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,

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.

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.

Differentiating microbial, anthropogenic, and thermogenic sources of carbon dioxide (CO₂) and methane (CH₄) in background air is an important element of understanding
upper ocean ecosystem processes. Here we present isotopic data of carbon dioxide and methane from the Fleur de Passion sailing research vessel which traveled from Dakar (Senegal) to Carbo Verde, the Azores, and to France between April and October 2019 as part of the larger Ocean Mapping Expedition by the Geneva based NPO Fondation Pacifique.

Atmospheric concentrations of N₂O, CO₂and CH₄ are currently steadily increasing, and in the case of N₂O, the increase in emissions is mainly linked to the increased use of fertilizers in agricultural soils. Stable isotope analysis of these trace gases is a valuable tool to better understand production and consumption pathways in soils and this process understanding will ultimately help to reduce greenhouse gas emissions from crop production.

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)
using respirometry and 13C stable isotope analysis. Hummingbirds were fed a 13C-enriched sugar

•  The air quality inside vehicles is affected by the intake of polluted air and by outgassing of fabrics.
•  Airlabs developed a portable air cleaner, the airbubbl, to remove particulate matter, NO2 and other pollutants from air. A new filter was designed to also remove formaldehyde.
•  Here, we present the performance of the new formaldehyde filter, also in comparison to a range of different adsorbents and catalysts.

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

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.

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.

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

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.

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.

Photosynthesis is a complex process that consumes carbon dioxide and water to produce oxygen and glucose. Studies to investigate leaf-level photosynthetic activity have been conducted using systems that control certain parameters such as light intensity or partial pressure of CO2. For instance, the LI-COR LI‑6800 Portable Photosynthesis System enables the user to control and measure light, temperature, CO2 and water vapor concentrations.

Particulate matter affects more people than any other ambient air pollutant, leading to increased risk of cardiovascular and respiratory diseases.  Levels of PM10 and PM2.5 in the developing world, especially southeast Asia and the Indian subcontinent, routinely exceed World Health Organization guidelines, often by a factor of 10 or more.  Despite their importance to poor air quality in urban areas in the developing world, the mechanisms that lead to heavy particulate loading are not well understood.

Oxygen is a major and vital component of the Earth atmosphere representing about 21% of its oomposition. It is consumed or produced through biochemical processes such as oombustion, respiration, and photosynthesis. Although atmospheric oxygen is not a greenhouse gas, It can be used as a top down constraint on the carbon cycle.The variation observations of oxygen in the atmosphere are very small, in the order of the few ppm's.

Photosynthesis and respiration of CO, by forests are two major unknowns in the global carbon cycle. They are the two largest and most variable fluxes, and their difference currently acts as a global net sink. With this project (2017-2020) we aim to provide new insights in the forest carbon balance by separately quantifying photosynthesis and respiration using atmospheric measurements. The method is based on the inverse relationship between oxygen (O,) and CO, which is different for photosynthesis and respiration (e.g. lshidoya et al., 2015).

Nitrous oxide (N₂O) gas is among the major contributors to global warming and ozone depletion in stratosphere. Quantitative estimate of N₂O production in various pathways and N₂O fluxes across different reservoirs is the key to understanding the role of N₂O in the global change. To achieve this goal, accurate and concurrent measurement of both N₂O concentration ([N₂O]) and its site-specific isotopic composition (SP-d¹⁵N), namely d¹⁵N-a and d¹⁵N-b, is desired.

In the last several years, economically motivated adulteration (EMA) of foods has received increased attention. Two popular targets are lemon juice and honey For both of these types of adulteration analyses, the FCC is evaluating the use of Cavity Ring Down Spectroscopy (CRDS) to establish its suitability in comparison to the well established technique Isotope Ratio Mass Spectrometry IRMS)

Natural gas analysis and methane specifically have become increasingly important by virtue of methane’s 28-36x greenhouse warming potential compared to CO₂ and accounting for 10% of total greenhouse gas emissions in the US alone. Determining the specific fingerprint of methane sources by quantifying the ethane to methane (C2:C1) ratios provides us with means to understand processes yielding methane and allows for sources of methane to be mapped and classified through these processes; i.e. biogenic or thermogenic, oil vs. gas vs. coal gas-related.

High-precision greenhouse gas (GHG) measurements in remote locations are typically conducted by mobile labs that host cumbersome and high-power analyzers.
The GasScouter is a new generation of high-performance and low-power GHG analyzers.
In this poster, we introduce the GasScouter and present the results collected through various lab testing and field deployments to validate the performance of the analyzer.

Preservation and restoration of wetlands have the potential to help sequester large amounts of carbon due to the naturally high primary productivity and slow turnover of stored soil carbon. However, the anoxic environmental conditions present in wetland soils are also the largest natural contributor to global methane emissions. Therefore, uptake, storage, and loss of CO₂ and CH₄ need to be carefully considered when evaluating the climate effects of land-use change.

Methane is a potent greenhouse gas that has a short-term global warming impact. It comes from a variety of natural and anthropogenic sources which include wetlands, landfills, oil/gas/coal extraction activities and natural gas distribution leaks. Locating and containing these emissions are critical to minimizing their environmental impacts and economically beneficial when retrieving large fugitive amounts. Generally, methane detection is conducted by making real-time atmospheric measurement and identifying large variations from the typical atmospheric concentration of 2 ppm.

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.

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.).

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.

A laboratory and field experiment compared fluxes of CO₂, CH₄ and N₂O measured with cavity ring-downspectroscopy (CRDS) and gas chromatography (GC). The comparison between CRDS and GC showed thataverage CO₂ fluxes were significantly higher for CRDS in both the laboratory and field, but the same experimental treatments effects were detected for both techniques. Compared to CRDS, the GC technique was severely limited in detecting CH₄ fluxes in both the laboratory and field.

The necessity for constant monitoring of greenhouse gases (GHGs) is clearly evident now more than ever. Moreover, interpreting and understanding the processes that dictate the production and consumption of these gases will allow for proper management of GHGs in order to mitigate its detrimental climate effects. Presence of oxygen, or lack of it, is the driving force for determining pathways within biochemical redox reactions. Experiments to find correlations between oxygen and greenhouse gases have helped us understand photosynthesis, denitrification and beyond.

With a global warming potential of nearly 300, N2O is a critically important greenhouse gas, contributing about 5 % of the US total GHG  emissions.  Agriculture soil management practices are the dominant source of anthropogenic N2O emissions, contributing nearly 75 % of US N2O emissions.  In urban areas, vehicle tailpipe emissions and waste water treatment plants are significant sources of N2O.  We report here a new mid-infrared laser-based cavity ring-down spectrometer (Picarro G5310) that was recently developed to measure sub-ppb ambient concentrations of two key green

Soil flux chamber measurements are a key tool for determining production and sequestration of direct and indirect greenhouse gases. The Picarro G2508 Cavity Ring-down Spectrometer radically simplifies soil flux analyses by providing simultaneous measurements of five gases: CO2, CH4, N2O, NH3, and H2O, and by ready field deployment.

High-salinity waters such as Seawater poses an operational and maintenance challenge to the measurements of water stable isotopes via Cavity Ring-Down Spectroscopy. As liquid samples are evaporated in the vaporizer peripheral before being sent to the CRDS analyzer, salt precipitates accumulate in the vaporizer chamber. As a result, the sample-to-sample memory performance degrades over time and frequent cleaning is required to maintain the peripheral performance and integrity.

In a paper published by the Integrated Carbon Observation System (ICOS), the drift performance of 47 Picarro analyzers of 3 different generations were compared (Yver Kowket al, Atmos. Meas. Tech. Discuss., 8, 4219–4272, 2015). The results show that methane drift (the minimum of the Allan standard deviation) was much better in first-generation G1000 analyzers.

Deuterium (dD) and oxygen (d18O) isotopes are powerful tracers of the hydrological cycle and have been extensively used for paleoclimate reconstructions as they can provide information on past precipitation,temperature and atmospheric circulation. More recently, the use of 17O excess derived from precise measurement of d17O and d18O gives new and additional insights in tracing the hydrological cycle whereas uncertainties surround this proxy.

Laser-based spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), provide a new, costeffective and more widely available approach to measure the oxygen isotope ratio in water molecules, H218O/H216O (d18O), and are used increasingly to measure d18O in the world’s oceans. Here, we present results froman interlaboratory comparison designed to evaluate the quality of CRDS-derived measurements, and theirconsistency with values measured by isotope ratio mass spectrometry (IRMS).

The isotopic composition of near surface (or planetary boundary layer) water vapor on the south coast of Iceland (63.83°N, 21.47°W) has been monitored in situ between November 2011 and April 2013. The calibrated data set documents seasonal variations in the relationship between δ¹⁸O and local humidity (ppmv) and between deuterium excess and δ¹⁸O. These seasonal variations are attributed to seasonal changes in atmospheric transport.

Insights into the effects of stormwater control measures (SCMs) on urban stream hydrology and in-stream processes are required to understand their effectiveness in mitigating the environmental problems associated with urbanization. Stable water isotopes were applied to understand processes occurring within SCMs and their effects on water sourcing in urban streams. We sampled ten events from June to November 2013 at four locations along a 360-m headwater stream reach in North Carolina and at four SCMs (two ponds, one wetland and one bioretention) that contribute to the reach.

Temperature reconstructions across Heinrich stadials 1–3 are presented from an absolute-dated speleothem from Abaco Island in the Bahamas to understand the nature of climate change across these intervals in the subtropical Atlantic. The stalagmite carbonate record, dated by the U–Th geochronometry technique, includes higher δ¹⁸O and δ¹³C values within Heinrich stadials 1, 2, and 3 followed by rapid declines at the end of the stadials.

A portable Wavelength Scanned-Cavity Ring-Down Spectrometer (Picarro L2120) fitted with a diffusion sampler (DS-CRDS) was used for the first time to continuously measure δ¹⁸O and δ²H of stream water. The experiment took place during a storm event in a wet tropical agricultural catchment in north-eastern Australia.

This study presents two methods for estimating methane emissions from a waste water treatment plant (WWTP) along with results from a measurement campaign at a WWTP in Valence, France. These methods, chamber measurements and tracer release, rely on Fourier transform infrared spectroscopy and cavity ring-down spectroscopy instruments. We show that the tracer release method is suitable for quantifying facility- and some process-scale emissions, while the chamber measurements provide insight into individual process emissions. Uncertainties for the two methods are described and discussed.

We present a study of methane emissions from oil and gas producing well pad facilities in the Barnett Shale region of Texas, measured using an innovative ground-based mobile flux plane (MFP) measurement system, as part of the Barnett Coordinated Campaign. Using only public roads, we measured the emissions from nearly 200 well pads over 2 weeks in October 2013.

The replacement of native species by invasive Phragmites australis in coastal wetlands may impact ecosystem processes including fluxes of the greenhouse gases (GHGs) carbon dioxide (CO₂) and methane (CH₄).

Fugitive greenhouse gas emissions from unconventional gas extraction processes (e.g. shale gas, tight gas and coal bed methane/coal seam gas) are poorly understood due in part to the extensive area over which these emissions may occur. We apply a rapid qualitative approach for source assessment at the scale of a large gas field.

Floods frequently produce deoxygenation and acidification in waters of artificially drained coastal acid sulfate soil (CASS) wetlands. These conditions are ideal for carbon dioxide and methane production. We investigated CO₂ and CH₄ dynamics and quantified carbon loss within an artificially drained CASS wetland during and after a flood.

Automated cavity ring down spectroscopy was used to make continuous measurements of dissolved methane, nitrous oxide, and carbon dioxide in a coral reef lagoon for 2 weeks (Heron Island, Great Barrier Reef). Radon (²²²Rn) was used to trace the influence of tidally driven pore water exchange on greenhouse gas dynamics. Clear tidal variation was observed for CH₄, which correlated to ²²²Rn in lagoon waters.

Estuaries have high rates of primary production and respiration and can be hotspots for carbon dioxide and methane enriched submarine groundwater discharge.

Automated in situ instrumentation captured high-resolution surface water pCO₂, CH₄ and²²²Rn data at the creek mouth, and ∼500 m upstream in a sub-tropical mangrove ecosystem (Southern Moreton Bay, Australia, S27.78°, E153.38°) over a spring-neap-spring tidal cycle (∼15 days) during November 2013.

We present a novel determination of the dissolution kinetics of inorganic calcite in seawater.