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  • Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw

    Peer Reviewed Literature
    Water Isotope Analyzers

    Pleistocene Yedoma permafrost contains nearly a third of all organic matter (OM) stored in circum-arctic permafrost and is characterized by the presence of massive ice wedges. Due to its rapid formation by sediment accumulation and subsequent frozen storage, Yedoma OM is relatively well preserved and highly biologically available (biolabile) upon thaw. A better understanding of the processes regulating Yedoma degradation is important to improve estimates of the response and magnitude of permafrost carbon feedbacks to climate warming.

  • Quantification of long-term wastewater fluxes at the surface water/groundwater-interface: An integrative model perspective using stable isotopes and acesulfame

    Peer Reviewed Literature
    Water Isotope Analyzers

    The suitability of acesulfame to trace wastewater-related surface water fluxes from streams into the hyporheic and riparian zones over long-term periods was investigated. The transport behavior of acesulfame was compared with the transport of water stable isotopes (δ18O or δ2H). A calibrated model based on a joint inversion of temperature, acesulfame, and piezometric pressure heads was employed in a model validation using data sets of acesulfame and water stable isotopes collected over 5 months in a stream and groundwater.

  • Characterizing moisture exchange between the Hawaiian convective boundary layer and free troposphere using stable isotopes in water

    Peer Reviewed Literature
    Water Isotope Analyzers

    The subtropical convective boundary layer (CBL) plays a critical role in climate by regulating the vertical exchange of moisture, energy, trace gases, and pollutants between the ocean surface and free troposphere. Yet bulk features of this exchange are poorly constrained in climate models. To improve our understanding of moisture transport between the boundary layer and free troposphere, paired measurements of water vapor mixing ratio and the stable isotope ratio 18O/16O are used to evaluate moist convective mixing and entrainment processes near the Big Island of Hawai′i.

  • Ice-vapor equilibrium fractionation factor of hydrogen and oxygen isotopes: Experimental investigations and implications for stable water isotope studies

    Peer Reviewed Literature
    Water Isotope Analyzers

    RATIONALE

    The equilibrium fractionation factors govern the relative change in the isotopic composition during phase transitions of water. The commonly used results, which were published more than 40 years ago, are limited to a minimum temperature of –33°C. This limits the reliability in cold regions. With recent instrumental developments it is now possible to test the accuracy of the earlier results as well as extend the temperature range.

  • Origin of sulfur and mode of gypsum formation in central Iraqi soils

    Peer Reviewed Literature
    Water Isotope Analyzers

    The δ18O and δD values of gypsum crystallization water together with δ18O and δ34S of sulfates were used as reliable techniques to study source of sulfur and mode of gypsum formation in selected central Iraqi soils. Six representative pedons on different geologic units were studied. The slope of 3.2 for δ18O and δD plot of gypsum crystallization water showed that evaporation was the major process of gypsum deposition in the study area. The mean δ34S value of +17.58 ‰ showed that Cretaceous sea sulfate followed by Tertiary is the source of sulfur in studied soils.

  • A depth-controlled tracer technique measures vertical, horizontal and temporal patterns of water use by trees and grasses in a subtropical savanna

    Peer Reviewed Literature
    Water Isotope Analyzers
    • As described in the two-layer hypothesis, woody plants are often assumed to use deep soils to avoid competition with grasses.
  • Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006).

  • Geochemical and isotopic variations in shallow groundwater in areas of the Fayetteville Shale development, north-central Arkansas

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    Exploration of unconventional natural gas reservoirs such as impermeable shale basins through the use ofhorizontal drilling and hydraulic fracturing has changed the energy landscape in the USA providing a vastnew energy source. The accelerated production of natural gas has triggered a debate concerning thesafety and possible environmental impacts of these operations. This study investigates one of the criticalaspects of the environmental effects; the possible degradation of water quality in shallow aquifers overlyingproducing shale formations.

  • Interannual variation of water isotopologues at Vostok indicates a contribution from stratospheric water vapor

    Peer Reviewed Literature
    Water Isotope Analyzers

    Combined measurements of water isotopologues of a snow pit at Vostok over the past 60 y reveal a unique signature that cannot be explained only by climatic features as usually done. Comparisons of the data using a general circulation model and a simpler isotopic distillation model reveal a stratospheric signature in the 17O-excess record at Vostok.

  • Quantifying sources of methane using light alkanes in the Los Angeles basin, California

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and C2–C5 alkanes were measured throughout the Los Angeles (L.A.) basin in May and June 2010. We use these data to show that the emission ratios of CH4/CO and CH4/CO2in the L.A. basin are larger than expected from population-apportioned bottom-up state inventories, consistent with previously published work.

  • Precise and accurate δ13C analysis of rock samples using Flash Combustion–Cavity Ring Down Laser Spectroscopy

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    The ratio of 13C to 12C in marine sedimentary rocks holds important clues to the evolution of the carbon cycle through Earth history. Isotopic analyses are traditionally carried out using isotope ratio mass spectrometry (IRMS), but this technique is labor-intensive, expensive and requires expert know-how.

  • Using cavity ringdown spectroscopy for continuous monitoring of δ13C(CO2) and ƒCO2 in the surface ocean

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    The role of the global surface ocean as a source and sink for atmospheric carbon dioxide and the flux strengths between the ocean and the atmosphere can be quantified by measuring the fugacity of CO2 (ƒCO2) as well as the dissolved inorganic carbon (DIC) concentration and its isotopic composition in surface seawater. In this work, the potential of continuous wave cavity ringdown spectroscopy (cw-CRDS) for autonomous underway measurements of ƒCO2 and the stable carbon isotope ratio of DIC [δ13C(DIC)] is explored.

  • Positive and negative impacts of five Austrian gravel pit lakes on groundwater quality

    Peer Reviewed Literature
    Water Isotope Analyzers

    Groundwater-fed gravel pit lakes (GPLs) affect the biological, organic, and inorganic parameters of inflowing groundwater through combined effects of bank filtration at the inflow, reactions within the lake, and bank filtration at the outflow. GPLs result from wet dredging for sand and gravel and may conflict with groundwater protection programs by removing the protective soil cover and exposing groundwater to the atmosphere.

  • Eemian interglacial reconstructed from a Greenland folded ice core

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling (‘NEEM’) ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records.

  • Tracing Atmospheric Nitrate in Groundwater Using Triple Oxygen Isotopes: Evaluation Based on Bottled Drinking Water

    Peer Reviewed Literature
    Water Isotope Analyzers

    The stable isotopic compositions of nitrate dissolved in 49 types of bottled drinkingwater collected worldwide were determined, to trace the fate of atmospheric nitrate(NO−3 atm) that had been deposited into subaerial ecosystems, using the17O anomalies(∆175 O) of nitrate as tracers. The use of bottled water enables collection of groundwaterrecharged at natural, background watersheds. The nitrate in groundwater had small∆17O values ranging from −0.2 ‰ to +4.5 ‰ (n = 49).

  • Mixing of Rhone River Water in Lake Geneva (Switzerland-France) Inferred from Stable Hydrogen and Oxygen Isotope Profiles

    Peer Reviewed Literature
    Water Isotope Analyzers

    Depth profiles were sampled at different locations throughout Lake Geneva on a monthly and seasonal basis over the course of two years and analyzed for their stable hydrogen and oxygen isotope compositions. The isotopic composition indicates an isotopic stratification in the metalimnion during summer and fall. This is related to mixing of Rhône River water, which in summer is dominated by snow and glacier melt waters, and lake water, with the latter having a homogenous isotopic composition.

  • Secondary Organic Aerosol Formation from Gasoline Vehicle Emissions in a New Mobile Environmental Reaction Chamber

    Peer Reviewed Literature
    Gas Concentration Analyzers

    We present a new mobile environmental reaction chamber for the simulation of the atmospheric aging of aerosols from different emissions sources without limitation from the instruments or facilities available at any single site. The chamber can be mounted on a trailer for transport to host facilities or for mobile measurements. Photochemistry is simulated using a set of 40 UV lights (total power 4 KW). Characterisation of the emission spectrum of these lights shows that atmospheric photochemistry can be accurately simulated over a range of temperatures from −7–25 °C.

  • Rapid Transformation of Inorganic to Organic and Plant-Available Phosphorous in Soils of a Glacier Forefield

    Peer Reviewed Literature
    Water Isotope Analyzers

    Chemical weathering of rocks or sediments is extremely important for the generation of soils, for the evolution of landscape, and as a main source of inorganic nutrients for plant growth and therefore for life. Temporal trends in weathering mechanisms, plant succession and nutrients availability in cold environments can be successfully studied in soil chronosequences along a glacier forefield. In the present paper, this was carried out in the pro-glacial area of Morteratsch. Different forms of phosphorous in the soil, stream and spring water chemistry were investigated.

  • Direct Determination of δ(D) and δ(18O) in Water Samples Using Cavity Ring Down Spectrometry: Application to bottled mineral water

    Peer Reviewed Literature
    Water Isotope Analyzers

    The repeatability, reproducibility and accuracy of the direct measurement of δ(D) and δ(18O) isotopes inwater samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample analysis was approximately 70 minutes. Application of the method toBrazilian bottled mineral water has shown that it is possible to trace the origin of the water to at least thestate level within Brazilian geographical regions.

  • Extreme Short-Term Stable Isotope Variability Revealed by Continuous Rainwater Analysis

    Peer Reviewed Literature
    Water Isotope Analyzers

    Continuous real-time analysis, at 30 sec intervals, of precipitation at an Australian tropical location revealed extreme and rapidly changing δ18O and δD values related to variations in moisture source areas, transport paths and precipitation histories. The range of δ18O (−19.6 to +2.6 ‰) and δD (−140 to +13 ‰) values from 5948 measurements of nine rain events over 15 days during an 8 month period at a single location was comparable to the range measured in 1532 monthly samples from all seven Australian GNIP stations from 1962–2002.

  • A Comparison of in-situ Aircraft Measurements of Carbon Dioxide to GOSAT Data Measured Over Railroad Valley Playa, Nevada, USA

    Peer Reviewed Literature
    Gas Concentration Analyzers

     In this paper we report vertical profiles of CO2 measured with a cavity ring-down spectrometer (CRDS, Picarro, Inc., 2301-m) on a research aircraft from near ground level to 8 km above mean sea level (a.m.s.l.). The airborne platform employed in this study is an Alpha Jet aircraft operated from NASA Ames Research Center. Flights were undertaken to Railroad Valley, Nevada, USA, to coincide with overpasses of the Greenhouse Gases Observing Satellite (GOSAT).

  • Hydrogeochemical and isotopic evidence for trans-formational flow in a sedimentary basin: implications for CO2 storage

    Peer Reviewed Literature
    Water Isotope Analyzers

    Deep saline aquifers are considered as the most promising option for geologic disposal of CO2. One of the main concerns, however, is the integrity of the caprocks between and above the storage formations. Here, a hydrogeochemical and isotopic investigation is presented, using ionic chemistry, stable isotopes (δ18O, δ2H and 87Sr/86Sr) and radiocarbon dating, on five saline aquifers on a regional scale, namely: Neogene Minghuazhen, Guantao, Ordivician, Cambrian and Precambrian, all found in the Bohai Bay Basin in North China.

  • Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS) technique

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Accurate measurements of carbon monoxide (CO) in humid air have been made usingthe cavity ring-down spectroscopy (CRDS) technique. The measurements of CO molefractions are determined from the strength of its spectral absorption in the near infraredregion (∼ 1.57 µm) after removing interferences from adjacent carbon dioxide (CO25 )and water vapor (H2O) absorption lines. Water correction functions that account forthe dilution and pressure-broadening effects as well as absorption line interferencesfrom adjacent CO2 and H2O lines have been derived for CO2 mole fractions between360–390 ppm.

  • Evaluation of a Cavity Ring-Down Spectrometer for In-Situ Observations of 13CO2

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    With the emergence of wide-spread application of cavity ring-down spectrometers (CRDS) to monitor δ13C in atmospheric CO2 there is a growing need to ensure well calibrated measurements. We characterized a cavity ring-down spectrometer system used for continuous in-situ monitoring of atmospheric 13CO2. We found no concentration dependency of the δ13C ratio within the range of 303–437 ppm.

  • Assessing the Rate and Timing of Leaf Wax Regeneration in Fraxinus Americana Using Stable Hydrogen Isotope Labeling

    Peer Reviewed Literature
    Water Isotope Analyzers

    RATIONALE

    Understanding leaf wax regeneration and recycling is crucial for plant physiology and paleoclimate studies. However, our recent isotope labeling experiments on a grass species (Phleum pratense) yielded different conclusions from published data on a tree species (Populus trichocarpa), with the former showing rapid regeneration and the latter little regeneration in mature leaves.

  • Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland?

    Peer Reviewed Literature
    Water Isotope Analyzers

    Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute signifi-cantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into5 the past are vital for validating models predicting the influence of ongoing climatechange. We investigated a potential meltwater proxy in Godthabsfjord (West Green- ˚land), where glacier meltwater causes seasonal excursions with lower oxygen isotopewater (δ18Ow) values and salinity.

  • Design and Performance of a Nafion Dryer for Continuous Operation at CO2 and CH4 Air Monitoring Sites

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    In preparation for the routine deployment of the Earth Networks greenhouse gas monitoring network, we have designed and tested a simple method for drying ambient airto below 0.2 % mole fraction H2O using a Nafion dryer. The inlet was designed for usewith a Picarro model G2301 cavity ring down spectrometer (CRDS) CO2/CH45 /H2O analyzer. The analyzer measures water vapor mixing ratio at the same frequency as CO2and CH4 and then corrects for the dilution and peak broadening effects of H2O on theCO2 and CH4 mixing ratios.

  • Ground-Based Remote Sensing of Tropospheric Water Vapour Isotopologues Within the Project MUSICA

    Peer Reviewed Literature
    Water Isotope Analyzers

    Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologues data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets.

  • Measuring Dissolved Organic Carbon d13C in Freshwaters Using Total Organic Carbon Cavity Ring-Down Spectroscopy (TOC-CRDS)

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    This article reports the first application of coupled total organic carbon cavity ring-down spectroscopy (TOC-CRDS) for the analysis of the δ13C signature of dissolved organic carbon (DOC) in freshwater samples. DOC represents a major, dynamic component of the global carbon cycle. The export of DOC from soils into rivers and groundwaters may be highly climate sensitive, and much of this export may occur in ephemeral fluxes. Thus, a robust, simple and inexpensive method for the continuous determination of DOC concentration and quality is urgently needed.

  • Calibration of TCCON column-averaged CO2: the first aircraft campaign over European TCCON sites

    Peer Reviewed Literature
    Gas Concentration Analyzers

    The Total Carbon Column Observing Network (TCCON) is a ground-based network of Fourier Transform Spectrometer (FTS) sites around the globe, where the column abundances of CO2, CH4, N2O, CO and O2 are measured. CO2 is constrained with a precision better than 5 0.25%. To achieve a similarly high accuracy, calibration to World Meteorological Organization (WMO) standards is required. This paper introduces the first aircraft calibration campaign of five European TCCON sites and a mobile FTS instrument.

  • Short-Term N2 Fixation Kinetics in a Moss-Associated Cyanobacteria 

    Peer Reviewed Literature
    Gas Concentration Analyzers

    N2 fixation by moss-associated cyanobacteria plays an important role in the nitrogen cycling of terrestrial ecosystems. Recent studies have mainly focused on boreal ecosystems; little is known about such association in other ecosystems. Moss-associated cyanobacteria are subject to rapid changes (hourly or less) in environmental conditions that may affect N2fixation kinetics.

  • Integrated assessment on groundwater nitrate by unsaturated zone probing and aquifer sampling with environmental tracers

    Peer Reviewed Literature
    Water Isotope Analyzers

    By employing chemical and isotopic tracers (15N and 18O in NO3), we investigated the main processes controlling nitrate distribution in the unsaturated zone and aquifer. Soil water was extracted from two soil cores drilled in a typical agricultural cropping area of the North China Plain (NCP), where groundwater was also sampled. The results indicate that evaporation and denitrification are the two major causes of the distribution of nitrate in soil water extracts in the unsaturated zone.

  • Isotopic and Geochemical Investigation of two Distinct mars Analog Environments Using Evolved Gas Techniques in Svalbard, Norway

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    The 2010 Arctic Mars Analog Svalbard Expedition (AMASE) investigated two distinct geologic settings on Svalbard, using methodologies and techniques to be deployed on Mars Science Laboratory (MSL). AMASE-related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions.

  • Evaluation of Factors Affecting Accurate Measurements of Atmospheric CO2 and CH4 by Wavelength-Scanned Cavity Ring-Down Spectroscopy

    Peer Reviewed Literature
    Gas Concentration Analyzers

    We examined potential interferences from water vapor and atmospheric backgroundgases (N2, O2, and Ar), and biases by isotopologues of target species, on accuratemeasurement of atmospheric CO2 and CH4 by means of wavelength-scanned cavity5 ring-down spectroscopy (WS-CRDS). Variations in the composition of the backgroundgas substantially impacted the CO2 and CH4 measurements: the measured amounts ofCO2 and CH4 decreased with increasing N2 mole fraction, but increased with increasing O2 and Ar, suggesting that the pressure-broadening effects (PBEs) increased asAr < O2 < N2.

  • Duration of Greenland Stadial 22 and ice-gas ∆age from counting of annual layers in Greenland NGRIP ice core

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    The NorthGRIP ice core chronology GICC05modelext is composed of the annual-layercounted GICC05 chronology to 60 kyr before 2000 AD (b2k), and an ice flow model dating the deepest part of the ice core to 123 kyr b2k. Determination of annual strata in ice5 beyond 60 kyr b2k has been challenged by the thinning of annual layers to < 1 cm andthe appearance of microfolds in some early glacial strata.

  • Tracing groundwater recharge sources in a mountain–plain transitional area using stable isotopes and hydrochemistry

    Peer Reviewed Literature
    Water Isotope Analyzers

    Mountain–plain transitional landscapes are especially important as groundwater recharge zones. In this study, the oxygen and hydrogen stable isotopic composition (δ18O and δD) of water and hydrochemical information were employed to quantify contribution ratios of different sources of groundwater recharge in the Ashikaga area of central Japan. The study area is situated between the Ashio Mountains and the Kanto Plain, and the Watarase River flows into the region parallel to the mountain–plain boundary.

  • Evaluation of Three New Laser Spectrometer Techniques for in-situ Carbon Monoxide Measurements

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Long-term time series of the atmospheric composition are essential for environmental research and thus require compatible, multi-decadal monitoring activities. However,the current data quality objectives of the World Meteorological Organization (WMO) for5 carbon monoxide (CO) in the atmosphere are very challenging to meet with the measurement techniques that have been used until recently. During the past few years, newspectroscopic techniques came on the market with promising properties for trace gasanalytics.

  • Geochemistry of a continental site of serpentinization, the Tablelands Ophiolite, Gros Morne National Park: A Mars analogue

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    The presence of aqueously altered, olivine-rich rocks along with carbonate on Mars suggest that serpentinization may have occurred in the past and may be occurring presently in the subsurface, and possibly contributing methane (CH4) to the martian atmosphere. Serpentinization, the hydration of olivine in ultramafic rocks, yields ultra-basic fluids (pH ⩾ 10) with unique chemistry (i.e. Ca2+–OH waters) and hydrogen gas, which can support abiogenic production of hydrocarbons (i.e.

  • Determining Water Sources in the Boundary Layer from Tall Tower Profiles of Water Vapor and Surface Water Isotope Ratios After a Snowstorm in Colorado 

    Peer Reviewed Literature
    Water Isotope Analyzers

    The D/H isotope ratio is used to attribute boundary layer humidity changes to the set of contributing fluxes for a case following a snowstorm in which a snow pack of about 10 cm vanished. Profiles of H2O and CO2 mixing ratio, D/H isotope ratio, and several thermodynamic properties were measured from the surface to 300 m every 15 min during four winter days near Boulder, Colorado.

  • First continuous shipboard d18O and dD measurements in sea water by diffusion sampling—cavity ring-down spectrometry

    Peer Reviewed Literature
    Water Isotope Analyzers

    Combined measurements of salinity and the oxygen/hydrogen stable isotope composition of marine
    waters can characterise processes such as freshwater mixing, evaporation, precipitation and sea-ice formation.
    However, stable isotope data with high spatial and temporal resolution are necessary for a detailed understanding
    of mixed water bodies with multiple inputs. So far analysis of d18O and dD values in water has been a relatively
    expensive, laboratory-based technique requiring collection of discrete samples. This has greatly limited the scope and

  • Ice-core net snow accumulation and seasonal snow chemistry at a temperate-glacier site: Mount Waddington, southwest British Columbia, Canada

    Peer Reviewed Literature
    Water Isotope Analyzers

    A 141 m-long ice core was recovered from Combatant  Col (51.385°N, 125.258°W, 3000 m a.s.l.), Mount Waddington, Coast Mountains, British Columbia, Canada.  Records of black carbon, dust, lead, and water stable-isotopes demonstrate that unambiguous seasonality is preserved throughout the core, despite summer surface snowmelt and temperate ice. High accumulation rates at the site (in excess of 4 m a-1ice-equivalent) limit modification of annual stratigraphy by percolation of surface meltwater. The ice-core record spans the period 1973-2010.

  • An Integrated Flask Sample Collection System for Greenhouse Gas Measurements

    Peer Reviewed Literature
    Gas Concentration Analyzers

    A one hour integrated flask sampling system to collect air in automated NOAA/ESRL12-flask packages is described. The integrating compressor system uses a mass flowcontroller to regulate the flow of air through a 15 l volume, thus providing a mixture of air5 collected over an hour-long period. By beginning with a high flow rate of 3800 standardliters per minute and gradually decreasing the flow rate over time to 290 standardliters per minute it is possible to obtain a nearly uniformly time averaged sample of airand collect it into a pressurized 0.7 l flask.

  • Direct determination of δ(D) and δ(18O) in water samples using cavity ring down spectrometry: Application to bottled mineral water

    Peer Reviewed Literature
    Water Isotope Analyzers

    The repeatability, reproducibility and accuracy of the direct measurement of δ(D) and δ(18O) isotopes in water samples were evaluated using Cavity Ring-Down Spectrometry, and values comparable with the Isotopic Ratio Mass Spectrometry were obtained. Memory effect correction was negligible after five successive injections, and the time for each sample analysis was approximately 70 minutes.

  • Analysis of Interactions between Surface Water and Groundwater by Using Water Chemistry and δD, δ18O—Case Study of Bulang River Basin

    Peer Reviewed Literature
    Water Isotope Analyzers

    There is a close relationship between surface water and groundwater in semi-arid and arid areas of China, and thus researching on the interactions of them is of importance for reasonable water resources development. This paper took Bulang River basin as case study, analysis and discussion were conducted to water chemistry and isotopes tests results of water samples. The results show that surface water in Bulang River basin mainly relies on precipitation recharge, partially on groundwater recharge, the hydrochemistry type of surface water is mainly Ca-HCO3 with low salinity.

  • Inter-comparison of two high-accuracy fast-response spectroscopic sensors of carbon dioxide: a case study

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Tunable diode laser absorption (TDL) and cavity ring-down spectroscopic (CRDS) sensors for atmospheric  carbon dioxide were co-deployed during summer and fall of 2010 in field and laboratory conditions at Los Alamos National Laboratory. Both sensors were characterized for accuracy and precision for ambient carbon dioxide measurements at ground level and compared using both laboratory and ambient field data.

  • A combustion setup to precisely reference 13C and 2H isotope ratios of pure CH4 to produce isotope reference gases of 13C-CH4 in synthetic air

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    Isotope records of atmospheric CH4 can be used to infer changes in the biochemistry of CH4. One factor limiting quantitative estimates of changes in the biogeochemistry of CH4 are the uncertainties of the isotope measurements due to the lack of a unique isotope reference gas, certified for 13C-CH4 or 2 5 H-CH4.

  • Effect of Stocking Rate on Soil-Atmosphere CH4 Flux during Spring Freeze-Thaw Cycles in a Northern Desert Steppe, China

    Peer Reviewed Literature
    Gas Concentration Analyzers

    The experiment was conducted at twelve grazing plots denoting four treatments defined along a grazing gradient with three replications: non-grazing (0 sheep/ha, NG), light grazing (0.75 sheep/ha, LG), moderate grazing (1.50 sheep/ha, MG) and heavy grazing (2.25 sheep/ha, HG). Using an automatic cavity ring-down spectrophotometer, we measured CH4 fluxes from March 1 to April 29 in 2010 and March 2 to April 27 in 2011.