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  • Decomposition of litter mixtures induces non-additive effects on soil priming across a riparian land use gradient

    Peer Reviewed Literature
    Gas Concentration Analyzers

    While litter traits have been used for decades to predict decomposition rates through the Leaf Economics
    Spectrum (LES) acquisitive to conservative trait lens, litter trait and litter mixture effects on soil carbon (C)
    priming effects (PE) is less known. To assess whether the LES can predict soil C PE during the decomposition of
    litter mixtures from complex ecosystems, a 99-day incubation experiment was conducted. The experiment
    involved soil and leaf litter from three Canadian riparian land uses (grasslands, deciduous agroforests, and

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    Human Ammonia Emission Rates under Various Indoor Environmental Conditions

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Ammonia (NH3) is typically present at higher concentrations in indoor air (∼10–70 ppb) than in outdoor air (∼50 ppt to 5 ppb). It is the dominant neutralizer of acidic species in indoor environments, strongly influencing the partitioning of gaseous acidic and basic species to aerosols, surface films, and bulk water. We have measured NH3 emissions from humans in an environmentally controlled chamber.

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    A simple method for rapid removal of the memory effect in cavity ring-down spectroscopy water isotope measurements

    Peer Reviewed Literature
    Water Isotope Analyzers

    Rationale
    The accuracy determined in the routine analysis of water isotopes (δ17O, δ18O, δ2H) using cavity ring-down spectroscopy is greatly affected by the memory effect (ME), a sample-to-sample carryover that biases measurements. This study aims to develop a simple method that rapidly removes the ME.

  • Reactive Chlorine Emissions from Cleaning and Reactive Nitrogen Chemistry in an Indoor Athletic Facility

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Indoor gas-phase radical sources are poorly understood but expected to be much different from outdoors. Several potential radical sources were measured in a windowless, light-emitting diode (LED)-lit room in a college athletic facility over a 2 week period. Alternating measurements between the room air and the supply air of the heating, ventilation, and air-conditioning system allowed an assessment of sources. Use of a chlorine-based cleaner was a source of several photolabile reactive chlorine compounds, including ClNO2 and Cl2.

  • Isotopic measurements in water vapor, precipitation, and seawater during EUREC4A

    Peer Reviewed Literature
    Water Isotope Analyzers

    In early 2020, an international team set out to investigate trade-wind cumulus clouds and their coupling to the large-scale circulation through the field campaign EUREC4A: ElUcidating the RolE of Clouds-Circulation Coupling in ClimAte. Focused on the western tropical Atlantic near Barbados, EUREC4A deployed a number of innovative observational strategies, including a large network of water isotopic measurements collectively known as EUREC4A-iso, to study the tropical shallow convective environment.

  • Understanding Sources of Atmospheric Hydrogen Chloride in Coastal Spring and Continental Winter

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Ambient 0.5 Hz hydrogen chloride (HCl) measurements were made in Canadian cities to investigate chlorine activation and constrain the tropospheric chlorine budget. Springtime HCl mixing ratios in a coastal city (St. John’s, NL) were up to 1200 parts per trillion by volume (pptv) with a median of 63 pptv and were consistently elevated during daytime. High time-resolution measurements allowed the attribution of events to general sources, including direct emissions. Most coastal HCl was related to sea-salt aerosol acid displacement (R1) and chlorine activation.

  • Validation of a new cavity ring-down spectrometer for measuring tropospheric gaseous hydrogen chloride

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Reliable, sensitive, and widely available hydrogen chloride (HCl) measurements are important for understanding oxidation in many regions of the troposphere. We configured a commercial HCl cavity ring-down spectrometer (CRDS) for sampling HCl in the ambient atmosphere and developed validation techniques to characterize the measurement uncertainties. The CRDS makes fast, sensitive, and robust measurements of HCl in a high-finesse optical cavity coupled to a laser centred at 5739 cm−1.

  • Development and Validation of a New In-Situ Technique to Measure Total Gaseous Chlorine in Ambient Air

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Total gaseous chlorine (TClg) measurements can improve our understanding of unknown sources of Cl to the atmosphere. Existing techniques for measuring TClg have been limited to offline analysis of extracted filters and do not provide suitable temporal information on fast atmospheric process. We describe high time-resolution in-situ measurements of TClg by combusting ambient air over a heated platinum (Pt) substrate coupled to a cavity ring-down spectrometer (CRDS).

  • Breath chemical markers of sexual arousal in humans

    Peer Reviewed Literature
    Gas Concentration Analyzers
  • Nitrogen removal by eutrophic coastal wetlands accomplished with CH4 emission reduction

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Coastal wetlands play an important role in nitrogen removal and are a vital blue carbon sink. The produced methane (CH4) in coastal wetlands has been recently identified as a possible carbon source for denitrification process, providing a significant contribution to coastal nitrogen cycling. However, the in-situ correlation between CH4 emissions and denitrification rate, as well as their coupling mechanism is still unclear.

  • Room-level ventilation in schools and universities

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Ventilation is of primary concern for maintaining healthy indoor air quality and reducing the spread of airborne infectious disease, including COVID-19. In addition to building-level guidelines, increased attention is being placed on room-level ventilation. However, for many universities and schools, ventilation data on a room-byroom basis are not available for classrooms and other key spaces. We present an overview of approaches for measuring ventilation along with their advantages and disadvantages.

  • Changes of ammonia concentrations in wintertime on the North China Plain from 2018 to 2020

    Peer Reviewed Literature
    Gas Concentration Analyzers

    The reduced economic and social activities during the Chinese Spring Festival provide a unique experiment to evaluate reductions in anthropogenic NH3 emissions in China. However, quantifying this unique scenario is challenging as meteorology may mask the real changes in observed NH3 concentrations. Here, we applied a machine learning technique to decouple the effects of meteorology and confirmed that the real (deweathered) NH3 concentration dropped to a minimum during the Spring Festival in 2019 and 2020 at both urban (Beijing) and rural (Xianghe) sites on the North China Plain.

  • Vehicular Emissions Enhanced Ammonia Concentrations in Winter Mornings: Insights from Diurnal Nitrogen Isotopic Signatures

    Peer Reviewed Literature
    Gas Concentration Analyzers

    A general feature in the diurnal cycle of atmospheric ammonia (NH3) concentrations is a morning spike that typically occurs around 07:00 to 10:00 (LST). Current hypotheses to explain this morning’s NH3 increase remain elusive, and there is still no consensus whether traffic emissions are among the major sources of urban NH3. Here, we confirmed that the NH3 morning pulse in urban Beijing is a universal feature, with an annual occurrence frequency of 73.0% and a rapid growth rate (>20%) in winter.

  • Methane and NO<sub>x</sub> Emissions from Natural Gas Stoves, Cooktops, and Ovens in Residential Homes

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Natural gas stoves in >40 million U.S. residences release methane (CH4)--a potent greenhouse gas--through post-meter leaks and incomplete combustion. We quantified methane released in 53 homes during all phases of stove use: steady-state-off (appliance not in use), steady-state-on (during combustion), and transitory periods of ignition and extinguishment. We estimated that natural gas stoves emit 0.8−1.3% of the gas they use as unburned methane and that total U.S. stove emissions are 28.1 [95% confidence interval: 18.5, 41.2] Gg CH4 year−1.

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    An open-source, automated, gas sampling peripheral for laboratory incubation experiments using cavity ring-down spectroscopy

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Spectroscopic instruments are becoming increasingly popular for measuring the isotopic composition and fluxes of a wide variety of gases in both field and laboratory experiments. The popularity of these instruments has created a need for automated multiplexers compatible with the equipment. While there are several such peripherals commercially available, they are currently limited to only a small number of samples (≤16), which is insufficient for some studies.

  • Hot moments drive extreme nitrous oxide and methane emissions from agricultural peatlands

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Agricultural peatlands are estimated to emit approximately one third of global greenhouse gas (GHG) emissions from croplands, but the temporal dynamics and controls of these emissions are poorly understood, particularly for nitrous oxide (N2O). We used cavity ring-down spectroscopy and automated chambers in a drained agricultural peatland to measure over 70,000 individual N2O, methane (CH4), and carbon dioxide (CO2) fluxes over 3 years.

  • An effective and automated approach for reducing infection risk from contaminated privacy curtains

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Privacy curtain contamination, including with multidrug-resistant organisms, and the associated infection transmission risks have been well described; however, current approaches for addressing these risks and available guidance are limited. The present study describes the successful reduction of curtain contamination in five different units within a tertiary care hospital utilizing continuous dry hydrogen peroxide (DHP™). Microbial load was reduced by 99.47 percent on Day 1 and statistically significant reductions were maintained throughout the 28-day study.

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    Uncertainties and limitations of using carbon‐13 and oxygen‐18 leaf isotope exchange to estimate the temperature response of mesophyll CO2 conductance in C3 plants

    Peer Reviewed Literature
    Water Isotope Analyzers
    • The internal CO2 gradient imposed by mesophyll conductance (gm) reduces substrate availability for C3 photosynthesis. With several assumptions, estimates of gm can be made from coupled leaf gas exchange with isoflux analysis of carbon ∆13C‐gm and oxygen in CO2, coupled with transpired water (H2O) ∆18O‐gm to partition gm into its biochemical and anatomical components.
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    Tracking the direct impact of rainfall on groundwater at Mt. Fuji by multiple analyses including microbial DNA

    Peer Reviewed Literature
    Water Isotope Analyzers

    A total of 2 to 3 million tons of spring water flushes out from the foot of Mt. Fuji, the largest volcanic mountain in Japan. Based on the concept of piston flow transport, residence time of stored groundwater at Mt. Fuji was estimated at  ∼  15–30 years by the 36Cl ∕ Cl ratio (Tosaki et al., 2011). This range, however, represents the average residence time of groundwater that was mixed before it flushed out.

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    Studying catchment storm response using event- and pre-event-water volumes as fractions of precipitation rather than discharge

    Peer Reviewed Literature
    Water Isotope Analyzers

    Catchment response to precipitation is often investigated using two-component isotope-based hydrograph separation, which quantifies the contribution of precipitation (i.e., event water Qe) or water from storage (i.e., pre-event water Qpe) to total discharge (Q) during storm events. In order to better understand streamflow-generating mechanisms, two-component hydrograph separation studies often seek to relate the event-water fraction Qe∕Q to storm characteristics or antecedent wetness conditions.

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    Stable Isotopes of Precipitation During Tropical Sumatra Squalls in Singapore

    Peer Reviewed Literature
    Water Isotope Analyzers

    Sumatra Squalls, organized bands of thunderstorms, are the dominant mesoscale convective systems during the intermonsoon and southwest monsoon seasons in Singapore. To understand how they affect precipitation isotopes, we monitored the δ value of precipitation daily and continuously (every second and integrated over 30 s) during all squalls in 2015. We found that precipitation δ18O values mainly exhibit a “V”‐shape pattern and less commonly a “W”‐shape pattern.

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    Measurement of Gross Photosynthesis, Respiration in the Light, and Mesophyll Conductance Using H218O Labeling

    Peer Reviewed Literature
    Water Isotope Analyzers

    A fundamental challenge in plant physiology is independently determining the rates of gross O2 production by photosynthesis and O2 consumption by respiration, photorespiration, and other processes. Previous studies on isolated chloroplasts or leaves have separately constrained net and gross O2 production (NOP and GOP, respectively) by labeling ambient O2 with 18O while leaf water was unlabeled. Here, we describe a method to accurately measure GOP and NOP of whole detached leaves in a cuvette as a routine gas-exchange measurement.

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    High-Frequency Water Isotopic Analysis Using an Automatic Water Sampling System in Rice-Based Cropping Systems

    Peer Reviewed Literature
    Water Isotope Analyzers

    High-resolution data on a field scale is very important for improving our understanding of hydrological processes. This is particularly the case for water-demanding agricultural production systems such as rice paddies, for which water-saving strategies need to be developed. Here we report on the application of an in situ, automatic sampling system for high-resolution data on stable isotopes of water (18O and 2H).

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    A randomized controlled trial of the impact of protein supplementation on leg lean mass and integrated muscle protein synthesis during inactivity and energy restriction in older persons

    Peer Reviewed Literature
    Water Isotope Analyzers

    In older persons, muscle loss is accelerated during physical inactivity and hypoenergetic states, both of which are features of hospitalization. Protein supplementation may represent a strategy to offset the loss of muscle during inactivity, and enhance recovery on resumption of activity. We aimed to determine if protein supplementation, with proteins of substantially different quality, would alleviate the loss of lean mass by augmenting muscle protein synthesis (MPS) while inactive during a hypoenergetic state.

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    A new interpretative framework for below-cloud effects on stable water isotopes in vapour and rain

    Peer Reviewed Literature
    Water Isotope Analyzers

    Raindrops interact with water vapour in ambient air while sedimenting from the cloud base to the ground. They constantly exchange water molecules with the environment and, in sub-saturated air, they evaporate partially or entirely. The latter of these below-cloud processes is important for predicting the resulting surface rainfall amount. It also influences the boundary layer profiles of temperature and moisture through evaporative latent cooling and humidity changes. However, despite its importance, it is very difficult to quantify this process from observations.

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    Novel Materials for Combined Nitrogen Dioxide and Formaldehyde Pollution Control under Ambient Conditions

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Formaldehyde (HCHO) and nitrogen dioxide (NO2) often co-exist in urban environments at levels that are hazardous to health. There is a demand for a solution to the problem of their combined removal. In this paper, we investigate catalysts, adsorbents and composites for their removal efficiency (RE) toward HCHO and NO2, in the context of creating a pollution control device (PCD). Proton-transfer-reaction mass spectrometry and cavity ring-down spectrometry are used to measure HCHO, and chemiluminescence and absorbance-based monitors for NO2.

  • Development of a Monitoring System for Semicontinuous Measurements of Stable Carbon Isotope Ratios in Atmospheric Carbonaceous Aerosols: Optimized Methods and Application to Field Measurements

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    Carbon content constitutes a major fraction of atmospheric particulate matter (PM) and directly influences the earth’s climate and human health. The stable carbon isotope ratios (δ13C) can be used to track potential sources and atmospheric processes of carbonaceous aerosols. Previously, determination of δ13C was always conducted in offline carbonaceous aerosol samples. The poor time-resolution results cannot provide information regarding the temporal evolution of δ13C at a short-time scale.

  • Impact of H2O2 Sorption by Polymers on the Duration of Aeration in Pharmaceutical Decontamination

    Peer Reviewed Literature
    Gas Concentration Analyzers

    As part of manufacturing a sterile drug product, we quantified the impact of H2O2 sorption by polymers  on the duration of aeration in pharmaceutical decontamination. Five polymers, which are typically used as materials/parts in sterile isolators, were investigated: polyethylene, polyvinyl chloride, Silicone, polyoxymethylene (POM), and chlorosulfonated polyethylene. Experiments were performed to estimate the storage capacity and diffusion coefficients of H2O2 in the polymer. Considering these key properties of

  • Design-oriented regression models for H2O2 decontamination processes in sterile drug product manufacturing considering rapidity and sterility

    Peer Reviewed Literature
    Gas Concentration Analyzers

    We developed regression models for designing rapid and effective H2O2 decontamination processes in the manufacturing of sterile drug products such as injectables. Decontamination, which is typically performed by using H2O2, is a critical changeover process used to establish a sterile environment for filling products. In the process, there is a = trade-off relationship between the duration of the process and the level of sterility assurance that needs to be considered in the design.

  • The Diffusion of Hydrogen Peroxide Into the Liquid Product During Filling Operations Inside Vaporous Hydrogen Peroxide - Sterilized Isolators Can Be Predicted by a Mechanistic Model

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Isolators are commonly used in filling operations of pharmaceutical products. To ensure an aseptic inner environment, isolators are regularly sterilized with vaporized hydrogen peroxide. However, despite extensive purging with air, some residual H2O2 remains within the isolator atmosphere and may thus end up in the liquid pharmaceutical drug product, which subsequently may cause oxidation and impact the product’s safety and efficacy. We aimed to evaluate the extent of this phenomenon and to model it.

  • Vapor Phase Hydrogen Peroxide Sanitization of an Isolator for Aseptic Filling of Monoclonal Antibody Drug Product -  Hydrogen Peroxide Uptake and Impact on Protein Quality

    Peer Reviewed Literature
    Gas Concentration Analyzers

    A monoclonal antibody drug product (DP) manufacturing process was transferred to a different production site, where aseptic filling took place within an isolator that was sanitized using vapor phase hydrogen peroxide (VPHP). A quality-by-design approach was applied for study design to understand the impact of VPHP uptake in the isolator on DP quality. A combination of small-scale and manufacturing-scale studies was performed to evaluate the sensitivity of the monoclonal antibody to hydrogen peroxide (H2O2) as well as VPHP uptake mechanisms during the filling process.

  • Fast oxidation of sulfur dioxide by hydrogen peroxide in deliquesced aerosol particles

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Atmospheric sulfate aerosols have important impacts on air quality, climate, and human and ecosystem health. However, current air-quality models generally underestimate the rate of conversion of sulfur dioxide (SO2) to sulfate during severe haze pollution events, indicating that our understanding of sulfate formation chemistry is incomplete. This may arise because the air-quality models rely upon kinetics studies of SO2 oxidation conducted in dilute aqueous solutions, and not at the high solute strengths of atmospheric aerosol particles.

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    Novel Materials for Combined Nitrogen Dioxide and Formaldehyde Pollution Control under Ambient Conditions

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Formaldehyde (HCHO) and nitrogen dioxide (NO2) often co-exist in urban environments at levels that are hazardous to health. There is a demand for a solution to the problem of their combined removal. In this paper, we investigate catalysts, adsorbents and composites for their removal effciency (RE) toward HCHO and NO2, in the context of creating a pollution control device (PCD). Proton-transfer-reaction mass spectrometry and cavity ring-down spectrometry are used to measure HCHO, and chemiluminescence and absorbance-based monitors for NO2.

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    Formation and emission of hydrogen chloride in indoor air

    Peer Reviewed Literature
    Gas Concentration Analyzers

    To improve our understanding of chlorine chemistry indoors, reactive chlorine species such as hydrogen chloride (HCl) must be analyzed using fast time-response measurement techniques. Although well studied outdoors, sources of HCl indoors are unknown. In this study, mixing ratios of gaseous HCl were measured at 0.5 Hz in the indoor environment using a cavity ring-down spectroscopy (CRDS) instrument. The CRDS measurement rate provides a major advance in observational capability compared to other established techniques.

  • Tracking ammonia morning peak, sources and transport with 1 Hz measurements at a rural site in North China Plain

    Peer Reviewed Literature
    Gas Concentration Analyzers

    The North China Plain has been identified as a global hotspot for ammonia (NH3). To date, NH3 surface observations in the region have mostly been obtained by passive samplers with a time resolution of weeks (e.g., AMoN-China), and few studies have been performed with fast-response instruments. Thus, the detailed temporal variations of NH3 concentrations are still unclear in the region.

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    Methane and nitrous oxide porewater concentrations and surface fluxes of a regulated river

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Greenhouse gas (GHG) emissions from rivers are a critical missing component of current global GHG models.
    Their exclusion is mainly due to a lack of in-situ measurements and a poor understanding of the spatiotemporal
    dynamics of GHG production and emissions, which prevents optimal model parametrization. We combined simultaneous
    observations of porewater concentrations along different beach positions and depths, and surface
    fluxes of methane and nitrous oxide at a plot scale in a large regulated river during three water stages: rising, falling,

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    A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Methane (CH4) is a strong greenhouse gas with a global warming potential 23 times larger than that of carbon dioxide. Characterizing ecosystems as either sources or sinks for methane and their magnitudes informs on biosphere contributions to the global CH4 budget and to warming of the atmosphere. We quantified methane fluxes for the first time in a neotropical alpine páramo (Valle de Los Conejos, Chirripó Massif, Costa Rica) and examined the relationships of these fluxes with topography, soil moisture and vegetation, during the transition from dry to rainy season.

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    CH4 uptake along a successional gradient in temperate alpine soils

    Peer Reviewed Literature
    Gas Concentration Analyzers

    The effects of climate change appear to be amplified in mountains compared with lowland areas, with rapid changes in plant community composition, soil properties, and increased substrate for biological development following retreat of glaciers. Associated soil gaseous fluxes in alpine ecosystems contribute to the global balance of greenhouse gases, but methane and carbon dioxide soil fluxes and their controls are not well known.

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    Metabolic Fates of Evening Crop-Stored Sugar in Ruby-Throated Hummingbirds (Archilochus colubris)

    Peer Reviewed Literature
    Carbon Isotope Analyzers

    During the day, hummingbirds quickly metabolize floral nectar to fuel high metabolic
    demands, but are unable to feed at night. Though stored fat is the primary nocturnal metabolic
    fuel, it has been suggested that hummingbirds store nectar in their crop to offset fat expenditure
    in the night or to directly fuel their first foraging trip in the morning. We examine the use of
    crop-stored sugar in the nocturnal energy budget of ruby-throated hummingbirds (Archilochus colubris)

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    The Influence of sea ice on ocean water vapor isotopes and Greenland ice core records

    Peer Reviewed Literature
    Water Isotope Analyzers

    A warming climate results in sea ice loss and impacts to the Arctic water cycle. The water isotope
    parameter deuterium excess, a moisture source proxy, can serve as a tracer to help understand hydrological
    changes due to sea ice loss. However, unlocking the sea ice change signal of isotopes from ice cores requires
    understanding how sea ice changes impact deuterium excess, which is unknown. Here we present the first
    isotope data linking a gradient of sea ice extents to oceanic water vapor deuterium excess values. Initial loss of

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    Central Europe temperature constrained by speleothem fluid inclusion water isotopes over the past 14,000 years

    Peer Reviewed Literature
    Water Isotope Analyzers

    The reasons for the early Holocene temperature discrepancy between northern hemispheric model simulations and paleoclimate reconstructions—known as the Holocene temperature conundrum—remain unclear. Using hydrogenisotopes of fluid inclusion water extracted from stalagmites from the Milandre Cave in Switzerland, we established a mid-latitude European mean annual temperature reconstruction for the past 14,000 years.

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    Local- and regional-scale measurements of CH4, d13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer

    Peer Reviewed Literature

    In this paper, we present an innovative CH4, δ13CH4, and C2H6 instrument based on cavity ring-down spectroscopy (CRDS). The design and performance of the analyzer is presented in detail. The instrument is capable of precision of less than 1‰ on δ13CH4 with 1 in. of averaging and about 0.1‰ in an hour. Using this instrument, we present a comprehensive approach to atmospheric methane emissions attribution.

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    Validation of ammonia diffusive and pumped samplers in a controlled atmosphere test facility using traceable Primary Standard Gas Mixtures

    Peer Reviewed Literature

    We report the determination of ammonia (NH3) diffusive sampling rates for six different designs of commercial
    diffusive samplers (CEH ALPHA sampler, Gradko diffusion tube, Gradko DIFRAM-400, Passam ammonia sampler,
    and ICS Maugeri Radiello radial sampler (blue and white turbulence barriers)), together with the validation
    test results for a pumped sampler (CEH DELTA denuder). The devices were all exposed in the UK's National
    Physical Laboratory's (NPL) controlled atmosphere test facility (CATFAC). For each of the seven diffusive

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    Evaluation of the IAGOS-Core GHG package H2O measurements during the DENCHAR airborne inter-comparison campaign in 2011

    Peer Reviewed Literature

    As part of the DENCHAR (Development and Evaluation of Novel Compact Hygrometer for Airborne Research) inter-comparison campaign in northern Germany in 2011, a commercial cavity ring-down spectroscopy (CRDS) based gas analyzer (G2401-m, Picarro Inc., US) was installed on a Learjet to measure atmospheric water vapor, CO2, CH4, and CO. The CRDS components were identical to those chosen for integration aboard commercial airliners within the IAGOS (In-service Aircraft for a Global Observing System) project.

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    High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques

    Peer Reviewed Literature
    Gas Concentration Analyzers

    Carbon dioxide and oxygen are tightly coupled in land-biospheres CO2 - O2 exchange processes, while they are not coupled in oceanic exchange. For this reason, atmospheric oxygen measurements can be used to constrain the global carbon cycle, especially oceanic uptake. However, accurately quantifying the small (~1-100 ppm) variations in O2 is analytically challenging due to the very large atmospheric background which constitutes about 20.9 % (~209500 ppm) of atmospheric air.

  • Application of a cavity ring‑down spectrometer to measurements of ambient ammonia using traceable primary standard gas mixtures

    Peer Reviewed Literature
    Gas Concentration Analyzers
    A correction for the undesirable effects of direct and indirect cross-interference from water vapour on ammonia (NH3) measurements was developed using an optical laser sensor based on cavity ring-down spectroscopy.
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    Effects of Variation in Background Mixing Ratios of N2, O2, and Ar on the Measurement of δ18O–H2O and δ2H–H2O Values by Cavity Ring-Down Spectroscopy

    Peer Reviewed Literature
    Water Isotope Analyzers

    Abstract. Cavity ring-down spectrometers have generally been designed to operate under conditions in which the background gas has a constant composition. However, there are a number of observational and experimental situations of interest in which the background gas has a variable composition. In this study, we examine the effect of background gas composition on a cavity ring-down spectrometer that measures δ18O–H2O and δ2H–H2O values based on the amplitude of water isotopologue absorption features around 7184 cm−1 (L2120-i, Picarro, Inc.).

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    Performance of Induction Module Cavity Ring-down Spectroscopy (IM-CRDS) for Measuring δ18O and δ2H Values of Soil, Stem, and Leaf Waters

    Peer Reviewed Literature
    Water Isotope Analyzers

    Rationale
    Induction module cavity ring-down spectroscopy (IM-CRDS) has been proposed as a rapid and cost-effective alternative to cryogenic vacuum distillation (CVD) and isotope ratio mass spectrometry (IRMS) for the measurement of δ18O and δ2H values in matrix-bound waters. In the current study, we characterized the performance of IM-CRDS relative to CVD and IRMS and investigated the mechanisms responsible for differences between the methods.