Premise
Water is the most limiting factor in dryland ecosystems, and plants are adapted to cope with this constraint. Particularly vulnerable are phreatophytic plants from groundwater-dependent ecosystems (GDEs) in regions that have to face water regime alterations due to the impacts of climate and land-use changes.

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

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.

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.

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.

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.

Atmospheric oxidation is dominated by the OH radical, although Cl atoms can play an important role under certain conditions.

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.

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.

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).

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.

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.

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.

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.

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.

EPA Method T0-11A EPA outlines practices for measuring formaldehyde using the 4,2-DNPH denuder method, subsequent derivatization, and analysis by HPLC. While the DNPH method has been a stalwart of air quality monitoring for decades, it provides only time-averaged exposure estimates (typically 8 or 24-hour), requires offline analysis at third-party labs, and continues to experience suspected bias effects associated with ozone and water vapor. Because values are reported significantly post-hoc, formaldehyde also cannot be integrated into air quality monitoring forecasts.

Oxygen (18O/16O) and deuterium (D/H) isotopes are a widespread tool to trace physical and chemical processes in hydrology and biogeosciences. Precision and throughput are key parameters for water isotope analysis. Here, we will present two new methodologies for the Picarro L2130-i Cavity Ring-Down Spectroscopy (CRDS) water isotope analyzer that allow the user to increase the throughput with compromising data quality.

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.

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.

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.

https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/rcm.9078
https://doi.org/10.1002/rcm.9078

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

• Ammonia is a toxic pollutant that has harmful effects on human health and the environment.

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.

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.