Describes recent developments in GC-C-CRDS-based instrumentation applied to isotope measurements in large molecules.

Describes a newly-developed analyzer for tracer-based measurements and shows results from field work using such a system.

Describes results from a Picarro N2O analyzer based in the mid-infrared spectral region.

Describes results of laboratory testing and field campaigns with Picarro's flight-ready greenhouse gas analyzer.

Describes field testing of Picarro's fast analyzer for eddy covariance flux measurements of greenhouse gases.

Describes liquid water and water vapor isotope measurements with the Picarro isotopic water analyzer.

Describes how CRDS works and shows hydrogen, oxygen and carbon isotope data for water vapor, evapotranspiration, food and agricultural applications.

Describes specific design aspects of WS-CRDS-based analyzers and how these details result in ultra-stable field measurements.

From the EGU 2009 General Assembly, describing measurements of edible oils and chocolates made with Picarro's iTOC-CRDS Isotopic Carbon Analyzer.

Describes work by INSTAAR, NOAA & Picarro on both liquid water and water vapor measurements of stable water isotopes.

Describes the first field data taken by Oregon State University of Picarro's dual-species Eddy-Covariance analyzer.

Describing work by CSIRO, CO2 CRC and Picarro to characterize sequestration site leaks using tracers and isotopes.

Picarro has developed an isotope analyzer for lab and field measurements of carbon isotopes in CO₂ with the goal of allowing turnkey analysis to be done without the need for flask samples and complex IRMS methods. Here we present a description of the analyzer and its technology as well as recent results from two different collaborators who utilized the analyzer.

Results presented from field trials at Woods Hole Oceanographic Institute and laboratory tests at INSTAAR of a newly available analyzer capable of performing continuous measurements of stable isotopes (δD and δ18O) of liquid water and / or water vapor samples.

Description of field-deployable instrumentation that measures carbon dioxide, methane, and water vapor with both high-accuracy and high-precision would reduce the uncertainty in the determination of terrestrial sources and sinks of these dominant greenhouse gases.

Picarro has developed a field-deployable, real time, ambient gas monitor capable of measuring atmospheric levels of carbon dioxide, methane, hydrogen sulfide, and ammonia with parts-per-billion (ppbv) sensitivity and water vapor with parts-per-million (ppmv) sensitivity. Results from field trials of three different CO2 analyzers at Harvard, Penn State, and the NOAA facility in Boulder CO are shown.

Describes development of and results obtained from an analyzer engineered by Picarro for measuring six important atmospheric contaminants (hydrogen sulfide, ammonia, nitrous oxide, carbon dioxide, water vapor and methane) that are of interest to researchers monitoring Concentrated Animal Feeding Operations (CAFOs).

Direct quantification of fossil fuel CO₂ (CO₂ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in situ CO₂, CO, and CH₄ measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009. The flask samples were analyzed for Δ¹⁴CO₂ and CO₂ to determine the recently added CO₂ff mole fraction.

We investigated the moisture origin and contribution of different water sources to surface runoff entering the headwaters of the Heihe River basin on the basis of NECP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) re-analysis data and variations in the stable hydrogen and oxygen isotope ratios (δD and δ¹⁸O) of precipitation, spring, river, and melt water.

The hydrogen and oxygen isotope ratios of water vapor can be measured with commercially available laser spectroscopy analyzers in real time. Operation of the laser systems in relatively dry air is difficult because measurements are non-linear as a function of humidity at low water concentrations. Here we use field-based sampling coupled with traditional mass spectrometry techniques for assessing linearity and calibrating laser spectroscopy systems at low water vapor concentrations.

Bats are one of the most successful mammalian groups, even though their foraging activities are restricted to the hours of twilight and night-time. Some studies suggested that bats became nocturnal because of overheating when flying in daylight. This is because—in contrast to feathered wings of birds—dark and naked wing membranes of bats efficiently absorb short-wave solar radiation. We hypothesized that bats face elevated flight costs during daylight flights, since we expected them to alter wing-beat kinematics to reduce heat load by solar radiation.

Methane was the most abundant hydrocarbon released during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. Beyond relevancy to this anthropogenic event, this methane release simulates a rapid and relatively short-term natural release from hydrates into deepwater.

A new technique for high-resolution simultaneous isotopic analysis of δ¹⁸O and δD in liquid water is presented. A continuous stream flash evaporator has been designed that is able to vapourise a stream of liquid water in a continuous mode and deliver a stable and finely controlled water vapour sample to a commercially available infrared cavity ring-down spectrometer.

The doubly labeled water method provides an objective and accurate measure of total energy expenditure in free-living subjects and is considered the gold-standard method for this measurement. Its use, however, is limited by the need to employ isotope ratio mass spectrometry (IRMS) to obtain the high-precision isotopic abundance analyses needed to optimize the dose of expensive ¹⁸O-labeled water. Recently, cavity-ring down spectroscopy (CRDS) instruments have become commercially available and may serve as a less expensive alternative to IRMS.

The Deepwater Horizon oil spill was unprecedented in total loading of petroleum hydrocarbons accidentally released to a marine ecosystem. Controversial application of chemical dispersants presumably accelerated microbial consumption of oil components, especially in warm Gulf of Mexico surface waters. We employed δ¹³C as a tracer of oil-derived carbon to resolve two periods of isotopic carbon depletion in two plankton size classes.

Hydrogen (δ₂H) and oxygen (δ¹⁸O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy (IRIS; specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk ‘as is’ using IRIS.

Direct quantification of fossil fuel CO2(CO2ff) in atmospheric samples can be used toexamine several carbon cycle and air quality questions. We collected in-situ CO2, CO,and CH4 measurements and flask samples in the boundary layer and free troposphere5 over Sacramento, California, USA, during two aircraft flights over and downwind ofthis urban area during spring of 2009. The flask samples were analyzed for ∆14CO2and CO2to determine the recently added CO2ff mole fraction. A suite of additionalgreenhouse gases including hydrocarbons and halocarbons were measured in thesame samples.

To monitor the continental carbon cycle, a fullyautomated low maintenance measurement system is installedat the Zotino Tall Tower Observatory in Central Siberia(ZOTTO, 60◦480N, 89◦210E) since April 2009. A cavity ring-down spectroscopy (CRDS) analyzer continuouslymeasures carbon dioxide (CO2) and methane (CH4) fromsix heights up to 301 m a.g.l. Buffer volumes in each airline remove short term CO2 and CH4 mixing ratio fluctuations associated with turbulence, and allow continuous, nearconcurrent measurements from all tower levels.

High-accuracy continuous measurements of greenhouse gases (CO₂ and CH₄) during the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) phase B campaign in Brazil in May 2009 were accomplished using a newly available analyzer based on the cavity ring-down spectroscopy (CRDS) technique. This analyzer was flown without a drying system or any in-flight calibration gases.

A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic¹³C/¹²C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively.

This study demonstrates the application of Wavelength-Scanned Cavity Ring-Down Spectroscopy (WS-CRDS) technology which is used to measure the stable isotopic composition of water. This isotopic water analyzer incorporates an evaporator system that allows liquid water as well as water vapor to be measured with high precision.

Eleven instruments for the measurement of ambient concentrations of atmospheric ammonia gas (NH₃), based on eight different measurement methods were inter-compared above an intensively managed agricultural field in late summer 2008 in S. Scotland. To test the instruments over a wide range of concentrations, the field was fertilised with urea midway through the experiment, leading to an increase in the average concentration from 10 to 100 ppbv.

Researchers investigating global climate change need measurements of greenhouse gases with extreme precision and accuracy to enable the development and benchmarking of better climate models. Existing atmospheric monitors based on non-dispersive infrared (NDIR) sensors have known problems – they are non-linear, sensitive to water vapor concentration, and susceptible to drift. Many cannot easily be simultaneously calibrated across different sites to the level of accuracy required for use in atmospheric studies.

Recent measurements of carbon isotopes in carbon dioxide using near-infrared, diode-laser-based cavity ring-down spectroscopy (CRDS) are presented. The CRDS system achieved good precision, often better than 0.2‰, for 4% CO₂ concentrations, and also achieved 0.15–0.25‰ precision in a 78 min measurement time with cryotrap-based pre-concentration of ambient CO₂ concentrations (360 ppmv). These results were obtained with a CRDS system possessing a data rate of 40 ring-downs per second and a loss measurement of 4.0?×?10 -11  cm -1  Hz -1/2 .

We describe the application of cavity ring-down spectroscopy (CRDS) to the detection of trace levels of ethylene in ambient air in a cold storage room of a fruit packing facility over a several month period. We compare these results with those obtained using gas chromatography (GC), the current gold standard for trace ethylene measurements in post-harvest applications. The CRDS instrument provided real-time feedback to the facility, to optimize the types of fruit stored together, and the amount of room ventilation needed to maintain sub-10 ppb ethylene levels for kiwi fruit storage.

An historical overview of laser-based, spectroscopic methods that employ high-finesse optical resonators is presented. The overview begins with the early work in atomic absorption (1962) and optical cavities (1974) that led to the first mirror reflectivity measurements in 1980. This paper concludes with very recent extensions of cavity-enhanced methods for the study of condensed-phase media and biological systems. Methods described here include cavity ring-down spectroscopy, integrated cavity output spectroscopy, and noise-immune cavity-enhanced optical heterodyne molecular spectroscopy.

High fluences inside cavity ring-down spectroscopy optical resonators lend themselves to fluorescence or Raman spectroscopy. An instrument at 488 nm was developed to measure extinction, and fluorescence of aerosols. A detection limit of 6 x 10^-9 cm^-1Hz^-1/2 (0.6 Mm^-1Hz^-1/2) was achieved. The fluorescence spectral power collected from a single fluorescent microsphere was 10 to 20 pW/nm. This power is sufficient to obtain the spectrum of a single microsphere with a resolution of 10 nm and signal-to-noise ratio of ~10.