater in an efficient and sustainable manner with an integrated water management approach. The management of groundwater needs reliable information about changes on groundwater quantity and quality. Environmental isotopes are the most important tools to provide this support. No matter which method we use to calculate the groundwater budget and flow equations, we need to determine boundary conditions or the physical boundaries of the domain. The Groundwater divide line or basin boundaries that separate the two adjacent basin recharge areas from each other must be drawn correctly to be successful in defining complex groundwater basin boundary conditions. Environmental isotope data, as well as other methods provide support for determining recharge areas of the aquifers, especially for karst aquifers, residence time and interconnections between aquifer systems. This study demonstrates the use of environmental isotope data to interpret and correct groundwater basin boundaries giving as an example the Yeniçıkrı basin within the main Sakarya basin. [ABSTRACT FROM AUTHOR]

This study examines the feasibility of tracing and quantifying the progress of different water sources along the water-effluent-SAT (Soil Aquifer Treatment) chain using 2H and 18O isotopes. The research was conducted at the Dan Region Reclamation Plant (Shafdan), which reclaims ~135 MCM/year of effluent for irrigation. Water samples representing different stages along the chain were taken in two surveys during 2010-2011 and 2014. δ18O and δ2H values were used for mixing ratios (MR) calculations, and compared with calculated MRs using chloride and carbamazepine concentrations. The results showed a relative enrichment of 18O and 2H in the Israeli water system compared to the regional groundwater, due to the addition of massive quantities of desalinated water. A linear correlation for δ2H vs. δ18O with a slope of 4.5 was found for the different freshwater sources and their mixing products, suggesting evaporation-mixing effects. MR values indicate on the spreading of new type of effluent originating from desalinated water in the aquifer. A dilution model explains the isotopic compositions in the water system and of the Shafdan effluents. Water isotopes have an advantage over other tracers, due to the ability to predict their ratio in the supply system and in the effluent, based on mass balance calculations and on knowledge of water supply volumes. [ABSTRACT FROM AUTHOR]

In this study, components of the food-web in Macao wetlands were quantified using stable isotope ratio techniques based on carbon and nitrogen values. The δC and δN values of particulate organic matter (δC and δN, respectively) ranged from −30.64 ± 1.0 to −28.1 ± 0.7 ‰, and from −1.11 ± 0.8 to 3.98 ± 0.7 ‰, respectively. The δC values of consumer species ranged from −33.94 to −16.92 ‰, showing a wide range from lower values in a freshwater lake and inner bay to higher values in a mangrove forest. The distinct dietary habits of consumer species and the location-specific food source composition were the main factors affecting the δC values. The consumer N-isotope enrichment values suggested that there were three trophic levels; primary, secondary, and tertiary. The primary consumer trophic level was represented by freshwater herbivorous gastropods, filter-feeding bivalves, and plankton-feeding fish, with a mean δN value of 5.052 ‰. The secondary consumer level included four deposit-feeding fish species distributed in Fai Chi Kei Bay and deposit-feeding gastropods in the Lotus Flower Bridge flat, with a mean δN value of 6.794 ‰. The tertiary consumers group consisted of four crab species, one shrimp species, and four fish species in the Lotus Flower Bridge Flat, with a mean δN value of 13.473 ‰. Their diet mainly comprised organic debris, bottom fauna, and rotten animal tissues. This study confirms the applicability of the isotopic approach in food web studies. [ABSTRACT FROM AUTHOR]

The aim of this study, known as the Stable Isotope Precipitation Sampling (SIPS) project, was to define a local meteoric water line (LMWL) for the island of Newfoundland using seasonal [...]

Stable heavy isotopes co-exist with their lighter counterparts in all elements commonly found in biology. These heavy isotopes represent a low natural abundance in isotopic composition but impose great retardation effects in chemical reactions because of kinetic isotopic effects (KIEs). Previous isotope analyses have recorded pervasive enrichment or depletion of heavy isotopes in various organisms, strongly supporting the capability of biological systems to distinguish different isotopes. This capability has recently been found to lead to general decline of heavy isotopes in metabolites during yeast aging. Conversely, supplementing heavy isotopes in growth medium promotes longevity. Whether this observation prevails in other organisms is not known, but it potentially bears promise in promoting human longevity. [ABSTRACT FROM AUTHOR]

Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometers (LAS) perform as well or better than IRMS. The new LAS technology has been combined with continuous flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system uncertainty and system mixing length into liquid and vapor components - useful measures for defining and improving the overall performance of the system. Critically, our methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. We also explain a method for introducing consecutive sections of isotopically distinct ice at the melt head to define the system-wide mixing length. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the WAIS Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ~ & 1 & m & × & 1.3 & cm² ice sticks to a temperature controlled melt head, where the ice is converted to a continuous liquid stream, and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the VSMOW-SLAP scale and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2 & mm. As an added check on our system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS-CFA systems, including optimizing liquid and vapor mixing lengths, determining melt rates for ice cores with different accumulation and thinning histories, and removing system-wide mixing effects that are convolved with the natural diffusional signal that results primarily from water molecule diffusion in the firn column. [ABSTRACT FROM AUTHOR]

The non-linear dynamics of stable carbon and hydrogen isotope signatures during methane oxidation by the methanotrophic bacteriaMethylosinus sporiumstrain 5 (NCIMB 11126) andMethylocaldum gracilestrain 14 L (NCIMB 11912) under copper-rich (8.9 µM Cu2+), copper-limited (0.3 µM Cu2+) or copper-regular (1.1 µM Cu2+) conditions has been described mathematically. The model was calibrated by experimental data of methane quantities and carbon and hydrogen isotope signatures of methane measured previously in laboratory microcosms reported by Feisthauer et al. [1]M. gracileinitially oxidizes methane by a particulate methane monooxygenase and assimilates formaldehyde via the ribulose monophosphate pathway, whereasM. sporiumexpresses a soluble methane monooxygenase under copper-limited conditions and uses the serine pathway for carbon assimilation. The model shows that during methane solubilization dominant carbon and hydrogen isotope fractionation occurs. An increase of biomass due to growth of methanotrophs causes an increase of particulate or soluble monooxygenase that, in turn, decreases soluble methane concentration intensifying methane solubilization. The specific maximum rate of methane oxidationυmwas proved to be equal to 4.0 and 1.3 mM mM−1h−1forM. sporiumunder copper-rich and copper-limited conditions, respectively, and 0.5 mM mM−1h−1forM. gracile. The model shows that methane oxidation cannot be described by traditional first-order kinetics. The kinetic isotope fractionation ceases when methane concentrations decrease close to the threshold value. Applicability of the non-linear model was confirmed by dynamics of carbon isotope signature for carbon dioxide that was depleted and later enriched in13C. Contrasting to the common Rayleigh linear graph, the dynamic curves allow identifying inappropriate isotope data due to inaccurate substrate concentration analyses. The non-linear model pretty adequately described experimental data presented in the two-dimensional plot of hydrogen versus carbon stable isotope signatures. [ABSTRACT FROM PUBLISHER]

Core sediments from five mangrove ecosystems along northern Kerala Coast were collected to evaluate the nature and sources of organic matter in these ecosystems. General sedimentary parameters (pH, Eh, grain size and total organic carbon) and biochemical constituents (carbohydrate, lipid and protein) were analysed. The protein-to-carbohydrate ratio and lipid-to-carbohydrate ratio were calculated to assess the quality of organic matter in core sediments. Higher concentrations of biochemical components were recorded in surface sediments, with a dominance of carbohydrates followed by lipids and proteins. Protein/carbohydrate ratio was found to be <1 in the entire study region indicating a large content of aged and/or non-living organic matter in mangrove sediments. This also confirms the involvement of heterotrophic microorganisms in the organic carbon dynamics of the study area. The bulk elemental ratio (total organic carbon/total nitrogen) varied between 11.39 and 24.14 in the study region, recording minimum value at Kunjimangalam and maximum at Pappinissery. Samples from Kadalundi recorded low total organic carbon/total nitrogen ratio throughout the core, indicated a marine signature. Stable carbon isotopic ratio (−29.19 to −23.87 ‰) in the sediments suggested the dominance of terrestrially derived organic matter. Principal component analysis revealed that mangrove litter addition, diagenesis and accumulation of organic matter on fine grained sediments are the major processes controlling the distribution of the parameters in the study area. [ABSTRACT FROM AUTHOR]

In this article we present geochemical and isotope characteristics of rocks of the Unerikan, Selitkan and Aezop-Yamalin volcano-plutonic zones of the eastern termination of the Mongol-Okhotsk Orogenic Belt. The obtained data demonstrate that the Mesozoic igneous rocks of the Mongol-Okhotsk sector of the Pacific Folded Belt were formed due to the melting of the continental crust in a tectonic setting corresponding to a suprasubduction one. [ABSTRACT FROM AUTHOR]

Reconstructions of Quaternary climate are often based on the isotopic content of paleo-precipitation preserved in proxy records. While many paleo-precipitation isotope records are available, few studies have synthesized these dispersed records to explore spatial patterns of late-glacial precipitation δ18O. Here we present a synthesis of 86 globally distributed groundwater (n = 59), cave calcite (n = 15) and ice core (n = 12) isotope records spanning the late-glacial (defined as ~50 000 to ~20 000 years ago) to the late-Holocene (within the past ~5000 years). We show that precipitation δ18O changes from the late-glacial to the late-Holocene range from -7.1‰ (δ18Olate-Holocene > δ18Olate-glacial) to C1.7‰ (δ18Olate-glacial > δ18Olate-Holocene), with the majority (77 %) of records having lower late-glacial δ18O than late-Holocene δ18O values. High-magnitude, negative precipitation δ18O shifts are common at high latitudes, high altitudes and continental interiors (δ18Olate-Holocene > δ18Olate-glacial by more than 3 ‰). Conversely, low-magnitude, positive precipitation δ18O shifts are concentrated along tropical and subtropical coasts (δ18Olate-glacial > δ18Olate-Holocene by less than 2 ‰). Broad, global patterns of late-glacial to late-Holocene precipitation δ18O shifts suggest that stronger-than-modern isotopic distillation of air masses prevailed during the late-glacial, likely impacted by larger global temperature differences between the tropics and the poles. Further, to test how well general circulation models reproduce global precipitation δ18O shifts, we compiled simulated precipitation δ18O shifts from five isotope-enabled general circulation models simulated under recent and last glacial maximum climate states. Climate simulations generally show better inter-model and model-measurement agreement in temperate regions than in the tropics, highlighting a need for further research to better understand how inter-model spread in convective rainout, seawater δ18O and glacial topography parameterizations impact simulated precipitation δ18O. Future research on paleo-precipitation δ18O records can use the global maps of measured and simulated late-glacial precipitation isotope compositions to target and prioritize field sites. [ABSTRACT FROM AUTHOR]

Over the last two decades, many quantitative paleoaltimetry reconstructions of the Tibetan Plateau have been published, but they are still preliminary and controversial, although several approaches have been combined paleontology and geochemistry, including vertebrate, plant, and pollen fossils as well as oxygen, carbon, and hydrogen isotopes. The Tibetan Plateau is the youngest and highest plateau on Earth, and its paleoaltimetry reconstructions are crucial to interpret its geodynamic evolution and to understand the climatic changes in Asia. Uplift histories of the Tibetan Plateau based on different proxies differ considerably, and two viewpoints are pointedly opposing on the paleoaltimetry estimations of the Tibetan Plateau. One viewpoint is that the Tibetan Plateau did not strongly uplift to reach its modern elevation until the Late Miocene, but another one, mainly based on stable isotopes, argues that the Tibetan Plateau formed early during the Indo-Asian collision and reached its modern elevation in the Paleogene or by the Middle Miocene. With either a geochemical or paleontological approach, the present is used as the key to the past. However, there are great difficulties because modern processes of isotopic fractionation and species for creature distribution are not easily precisely determined. In addition, the climatic and environmental backgrounds of past geological times have massive differences from the present, and associated adjustments are influenced by many human factors. In the future work, the applications of multidisciplinary comprehensive methods and cross-checks of their results will be productive, and we look forward to achieving more reliable estimates for paleoelevations of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Carbon dioxide capture and sequestration (CCS) in deep geological formations has recently emerged as an important option for reducing greenhouse gas (GHG) emissions, and due to the complexity of the issue, CCS has turned into a multiple-discipline research area. Environmental isotopes have been used in various CCS projects worldwide for evaluating trapping mechanisms, selecting storage sites, and monitoring for storage safety. Environmental isotopes are found useful in the investigation of many CCS issues and are particularly effective in identifying phase states (free, dissolved, and mineral state), and in quantifying structural, solubility, and mineral trapping forms of CO2. We used published laboratory results to successfully verify different methods for quantifying structural trapping mechanisms. Our results show that, in short time scales, saturation of the formation with free CO2-phase can be obtained from oxygen isotope measurements on CO2 and/or reservoir brine, and carbon isotope of dissolved inorganic carbon can be used to trace dissolution in brine. Carbon isotopes and other parameters, such as CO2/3He ratio, can also be used to confirm the mineral trapping mechanism in natural gas fields. Environmental isotopes can also be used to distinguish mineralogical composition of formations, and to identify hydrodynamic conditions for site selection in addition to monitor potential CO2 leakage. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Oceanography is the property of Instituto Oceanografico da Universidade de Sao Paulo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To elucidate the mechanism for how the East Asian Monsoon (EAM) variability have influenced the isotope proxy records in Japan, we explore the primary driver of variations of precipitation isotopes at multiple temporal scales (event, seasonal and inter-annual scales). Using a new 1-year record of the isotopic composition of event-based precipitation and continuous near-surface water vapor at Nagoya in central Japan, we identify the key atmospheric processes controlling the storm-to-storm isotopic variations through an analysis of air mass sources and rainout history during the transport of moisture to the site, and then apply the identified processes to explain the inter-annual isotopic variability related to the EAM variability in the historical 17-year long Tokyo station record in the Global Network of Isotopes in Precipitation (GNIP). In the summer, southerly flows transport moisture with higher isotopic values from subtropical marine regions and bring warm rainfall enriched with heavy isotopes. The weak monsoon summer corresponds to enriched isotopic values in precipitation, reflecting higher contribution of warm rainfall to the total summer precipitation. In the strong monsoon summer, the sustaining Baiu rainband along the southern coast of Japan prevents moisture transport across Japan, so that the contribution of warm rainfall is reduced. In the winter, storm tracks are the dominant driver of storm-to-storm isotopic variation and relatively low isotopic values occur when a cold frontal rainband associated with extratropical cyclones passes off to the south of the Japan coast. The weak monsoon winter is characterized by lower isotopes in precipitation, due to the distribution of the cyclone tracks away from the southern coast of Japan. In contrast, the northward shift of the cyclone tracks and stronger development of cyclones during the strong monsoon winters decrease the contribution of cold frontal precipitation, resulting in higher isotopic values in winter precipitation. Therefore, year-to-year isotopic variability in summer and winter Japanese precipitation correlates significantly with changes in the East Asian summer and winter monsoon intensity (R = -0:47 for summer, R = 0:42 for winter), and thus we conclude that the isotope proxy records in Japan should reflect past changes in the East Asian Monsoon. Since our study identifies the climate drivers controlling isotopic variations in summer and winter precipitation, we highlight the retrieval of a record with seasonal resolution from paleoarchives as an important priority. [ABSTRACT FROM AUTHOR]

Isotopically light sulphur in sedimentary pyrite was generally predominant during the Cretaceous as a consequence of volcanic and hydrothermal activity and bacterial sulphate reduction (BSR). However, we report super-high sulphur isotopic compositions of sedimentary pyrite ([delta][sup.34]S +89.3%) from late mid-Cretaceous sediments from the Central Apennines, Italy. These exceptionally high [delta][sup.34]S values are not consistent with current models for interpreting the geological record for sulphur isotopes because these cannot explain the extreme isotopic fractionation observed in our study. Precise details of the mechanism for producing pyrite so highly enriched in 34S remain elusive, but the large variation in [delta][sup.34]S values (>70 [per thousand]) within the analysed samples and the considerable micro-scale variations in [sup.34]S (up to 50[per thousand] even within a single nodule) indicate a complex mechanism of sulphate reduction and pyrite precipitation. This includes early removal of isotopically light [H.sub.2]S by pyrite precipitation in the water column, diffusion and advection of [H.sub.2]S and S[O.sub.4.sup.2-], and finally BSR. Similar but less severe conditions occur in the Black Sea and in deep ocean sediments. These new findings provide new insights for the interpretation of the palaeoceanographic conditions that prevailed during the Mesozoic. doi: 10.1144/0016-76492009-161.

Spatial or temporal isotopic variation, or both, in primary producers must be controlled for when investigating the foraging and trophic ecology of top consumers using isotopic data. Populations of the sister species Zalophus californianus and Z. wollebaeki are separated by approximately 3,350 km in the eastern tropical Pacific Ocean, which prevents contact and mixing between the 2 populations. To explore differences in trophic ecology between these species, as well as the impact of differences in baseline food-web isotope values between the 2 regions, we compared conventional dietary data derived from analyses of scat contents to isotopic values of hair collected from pups at 13 rookeries in the Gulf of California (Z. californianus) and 11 rookeries on the Galapagos Islands (Z. wollebaeki). Mean [+ or -] 1 SD [[delta].sup.13]C and [[delta].sup.15]N values were -15.9[per thousand] [+ or -] 0.5[per thousand] and 21.8 [+ or -] 0.7[per thousand] in the Gulf of California, whereas for the Galapagos they were -14.5[per thousand] [+ or -] 0.5[per thousand] and 13.1[per thousand] [+ or -] 0.5[per thousand]. Examination of scat data suggested overlap in 6 of the 10 most common prey consumed by sea lions. Trophic level (TL) derived from scat analysis was positively related with 615N values for the Gulf of California rookeries, but estimates of TL for each region were similar (4.4 for Galapagos and 4.1 for Gulf of California), suggesting that foraging behavior makes a limited contribution to the large difference in [[delta].sup.15]N value between the 2 populations. Particulate organic matter [[delta].sup.15]N values near the Galapagos Islands are -5.3[per thousand] lower than values in the Gulf of California, suggesting that the baseline food-web values account for approximately two-thirds of the observed difference in pup hair [[delta].sup.15]N values. This study may provide clues to better understand isotopic values of marine top predators migrating across the eastern Pacific Ocean. Key words: carbon, feeding habits, nitrogen, sea lions, stable isotopes, trophic level

A new secondary isotopic reference material has been prepared from Puerto Rico precipitation, which was filtered, homogenised, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material, designated as USGS48, is intended to be one of two isotopic reference waters for daily normalisation of stable hydrogen (δ2H) and stable oxygen (δ18O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The δ2H and δ18O values of this reference water are−2.0±0.4 and−2.224±0.012 ‰, respectively, relative to Vienna Standard Mean Ocean Water on scales normalised such that the δ2H and δ18O values of Standard Light Antarctic Precipitation reference water are−428 and−55.5 ‰, respectively. Each uncertainty is an estimated expanded uncertainty (U=2uc) about the reference value that provides an interval that has about a 95 % probability of encompassing the true value. This isotopic reference water is available by the case of 144 glass ampoules containing 5 mL of water in each ampoule. [ABSTRACT FROM PUBLISHER]

Hydrogeochemistry and environmental isotope data were utilized to understand origins and characteristics of the thermal springs in southern Gaoligong Mountains, China. The groundwater at the thermal springs has low values of total dissolved solids, and its main water types are Na-HCO. The thermal springs are mainly recharged from meteoric precipitations. The recharge areas are located near the springs at an approximate elevation of 1,800 m. The groundwater of the thermal springs is immature and partially equilibrated with a strong mixture of the shallow cold waters during the flow process. The shallow cold water accounts for more than 90 %. The temperatures of thermal reservoir that feed the springs are between 146 and 260 °C, and the calculated groundwater circulation depths range from 2,000 to 5,700 m below ground surface. [ABSTRACT FROM AUTHOR]

Hillslopes are the dominant landscape components where incoming precipitation becomes groundwater, stream-flow or atmospheric water vapor. However, directly observing flux partitioning in the soil is almost impossible. Hydrological hillslope models are therefore being used to investigate the processes involved. Here we report on a modeling experiment using the Catchment Modeling Framework (CMF) where measured stable water isotopes in vertical soil profiles along a tropical mountainous grassland hillslope transect are traced through the model to resolve potential mixing processes. CMF simulates advective transport of stable water isotopes 18O and ²H based on the Richards equation within a fully distributed 2-D representation of the hillslope. The model successfully replicates the observed temporal pattern of soil water isotope profiles (R² 0.84 and Nash--Sutcliffe efficiency (NSE) 0.42). Predicted flows are in good agreement with previous studies. We highlight the importance of groundwater recharge and shallow lateral subsurface flow, accounting for 50 and 16% of the total flow leaving the system, respectively. Surface runoff is negligible despite the steep slopes in the Ecuadorian study region. [ABSTRACT FROM AUTHOR]

For the past 10 y Health Canada has operated a Fixed Point Surveillance Network of NaI(Tl) detectors across Canada. Deployed for both emergency response and daily monitoring of airborne radiation in the environment, a spectral stripping method allowed measurement of certain isotopes well below the ambient dose rate. These include 133Xe, 135Xe and 41Ar, typical of emissions from operating nuclear reactors. In an effort to increase the number of isotopes measured at these low levels a new technique of spectral fitting using spectral templates is being implemented. However, this requires very accurate spectral templates that can be difficult or impossible to obtain empirically for environmental measurements of airborne radio-isotopes. Therefore, a method of efficiently using Monte Carlo techniques to create these templates was developed. [ABSTRACT FROM AUTHOR]

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Direct fossil evidence for early microbial life on Earth is rare. Microbiological data indicate that sulfate and iron reduction are both among the earliest forms of microbial respiration, and direct evidence for the early origin of sulfate reduction comes from sulfur isotopic anomalies in ancient sediments. Fe isotope geochemistry potentially provides a new way of identifying microbial iron reduction early in Earth's history. We present Fe isotopic data for sedimentary pyrite from the 2.7 Ga Belingwe sedimentary basin in Zimbabwe. Isotopically light Fe and a remarkable covariation between Fe and S isotopes provide strong evidence for coexisting Fe and S reduction. Our results are consistent with an early origin for sulfate reduction and provide direct geochemical evidence for the antiquity of bacterial Fe reduction. The covariation of Fe and S isotopes may provide a useful new tracer of microbial evolution early in Earth history. Keywords: Fe isotopes, microbial Fe reduction, early life, iron, Belingwe.

The application of stable isotopes in speleothem records requires an understanding of the extent to which speleothem calcite isotopic compositions reflect the compositions of the cave waters from which they precipitate. To test for equilibrium precipitation, modern speleothem calcite was grown on glass plates, so that the carbon and oxygen isotope composition of the calcite and the water from which it precipitated could be directly compared. The plates were placed on the tops of three actively growing stalagmites that occupy a 1 [m.sup.2] area in Harrison's Cave, Barbados, West Indies. Only some of the plate [delta][sup.13]C values and none of the plate [delta][sup.18]O values correspond to equilibrium values, indicating significant kinetic isotope effects during speleothem calcite growth. We investigate herein mechanisms that may account for the kinetic isotope effects. On each plate, speleothem calcite was deposited with distinct [delta][sup.18]O and [delta][sup.13]C compositions that increase progressively away from the growth axis, with up to 6.6 [per thousand] [sup.13]C and 1.7 [per thousand] [sup.18]O enrichments. The positive [delta][sup.13]C versus [delta][sup.18]O trends are likely a result of [sup.18]O and [sup.13]C Rayleigh-distillation enrichment in the HC[O.sup.-.sub.3] reservoir owing to progressive C[O.sub.2] degassing and CaC[O.sub.3] precipitation. The magnitude of the [delta][sup.13]C versus [delta][sup.18]O slope is likely controlled by the extent to which C[O.sub.2] hydration-hydroxylation reactions buffer the oxygen isotope composition of the HC[O.sup.-.sub.3] reservoir during calcite precipitation. Complete oxygen isotopic buffering of the HC[O.sup.-.sub.3] reservoir by C[O.sub.2] hydration-hydroxylation reactions will produce a vertical [delta][sup.13]C versus [delta][sup.18]O slope in calcite sampled along a growth layer. As oxygen isotope buffering of the HC[O.sup.-.sub.3] reservoir decreases to no buffering, the [delta][sup.13]C versus [delta][sup.18]O slope in calcite sampled along a growth layer will decrease from vertical to 0.52 at the cave temperature. In this study, modern speleothem calcite sampled along the growth layer produced a [delta][sup.13]C versus [delta][sup.18]O slope of 3.9, indicating incomplete oxygen isotope buffering of the HC[O.sup.-.sub.3] reservoir during calcite precipitation. Both modern and Holocene speleothem calcite from Barbados, sampled temporally along the growth axis, shows similar positive [delta][sup.13]C versus [delta][sup.18]O slopes. These results, along with the spatial variations in glass plate calcite carbon and oxygen isotope compositions, suggest that the isotopic composition of the Holocene speleothems is in part controlled by non-equilibrium isotope effects. In addition, there is a correlation between stalactite length and oxygen and carbon isotope ratios of calcite precipitated on the corresponding stalagmite and glass plate, which may be due to [sup.13]C and [sup.18]O enrichment of the HC[O.sup.-.sub.3] reservoir during C[O.sub.2] degassing--calcite precipitation along the overhanging stalactite. We compiled 165 published speleothem stable isotope records with a global distribution and found that most of these records show a positive covariation between [delta][sup.13]C and [delta][sup.18]O values. Speleothem stable isotope records may be influenced by kinetic isotope effects such that temperature-controlled equilibrium fractionation models alone cannot directly explain the significance of the variations in these records. Advancing the interpretation of these records requires the calibration of cave environmental conditions with the non-equilibrium isotope effects that cause [delta][sup.13]C and [delta][sup.18]O covariations in speleothems. Keywords: kinetic isotope effects, speleothems, oxygen isotopes, carbon isotopes, non-equilibrium, Barbados.

The Palaeogene Slieve Gullion Igneous Centre in southern Armagh, Northern Ireland, consists of a layered central intrusive complex surrounded by a prominent and slightly older ring-dyke that intrudes both Lower Palaeozoic sedimentary rocks and the Caledonian Newry Granodiorite pluton (452 Ma). The ring-dyke comprises two major rock types: porphyritic felsite and porphyritic granophyre. We analysed both ring-dyke lithologies, both types of country rock, and a local Palaeogene basalt dyke sample for Sr and Nd isotopes. Trace element and whole rock data for this suite suggest that there are two distinct groups of both felsite and granophyre: one Si-rich and one Si-poor, most likely representing two magmas from a zoned chamber and their mushy chamber wall equivalents (McDonnell et al. 2004). Isotope data show the low-Si rocks to be higher in radiogenic Sr than the high-Si rocks, which is inconsistent with a simple AFC-scenario of increasing sediment assimilation with higher degrees of differentiation. However, using MORB-type basalt as a starting composition, the low-Si ring-dyke rocks can be modelled through AFC with Lower Palaeozoic sedimentary rock as the contaminant. The decreasing 87Sr/86Sr trend from low-Si to high-Si dyke rocks, in turn, represents a second stage of contamination. Selective assimilation of the most fusible portions ofNewry Granodiorite, which is lower in radiogenic Sr than the local sedimentary rocks, appears to be the most plausible solution. The Sr and Nd data are consistent with (a) at least a two-stage contamination history during upper crustal residence and storage, whereby fractionating magmas of basaltic and intermediate composition are contaminated by local sedimentary rocks, giving rise to rhyolite magmas that experience additional shallow contamination by Newry Granodiorite, and (b) a zoned rhyolite magma chamber where high-Si magma is stored in the upper part of the chamber where crystallization and crustal contamination are most extensive. Keywords: ring-dyke, Northern Ireland, crustal contamination, isotopes.

Cosmogenic [sup.26]Al and [sup.10]Be in alluvial gravel on a strath 150 m above the San Juan River, Utah, reveal a depositional age of 1.36 +0.20/-0.15 Ma. This gravel is correlative with a series of terraces that grade to Glen Canyon on the Colorado River, indicating a similar age for incision there. The calculated incision rate, 110 [+ or -] 14 m/m.y., is somewhat slower than that of the Colorado River in the eastern Grand Canyon and suggests active steepening of the Colorado River. The cosmogenic nuclides also indicate rapid erosion in the sediment source area and are consistent with alluviation due to enhanced Pleistocene erosion in the San Juan Mountains. Keywords: cosmogenic, burial age, San Juan River, Colorado Rivel, terrace deposits.

In recent years, two end-member models for the formation of supercontinents have emerged. In the classical Wilson cycle, oceanic crust generated during supercontinent breakup (the interior ocean) is consumed during subsequent amalgamation so that the supercontinent turns 'inside in' (introversion). Alternatively, following supercontinent breakup, the exterior margins of the dispersing continental fragments collide during reassembly so that the supercontinent turns 'outside in' (extroversion). These end-member models can be distinguished by comparing the Sm-Nd crust-formation ages of accreted mafic complexes (e.g., ophiolites) in the collisional orogens formed during supercontinent assembly with the breakup age of the previous supercontinent. For supercontinents generated by introversion, these crust-formation ages postdate rifting of the previous supercontinent. For supercontinents generated by extroversion, the oceanic lithosphere consumed during reassembly predates breakup of the previous supercontinent, so that crust-formation ages of accreted mafic complexes are older than the age of rifting. In the Paleozoic Appalachian-Caledonide-Variscan orogen, a key collisional orogen in the assembly of Pangea, crust-formation ages of accretionary mafic complexes postdate the formation of the Iapetus Ocean (i.e., are younger than ca. 0.6 Ga), suggesting supercontinent reassembly by introversion. By contrast, the Neoproterozoic East African and Brasiliano orogens, which formed during the amalgamation of Gondwana, are characterized by mafic complexes with crust-formation ages (ca. 0.75-1.2 Ga) that predate the ca. 750 Ma breakup of Rodinia. Hence, these complexes must have formed from lithosphere in the exterior ocean that surrounded Rodinia, implying that this ocean was consumed during the amalgamation of Gondwana. These data indicate that Pangea and Gondwana were formed by introversion and extroversion, respectively, implying that supercontinents can be assembled by fundamentally distinct geodynamic processes. Keywords: supercontinent, introversion, extroversion, Sm-Nd isotopes.

The low Re abundance in arc-type volcanic rocks characterized by high [sup.187]Os/[sup.188]Os ratios is an unsolved puzzle of the [sup.187]Re[sup.187]Os isotope system, leaving a significant gap in our understanding of the evolution of the upper mantle-continental crust system. Here we report new observations of high Re concentrations in fresh, submarine-erupted--i.e., relatively undegassed--island arc-like volcanic glasses dredged from the eastern Manus Basin, offshore Papua New Guinea. These observations, together with previously published reports of high Re concentrations in arc-type melt inclusions, indicate that undegassed arc-type volcanic rocks and the mantle wedge are enriched in Re. Consequently, the Re concentration in the continental crust is likely to be as high as ~2 ppb, much higher than previously estimated. The low Re concentrations in subaerial arc-type volcanic rocks are probably due to Re loss during magma degassing. Keywords: rhenium enrichment, Yb/Re, Cu/Re, submarine arc-type volcanic glasses, Manus Basin, continental-crust composition.

Strontium isotopes are a unique tool to study soil-erosion dynamics. Changes in Sr isotope ratios ([87.sup]Sr/[.sup.86]Sr) provide a record of late Quaternary landscape denudation of the Edwards Plateau of central Texas, United States. The use of Sr isotopes as a tracer for soil erosion is based on the observation that, in central Texas, the [sup.87]Sr/[sup.86]Sr ratio of soil correlates with soil thickness. Plants and animals express the [sup.87]Sr/[sup.86]Sr ratio of exchangeable Sr in the soil. Therefore, we use changes in Sr isotope ratios through a well-dated stratigraphic sequence of fossil plants and animals in Hall's Cave, Kerr County, Texas, as a proxy for temporal changes in soil thickness. By using this record we are able to characterize late Quaternary climate-driven soil-erosion dynamics on the Edwards Plateau. We find that continuous erosion removed at least 180 cm of soil at a constant minimum rate of 11 cm/k.y.; this continuous phase of erosion ended ca. 5 ka. The Sr isotope record of soil erosion is consistent with late Quaternary environmental change in central Texas that has been independently modeled by using local and regional climate records. However, the rate of this climate-driven soil-erosion event was an order of magnitude slower than recent soil erosion caused by human land use. These results link erosion to century- to millennial-scale climate change and are cautionary evidence that even greater landscape degradation may result from coincident climatic variability and anthropogenic influences. Keywords: soil erosion, strontium, isotopes, Edwards Plateau, Quaternary.

Zooplankton are commonly used to establish a baseline isotopic signature for pelagic production in lakes. Our objective was to evaluate this approach by quantifying among-lake and within-lake variability of [[delta].sup.13]C and [[delta].sup.15]N for different taxa of pelagic zooplankton. We measured the [[delta].sup.13]C and [[delta].sup.15]N of Daphnia, Holopedium, and calanoid copepods from four lakes sampled from June to November 2001 and from eight additional lakes sampled once in midsummer. In the four lakes with temporal sampling, within-lake differences due to taxonomic grouping accounted for 36.7% of the variance in [[delta].sup.15]N and 41.7% of the variance in [[delta].sup.13]C. Among all lakes, the [[delta].sup.15]N of calanoid copepods was on average 2.55[per thousand] and 2.44[per thousand] higher than Daphnia or Holopediurn, respectively, whereas the [[delta].sup.13]C of calanoid copepods was 2.19[per thousand] and 2.23[per thousand] lower than Daphnia or Holopedium, respectively. If [sup.15]N fractionation is similar among species, the differences in [[delta].sup.15]N suggest that calanoid copepods either feed at a higher trophic position in the food web or they have a consistently higher baseline [[delta].sup.15]N signature than Daphnia or Holopedium among lakes. Differences in [[delta].sup.13]C suggest that zooplankton taxa in the pelagia of lakes have different food sources. We conclude that species composition and feeding behaviors of the zooplankton community should be considered before making among-lake comparisons of food web structure. We show that Daphnia is a useful isotopic baseline for organisms that rely on primary production in lakes.

We compared stable-isotope ([delta][sup.13]C and [delta][sup.15]N) and gut-content analyses of macroinvertebrate foodwebs in saline wetlands of the Laramie Basin, Wyoming, USA. Standard assumptions of stable-isotope fractionation between trophic levels (

Paul J. Hearty (2) Abstract: Marine isotope stage (MIS) 11 may well represent one of the most significant interglacial highstand events of the past million years. Ocean volume changes charted [...]

The Jiapigou gold belt (>150 t Au), one of the most important gold-producing districts in China, is located at the northeastern margin of the North China Craton. It is composed of 17 gold deposits with an average grade around 10 g/t Au. The deposits are hosted in Archean gneiss and TTG rocks, and are all in shear zones or fractures of varying orientations and magnitudes. The δS values of sulfide from ores are mainly between 2.7 ‰ and 10 ‰. The Pb isotope characteristics of ore sulfides are different from those of the Archean metamorphic rocks and Mesozoic granites and dikes, and indicate that they have different lead sources. The sulfur and lead isotope compositions imply that the ore-forming materials might originate from multiple, mainly deep sources. Fluid inclusions in pyrite have He/He ratios of 0.6 to 2.5 Ra, whereas their Ar/Ar ratios range from 1,444 to 9,805, indicating a dominantly mantle fluid with a negligible crustal component. δO values calculated from hydrothermal quartz are between −0.2 ‰ and +5.9 ‰, and δD values of the fluids in the fluid inclusions in quartz are from −70 ‰ to −96 ‰. These ranges suggest dominantly magmatic water with a minor meteoric component. The noble gas isotopic data, along with the stable isotopic data, suggest that the ore-forming fluids have a dominantly mantle source with minor crustal addition. [ABSTRACT FROM AUTHOR]

We established a multi-proxy time series comprising analyses of major elements in bulk sediments, Sr and Nd isotopes, grain size of terrigenous fraction, and d18O and d13C in tests of Neogloboquadrina pachyderma (sinistral) from a marine sediment sequence recovered off the Orange River. The records reveal coherent patterns of variability that reflect changes in wind strength, precipitation over the river catchments, and upwelling of cold and nutrient-rich coastal waters off western South Africa. The wettest episode of the Holocene in the winter rainfall zone (WRZ) of South Africa occurred during the "Little Ice Age" (700-100 cal years BP) most likely in response to a northward shift of the austral westerlies. Wet phases and strengthened coastal water upwellings are companied by a decrease of Agulhas water leakage into the South Atlantic and a reduced dust incursion over Antarctica, as indicated in previous studies. A continuous aridification trend in the WRZ and a weakening of the southern Benguela Upwelling System (BUS) between 9000 and 5500 cal years BP parallel with increase of dust deposition over Antarctica and an enhanced leakage of warm Agulhas water into the eastern South Atlantic. The temporal relationship between precipitation changes in the WRZ, the thermal state of the coastal surface water, and leakage of warm water in the South Atlantic, and variation of dust incursion over Antarctica suggests a causal link that most likely was related to latitudinal shifts of the Southern Hemisphere westerlies. Our results of the mid-Holocene time interval may serve as an analogue to a possible long-term consequence of the current and future southward shift of the westerlies. Furthermore, warming of the coastal surface water as a result of warm Agulhas water incursion into the southern BUS may affect coastal fog formation. [ABSTRACT FROM AUTHOR]

Chemical and isotopic data in atmospheric precipitation, surface water, and groundwater in arid Rasafeh area, northeast Syria, are used to clarify the status of groundwater quality, the interaction of water components, groundwater dating, and vulnerability to anthropogenic contamination. Interpretation of chemical data with thermodynamic calculation reveals that the dissolution of evaporate mineral is the main factor of high salinity. The δO and δH relationships indicate that the groundwater is fed by mixing water from Euphrates River and precipitation and the isotope balance equation were used to estimate the contribution of the Euphrates River to the aquifers recharge. High tritium content, together with high C activity in the majority of groundwater samples, indicate shorter residence times and consequently potentially greater recharge. The presence of high nitrate concentration associated with high tritium concentration in both shallow and deep aquifer units indicates the presence of high permeability, so that groundwater is highly susceptible to anthropogenic contamination. Nitrate seems to derive exclusively from the application of N fertilizers. The high nitrate values are characteristic of the areas with intensive agricultural activity, indicating the importance of irrigated return flow on the groundwater. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sewage inputs are routinely mapped with stable isotopes (15N) in organisms. [•] We tested whether choice of species influences spatial 15N distributions. [•] Spatial gradients were consistent between algae, seagrasses, crabs, and fish. [•] A match of sewage-N signals in multiple marine taxa has not been reported before. [•] Spatially-coupled transfers in the food web produce the congruence of N imprints. [Copyright &y& Elsevier]

Compared with physico-chemical deposition measurement methods, lichens are able to identify the long-term overall effects of high N pollution concentrations in the air. In addition, the natural abundances of the stable isotope of N,15N, are being widely used in research on N cycling in ecosystems. They can also be used as instruments for source attribution. In this study, epiphytic lichens were tested to determine whether their respective N content and δ15N ratios can be used to estimate N deposition rates and to locate various sources of N compounds. Epiphytic lichen and bark samples were collected from around various deposition measurement field stations at different sites in the western part of Germany. The N content of epiphytic lichens reflects the species-specific, agriculture-related circumstances of N deposition at various sites in Germany. At the same time, δ15N signatures of the different investigated epiphytic lichen species and bark samples are highly depleted in15N under high ammonium deposition. The different surface types of lichens and barks exhibit different concentrations of N and δ15N ratios, despite being exposed to similar N deposition rates. The verification of highly negative δ15N ratios at sites with local and regional emitters shows that source attribution is possible by comparing different δ15N signatures in areas with a wide range of different N deposition types and the corresponding differences in δ15N among various source N pools. Especially nitrophytic lichens can support the on-site instrumentation measuring N deposition by qualification and quantification. [ABSTRACT FROM PUBLISHER]

Two Nd and Pb isotope time series of hydrogenous ferromanganese crusts, one from the Tehuantepec Ridge in the deep eastern equatorial Pacific and the other from Blake Plateau in the shallow northwestern Atlantic, which cover the past 7-8 m.y., show no variations coincident with the final closure of the Panama gateway, estimated as ca. 3.5 Ma. The record of the Atlantic crust located in the present-day Gulf Stream shows a shift in isotope composition from ca. 8 to 5 Ma that is explained by a diminishing supply of Pacific water. It is argued that the major restriction of water-mass exchange through the Panama gateway occurred before 5 Ma and thus cannot serve as a direct cause of the onset of Northern Hemisphere glaciation. The absence of a significant signature in the isotope records from the Pacific crust suggests that the volume of water exchanged with the Atlantic through shallow archipelagic straits of the gateway during the 3-4 m.y. prior to closure was too small to influence the radiogenic isotope composition of Pacific deep water.

Introduction Ground water is the dominant water resource in most agricultural watersheds, yet its quality is threatened by the very population and industry that it supports. Assessing the risk of [...]