Infrared Gas Analyzer Research Articles

CO2 emission from soil in silage maize irrigated with wastewater under deficit irrigation in direct sowing practice

It is necessary to understand and measure the impact of tillage and irrigation practices on CO2 emissions from the soil with an environmental sensitivity, while wastewater irrigation increases crop biomass yield. The main objective of the present study was to investigate the changes and reasons in CO2 emissions from soil conventional and conservative tillage under different levels of wastewater irrigation. The CO2 emission from tillage-sowing to harvest over the regular measurements with a EGM-5 infrared gas analyzer device was investigated with three replicates in three deficit irrigation levels (0%, 33%, and 67%) of domestic recycled wastewater in conventional tillage and direct sowing practices. Binary relationships of CO2 emissions with H2O emission, air temperature, and the soil temperature and moisture measured at three different depths (5 cm, 10 cm, 20 cm) were also investigated and strong (p < 0.01) positive linear correlations were determined. Wastewater irrigation and conventional tillage significantly increased CO2 emissions compared to freshwater irrigation and direct sowing practice, while deficit irrigation practice decreased it. The direct sowing reduced seasonal CO2 emissions 25.1% and 26.1% for per unit area (1 ha) of silage maize and per unit of fresh silage yield (1 kg), respectively, compared to conventional tillage. The lowest CO2 emission per unit area and yield was determined in full irrigation treatment with freshwater in direct-sowing, while, in wastewater applications, it was determined in irrigation levels 33% per unit area and 67% per unit yield, under direct sowing. Thirty-three percent and 67% treatments in direct sowing resulted in less seasonal CO2 emissions as 38.7% per unit area and 13.8% per unit fresh silage yield, respectively compared to full irrigation treatment with freshwater in conventional tillage. Mean CO2 emissions in these treatments were found lower 17.9% per unit area and higher 17.8% per unit fresh silage yield compared to the full irrigation treatment with freshwater in direct-sowing. It was concluded that CO2 emissions per unit yield could be decreased with 33% water saving under wastewater irrigation conditions, and could be achieved environmental additional benefits from more decreasing CO2 emission by direct sowing also.

Using an IR camera to improve leaf area and temperature measurements: A new method for increasing the accuracy of photosynthesis-related parameters

Accurate measurements of leaf temperature and area are crucial to calculate leaf gas exchange parameters when using portable gas analysers such as the LI-6400 XT portable photosynthesis system (LI‐COR Inc., Lincoln, USA). The importance of leaf temperature data is well known for robust measurements, but there are still technical limitations in measuring it with full accuracy. Here we present a tentative solution by incorporating leaf temperature measurements with thermal imaging. An infrared (IR) camera (IRay T3 Pro, Shandong, China) was combined with a LI-6400XT to measure mean leaf temperatures while avoiding leaf thermal heterogeneity and to accurately calculate leaf area while avoiding destructive sampling. The thermal heterogeneity of Helianthus annuus and Zea mays leaves were studied. We then evaluated the accuracies of leaf area and temperature measurements obtained for 9 species and discussed the influences of these measurements on the resulting photosynthesis-related parameters. Our results provide direct visual evidence of the thermal heterogeneity of leaves in an infrared gas analyzer (IRGA) chamber. The temperature differences across the leaf surface were as high as 0.28°C∼1.38°C, causing large errors in stomatal conductance (gs, -5.07%∼-55.02%) and intercellular CO2 concentrations (Ci, -0.41%∼-6.72%). The IR camera reduced the area measurement error (-0.71∼0.29 cm2) and greatly increased the accuracy by -11.12%∼17.60% for the net photosynthesis (Pn) and transpiration rate (E) and by -11.24%∼17.69% for gs calculations. Our results showed that combining an IR camera with LI-6400XT can improve leaf area measurements, avoid thermal heterogeneity in leaves and thus dramatically improve the accuracy of photosynthesis-related parameter calculations under semi controlled and moderate climate conditions.

A Noninvasive Gas Exchange Method to Test and Model Photosynthetic Proficiency and Growth Rates of In Vitro Plant Cultures: Preliminary Implication for Cannabis sativa L.

Simple SummaryThe gas exchange system presented herein integrates open-flow/force ventilation, LED technology, and micropropagation to determine the impact of environmental factors (e.g., [CO2], sucrose, light intensity) on the photosynthetic capacity of cultured plantlets. This system was developed and tested on Cannabis sativa L., an emerging crop of high economic value, for which micropropagation has become an important aspect of production. Since conventional micropropagation avenues can minimize photosynthetic performance, this system offers fresh opportunities to examine the role of light signaling and photosynthesis in micropropagation to investigate and overcome in-vitro-associated morphophysiological disorders. By maintaining [CO2] at controlled levels (400 and 1200 ppm) with calibrated light intensities, photosynthetic light response curves were prepared based on net carbon exchange rates (NCERs) to paint a picture of the dynamic, combinational influences of irradiance, [CO2], and additional factors on photosynthetic performance. Additionally, NCERs were continuously monitored during a 24 h light/dark period under standard conditions to provide estimates of relative growth rates (daily C-gain). Thus, a system is presented with the ability to answer questions about the nature of in vitro plant physiology related to carbon dynamics, that would otherwise be difficult to assess. Supplemental sugar additives for plant tissue culture cause mixotrophic growth, complicating carbohydrate metabolism and photosynthetic relationships. A unique platform to test and model the photosynthetic proficiency and biomass accumulation of micropropagated plantlets was introduced and applied to Cannabis sativa L. (cannabis), an emerging crop with high economic interest. Conventional in vitro systems can hinder the photoautotrophic ability of plantlets due to low light intensity, low vapor pressure deficit, and limited CO2 availability. Though exogenous sucrose is routinely added to improve in vitro growth despite reduced photosynthetic capacity, reliance on sugar as a carbon source can also trigger negative responses that are species-dependent. By increasing photosynthetic activity in vitro, these negative consequences can likely be mitigated, facilitating the production of superior specimens with enhanced survivability. The presented methods use an open-flow/force-ventilated gas exchange system and infrared gas analysis to measure the impact of [CO2], light, and additional factors on in vitro photosynthesis. This system can be used to answer previously overlooked questions regarding the nature of in vitro plant physiology to enhance plant tissue culture and the overall understanding of in vitro processes, facilitating new research methods and idealized protocols for commercial tissue culture.

Design and fabrication of an improved dynamic flow cuvette for 13CO2 labeling in Arabidopsis plants

BackgroundStable isotope labeling is a non-invasive, sensitive means of monitoring metabolic flux in plants. The most physiologically meaningful information is obtained from experiments that take advantage of the natural photosynthetic carbon assimilation pathway to introduce a traceable marker with minimal effects on the physiology of the organism. The fundamental substrate in isotopic labeling experiments is 13CO2, which can reveal the earliest events in carbon assimilation and realistically portray downstream metabolism when administered under conditions suitable for making kinetic inferences. Efforts to improve the accuracy and resolution of whole plant labeling techniques have focused on improvements in environmental control, air flow characteristics, and harvesting methods.ResultsHere we present a dynamic flow cuvette designed for single Arabidopsis thaliana labeling experiments. We have also verified its suitability for labeling Nicotiana benthamiana and essential oils in Pelargonium graveolens. Complete plans for fabrication of this device are included. The design includes three important innovations. First, uniform, circular air flow over the rosette surface is accomplished by a fan and deflector that creates a mini-cyclone effect within the chamber interior. Second, a network of circulating canals connected to a water bath provides temperature control to within ± 0.1 ºC under variable irradiance, humidity, and air flow conditions. When photosynthetically active radiation (PAR) was varied over a range of 1000 μEinsteins m−2 s−1 with no adjustment to the external temperature control system, the abaxial leaf temperature changed by < 3 ºC/1000 PAR. Third, the device is fully compatible with liquid nitrogen quenching of metabolic activity without perturbation of the light environment. For short labeling experiments (< 10 s), the most critical variable is the half-life (t1/2) of the atmosphere within the chamber, which determines the maximum resolution of the labeling system. Using an infrared gas analyzer, we monitored the atmospheric half-life during the transition from 12CO2 to 13CO2 air at different flow rates and determined that 3.5 L min−1 is the optimal flow rate to initiate labeling (t1/2 ~ 5 s). Under these conditions, we observed linear incorporation of 13C into triose phosphate with labeling times as short as 5 s.ConclusionsAdvances in our ability to conduct short term labeling experiments are critical to understanding of the rates and control of the earliest steps in plant metabolism. Precise kinetic measurements in whole plants using 13CO2 inform metabolic models and reveal control points that can be exploited in agricultural or biotechnological contexts. The dynamic labeling cuvette presented here is suitable for studying early events in carbon assimilation and provides high resolution kinetic data for studies of metabolism in intact plants under physiologically realistic scenarios.

Temporal variation of soil CO2 emission in different land uses in the Caatinga

CO2 is an important gas for the biological cycle, as it plays a fundamental role in regulating the planet's temperature. Modifications in ecosystems promote an imbalance in carbon dynamics, causing more significant release into the atmosphere. The Caatinga biome, a dry forest type, has been anthropized since before the beginning of Brazil's colonization. Knowledge about the consequences of this anthropization in carbon stock changes in the soil is still scarce. This work aimed to evaluate the soil CO2 efflux in preserved and degraded sites in the Caatinga. CO2 emissions were collected in the field using an Infrared Gas Analyzer at four sampling points in the dry and rainy seasons of 2017. Texture, reactivity, nutrient content, and soil porosity were measured. Base saturation and texture were similar in the preserved and degraded sites. Preserved sites have higher C, N, P, and available water contents. Emission of CO2 increased with available water after rain events. Temperature, soil moisture, and land use influenced CO2 efflux, indicating the complexity of understanding the phenomenon. Degraded sites registered lower C stock and CO2 influx as an indication of desertification.

Change in the photochemical and structural organization of thylakoids from pea (Pisum sativum) under salt stress

Salt can induce adverse effects, primarily on the photosynthetic process, ultimately influencing plant productivity. Still, the impact of salt on the photosynthesis process in terms of supercomplexes organization of thylakoid structure and function is not understood in Pea (Pisum sativum). To understand the structure and function in the leaves and thylakoids under salt (NaCl) treatment, we used various biophysical and biochemical techniques like infrared gas analyzer, chlorophyll a fluorescence, circular dichroism, electron microscopy, blue native gels, and western blots. The net photosynthetic rate, transpiration rate, and stomatal conductance were reduced significantly, whereas the water use efficiency was enhanced remarkably under high salt conditions (200 mM NaCl). The photochemical efficiency of both photosystem (PS) I and II was reduced in high salt by inhibiting their donor and acceptor sides. Interestingly the non-photochemical quenching (NPQ) is reduced in high salt; however, the non-regulated energy dissipation (NO) of PSII increased, leading to inactivation of PSII. The obtained results exhibit inhibition of NAD(P)H dehydrogenase (NDH) mediated pathway-dependent cyclic electron transport under salinity caused a decrease in proton motive force of ΔpH and Δψ. Further, the electron micrographs show the disorganization of grana thylakoids under salt stress. Furthermore, the macro-organization and supercomplexes of thylakoids were significantly affected by high salt. Specifically, the mega complexes, PSII-LHCII, PSI-LHCI, and NDH complexes were notably reduced, ultimately altering the electron transport. The reaction center proteins of oxygen-evolving complexes, D1 and D2 proteins were affected to high salt indicating changes in photochemical activities.

Physicochemical Parameters and Microbial Community in Anaerobic Digestion of Organic Wastes

The demand for an alternative source of energy and challenge of increase in wastes pollution initiates the need for renewable energy and management of waste using anaerobic digestion (AD). Anaerobic digestion is an effective and efficient method of waste treatment and energy generation. The study focused on investigating the physicochemical parameters and microbial community in anaerobic digestion of organic wastes and was conducted using chicken wastes and food wastes as organic substrate under semi-continuous conditions at hydraulic retention time (HRT) of forty-two (42) days in fifteen liter (15L) fabricated digesters labeled D1, D2 and D3 at 37OC. The pH, volatile fatty acid (VFA), moisture content (MC), total ammonia, total solid, volatile solid, alkalinity was assessed before and after digestion while the microbial community diversity was analyzed using 16S rRNA amplicon-based nextgeneration sequencing (NGS). The results indicated a pH value of 6.65 ± 0.12, 7.27 ± 0.13, 6.43 ± 0.27, volatile fatty acid of 72.17 ± 1.42, 58.35 ± 2.58, 40.56 ± 0.38 and moisture content of 98.9 ± 2.65, 92.3 ± 1.81, 96.4 ± 3.60 at day 42 for D1 (Chicken waste and food wastes), D2 (Chicken wastes+), D3 (control) respectively. A collective biogas yield of 686±17.00 kpa for D1, 700±11.00kpa for D2 and 521±21.00 kpa for D3 were recorded. The characterization of biogas analyzed with nondispersive infrared (NDIR) gas analyzer (gas board 3100p) revealed a percentage methane content of 46.11±1.11, 52.4±1.05, 50.31±1.33 for D1, D2 and D3 respectively. The microbial community identified phylum Bacteroidetes, Firmicutes, proteobacteria, Tenericutes, Verrucomicrobia, Actinobacteria, Euryarchaeota among others. The study shows that physicochemical properties and microbial community diversity are useful tools to indicate digester performance and also to enhance anaerobic digestion process.

Development of Plant Photosynthesis Automatic Monitor Based on Infrared Gas Analysis

Development of Plant Photosynthesis Automatic Monitor Based on Infrared Gas Analysis

Anatomia foliar e parâmetros fotossintéticos de Vellozia squamata Pohl (Velloziaceae) desenvolvendo-se sob diferentes intensidades luminosas ao longo do cultivo in vitro

ABSTRACT The present work evaluates photosynthetic parameters and the leaf anatomy of plants of Vellozia squamata Pohl (Velloziaceae) in each phase of in vitro production, with wild plants serving as a control. The anatomical approach was done for the leaf middle portion. The photosynthetic curves were obtained with an infra-red gas analyzer. The in vitro plantlets showed the thinner and poorest developed leaves, the wild plants had the thickest and most developed leaves, and the plants in acclimatization showed intermediate features. The physiological pattern was similar, and the in vitro plantlets were not capable of net carbon absorption. The young seedlings at the garden showed a maximal net carbon assimilation rate inferior to the wild plants. In conclusion, the light intensity for the in vitro phase should be adjusted to produce seedlings.

Quantitative effects of environmental variation on stomatal anatomy and gas exchange in a grass model

Stomata are cellular pores on the leaf epidermis that allow plants to regulate carbon assimilation and water loss. Stomata integrate environmental signals to regulate pore apertures and adapt gas exchange to fluctuating conditions. Here, we quantified intraspecific plasticity of stomatal gas exchange and anatomy in response to seasonal variation in Brachypodium distachyon. Over the course of 2 years, we (a) used infrared gas analysis to assess light response kinetics of 120 Bd21-3 wild-type individuals in an environmentally fluctuating greenhouse and (b) microscopically determined the seasonal variability of stomatal anatomy in a subset of these plants. We observed systemic environmental effects on gas exchange measurements and remarkable intraspecific plasticity of stomatal anatomical traits. To reliably link anatomical variation to gas exchange, we adjusted anatomical g smax calculations for grass stomatal morphology. We propose that systemic effects and variability in stomatal anatomy should be accounted for in long-term gas exchange studies.

Photosynthesis of Physalis peruviana under different densities of photons and saline stress

Physalis peruviana L. is a solanacea that has been gaining prominence due to its fruits presenting good acceptance in the national and international market. However, several abiotic factors, such as salinity, can cause physiological disturbances in plants, and these changes may be of greater or lesser intent according to species. Therefore, the objective of the present work was to evaluate the physiological behavior of P. peruviana submitted to different fluxes of photosynthetically active photons (PPFD) and saline stress. The experimental design was a randomized block design with three saline levels (ECw) (0.5, 2.75 and 5.00 dS m-1) with four replications. Gas exchange measurements were performed with a portable infrared gas analyzer. Liquid CO2 assimilation, stomatal conductance, internal CO2 concentration, water use efficiency and instantaneous carboxylation efficiency were measured. Data were subjected to analysis of variance by F test and in cases of significance applied to regression analysis. The increase in PPFD provided reductions in stomatal conductance up to the density of approximately 400 μmol m-2s-1, being more pronounced in ECw of 2.75 and 5.0 dS m-1. The maximum CO2 assimilation rates in the three salinities are different according to the PPFD. The salinity of irrigation water reduced the quantum efficiency of photosynthesis in P. peruviana plants.

Alternative oxidase (AOX) in the carnivorous pitcher plants of the genus Nepenthes: what is it good for?

The carnivorous pitcher plants of the genus Nepenthes have evolved modified leaves that act as pitcher traps. The traps are specialized for prey attraction, capture, digestion and nutrient uptake but not for photosynthetic assimilation. In this study, we used antibodies against different photosynthetic (D1, Lhcb2, Lhcb4, RbcL) and respiratory-related (AOX, COXII) proteins for semi-quantification of these proteins in the assimilation part of the leaves and the pitcher traps of different Nepenthes species and hybrids. Different functional zones of the trap and the traps from different ontogenetic stages were investigated. The pitcher traps of the distantly related species Sarracenia purpurea ssp. venosa were used as an outgroup. In addition, chlorophyll fluorescence and infrared gas analysis were used for measurements of the net rate of photosynthesis (AN) and respiration in the dark (RD). The pitcher traps contained the same or lower abundance of photosynthesis-related proteins in accordance with their low AN in comparison to the assimilation part of the leaves. Surprisingly, all traps contained a high amount of alternative oxidase (AOX) and low amount of cytochrome c oxidase subunit II (COX II) than in the assimilation part of the leaves. Thermal imaging did not confirm the role of AOX in pitcher thermogenesis. The pitcher traps contain a high amount of AOX enzyme. The possible role of AOX in specialized pitcher tissue is discussed based on knowledge of the role and function of AOX in non-carnivorous plants. The roles of AOX in prey attraction, balance between light and dark reactions of photosynthesis, homeostasis of reactive oxygen species, digestive physiology and nutrient assimilation are discussed.

Competitive ability of canola (Brassica napus var. oleifera) hybrids with black oat (Avena strigosa) in a subtropical environment

The objective of this study was to assess the competitive ability of canola (Brassicanapus var. oleifera) hybrids in competition with black oat (Avena strigosa) in a subtropical environment. The experiments were conducted in a greenhouse where canola hybrids ‘Hyola 61,’ ‘Hyola 76,’ ‘Hyola 433,’ and ‘Hyola 571’ were tested individually for their competitive performance with black oat. The plant proportion between black oat and the canola hybrid was changed (100%:0%; 75%:25%; 50%:50%; 25%:75%; and 0%:100%) while keeping the total population of plants constant (20 plants plot‑1). Photosynthesis rate (μmol m-2 s-1), internal CO2 concentration (μmol mol-1), and transpiration rate (mol H2O m-2 s-1) were assessed using an infrared gas analyzer 55 days after emergence. Leaf area (m2 m-2) and dry matter (g m-2) were also assessed on the same day. The data set was analyzed by the replacement series method for competition studies. There was evidence of intense competition between canola and black oat, independent of plant proportion. The competitive ability of canola was distinct among hybrids; Hyola 571 performed better than the others in the competition against black oat. Choosing the most competitive hybrid, such as Hyola 571, helps maintain high canola grain yield levels in areas infested with black oat. Highlights: There is difference in competition among canola hybrids against black oat; Hyola 571 performed better in the competition; Preference should be given for most competitive canola genotypes against weeds, and weed control should be carried out early in the critical period of interference; Aggressiveness is the most preponderant parameter in determining canola genotypes with superior ability in competition against weeds.

In-depth temperature and smoke production of charring wood under a constant external heat flux

The combustion characteristics of charring wood have been studied experimentally in a well-ventilated environment of a smoke chamber. A numerical simulation has also been performed for a limited case, with the Fire Dynamics Simulator, to estimate the burning environment. A horizontally placed specimen (ponderosa pine) with a moisture content of 0% or 20% is exposed to a radiant flux (25 kW/m2), with or without flaming ignition. Simultaneous measurements of the specimen’s in-depth temperature and the mass loss determine the charring front (rate) at 300 °C and the gasification rate, respectively. These condensed-phase conditions relate directly to real-time variations of gas-phase quantities: the specific optical density of smoke and the concentrations of toxic gases measured by a Fourier transform infrared gas analyzer. In-depth temperature trends are similar whether the flame exists, whereas the smoke and toxicants’ concentrations are substantially different. After the charring front moves through the specimen, the oxidative pyrolysis continues under the irradiation at high temperatures (up to ∼550 °C). Carbon monoxide and acrolein are produced continuously throughout the test, and the results indicate strong correlations. Although char formation of wood is favorable for fire safety, consequent incomplete combustion produces smoke and toxicants.

Application of gas analyzers for the control of fuel in the air environment of rocket and space industry enterprises

The presented work shows the necessity of organization of individual instrumental control of the content of rocket fuel and its products in the air of rocket-space industry enterprises. No accurate analysis of gas analyzers presented on the Russian market, providing individual instrumental control of concentrations of heptyl and its derivatives in the workplace air is available. Therefore, the task of express, automatic, selective and simultaneous monitoring of heptyl vapors and derivatives of its transformation in the air of industrial premises by one instrument and replacing the imported gas analyzers remains urgent. It is shown that the solution of the posed problem is possible on the basis of the optical absorption method. The requirements to be met by the gas analyzer are formulated. Approximate wavelengths at which simultaneous measurement of concentrations of heptyl and its derivatives in an air sample is possible have been determined. The ways of realization of individual gas analyzers having small mass-size characteristics are outlined. Structural schemes for infra-red gas analyzers have been proposed: multi-channel; single-channel (with frequency modulation of radiation). Tasks for further research are formulated.

Gas Emission Study of the Polyacrylonitrile-Based Continuous Pilot-Scale Carbon Fiber Manufacturing Process

Despite the many positive aspects of carbon fiber arising from its light-weighting potential, high cost and related environmental impact may inhibit even wider usage of the material in future. The need to incinerate gaseous emissions generated during manufacture significantly contributes to both eco-impact and cost, while information regarding these emissions on a production line scale is lacking due to the confidentiality behind commercial carbon fiber manufacturing. A detailed assessment of the evolved gases generated during carbon fiber production and the underlying mechanisms using a state-of-the-art production scale research facility and in situ Fourier transform infrared gas analysis is reported for the first time. A commercially available polyacrylonitrile precursor was converted into carbon fibers, analyzing the most significant exhaust gases from each production step. To identify and quantify the evolved gases during transformation from the precursor to carbon fibers, the evolution of the chemical composition and mass throughout the process was studied. The emissions of HCN, NH3, CO, and CH4 were analyzed and correlated with the changing elemental composition of the processed fibers. Changes in the concentration of specific elements in the fibers were shown to be mirrored by the composition of the gaseous emissions, and responsible chemical mechanisms were introduced.

Ecophysiological responses of Terminalia sericea to fire history in a semi-arid woodland savanna, central Namibia

Woody vegetation is increasing in savanna ecosystems worldwide. Fire is frequently used as a management tool to decrease bush encroachment, but knowledge regarding the underlying leaf-level ecophysiological responses to fire history is lacking. In southern Africa, Terminalia sericea is a dominant encroaching species that resprouts readily following fires. The impact of fire on leaf-level photosynthesis, transpiration, conductance and water use efficiency was investigated using infrared gas analysis. Data were collected in three areas on the Waterberg Plateau with different fire histories (fire occurring 2, 3 and 15 years prior to sampling). Leaf-level photosynthetic rates were comparable to the relatively high rates shown by other encroaching bush species. In contrast to expectations, ecophysiological variables did not differ among plants in areas with different fire histories. However, photosynthetic rates were highly sensitive to variation in light level, suggesting that canopy structural differences may affect carbon fixation and growth rates at the whole-plant level. Encroachment by T. sericea may be facilitated, at least in part, by high leaf-level photosynthetic rates that are insensitive to long-term fire history on sandy, low-nutrient soils.

Ammonia Generation System for Poultry Health Research Using Arduino.

An ammonia gas (NH3) generator was developed to maintain a set concentration of ammonia gas in a controlled environment chamber to study poultry physiological responses to sustained elevated levels of ammonia gas. The goal was to maintain 50 parts per million (ppm) of ammonia gas in a 3.7 m × 4.3 m × 2.4 m (12 ft × 14 ft × 8 ft) controlled environment chamber. The chamber had a 1.5 m3/s (3000 cfm) recirculation system that regulated indoor temperature and humidity levels and a 0.06 m3/s (130 cfm) exhaust fan that exchanged indoor air for fresh outdoor air. The ammonia generator was fabricated by coupling ultrasonic humidifiers with an Arduino-based microcontroller and a metallic oxide MQ-137 ammonia gas sensor. Preliminary evaluation under steady conditions showed the average MQ-137 gas sensor accuracy was within 1.4% of the 65.4 ppm concentration measured using a highly accurate infrared gas analyzer. Further evaluation was performed for a setpoint concentration of 50 ppm where ammonia generator reservoirs were filled with 2% or 10% ammonia liquid. For the system tested, it was found that two generators operating at the same time filled with 3.8 L (1.0 gallon) of 2% ammonia cleaning liquid each (7.6 L or 2.0 gallons total) could maintain a gas level of 49.45 ± 0.79 ppm in the chamber air for a duration of 30 h before refilling was required. One generator filled with 3.8 L of 10% ammonia cleaning liquid could maintain 51.24 ± 1.53 ppm for 195 h. Two ammonia generators were deployed for a six-week animal health experiment in two separate controlled environment chambers. The two ammonia generators maintained an average ammonia concentration of 46.42 ± 3.81 ppm and 45.63 ± 4.95 ppm for the duration of the experiment.

Investigating green roofs' CO2 sequestration with cold- and drought-tolerant plants (a short- and long-term carbon footprint view).

In recent years, green roofs have become the subject of increasing interest because of their good aesthetic qualities, energy conservation, and ability to reduce thermal island effect and absorb greenhouse gases, especially carbon dioxide (CO2). Given the typically significant carbon emission of construction activities, adding any extra component to a structure increases the amount of carbon to be released during the execution stage. This also applies to green roofs, which require more materials and more extensive construction activities than traditional roofs. However, plants of green roofs absorb substantial amounts of CO2 during their lifetime, thus leaving both short- and long-term positive impacts on the building's carbon footprint. This study investigated the short- and long-term effects of green roofs on carbon footprint, as compared to conventional roofs. For this investigation, the CO2 uptake of eight plant species with suitable drought- and cold-resistant properties was measured by infrared gas analysis (IRGA), and the effect of green roof on the building's carbon footprint was analyzed using the software Design Builder. The results showed that building a green roof instead of a traditional roof increases the carbon emission of the construction process by 4.6 kg/m2 of roof area. Investigations showed that, under high light intensities (1500-2000 μmol/m2 s), Sedum acre L. has the best performance in compensating the extra carbon emission imposed on the construction process (in 264 days only). Under low light intensities (1000-1500 μmol/m2 s), Frankenia laevis showed the best increase in the amount of carbon uptake (2.27 kg/m2 year).

Based on Atmospheric Physics and Ecological Principle to Assess the Accuracies of Field CO2/H2O Measurements From Infrared Gas Analyzers in Closed‐Path Eddy‐Covariance Systems

AbstractField CO2/H2O measurements from infrared gas analyzers in closed‐path eddy‐covariance systems have wide applications in earth sciences. Knowledge about exactness of these measurements is required to assess measurement applicability. Although the analyzers are specified with uncertainty components (zero drift, gain drift, cross‐sensitivities, and precision), exactness for individual measurements is unavailable due to an absence of methodology to comprehend the components as an overall uncertainty. Adopting an advanced definition of accuracy as a range of all measurement uncertainty sources, the specified components are composited into a model formulated for studying analyzers’ CO2/H2O accuracy equations. Based on atmospheric physics and environmental parameters, the analyzers are evaluated using the equations for CO2 accuracy (±0.78 µmolCO2 mol−1, relatively ±0.18%) and H2O accuracy (±0.15 mmolH2O mol−1). Evaluation shows that precision and cross‐sensitivity are minor uncertainties while zero and gain drifts are major uncertainties. Both drifts need adjusting through zero/span procedures during field maintenance. The equations provide rationales to guide and assess the procedures. H2O span needs more attentions under humid conditions. Under freezing conditions while H2O span is impractical, this span is fortunately unnecessary. Under the same conditions, H2O zero drift dominates H2O measurement uncertainty. Therefore, automatic zero becomes a more applicable and necessary tactic. In general cases of atmospheric CO2 background, automatic CO2 zero/span procedures can narrow CO2 accuracy by 36% (±0.74 to ± 0.47 µmolCO2 mol−1). Automatic/manual H2O zero/span procedures can narrow H2O accuracy by 27% (±0.15 to ±0.11 mmolH2O mol−1). While ensuring system specifications, the procedures guided by equations improve measurement accuracies.