Atmospheric Concentrations Research Articles

Flowering seasonality and airborne pollen recent trends in Sierra de las Nieves, the southernmost National Park in continental Spain

Sierra de las Nieves is the southernmost National Park in continental Spain and, in a global warming scenario, it is important to determine the impacts of climatic variations on the vegetation, with special relevance to their reproductive cycles. The flowering seasonality and intensity of the dominant anemophilous species usually reflect the response of the vegetation to climate variations, which can be monitored through the atmospheric pollen concentrations. In this study, airborne pollen was analysed for 6 years (2018–2023). A pollen calendar was elaborated to show the flowering seasonality and intensity of the dominant anemophilous taxa. Spring was the season with the highest airborne pollen diversity and intensity, Quercus being the pollen type with the highest concentrations. We observed that weather conditions influenced the presence of airborne pollen. Precipitation and relative humidity reduce pollen concentrations, while temperature rises increase them during the pre-peak period and reduce them during the post-peak. Wind dynamics play different roles depending on the pollen type considered given the heterogeneous distribution of the pollen emission sources. Significant advances were detected in the start date of the main pollen season of Quercus and Olea, as well as in the peak date of Quercus. On the contrary, other taxa such as Pinus or Poaceae did not show any trend. This brings to the fore that the responses to climatic variations may differ from one taxon to another, a continuous study in natural areas being required for detecting possible changes in the observed trends.

An Ambient Measurement Technique for Vehicle Emission Quantification and Concentration Source Apportionment.

We develop a new technique called plume regression where fast response instruments located at the roadside are used to measure exhaust plumes of passing vehicles. The approach is used to generate highly disaggregated vehicle emissions information by vehicle type, which compares well with traditional vehicle emission remote sensing. Additionally, the technique provides valuable new information on ambient concentration source apportionment by vehicle type. The technique is flexible enough to consider a wide range of air pollutants and be deployed at roadside ambient monitoring locations. The new approach is used to quantify emissions and concentration source apportionment for ammonia (NH3) and nitrogen oxides (NOx). We find that emissions of NH3 are generally very well controlled from diesel vehicles including those with selective catalytic reduction systems that use NH3 to reduce emissions of NOx. By contrast, gasoline passenger cars are shown to be the dominant contributor to NH3 emissions, which increase with vehicle mileage. Average fuel-specific NH3 emission factors for gasoline vehicles range from 0.3 to 1.2 g kg-1, while diesel vehicle emission factors remain below 0.06 g kg-1, with the exception of Euro VI buses with the latest regulatory provisions (0.5 g kg-1).

Prenatal exposure to ambient fine particulate matter and child lung function in the CANDLE cohort

Background Ambient fine particulate matter (PM2.5) exposure adversely impacts child airway health; however, research on prenatal PM2.5 exposure, and child lung function is limited. We investigated these associations in the ECHO-PATHWAYS Consortium, focusing on the role of exposure timing during different phases of fetal lung development. Methods We included 675 children in the CANDLE cohort born between 2007 and 2011 in Memphis, TN, USA. Prenatal exposure to ambient PM2.5 was estimated using a spatiotemporal model based on maternal residential history and averaged over established prenatal periods of lung development. Forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) were measured by spirometry at age 8–9 years. We used linear regression and Bayesian Distributed Lag Interaction Models (BDLIM) to estimate associations between exposure and lung function z-scores, adjusting for maternal/child characteristics, prenatal/postnatal tobacco exposure, and birth year/season, and evaluating effect modification by child sex and allergic sensitization. Results The average ambient concentration of PM2.5 during pregnancy was 11.1 µg/m3 (standard deviation:1.0 µg/m3). In the adjusted linear regression and BDLIM models, adverse, but not statistically significant, associations were observed between exposure during the pseudoglandular (5–16 weeks of gestation) and saccular (24–36 weeks) phases of lung development and FEV1 and FVC. The strongest association was between a 2 μg/m3 higher concentration of PM2.5 during the saccular phase and FEV1 z-score (−0.176, 95% Confidence Interval [CI]: −0.361, 0.010). The FEV1/FVC ratio was not associated with PM2.5 in any exposure window. No effect modification by child sex or allergic sensitization was observed. Conclusions We did not find strong evidence of associations between prenatal ambient PM2.5 exposure and child lung function in a large, well-characterized study sample. However, there was a suggested adverse association between FEV1 and exposure during late pregnancy. The saccular phase of lung development might be an important window for exposure to PM2.5.

Determining the Exposure Routes and Risk Assessment of Isocyanates in Indoor Environments.

Isocyanates are used as raw materials for polyurethane foams, paints, and building materials. The isocyanates can cause acute adverse health effects such as irritation of the respiratory tract, skin, and eyes, and induce asthma and sick house syndrome. However, investigations into the potential sources and risk assessments of indoor isocyanates are limited. Thus, this study aimed to determine the sources and exposure routes of isocyanates and to assess their risk in indoor environments. The results showed that household products, such as infant chairs, mattresses, and polyurethane foam spray, used in indoor environments are potential sources of atmospheric isocyanic acids (ICA). Toluene diisocyanate and methyl isocyanate pose relatively high risks to indoor environments. Total concentrations of isocyanates ranged from 38.2 to 1570ngg-1 in infant chairs, mattresses, and spray polyurethane foams. The indoor products can be indoor sources of ICA because emission rates of ICA from household products were observed in all products (0.0536-1.37ngg-1 d-1). Field observations showed that isocyanate concentrations in house-dust samples ranged from 0.194±0.126 (ethyl isocyanate) to 70.1±67.8 (ICA)ngg-1. Atmospheric isocyanate concentrations ranged from 0.0030±0.020 (propyl isocyanate) to 26.0±14.3 (ICA)ng m-3. An estimation of human exposure demonstrated that air inhalation was the major route of isocyanate exposure. The minimum margin of exposure values of methyl isocyanate and toluene diisocyanate were 523 and 655, respectively, for children, indicating that they may pose a relatively high risk.

Association Between Particulate Matter Pollutants and Ophthalmology Visits for Ocular Surface Irritation and Allergy.

The World Health Organization has declared climate change to be "the single biggest health threat facing humanity", yet there are limited studies on the impact of climate change-related air pollution on ocular health. To explore associations between ocular surface irritation and allergy-related daily outpatient office visits with daily ambient particulate matter (PM) levels in the Denver Metropolitan Area. Daily visit counts of ophthalmology outpatient offices were obtained from an academic health center (October 1st, 2015 to January 27th, 2023). Daily ambient average concentrations of PM ≤ 10µm in diameter (PM10) and 2.5 micrometers or less in diameter (PM2.5) were obtained. Data were analyzed using distributed lag nonlinear models while accounting for the cumulative lagged effects of PM10 and PM2.5 for visits. Modifications due to temperature were assessed using stratified models. There were 144,313 ocular surface irritation and allergy visits to ophthalmic clinics during the study period. Daily visit counts increased with increasing daily ambient PM10 and PM2.5 concentrations. Five-day cumulative ambient PM10 concentrations at 80, 90, 100, and 110 µg/m3 showed higher rate ratios at each level from 1.77 (95% CI: 1.71, 1.84) at concentration of 80 to 2.20 (95% CI: 2.09, 2.30) for concentration of 110 µg/m3. Similarly, the visit rate ratios increased as the daily PM2.5 concentration increased, but this gradient effect was not significantly higher as the concentration increased. The effect of PM10 was higher on days when the temperature was below the average. Temperature did not affect the association between daily visit counts and PM2.5. This study found that ambient PM increased the rate of ophthalmology visits due to ocular surface irritation and allergies. Most importantly, this association increased in magnitude with higher ambient PM concentrations. Additional studies are required to fully understand the effects of climate change-related stressors on ocular health.

Reductions in atmospheric levels of non-CO2 greenhouse gases explain about a quarter of the 1998-2012 warming slowdown

The observed global mean surface temperature increase from 1998 to 2012 was slower than that since 1951. The relative contributions of all relevant factors including climate forcers, however, have not been comprehensively analyzed. Using a reduced-complexity climate model and an observationally constrained statistical model, here we find that La Niña cooling and a descending solar cycle contributed approximately 50% and 26% of the total warming slowdown during 1998-2012 compared to 1951-2012. Furthermore, reduced ozone-depleting substances and methane accounted for roughly a quarter of the total warming slowdown, which can be explained by changes in atmospheric concentrations. We identify that non-CO2 greenhouse gases played an important role in slowing global warming during 1998-2012.

From molecular precursors to ultra-high temperature ceramics: A novel synthesis of hafnium carbonitride nanoceramics

Hafnium carbonitride (HfCxN1–x) ceramics have drawn considerable interest due to their exceptional mechanical and thermophysical properties. Herein, we report a novel single-source precursor with Hf–N bonds as the main chain and fabricate HfCxN1–x ceramics after pyrolysis of the precursor. The synthesis, ceramic conversion, and microstructural evolution of the single-source precursor as well as the derived HfCxN1–x ceramics treated under various atmospheres were investigated. The results indicate that in an argon atmosphere, the nitrogen content within HfCxN1–x decreases with rising temperature. While under a nitrogen atmosphere, the high concentration of N2 facilitates the rapid conversion of HfO2 to Hf7O8N4, which subsequently promotes the transformation of the HfCxN1–x solid solution ceramics. During this process, there is also an inhibitory effect of N2 on the tendency of HfN into HfC. Moreover, the desired chemical composition of HfCxN1–x can be regulated by adjusting the N2 concentration in the heat treatment atmosphere. The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfCxN1–x ceramics.

Evaporation and combustion of low asphaltene heavy oil droplets under conditions representative of practical applications

The evaporation and burning characteristics of isolated heavy fuel oil (HFO) droplets are experimentally studied at conditions representative of practical applications, producing novel, detailed results on the effect of oxygen concentration. Also, and for the first time for HFO, the temporal evolution of the flame stand-off ratio (based on CH* emission) and the cenosphere burning size are presented along with the droplet size histories. The effect of ambient oxygen concentration is first analyzed qualitatively, identifying different sub-stages. Later, a quantitative analysis is presented in terms of ignition delay time, micro-explosion regimes, shell swelling ratio, cenosphere size and several time metrics. The results show that, as ambient oxygen changes, the liquid and solid stages show marked differences not only in terms of time scales but also in the transitions of burning regimes. Cenospheres generated in oxygen-free conditions are found to be ∼1.4 times larger than those in droplet combustion. Although similar in size, the solid-to-liquid consumption time ratio in 5% O2 is found to be significantly longer, about twice than for the 10% O2 ambient. The characterization of these differences is thought to be relevant not only for oil flames but also for the promising future of heavy oil gasification applications.

Chloroplast redox state mediates the short-term regulation of leaf isoprene emission.

Isoprene emission from plants not only confers thermoprotection, but also has profound impacts on atmospheric chemistry and the climate. Leaf isoprene emission is dynamically regulated in response to various environmental cues, but the exact mechanism remains unclear. It has been proposed that chloroplast redox/energy state or cytosolic phosphoenolpyruvate carboxylation regulates isoprene biosynthesis and consequently emission, and the latter has been disproven by recent literature. However, the possible covariation of chloroplast redox/energy state and cytosolic PEP carboxylation in previous experiments impedes the independent examination of the former hypothesis. We developed an index of chloroplast redox state and showed its validity by examining the relationships between the index and the rates of certain processes which have been demonstrated to be affected or unaffected by chloroplast redox/energy state. According to the former hypothesis alone, we modelled how isoprene emission rate (IER) responded to different short-term environmental variations, and compared theoretical predictions with experimental data. We predicted that no matter which environmental factor was varied, IER would respond to the index of chloroplast redox state with similar velocities. We found that IER showed comparable increasing rates in response to the increase in the index of chloroplast redox state caused by different environmental variations (0.0479, 0.0439 or 0.0319 when ambient CO2 concentration, photosynthetic photon flux density or leaf temperature was varied, respectively). These results support that chloroplast redox/energy state regulates isoprene biosynthesis, leading to dynamic isoprene emission in nature.

Accurate and efficient prediction of atmospheric PM1, PM2.5, PM10, and O3 concentrations using a customized software package based on a machine-learning algorithm.

Particulate matter (PM) and ozone (O3) pollution have been attracting increasing attention recently due to their severe harm to human health. PM and O3 are secondary pollutants, and there remain significant challenges in accurately and efficiently predicting their concentrations in the atmosphere. In this study, one-year monitoring data of PM1, PM2.5, PM10, and O3 concentrations as well as meteorological parameters and concentrations of various precursors (i.e., nitrogen oxides, SO2, CO, alkanes, aldehydes, and ketones) are obtained at a monitoring site in central China's Hunan province. The eXtreme Gradient Boosting model is trained and tested to achieve efficient and accurate predictions of the concentrations of the four pollutants. The effects of different datasets, input features, and model parameters on the prediction accuracy are investigated. Principal component analysis is employed to further reduce the dimensions of features, increasing the prediction efficiency. Finally, all model training and prediction processes are incorporated in an executable application using the PyQt5 framework to build a user interface. The customized software supports user-defined modeling. The software can simultaneously predict PM1, PM2.5, PM10, and O3 concentrations, making the prediction process convenient.

Influence of local meteorology and gaseous pollutant emissions on atmospheric nanoparticle concentrations in a pedestrian way in urban region

The roadside environment is one of the major sources of nanoparticle emission in the urban regions. The complex mixture of different pollutants makes it hard to understand the dynamics and behavior of nanoparticles. The study aims to analyze the dynamics of atmospheric nanoparticles ranging from 10 to 1000 nm along with local meteorological conditions and gaseous pollutants in a pedestrian way at a busy street in Delhi, a megalopolis in India, during all five major seasons of the study area. Nucleation mode particles were higher during the spring season, whereas the contribution of Aitken mode particles dominated the total particle number concentrations in the rest of the seasons. Due to the influence of vehicular sources, rush hour concentrations were higher than during non-rush hours. Thus, the diurnal pattern in particle concentration strongly coincided with emissions associated with the vehicular flow. During the winter season, the average total particle number concentration was observed to be maximum (4.1 × 104 cm-3) with a higher surface area of particles of 3.5 × 10-3 mm2m-3. Compared to the monsoon season, the concentration of NOX was 5 times higher in winter. The boundary layer height in the study region ranged from 600 to 2400 m during different seasons, and the maximum ventilation coefficient was observed to be >3000 m2s-1 during summer. Precipitation reduced the concentration of particles by half, from 2.2 x 104 to 1.1 x 104 cm-3, due to wet scavenging. The study revealed that the concentrations of particles depend not only on primary emissions but also are influenced by local meteorology and other co-emitted pollutants. Understanding the dynamics of atmospheric nanoparticles in urban roadside environments as outlined in this study is crucial to devise necessary mitigation measures for people residing near the road in order to reduce health impact and improve air quality.

Inverse Trend Between Tree Pollen and Fungal Concentrations With Allergic Sensitization Rates in Seoul for 25 Years.

A growing number of individuals are developing allergic diseases due to pollen exposure. Seasonal variations and increased pollen concentrations have occurred with the increased rates of allergic sensitization among both children and adults. Temperature significantly influences pollination, particularly in spring- and early summer-flowering plants, with weather conditions affecting pollen allergen levels. Human activities, including agriculture and deforestation, increase carbon emissions, leading to higher atmospheric CO₂ levels that may enhance allergenic plant productivity. Climate change affects the range of allergenic plant species and length of pollen season. Studies indicate that higher CO₂ and temperature levels are linked to increased pollen concentrations and allergenicity, whereas atmospheric fungal concentrations have declined annually over the past 25 years. Despite more intense precipitation in summer and autumn, the number of rainy days has decreased across all seasons. This concentration of rainfall over shorter periods likely prolongs the dry season and shortens the period of fungal sporulation. Future climate changes, including atmospheric dryness, drought, and desertification could further decrease allergenic fungal sporulation. It remains unclear whether the inverse relationship between pollen and fungal concentrations and distributions directly results from climate change. It is crucial to evaluate the patterns of aeroallergens and their associated health risks.

Variations in air pollution before, during and after the COVID-19 lockdown in Peruvian cities.

The high concentrations of air pollutants in Peru remain a persistent problem, significantly impacting public health. Understanding the extent to which the COVID-19 lockdown affected these contaminants is crucial. To determine variations in NO2, O3, CO, and SO2 concentrations in 10 Peruvian cities before, during, and after lockdown. A comparative ecological study was conducted in urban areas of 10 major Peruvian cities using the Google Earth Engine (GEE) platform. Data on atmospheric pollutant concentrations were extracted from the Sentinel-5P/TROPOMI satellite images for the period between March 16 and June 30, across the years 2019, 2020, 2021, and 2022, for comparative analysis. The Wilcoxon test was used to evaluate changes between the study periods. We included 10 urban cities located across three geographic regions of Peru. Most urban cities experienced a decrease in NO2 concentrations and an increase in O3 and CO levels during the lockdown, while SO2 concentrations remained relatively constant. The lockdown has caused variations in NO2, O3 and CO concentrations. Future studies with accurate data on air pollutant concentrations are needed to ensure targeted and effective interventions.

Adapting fodder oats to climate change: Enhancing growth, yield, and microbial dynamics under elevated CO2 and temperature

The effects of elevated atmospheric carbon dioxide concentration (e[CO2]) and temperature (e°T) on various traits of oat (Avena sativa L.) varieties using open-top chambers (OTC) were investigated. A simulated environment was created for the experiment i.e., ambient temperature and CO2 (a°T + a[CO2]); elevated temperature (3 °C > ambient temperature) (e°T); elevated CO2 (550 ± 50 ppm) (e[CO2]); and a combination of ambient temperature with elevated CO2 (a°T + e[CO2]), for accessing the effect of e°T and e[CO2] on oats. a°T + e[CO2] increased plant height to 121 cm compared to 114 cm in a°T + a[CO2] and 111 cm in e°T + e[CO2]. Seed weight was highest in a°T + e[CO2] (3.09 g) compared to 2.53 g in a°T + a[CO2] and 2.60 g in e°T + e[CO2]. Leaf number and tillers were significantly higher in a°T + e[CO2] (61.4 leaves, 10 tillers) than in a°T + a[CO2] (27.6 leaves, 5.6 tillers) and e°T + e[CO2] (44.3 leaves, 6.93 tillers). Chlorophyll content was highest in a°T + e[CO2] (5.13 mg/g) compared to 3.61 mg/g in a°T + a[CO2] and 1.47 mg/g in e°T + e[CO2]. In contrast, germination rate was best in a°T + a[CO2] (81.6 %) compared to e°T + e[CO2] (60.3 %) and a°T + e[CO2] (63.1 %). Malondialdehyde (MDA), a stress marker, was significantly higher in e°T + e[CO2] (1.35 nmol/g) compared to a°T + a[CO2] (0.299 nmol/g). Membrane stability index (MSI) was lowest in e°T + e[CO2] (13.2) compared to 20.9 in a°T + a[CO2], indicating greater stress under e°T + e[CO2]. Starch content in a°T + e[CO2] (14.6 %) was more than double that of a°T + a[CO2] (7.09 %). Microbial activity also showed significant differences. Dehydrogenase was highest in e°T + e[CO2] (13.86 µg/g/day) compared to a°T + a[CO2] (8.80) and a°T + e[CO2] (12.62). Total bacterial count (TBC) increased in e°T + e[CO2] (72) compared to a°T + a[CO2] (61). Similarly, phosphate-solubilizing bacteria (PSB) and fungi (PSF) were highest in e°T + e[CO2] (PSB: 104.5, PSF: 8.5) compared to a°T + a[CO2] (PSB: 75.0, PSF: 4.0). Rhizobium and Azotobacter counts were elevated in a°T + e[CO2] (95 and 94) compared to a°T + a[CO2] (72.5 and 42.0), showing a strong positive impact of e[CO2] on microbial populations. Specific oat varieties such as JHO-2000–4 and JHO-99–2 performed best under these conditions, showing higher yields and better stress tolerance. While e[CO2] offers substantial benefits to oat plant growth and soil microbial activity, the additional stress from e°T complicates these benefits.

Bioinspired Moisture‐Driven Soft Robotic Actuator

Multifunctional materials in nature, utilizing atmospheric water content, offer solutions to challenges in soft‐actuating materials research. The leaf of Arundo donax, an invasive plant, showcases exceptional properties: structural integrity, passive actuation, tunability, load‐bearing capacity, longevity, and an integrated battery‐free fluid generation and distribution mechanism. These functions coexist within a thin (≈130 μm) and lightweight structure with simple compositions. The study investigates material composition, passive fluid transport, water harvesting structures, and mechanical properties, revealing unexpected correlations between surface and internal structures. Additionally, tunable actuation, suitable for origami‐based mechanisms, is explored. Testing an energy‐free, moisture‐triggered soft robotic gripper, its ability to lift over 50 times its weight while maintaining sufficient softness for delicate tasks is demonstrated. This unit‐wise structure‐based actuation offers promise for soft robotics, with favorable fabrication possibilities and motion manipulation.

How Can Land Use Management in Traditional Cultural Landscapes Become a Policy Instrument for Soil Organic Carbon Sequestration and Climate Change Mitigation? A Transylvanian Case Study

Changes in land use from high-nature-value grasslands to arable fields reduce the organic carbon stock in soil, increasing atmospheric carbon concentrations. Maintaining grasslands through traditional agricultural techniques can mitigate climate change by transferring atmospheric carbon to the soil. Benefits of soil organic carbon sequestration include improved soil properties and enhanced ecosystem services and biodiversity. With Romania’s ratification of the Paris Agreement, it is crucial to review climate-related agricultural policies and incentivize carbon sequestration practices in organic soils. This paper presents a soil carbon study in Transylvania’s Târnava Mare region, Romania, known for its preserved cultural landscapes. Soil samples were taken at a depth of 60 cm to assess organic carbon pools under grassland and arable land management across three soil classes: Cernisoils, Hidrisoils, and Luvisoils. Several statistical tests were applied to evaluate the most significant drivers of soil organic carbon sequestration including land use, soil class, and soil depth. The results indicate that land management has the largest impact, with grasslands storing 45% more carbon than arable land on average. This finding should be integrated into national climate action plans, prioritizing the preservation of grasslands and sustainable agricultural practices to support soil organic carbon sequestration.

African dust: Occurrence, health consequences, and impacts on Texas

The drylands of North Africa (Sahara and Sahel) are the world’s largest sources of airborne dust. Clouds of African dust aerosols have been long known to be blown westwards across the Atlantic, and by the 1990s were recognized to be transported across and over Texas. African dust incursions in Texas typically happen several times per year in late spring and summer, manifesting as hazy skies overhead and increased ground-level concentrations of PM2.5 (particulate matter fine enough to be inhaled into the human lower respiratory tract). African dust exposure has many reported human health effects in Europe and the Caribbean, including increased all-cause mortality and increased respiratory and cardiovascular disease morbidity and mortality. In Texas, African dust’s greatest impacts occur in the Houston metropolitan area where it has been quantitatively shown to increase ambient aerosol concentrations. The potential of African dust increasing concentrations of inhalable particulate matter beyond regulatory limits is of concern. A sequence of investigations filtering particles from the air, measuring their concentrations, and subjecting them to elemental analysis documented far-transported African dust’s role in air quality in Houston and Galveston. African dust’s contributions to air pollution have been separated from those of local soils and industrial emissions, and Saharan-Sahelian dust has been indicated to sometimes constitute the majority of PM2.5 mass in Houston. While studies show the presence of inhalable metals and microorganisms including opportunistic pathogens during Saharan air incursions in Houston, the human health effects of African dust in Texas remain yet unspecified and merit further investigation. Keywords: aerosols; Africa, Northern; air pollution; dust; particulate matter; public health; Texas

Incorporating Diurnal and Meter-Scale Variations of Ambient CO2 Concentrations in Development of Direct Air Capture Technologies.

To be implemented on climate-relevant scales, direct air capture of CO2 (DAC) will require large capital-intensive facilities and careful attention to cost minimization. In making decisions among potential sites for DAC facilities, all of the factors that will impact process cost and efficiency should be considered. In this paper we focus on a factor that has previously received little attention in the DAC community, namely variations in atmospheric conditions on hourly time scales and length scales of meters. We present data curated from extensive previous studies of biosphere-atmosphere fluxes with observations of CO2 concentration, temperature, and relative humidity (RH) with hourly resolution from many sites in North America. These include locations where typical diurnal variations in CO2 concentration during summer months exceeds 150 ppm. These variations are larger than the seasonal variations that exist between averaged CO2 concentrations in winter and summer, and they are highly correlated with diurnal variations in temperature and RH. Diurnal variations are dependent on the height above ground at which CO2 concentrations are measured, with smaller variations existing at heights of 10 m or more than at ground level. We illustrate the potential implications of these short-term variations for the operation and optimization of a DAC process with process-level calculations for a specific adsorption-based process using amine-rich adsorbents.

Elevated CO2 Concentration Extends Reproductive Growth Period and Enhances Carbon Metabolism in Wheat Exposed to Increased Temperature.

Both elevated atmospheric CO2 concentration ([CO2]) and increased temperature exert notable influences on wheat (Triticum aestivum L.) growth and productivity when examined individually. Nevertheless, limited research comprehensively investigates the combined effects of both factors. Winter wheat was grown in environment-controlled chambers under two concentrations of CO2 (ambient CO2 concentration and ambient CO2 concentration plus 200 µmol mol-1) and two levels of temperature (ambient temperature and ambient temperature plus 2°C). The phenology, photosynthesis, carbohydrate and nitrogen metabolism, yield and quality responses of wheat were investigated. Elevated [CO2] did not counteract warming-induced shortening of wheat phenological period but prolonged grain filling. Even though photosynthetic adaptation occurred during the reproductive growth period, elevated [CO2] still significantly enhanced carbohydrate accumulation under warming, particularly at the grain filling stage, thereby increasing yield by 20.1% compared with the ambient control. However, elevated [CO2] inhibited nitrogen assimilation at the grain filling stage under increased temperature by downregulating the expression levels of TaNR, TaNIR, TaGS1 and TaGOGAT and reducing glutamine synthetase activity, which directly led to a significant decrease of 19.4% in grain protein content relative to the ambient control. These findings suggest that elevated [CO2] will likely increase yield but decrease grain nutritional quality for wheat under future global warming scenarios.

Application of additional dose of N could sustain rice yield and maintain plant nitrogen under elevated ozone (O3) and carbon dioxide (CO2) condition

IntroductionGlobal food security is challenged by the increasing levels of air pollutants like ozone (O3) through their impacts on crop productivity. The present study was conducted to quantify the interactive effect of elevated ozone (O3) and carbon dioxide (CO2), on different rice varieties in northern India.MethodsAn experiment was conducted in Genetic H field, Environment science, IARI for two consecutive years (2020 and 2021) during the kharif season, to quantify the impact of elevated O3 and CO2 interaction on productivity, and plant N in three rice varieties (Pusa basmati 1121, Nagina 22, IR64 Drt1) under different nitrogen (N) management practices. Rice crop was grown in Free Air Ozone-Carbon dioxide Enrichment rings (FAOCE) rings with two levels of O3 (elevated 60 ±10ppb and ambient) and two levels of CO2 (elevated, 550±25 ppm and ambient) concentration and their interaction with two N fertilizer treatments i.e., 100% RDN (recommended dose of N) and 125% RDN.Results and discussionElevated O3 significantly decreased physiological parameters like photosynthesis rate, stomatal conductance and transpiration rate of the crop. Grain yield reduced by 7.2-7.5%, in Pusa Basmati 1121 and from 6.9-9% in IR64 Drt1 varieties in elevated O3 treatment as compared to ambient treatment. Yield reduction in Nagina 22 variety was not significant in elevated O3 treatment. Elevated CO2 concentration of 550 ppm was able to fully compensate the yield loss in Nagina 22 variety and partially compensate (3.9-8.0%) in Pusa Basmati 1121 and IR64 Drt1 varieties. Grain N concentration in rice varieties decreased by 10.8-14.7% during first year and by 7.8-20.6% during second year in elevated O3 plus CO2 interaction treatment than ambient. Grain N uptake also decreased (13.2-17.1% in first year and 4.5-22.8% in second year) in elevated O3 plus CO2 interaction treatment as compared to ambient. Application of additional 25% of recommended dose of N improved grain N concentration, grain N uptake as well as available N of soil as compared to 100% RDN treatment in elevated O3 plus CO2 interaction treatment. Additional 25% N dose could help in sustaining rice productivity and quality under elevated O3 and CO2 condition.