Nitrogen removal by eutrophic coastal wetlands accomplished with CH4 emission reduction
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
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
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
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 NOx Emissions from Natural Gas Stoves, Cooktops, and Ovens in Residential Homes
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.
Recent Advances in Real-time, Continuous, Sub-ppb Formaldehyde Measurements at Ambient Air Quality Monitoring Stations
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.
Improved throughput for δ18O and δD measurements of water with Cavity Ring-Down Spectroscopy
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.
An open-source, automated, gas sampling peripheral for laboratory incubation experiments using cavity ring-down spectroscopy
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
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
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.
Continuous and simultaneous measurement of triple-oxygen and hydrogen isotopes of liquid and vapor during evaporation experiments
https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/rcm.9078
https://doi.org/10.1002/rcm.9078
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
Tracking the direct impact of rainfall on groundwater at Mt. Fuji by multiple analyses including microbial DNA
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.
Studying catchment storm response using event- and pre-event-water volumes as fractions of precipitation rather than discharge
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.
Stable Isotopes of Precipitation During Tropical Sumatra Squalls in Singapore
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.
Measurement of Gross Photosynthesis, Respiration in the Light, and Mesophyll Conductance Using H218O Labeling
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-Frequency Water Isotopic Analysis Using an Automatic Water Sampling System in Rice-Based Cropping Systems
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).
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
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.
A new interpretative framework for below-cloud effects on stable water isotopes in vapour and rain
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.
Novel Materials for Combined Nitrogen Dioxide and Formaldehyde Pollution Control under Ambient Conditions
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
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
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
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
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
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
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.
Novel Materials for Combined Nitrogen Dioxide and Formaldehyde Pollution Control under Ambient Conditions
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.
Formation and emission of hydrogen chloride in indoor air
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
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.
Methane and nitrous oxide porewater concentrations and surface fluxes of a regulated river
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,
A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects
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.
CH4 uptake along a successional gradient in temperate alpine soils
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.
High-precision cavity ringdown measurements of δ13CO2 and δ13CH4 along the Eastern North Atlantic onboard the sailing research vessel Fleur de Passion
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.
Measuring isotopic N2O, CO2 and CH4 soil flux with cavity ring-down spectroscopy
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.
Metabolic Fates of Evening Crop-Stored Sugar in Ruby-Throated Hummingbirds (Archilochus colubris)
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)
Monitoring the efficiency of a portable air cleaner for formaldehyde removal with a Cavity Ring-Down Spectrometer
• 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.
The Influence of sea ice on ocean water vapor isotopes and Greenland ice core records
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
Central Europe temperature constrained by speleothem fluid inclusion water isotopes over the past 14,000 years
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.
Local- and regional-scale measurements of CH4, d13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer
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.
Validation of ammonia diffusive and pumped samplers in a controlled atmosphere test facility using traceable Primary Standard Gas Mixtures
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
Evaluation of the IAGOS-Core GHG package H2O measurements during the DENCHAR airborne inter-comparison campaign in 2011
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.
High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques
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.
High Precision Continuous and Real-Time Measurement of Oxygen Using Cavity Ring-Down Spectroscopy for Photosynthetic Light-Response Studies
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.
Quantification of Ammonia and Greenhouse Gases in Ambient Air of a Livestock House Using a Single Near-Infrared Cavity-Ringdown Spectroscopy Instrument
Stable carbon isotope analysis of airborne particulate matter using a carbon aerosol analyzer and a cavity ringdown spectrometer
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.
High-Precision Continuous and Real-Time Measurements of Atmospheric Oxygen Using CRDS
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.