Infrared Gas Analyzer Research Articles

Fluxfinder: An R Package for Reproducible Calculation and Initial Processing of Greenhouse Gas Fluxes From Static Chamber Measurements

AbstractFluxes of greenhouse gases are a critical component of the earth's natural climate, but anthropogenic emissions have created an imbalance and resulted in global climate change. Quantifying the emission of these gases is vital to our understanding of their sources and sinks, both natural and anthropogenic. The static chamber method, in which a system of interest is enclosed, and gas concentrations are measured over time, is widely used to estimate fluxes of greenhouse gases. With the development of instruments such as infrared gas analyzers (IRGAs) supporting high‐frequency concentration data, there is a growing need for open‐source workflows to calculate fluxes. Here we present fluxfinder, an R package designed to support reproducible calculations and processing of greenhouse gas fluxes measured with the static chamber method. The package includes raw data file parsing from widely used IRGAs, metadata matching, unit conversion, flux estimations, and initial quality assurance/quality control (QA/QC). Diagnostic graphical plots provide a transparent way to differentiate between measurement issues and nonlinear behavior. The package is also designed to be easily integrated with the gasfluxes package for further fitting of nonlinear concentration‐time models, allowing alternative or additional flux QA/QC. The fluxfinder package offers a flexible workflow that is easily adaptable to promote open and reproducible greenhouse gas flux estimations.

Measuring CO2 assimilation of Arabidopsis thaliana whole plants and seedlings

Photosynthesis is an essential process in plants that synthesizes sugars used for growth and development, highlighting the importance of establishing robust methods to monitor photosynthetic activity. Infrared gas analysis (IRGA) can be used to track photosynthetic rates by measuring plant CO2 assimilation and release. Although much progress has been made in the development of IRGA technologies, challenges remain when using this technique on small herbaceous plants such as Arabidopsis thaliana. The use of whole plant chambers can overcome the difficulties associated with applying bulky leaf clamps to small delicate leaves. However, respiration from the roots and from soil-based microorganisms may skew these gas exchange measurements. Here, we present a simple method to efficiently perform IRGA on A. thaliana plants using a whole plant chamber that removes the confounding effects of respiration from roots and soil-based microorganisms from the measurements. We show that this method can be used to detect subtle changes in photosynthetic rates measured at different times of day, under different growth conditions, and between wild-type and plants with deficiencies in the photosynthetic machinery. Furthermore, we show that this method can be used to detect changes in photosynthetic rates even at very young developmental stages such as 10 d-old seedlings. This method contributes to the array of techniques currently used to perform IRGA on A. thaliana and can allow for the monitoring of photosynthetic rates of whole plants from young ages.

Wind speed affects the rate and kinetics of stomatal conductance.

Understanding the relationship between wind speed and gas exchange in plants is a longstanding challenge. Our aim was to investigate the impact of wind speed on maximum rates of gas exchange and the kinetics of stomatal responses. We conducted experiments in different angiosperm and fern species using an infrared gas analyzer equipped with a controlled leaf fan, enabling precise control of the boundary layer conductance. We first showed that the chamber was adequately mixed even at extremely low wind speed (<0.005 m s-1) and evaluated the link between fan speed, wind speed, and boundary layer conductance. We observed that higher wind speeds led to increased gas exchange of both water vapor and CO₂, primarily due to the increase in boundary layer conductance. This increase in transpiration subsequently reduced epidermal pressure, leading to stomatal opening. We documented that stomatal opening in response to light was 2.5 times faster at a wind speed of 2 m s-1 compared to minimal wind speed in Vicia faba, while epidermal peels in a buffer with no transpiration exhibited a similar opening rate. The increase in stomatal conductance under high wind was also observed in four angiosperm species under field conditions, but it was not observed in Boston fern (Nephrolepis exaltata), which lacks epidermal mechanical advantage. Our findings highlight the significant impact of boundary layer conductance on determining gas exchange rates and the kinetics of gas exchange responses to environmental changes.

Assessing the response lettuce and arugula to MC-LR-contaminated water irrigation: photosynthetic changes and antioxidant defense.

Irrigation of crops with cyanotoxin-contaminated water poses a significant risk to human health. The direct phytotoxic effects of microcystin-LR (MC-LR), one of the most toxic and prevalent microcystin variants in water bodies, can induce physiological stress and hinder crop development and production. This study investigated the impact of environmentally relevant concentrations of MC-LR (1 to 10µg L-1) on photosynthetic parameters and antioxidant response of lettuce (Lactuca sativa L.) and arugula (Eruca sativa L.) following irrigation with contaminated water. During the 15-day experiment, lettuce and arugula were exposed to various concentrations of MC-LR, and their photosynthetic rates, stomatal conductance, leaf tissue transpiration, and intercellular CO2 concentrations were measured using an infrared gas analyzer. These results suggest that the influence of MC-LR on gas exchange in crops is concentration-dependent, with notable disruptions during exposure and recovery tendency during detoxification. Antioxidant response analysis revealed that glutathione S-transferase (GST) and superoxide dismutase (SOD) activities were upregulated during the exposure phase in the presence of MC-LR. However, GST activity decreased during the detoxification phase in both crops, although the effects of the toxin at 10µg L-1 were still evident in arugula. The internal H2O2 concentration in the crops increased after exposure to MC-LR, showing a time- and concentration-dependent pattern, with an increase during the exposure phase (days 1-7) and a decrease during the detoxification phase (days 8-15). Irrigation of lettuce and arugula with MC-LR-contaminated water affected various aspects of the photosynthetic apparatus and antioxidant responses, which could influence the general health and productivity of exposed crops at environmentally relevant microcystin concentrations. Furthermore, investigation of additional vegetable species and long-term MC-LR exposure can be crucial for understanding the extent of contamination risk, detoxification mechanisms, and other parameters affecting these crops.

Effects of Wildfire and Logging on Soil CO2 Efflux in Scots Pine Forests of Siberia

Wildfires and logging play an important role in regulating soil carbon fluxes in forest ecosystems. In Siberia, large areas are disturbed by fires and logging annually. Climate change and increasing anthropogenic pressure have resulted in the expansion of disturbed areas in recent decades. However, few studies have focused on the effects of these disturbances on soil CO2 efflux in the vast Siberian areas. The objective of our research was to evaluate differences in CO2 efflux from soils to the atmosphere between undisturbed sites and sites affected by wildfire and logging in Scots pine forests of southern Siberia. We examined 35 plots (undisturbed forest, burned forest, logged plots, and logged and burned plots) on six study sites in the Angara region and four sites in the Zabaikal region. Soil CO2 efflux was measured using an LI-800 infrared gas analyzer. We found that both fire and logging significantly reduced soil efflux in the first years after a disturbance due to a reduction in vegetation biomass and consumption of the forest floor. We found a substantially lower CO2 efflux in forests burned by high-severity fires (74% less compared to undisturbed forests) than in forests burned by moderate-severity (60% less) and low-severity (37% less) fires. Clearcut logging resulted in 6–60% lower soil CO2 efflux at most study sites, while multiple disturbances (logging and fire) had 48–94% lower efflux. The soil efflux rate increased exponentially with increasing soil temperature in undisturbed Scots pine forests (p &lt; 0.001) and on logged plots (p &lt; 0.03), while an inverse relationship to soil temperature was observed in burned forests (p &lt; 0.03). We also found a positive relationship (R = 0.60–0.83, p &lt; 0.001) between ground cover depth and soil CO2 efflux across all the plots studied. Our results demonstrate the importance of disturbance factors in the assessment of regional and global carbon fluxes. The drastic changes in CO2 flux rates following fire and logging should be incorporated into carbon balance models to improve their reliability in a changing environment.

PSV-26 Effect of addition of Ascophyllum nodosum and Asparagopsis taxiformis, alone or in combination, to an herbage-based diet on in vitro fermentation in continuous culture

Abstract This study investigated the effect of individual or simultaneous addition of two macroalgae species on in vitro fermentation in continuous culture. Four single-flow continuous culture fermentors were fed an orchardgrass herbage-based (orchardgrass; Dactylis glomerata L.) basal diet and randomly assigned one of four treatments: 1) control (CON), no macroalgae addition; 2) Ascophyllum nodosum dosed at 2.5% dry matter (DM; ASC); 3) Asparagopsis taxiformis dosed at 0.5% DM (ATX); and 4) A. nodosum (2.5% DM) + A. taxiformis (0.5% DM) dosed simultaneously (AS+AT). Four experimental periods were conducted in a randomized block design with 7 d of treatment adaptation and 3 d of sample collection. Fermentors were fed 82 g of DM per day in 4 equal feedings. In the last 3 d of each experimental period, daily samples of total effluent were taken for analyses of ammonia N and volatile fatty acids (VFA). Effluent was composited by fermentor and analyzed for DM, ash, neutral and acid detergent fiber, and crude protein. Purine concentrations of effluent and bacterial isolates were determined to estimate partitioning of N flow into feed, bacterial, and ammonia N fractions. Methane (CH4) emissions were measured in each fermentor every 15 min using a Fourier transform infrared gas analyzer, and pH was recorded every 2 min. Data were analyzed using the MIXED procedure of SAS v 9.4 with pre-planned contrasts comparing each individual macroalgae to CON (CON vs. ASC and CON vs. ATX) and comparing A. taxiformis with and without simultaneous addition of A. nodosum (ATX vs. AS+AT). Significance was declared at P ≤ 0.05 and tendencies at 0.05 &amp;lt; P ≤ 0.10. Nutrient digestibilities, CH4 emissions, pH, and N metabolism variables were not affected (P &amp;gt; 0.10) in ASC compared with CON, but total VFA concentration increased (P &amp;lt; 0.05) by 10%. Contrarily, the ATX diet tended (P = 0.61) to have reduced true organic matter digestibility, reduced (P &amp;lt; 0.05) total VFA concentration by 11%, and reduced (P &amp;lt; 0.05) CH4 production by 99.9% versus CON. Simultaneous the combination of microalgae (AS+AT) did not further reduce (P &amp;gt; 0.10) nutrient digestibility or total VFA concentration compared with ATX, and did not change (P &amp;gt; 0.10) the degree of CH4 inhibition. However, A. nodosum did not mitigate (P &amp;gt; 0.10) any of the negative effects on fermentation associated with A. taxiformis, as nutrient digestibilities and N metabolism variables in AS+AT were also not different (P &amp;gt; 0.10) from ATX. While the macroalgae species, A. nodosum and A. taxiformis, led to different fermentation patterns when added individually to continuous culture fermentors, no negative or positive interactions were observed from their simultaneous addition.

Biosolid as an alternative source of nutrients in chrysanthemum cultivation

The objective was to evaluate the biosolids as an alternative source of nutrients in the production of chrysanthemums by adding increasing doses to the cultivation substrate. The experimental design was in blocks with 6 treatments and 5 replications. The treatments consisted of the mixture (commercial substrate + biosolid) at the concentrations: 20%, 40%, 60% and 80% of biosolid + two controls (100% of biosolid and 100% of substrate). The experiment was conducted in a greenhouse for 90 days. Physiological parameters, number of flower buds, dry biomass and nutrient accumulation were evaluated. Physiological parameters were evaluated using the Infrared Gas Analyzer. The number of flower buds was evaluated by counting. Biomass was determined after drying the structures and then calculated the accumulation of nutrients. A total of 90 plants were evaluated. Concentrations of up to 40% of biosolid promoted a greater number of flower buds, dry biomass and nutrient accumulation. Concentrations above 60% lower number of buds, biomass increment and nutrient accumulation. It is concluded that the biosolid has potential as an alternative source of nutrients in the cultivation of chrysanthemums, indicating concentrations of up to 40% and the nutrient content of each batch generated must be verified.

Leaf gas exchange, water use, and yield of Marula (Sclerocarya birrea) and Kei Apple (Dovyalis caffra): South African indigenous fruit trees with domestication potential

Conventional crop production is expected to decline in the future in sub-Saharan Africa due to the rising costs of inputs, soil degradation, and increasing water scarcity related to climate variability and change. South Africa has more than 30 species of indigenous fruit trees that are adapted to grow under harsh conditions, yet these species are currently underutilized. Their cultivation is constrained by the lack of detailed ecophysiological information required to develop effective management strategies that optimize tree performance. In this study we investigated how two species with domestication potential namely Marula (Sclerocarya birrea) and Kei apple (Dovyalis caffra) responded to climate and soil factors over a period of two years (2019–2021). Photosynthesis, transpiration, and yield were quantified for mature trees growing in experimental orchards in the Mpumalanga Province of South Africa. Leaf gas exchange data were collected at selected intervals during the growing season using an infrared gas analyser while whole tree transpiration rates were quantified using the heat ratio method of monitoring sap flow. These data were used to parameterize a big leaf Penman-Monteith (PM) model to estimate the transpiration dynamics of individual trees at the daily time step. S. birrea's transpiration responded strongly to both climatic and soil water content variations while the water use of D. caffra was driven mostly by climatic factors. Transpiration rates averaged 0.30 L/m2 of leaf area for S. birrea while that of D. caffra was around 0.45 L/m2. Both species exhibited significant alternate bearing with yield of individual trees fluctuating by more than 50 % between successive years. For the 2019/20 season, water productivity (grams of fruit per litre of water transpired) varied between 6.2 and 17.4 g/L for S. birrea and between 24.3 and 41.7 g/L for D. caffra. Whole tree transpiration by both species were accurately predicted using the PM model albeit with different parameters for each species. This study demonstrates that a simple PM model can accurately estimate the water requirements of these species in other growing regions.

Application of sensing techniques for quantifying CO2 flux and dynamics in environments affected by the fundão dam collapse, mariana, Brazil

The District of Mariana in Minas Gerais, Brazil, witnessed one of the largest natural disasters in history. It involved the deposition of thousands of cubic meters of mining waste on soils near tributaries of the Doce River, resulting in degraded areas and a new environmental landscape. Numerous studies have focused on changes in soil microbiota and physical-chemical attributes. However, studies quantifying and analyzing carbon flux (FCO2) dynamics in the field using proximal sensors under varying temperatures, humidity conditions, and vegetation cover are scarce and nearly nonexistent. These studies could aid in monitoring the recovery of degraded areas and in understanding FCO2 dynamics in such environments. The aim of this study was to quantify and assess FCO2 dynamics using combined sensing techniques in diverse mining-affected areas, comparing different stages of recovery and their vegetation impact, and linking the results to pedoenvironmental factors. To achieve this, four areas were carefully selected and evaluated: affected pasture (AP), pasture (P) (non-affected), mix (MIX), and native trees (NT). In each area, readings were taken using an Infrared gas analyzer (IRGA) sensor, and temperature and soil moisture were measured. Additionally, soil samples were collected for chemical, physical, and biological characterization. Normalized Difference Vegetation Index (NDVI) assessments were conducted using satellites to evaluate vegetation cover. Non-parametric tests (Kruskal Wallis and Principal Component Analyses - PCA) were employed to evaluate differences between the areas and to assess the correlation among the environmental variables. The P area had the highest FCO2 and total organic carbon (TOC), differing significantly from the other site areas. Conversely, AP had the lowest FCO2 and was distinct from other sites. The MIX and NT areas had intermediate FCO2 and TOC values, which were statistically similar to each other. PCA identified distinct patterns in FCO2, soil temperature, and moisture. FCO2 was positively correlated with soil temperature and negatively correlated with moisture. There was a relationship between the biological variables microbial quotient (qMic), metabolic quotient (qCO2), COT, and FCO2. qMic reached the highest values in the MIX area, decreasing linearly from NT to P. Conversely, AP had the lowest qMic. qCO2 had the highest value in AP and NT. The proximal IRGA sensor effectively quantified FCO2 and differentiated mining tailing-affected areas. This assessment incorporated soil temperature, moisture sensors, vegetation index, and soil attribute data. The FCO2 levels were higher in P areas and lower in AP areas. Elevated FCO2 levels were correlated with a high soil temperature and low humidity. In AP, qMic was low, and qCO2 was high, indicating lower FCO2 levels. Conversely, P exhibited a higher FCO2. Higher NDVI values were correlated with elevated FCO2 in areas with specific vegetation cover during environmental recovery, while lower NDVI areas had lower FCO2 levels.

Anatomical and physiological responses of roots and rhizomes in Oryza longistaminata to soil water gradients.

Roots and rhizomes are critical for the adaptation of clonal plants to soil water gradients. Oryza longistaminata, a rhizomatous wild rice, is of particular interest for perennial rice breeding due to its resilience under abiotic stress conditions. While root responses to soil flooding are well-studied, rhizome responses to water gradients remain underexplored. We hypothesize that physiological integration of Oryza longistaminata mitigates heterogeneous water deficit stress through interconnected rhizomes, and both roots and rhizomes respond to contrasting water conditions. We investigated the physiological integration between mother plants and ramets, measuring key photosynthetic parameters (photosynthetic and transpiration rate, and stomatal conductance) using an Infrared Gas Analyzer. Moreover, root and rhizome responses to three water regimes (flooding, well-watered, and water deficit) were examined by measuring radial water loss and apparent permeance to O2, along with histochemical and anatomical characterization. Our experiment highlights the role of physiological integration via interconnected rhizomes in mitigating water deficit stress. Severing rhizome connections from mother plants or ramets exposed to water deficit conditions led to significant decreases in key photosynthetic parameters, underscoring the importance of rhizome connections in bidirectional stress mitigation. Additionally, O. longistaminata rhizomes exhibited constitutive suberized and lignified apoplastic barriers, while such barriers were induced in roots under water stress. Anatomically, both rhizomes and roots respond similarly to water gradients, showing thinner diameters under water deficit conditions and larger diameters under flooding conditions. Our findings indicate that physiological integration through interconnected rhizomes helps alleviate water deficit stress when either the mother plant or the ramet is experiencing water deficit, while the counterpart is in control conditions. Moreover, O. longistaminata can adapt to various soil water regimes by regulating anatomical and physiological traits of roots and rhizomes.

High contribution of an invasive macroalgae species to beach wrack CO2 emissions

Accumulations of macroalgal wrack are important for adequate functioning of the beach ecosystem. However, the sudden beaching of seaweed masses smothers the coastline and forms decomposing piles on the shore, harming tourism-based economies, but also affecting the beach ecosystem metabolism. The decomposition of sudden pulses of wrack can modify the biogeochemistry of beach sands and increase greenhouse gas (GHG) emissions. The presence of invasive species in the wrack deposits can superimpose harmful effects on the beach functioning. We quantified the wrack biomass of Rugulopteryx okamurae, an invasive species of extreme impact, on five sandy beaches from the Atlantic coast of the Strait of Gibraltar (Spain), and we tested the effects on in situ respiratory CO2 fluxes using an infrared gas analyser. All the beaches showed massive accumulations of Rugulopteryx wrack deposits. However, the biomass changed significantly between beaches, ranging (mean ± SE) from 968.3 ± 287.7 kg m−1 to 9210 ± 1279.4 kg m−1 of wet weight. Wrack supported high respiration rates, with CO2 fluxes averaging (±SE) 19.15 ± 5.5 μmol CO2 m−2 s−1 across beaches, reaching astounding maximum peaks of 291 μmol CO2 m−2 s−1. The within-beach variability was related to the distance of the wrack deposits from the shoreline, as the average metabolic rates tended to increase significantly from the swash to the drift line. Thicker wrack and a more degraded algae stage showed significantly higher CO2 fluxes. We estimated that the annual CO2 flux of R. okamurae in our study area ranged between 0.39 (±0.01) and 23.30 (±11.33) kg C m−2 y−1. We suggest that massive amounts of beach wrack can become a globally significant contributor to GHG emissions that can offset any potential carbon-sink capacity of macroalgal forests. However, the piles of wrack located several meters above the drift line showed non-measurable CO2 efflux. Transferring beach wrack from swash to drier upper-beach areas, a common practice in many coastal regions suffering from massive wrack accumulations, might help reduce GHG emissions while removing the wrack stockpiles from the intertidal. However, this practice is not necessarily suitable for all beaches and can create ecological and conservation problems in the dune system. There is an urgent need to implement practical and sustainable management practices for massive wrack deposits capable of presenting various solutions to achieve a balance between conservation and recreation actions, answering the consequences of a problem that links both, environmental and economic issues.

CO2 emissions of tropical peat soils under controlled groundwater table depths: A laboratory-based experiment

The groundwater table (GWT) is widely recognized as a key factor influencing CO2 emissions in tropical peatlands. However, previous studies investigating this relationship have reported diverse results. This variability likely stems from the dynamic nature of field-based groundwater conditions. To address this, our study investigated the relationship between controlled GWT and CO2 emissions in a laboratory experiment using PVC columns filled with peat soil. GWT depths were adjusted to 20 cm, 30 cm, 40 cm, 50 cm, and 60 cm within a large container filled with peat pore water. CO2 emissions were measured using an Infra Red Gas Analyzer - Environmental Gas Monitoring-4 instrument, with a closed-chamber system. Our findings revealed significant differences in CO2 emissions between treatments, except for the transition from 20 cm to 30 cm GWT. Correlation analysis showed a positive correlation (R² = 0.25). Notably, CO2 emission factor values based on average yearly emission rates displayed a substantial increase with decreasing GWT, exhibiting a strong exponential relationship (R² = 0.99).

Carbon dioxide fluxes in Alpine grasslands at the Nivolet Plain, Gran Paradiso National Park, Italy 2017–2023

We introduce a georeferenced dataset of Net Ecosystem Exchange (NEE), Ecosystem Respiration (ER) and meteo-climatic variables (air and soil temperature, air relative humidity, soil volumetric water content, pressure, and solar irradiance) collected at the Nivolet Plain in Gran Paradiso National Park (GPNP), western Italian Alps, from 2017 to 2023. NEE and ER are derived by measuring the temporal variation of CO2 concentration obtained by the enclosed chamber method. We used a customised portable non-steady-state dynamic flux chamber, paired with an InfraRed Gas Analyser (IRGA) and a portable weather station, measuring CO2 fluxes at a number of points (around 20 per site and per day) within five different sites during the snow-free season (June to October). Sites are located within the same hydrological basin and have different geological substrates: carbonate rocks (site CARB), gneiss (GNE), glacial deposits (GLA, EC), alluvial sediments (AL). This dataset provides relevant and often missing information on high-altitude mountain ecosystems and enables new comparisons with other similar sites, modelling developments and validation of remote sensing data.

Exploring glycine root uptake dynamics in phosphorus and iron deficient tomato plants during the initial stages of plant development

BackgroundPhosphorus (P) and iron (Fe) deficiencies are relevant plants nutritional disorders, prompting responses such as increased root exudation to aid nutrient uptake, albeit at an energy cost. Reacquiring and reusing exudates could represent an efficient energy and nitrogen saving strategy. Hence, we investigated the impact of plant development, Fe and P deficiencies on this process.Tomato seedlings were grown hydroponically for 3 weeks in Control, -Fe, and -P conditions and sampled twice a week. We used Isotope Ratio Mass-Spectrometry to measure δ13C in roots and shoots after a 2-h exposure to 13C-labeled glycine (0, 50, or 500 μmol L−1). Plant physiology was assessed with an InfraRed Gas Analyzer and ionome with an Inductively Coupled Plasma Mass-Spectrometry.ResultsGlycine uptake varied with concentration, suggesting an involvement of root transporters with different substrate affinities. The uptake decreased over time, with -Fe and -P showing significantly higher values as compared to the Control. This highlights its importance during germination and in nutrient-deficient plants. Translocation to shoots declined over time in -P and Control but increased in -Fe plants, suggesting a role of Gly in the Fe xylem transport.ConclusionsRoot exudates, i.e. glycine, acquisition and their subsequent shoot translocation depend on Fe and P deficiency. The present findings highlight the importance of this adaptation to nutrient deficiencies, that can potentially enhance plants fitness. A thorough comprehension of this trait holds potential significance for selecting cultivars that can better withstand abiotic stresses.

Low–carbon regulation method for greenhouse light environment based on multi–objective optimization

Controlled environment agriculture is uniquely positioned to contribute to the decarbonization of cities due to its low carbon emissions and high energy efficiency in the food supply process. The energy consumed by the horticultural industry to supplemental lighting is enormous, but improvements in the light environment of greenhouse plants are essential. To make light regulation compatible with low carbon and environmentally friendly while improving photosynthetic production, experiments on tomato plant measurements with nested light intensity, spectra, carbon dioxide concentration and temperature were carried out in a solar greenhouse based on an infrared gas analyzer and machine learning. Based on the photosynthetic response to the photosynthetic photon flux density and red–blue ratio under multi–environmental conditions, the photosynthesis prediction model was developed using the least squares support vector regression, and model hyperparameter optimization was achieved by genetic algorithm nested cross–validation. A calculation method of carbon emissions from supplemental lighting was proposed, and the low–carbon light regulation was abstracted into multi–objective optimization for the solution. Based on the comprehensive objective evaluation method, low–carbon targets for light regulation were obtained through decision–making. The results showed that the developed prediction model with root mean square error of 1.069 and determination coefficient of 0.976, which is both accurate and fast, realizes the description and expression of the net photosynthetic rate in response to the environments. The optimal targets contain two–dimensional information of light intensity and spectra, and reduces carbon emissions by a maximum of 14.85% compared to the light saturation objective based on single–objective optimization at 95.49 % of the net photosynthetic rate. The method is energy efficient and suitable for supporting multi–spectral light environment regulation applications and guiding the greenhouse environment management under the demand of carbon reduction.

Acquisition of green algal photobionts enables both chlorolichens and chloro-cyanolichens to activate photosynthesis at low humidity without liquid water.

Cyanobacteria require liquid water for photosynthesis, whereas green algae can photosynthesise with water vapour alone. We discovered that several Lobaria spp. which normally have cyanobacteria as the sole photobiont, in some regions of the trans-Himalayas also harboured green algae. We tested whether green algal acquisition was: limited to high elevations; obtained from neighbouring chloro-Lobaria species; enabled photosynthesis at low humidity. Lobaria spp. were collected from 2000 to 4000 m elevation. Spectrophotometry quantified green algal abundance by measuring chlorophyll b (absent in cyanobacteria). Thalli cross-sections visually confirmed green algal presence. We sequenced gene regions: Lobaria (ITS-EF-1α-RPB2), green algae (18S-RBC-L) and Nostoc (16S). Phylogenetic analysis determined myco-photobiont associations. We used a custom closed-circuit gas exchange system with an infrared gas analyser to measure CO2 exchange rates for desiccated specimens at 33%, 76%, 86% and 98% humidity. Cross-sections revealed that the photobiont layers in putative cyano-Lobaria contained both cyanobacteria and green algae, indicating that they should be considered chloro-cyanolichens. Chloro-Lobaria had no visible cephalodia nor cyanobacteria in the photobiont layer. Chloro-Lobaria and chloro-cyano-Lobaria had comparable levels of chlorophyll b. Chloro-Lobaria usually contained Symbiochloris. Chloro-cyano-Lobaria mainly associated with Parachloroidium and Nostoc; infrequently with Symbiochloris, Apatococcus, Chloroidium, Pseudochlorella, Trebouxia. Sequences from two green algal genera were obtained from within some thalli. Desiccated specimens of every Lobaria species could attain net photosynthesis with light exposure and 33% humidity. CO2 exchange dynamics over a five-day period differed between species. At all elevations, chloro-cyano-Lobaria spp. had abundant green algae in the photobiont layer, but green algal strains mostly differed to those of chloro-Lobaria spp. Both chloro-Lobaria and chloro-cyano-Lobaria were capable of conducting photosynthesis without liquid water. The data strongly suggest that they attained positive net photosynthesis.

Enhanced ecosystem carbon sink in shrub-grassland ecotone under grazing exclusion on Tibetan plateau

Grassland degradation is a prevalent issue at the interface of shrubland and grassland ecosystems, particularly susceptible to environmental changes. To counteract the degradation, grazing exclusion has been proposed as a dominant restoration strategy on the Tibetan plateau, the world's largest and highest plateau. However, the impact of degradation and subsequent restoration on the carbon dynamics consist of carbon sink / source capacity of shrub-grassland ecotones remain unclear. Therefore, in this study, using a transparent chamber (0.8 m in length × 0.8 m in width × 0.6 m in height) attached to an infrared gas analyzer, the in situ field investigation was performed to measure the gross ecosystem primary productivity (GEP), ecosystem respiration (Re), net ecosystem CO2 exchange (NEE), and environmental factors over a four-year continuous period in lightly and heavily degraded shrub-grassland ecotones during recover process on the Tibetan Plateau. Our result showed that: 1). Shrub-grassland ecotone acts as a net CO2 sink, with the maximum NEE occurring in July during the growing season. 2). Ecotone degradation diminishes the carbon sequestration capacity. Specifically, the annual GEP, Re, and NEE rates decrease by 14.1 %, 7.3 %, and 27.2 %, respectively, in the heavily degraded ecotone compared to the lightly degraded counterpart. 3). Grazing exclusion positively influenced the carbon sequestration capacity, particularly in heavily degraded ecotone, which leads to a substantial increase in the annual GEP, Re, and NEE rates of 15.4 % and 33.4 %, 12.3 % and 20.9 %, 22.25 % and 64.9 % for lightly and heavily degraded ecotones, respectively. 4). A piecewise structural equation model reveals that soil moisture and soil temperature are pivotal drivers influencing NEE. 5) Correlation analysis shows that NEE was negatively correlated with soil temperature during April to June and September to October but was positively correlated with soil temperature during July to August. In contrast, NEE displays a consistent negative correlation with soil moisture throughout the growing season. This research provides new insights on grassland degradation and restoration for carbon sequestration in alpine shrub-grassland ecotones and highlights their implications for sustainable management of alpine ecosystems.

Integrated water management practice in tropical peatland agriculture has low carbon emissions and subsidence rates

Hydrological management in the use of peatland for agriculture is the backbone of its sustainability and a critical factor in climate change mitigation. This study evaluates the application of an integrated water management practice known as the “Water Management Trinity” (WMT), implemented since 1986 on a coconut plantation on the eastern coast of Sumatra, in relation to CO2 emissions and subsidence rates. The WMT integrates canals, dikes, and dams with water gates to regulate water levels for both coconut agronomy and the preservation of the peat soil. The WMT has successfully regulated and maintained an average yearly water table depth of −45 to −51 cm below the surface. The methodology involved a closed chamber method for measuring soil CO2 flux using a portable Infrared Gas Analyzer, conducted weekly over a six-month period to cover dry and rainy season at bi-modal climate condition. Subsidence measurements have been ongoing from 1986 to 2022. The results show bare peat soil has heterotrophic respiration CO2 emissions of 7.77 t C–CO2 ha−1 yr−1, while in coconut plantations 7.99 t C–CO2 ha−1 yr−1, similar to emissions in mineral soils. Autotrophic respiration leads to the overestimation of CO2 emissions on peatland and accounts for 212–424% of the total emissions. The cumulative subsidence from 1986 to 2022 is −56.3 cm, with a soil rise of +0.8 cm in 2022, indicating a flattening rate of subsidence. This is characterized by an increase in bulk density at the surface from 0.072 to 0.144 gr/cm3, with approximately 81% of the subsidence being due to compaction. The statistical analysis found no relationship between water table depth and CO2 emissions, indicating that water table depth cannot be used as a predictor for CO2 emissions. In summary, peatland agriculture has a promising future when managed sustainably using an integrated hydrological management system.

Investigation of gaseous emissions and ash deposition in a pilot-scale PF combustor co-firing cereal co-product biomass with coal

This study presents the results of investigations into the gaseous emissions and ash deposition characteristics from combustion of Cereal Co-product mixed with coal in a 100 kWth pulverised fuel combustor. Combustion gas emission samples for CO2 , O2 , H2O, SO2 , CO, NO, NO2 , N2O, HCl, HF, were obtained on-line by a high resolution multi-component Fourier Transform Infra-Red gas analyser. Ash deposit samples were collected from the flue gas using three air-cooled probes that simulate heat exchanger tubes with surface temperatures of 500, 600 and 700 °C. The deposits formed were analysed using SEM/EDX and XRD techniques to assess their corrosion potential.

Simultaneous and Independent Abaxial and Adaxial Gas Exchange Measurements.

Stomata can be distributed exclusively onthe abaxial or adaxial leaf surface,but theyare mostcommonly found on bothleaf surfaces. Variations in stomatal arrangement, patterning, and the impact on photosynthesis can be measured using an infrared gas exchange system. However, when using standard gas exchange techniques, both surfaces are measured together and averaged to provide leaf-level values. Employing an innovative gas exchange apparatus with two infrared gas analyzers, separate gaseous flux from both leaf surfaces can be quantified simultaneously and independently. Here, we provide examples of typical measurements that can be performed using a "split chamber" gas exchange system.