Carbon Dioxide Concentration Research Articles

Synoptic Patterns Associated with Turbulent Fluxes of Water Vapor and Carbon Dioxide in Northern New England

Abstract Synoptic-scale weather patterns affect local meteorological variables, such as vapor pressure deficit (VPD), temperature, and insolation, that are known to influence evapotranspiration (ET) and net CO2 flux (FC). However, little research exists that links synoptic-scale patterns to ET and FC. In this study, we seek to understand how synoptic-scale patterns influence ET and FC for the temperate mixed-hardwood forest at Hubbard Brook Experimental Forest (HBEF) in New Hampshire, United States. We use self-organizing maps to identify the most common synoptic pattern types impacting HBEF during the 2016–21 growing seasons and determine how ET and FC vary with these synoptic pattern types. Our analysis reveals that high ET and most negative FC days occur for the weather pattern phases starting after the departure of a low pressure system and through the approach of a high pressure system. ET and the magnitude of FC remain high if the latitude of the high is south of HBEF but moderate (especially for ET) if the high is to the north and causes east winds to advect a humid maritime air mass over the region. ET is lowest when HBEF is located between high pressure to the east and low pressure to the west, which causes humid southerly flow to decrease VPD and insolation. Meanwhile, FC magnitude may remain high when this pattern occurs in June–July when photosynthetic capacity is at its highest. Our results suggest that future changes in the frequency of passing low pressure systems and pathways of high pressure systems could impact the fluxes of water and CO2 from this forest. Significance Statement For decades, we have understood that local meteorological variables, such as insolation, temperature, and relative humidity, have a strong influence on a forest ecosystem’s use of water and carbon dioxide, two important greenhouse gases. We also understand that large-scale weather patterns and their interactions with forests shape these local meteorological conditions. This research advances knowledge of the relationship between various large-scale weather patterns and their impacts on forest’s use of water and carbon dioxide via local meteorological variables for a mixed-hardwood forest in the Northeastern United States. Connecting these results to the frequency of these various large-scale weather pattern types projected by global climate models will help us predict how forest ecosystems will influence water vapor and carbon dioxide concentrations and thus impact global climate.

Effects of defatted rice bran-fortified bread on gut microbiome, cardiovascular risk, gut discomfort, wellbeing and gut physiology in healthy adults with low dietary fibre intake.

Effects of defatted rice bran-fortified bread on gut microbiome, cardiovascular risk, gut discomfort, wellbeing and gut physiology in healthy adults with low dietary fibre intake.

Efficient capture and detoxification of gaseous arsenic trioxide from flue gas using silicomanganese alloy dust.

Efficient capture and detoxification of gaseous arsenic trioxide from flue gas using silicomanganese alloy dust.

Exergy Analysis of Oxy-Biogas Combustion with Different Rates of the CO2 Content

This work presents the exergetic evaluations of the oxy-biogas combustion process in an adiabatic furnace for the cases of biogas involving different carbon dioxide (CO2) concentrations. A three-dimensional steady-state computational fluid dynamics model was developed for combustion simulation. The model was first verified with the data of oxy-natural gas and showed good agreement with the data. Thus, simulation studies were performed for the oxy-biogas combustion with different CO2 concentrations of biogas fuel, from 10 vol% to 40 vol% with a 10% increment, at a constant input power capacity. The results show that the sum of specific thermo-mechanical and chemical exergy of combustion products has a decreasing trend with increasing CO2 content in biogas. However, the exergy flow rates of the combustion products increased with the increase in CO2 due to the increasing mass flow rates. Increasing the CO2 level in biogas led to an increase in the chemical exergy fraction of the combustion products. Thus, the exergy loss fractions resulting from incomplete combustion varied increasingly from 5.8 % to 13.8 % in the range from 10 % CO2 to 40 % CO2 contents of biogas.

Effects of ammonia and carbon dioxide concentration variation on ammonia-diesel blended fuel combustion in CO2/O2 atmosphere

Effects of ammonia and carbon dioxide concentration variation on ammonia-diesel blended fuel combustion in CO2/O2 atmosphere

Data on transgenerational memory effects of photosynthetic efficiency of twelve wheat varieties under elevated carbon dioxide concentration and reduced soil water availability

Data on transgenerational memory effects of photosynthetic efficiency of twelve wheat varieties under elevated carbon dioxide concentration and reduced soil water availability

Identification of Southern Ocean Upwelling From Biogeochemical‐Argo Floats

AbstractThe Southern Ocean surrounds the continent of Antarctica, linking the southern regions of the Atlantic, Indian, and Pacific Oceans. It plays a fundamental role in the global overturning circulation, and is a location of intense upwelling of deep water. The deep water that upwells is rich in nutrients, depleted in oxygen (O2), and enriched in carbon dioxide (CO2). Southern Ocean upwelling is thus important to the global carbon cycle through its impact on global ocean productivity and through its influence on air‐sea CO2 exchange. However, because of its widespread nature in time and space, and its underpinning weak vertical flows, it is challenging to detect Southern Ocean upwelling from observations. In a novel approach, we utilize measurements from Biogeochemical‐Argo floats deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling project, to identify Southern Ocean upwelling through its biogeochemical fingerprint. Our approach detects upwelling by examining surface carbon dioxide ([CO2]) and oxygen ([O2]) concentration Relative to Saturation (CORS). Differences between observed (calculated from pH for CO2) and saturating gas concentrations are used to fingerprint upwelling. Spatial analysis of the identified upwelling reveals a latitudinal gradient in upwelling, with the maximum toward the south of the Antarctic Circumpolar Current. Furthermore, our observational diagnostics provides some support of previous model‐based propositions of a focalization of Southern Ocean upwelling on hotspots of complex topography. Ongoing analysis with our approach can provide further insight into the nature and spatio‐temporal variability of Southern Ocean upwelling.

Coverage‐Limiting Factors Affecting the Monitoring of Urban Emissions With the Orbiting Carbon Observatory Missions

AbstractA growing number of space‐based platforms, like the Orbiting Carbon Observatory (OCO‐2 and OCO‐3) missions, observe Earth's atmospheric carbon dioxide concentrations with high accuracy and precision. With the original goal of constraining natural fluxes at regional to global scales, these instruments have now become popular tools for studying anthropogenic emissions from cities around the world. As signatories of the Paris Climate Agreement are expected to produce nationally determined contributions (NDC) to global carbon emissions, continued monitoring, reporting, and verification (MRV) of these estimates will be essential. While the use of OCO‐2 and OCO‐3 missions for MRV purposes is increasing, several physical and environmental factors limit data collection. Using the continental United States as a test case, the influences of orbital mechanics and environmental factors on local‐ and national‐level emissions estimates are explored through a series of linear and multi‐linear regressions to predict each instrument's effective revisit time. Results suggest that, due to environmental factors, western regions of the U.S. are more likely to be constrained at a sub‐annual scale than eastern regions, with effective instrument revisit times days. East coast cities have effective revisit times days; however, this varies seasonally. The characteristics of the instruments' orbits also vary the frequency of urban observations in both space and time. Implications for observation‐derived emission estimates at local and national scales and remedies for such shortcomings in future missions are discussed.

Crops and rising atmospheric CO2: friends or foes?

Rising atmospheric carbon dioxide concentration ([CO2]) is a ubiquitous global change with direct and indirect impacts on crops. The increase in atmospheric [CO2] since the industrial revolution has stimulated photosynthesis in crops and reduced stomatal conductance and canopy transpiration. These physiological changes result in a "CO2 fertilization effect" contributing to greater crop yields. However, CO2 is a greenhouse gas and has been the major contributor to increased radiative forcing and warmer global temperatures, resulting in more extreme weather events, with negative consequences for crop production. While the benefits of rising [CO2] have stimulated productivity to date, they may soon be outweighed by the challenges of rising temperatures and altered precipitation on plant productivity. Rising atmospheric [CO2] also reduces the nutritional value of crops, reducing protein content and the concentration of key micronutrients. Distinct physiological mechanisms contribute to changes in crop nutritional value at elevated [CO2], but there is potential to harness genetic diversity in nutrient content and for biofortification to counteract the negative impacts of rising [CO2] on crop quality. Crop improvement strategies that both adapt crops to future environments and mitigate the negative environmental impacts of agriculture are critical to ensuring future agricultural and nutritional sustainability.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.

Contribution of Carbon Dioxide Concentration to the Diurnal Variation in Land Surface Carbon Dioxide Uptake From the Atmosphere.

Gross primary productivity (GPP) is the key pathway for CO2 uptake by terrestrial ecosystems. Diurnal variation in atmospheric CO2 concentration ([CO2]) can reach 5%-15%, yet the extent to which (CO2) contributes to diurnal GPP variations across biomes and how this contribution varies across climate gradients remain unclear. Here, we used global half-hourly eddy covariance observations to quantify the importance of (CO2) in driving diurnal GPP variations and investigated the environmental factors influencing this response. On average, the relative contribution of (CO2) to diurnal GPP variations, calculated through multivariate regression, was 11% across all sites, comparable to the contributions of vapour pressure deficit (13%) and soil moisture (11%). We also observed systematic differences in the contribution of (CO2) to GPP variability across ecosystems with different plant functional types and climate conditions. Variation in the contribution of (CO2) to GPP is primarily driven by temperature-related variables. At long-term sites, we identified a significant upward trend in (CO2) influence on GPP over time, suggesting an increasing role of (CO2) in explaining GPP variations. This study quantified the importance of (CO2) to the diurnal variations of GPP across globally distributed ecosystems and highlighted that it makes a significant contribution to diurnal GPP patterns.

ВДОСКОНАЛЕННЯ ВЕНТИЛЯЦІЇ У ФІТНЕС ЦЕНТРІ

A physical model of ventilation of a fitness hall has been developed under conditions of varying visitor load and intensity of physical exercise. The ventilation rate of a fitness room and required amount of supply ventilation air when forming comfortable microclimate in a room under conditions of different intensity of physical exercises were determined. The results of experimental and theoretical studies of dependence of multiplicity of supply and exhaust ventilation depending on the number of visitors to the fitness hall, taking into account intensity of their physical activity and the value of internal air temperature are presented. The method of determining the volumetric and mass flow rate of supply ventilation air and the ventilation rate depending on temperature of the indoor air, carbon dioxide concentration, atmospheric pressure, number of visitors, their gender, age and intensity of physical exercises has been improved.

Increased temperature and CO2 induce plasticity and impose novel selection on plant traits.

Climate change is simultaneously increasing atmospheric carbon dioxide concentrations ([CO2]) and temperatures. We conducted a multi-factorial growth chamber experiment to examine how these climate change factors interact to influence the expression of ecologically-relevant traits, clines in these traits, and natural selection on morphology and phenology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado, USA. Plastic shifts in a key allocation trait (root mass fraction) in response to temperature accord with the direction of selection for probability of flowering, indicating that plasticity in this trait could be adaptive. However, plasticity in a foliar functional trait (leaf dry matter content) in response to temperature and [CO2] did not align with the direction of selection, indicating that plasticity could reduce fitness based on plant carbon allocation strategies. For another ecologically-important phenotype, selection favors resource acquisitive trait values (higher specific leaf area) under elevated [CO2] and resource conservative trait values (lower specific leaf area) at lower [CO2], despite the lack of plasticity in this trait. This pattern of selection counters published reports that elevated [CO2] induces low specific leaf area but could enable plants to reproduce across a greater period of the growing season under increasingly warm climates. Indeed, warmer temperatures prolonged the duration of flowering. This plasticity is likely adaptive, as selection favored increased flowering duration in the higher temperature treatment level. Thus, the two major results that emerged from our study are that climate change could impose novel and unanticipated patterns of natural selection on plant traits and that plasticity in these traits can be a maladaptive response to stress.

A practical metric for estimating the current climate forcing of natural mires

Abstract Commensuration of the radiative effects of different greenhouse gases (GHGs) is crucial for understanding the effects of land cover and ecosystem changes on the global climate. However, none of the current commensuration approaches are suitable for addressing the current climatic effect of mire ecosystems as compared to the situation in which such mires would not exist. The mire ecosystems have accumulated carbon for millennia, creating a negative perturbation to the atmospheric carbon dioxide content, but at the same time they emit methane into the atmosphere. Thus, the functioning of mires involves GHG fluxes with opposing effects on Earth’s radiative balance. Here, based on a simple radiative forcing (RF) model, we propose a new metric for commensuration of the effects of accumulated carbon and methane emission (ACME) on Earth’s energy balance. This ACME approach is applicable to natural mires with a significant part of their carbon accumulated more than 1000 years ago and requires relatively few input data. We demonstrate the feasibility of the ACME approach by applying it to a set of northern mires. The ACME-based RF estimate indicates that these mires have a cooling effect on the current climate, contrary to what a global warming potential-based calculation suggests, since the climatic effect is dominated by the sustained carbon accumulation. By applying the new metric with varying estimates of the total carbon storage and methane emission of northern mires, we estimate the current RF of these mires to range from –0.49 to –0.26 W m-2.

Intercomparison of in-well, depth profile and online soil gas measurements for estimating petroleum natural source zone depletion rates: Will in-well gas samples suffice?

Intercomparison of in-well, depth profile and online soil gas measurements for estimating petroleum natural source zone depletion rates: Will in-well gas samples suffice?

Impact of climate change on arsenic concentrations in paddy rice and the associated dietary health risks in Asia: an experimental and modelling study.

Impact of climate change on arsenic concentrations in paddy rice and the associated dietary health risks in Asia: an experimental and modelling study.

Warming increased the promotion of atmospheric CO2 concentration on biological nitrogen fixation by changing the nifH gene community.

Warming increased the promotion of atmospheric CO2 concentration on biological nitrogen fixation by changing the nifH gene community.

Could hybrid work schedules offer infection risk reductions? Insights from a CO2 Sensor and Modeling Study.

Could hybrid work schedules offer infection risk reductions? Insights from a CO2 Sensor and Modeling Study.

Estimation of Total Carbon Stock and Mangrove Health Index in Sidoarjo using Machine Learning Spectral Analysis Method of Sentinel-2A Satellite Imagery

The mangrove ecosystem has the potential ability to absorb carbon dioxide better than other forest ecosystems. It is noted that mangrove forests have an important role in reducing the concentration of carbon dioxide in the air. Changes in land cover conditions, massive development of urban areas, and the large need for housing in the Sidoarjo are the main causes of the decline in the area of mangrove forests which have been converted into fish ponds and residential areas. This triggers a decline in the quality of mangroves and will directly impact on reducing the capacity to store carbon reserves in Sidoarjo Regency. Biomass estimation calculations were carried out using the NDVI algorithm from remote sensing results using Sentinel Imagery – 2A. Apart from that, the mangrove health index was also calculated using the GCI (Green Chlorophyll Index), SIPI (Structure Insensitive Pigment Index), NBR (Normalized Burn Ratio), and ARVI (Atmospherically Resistant Vegetation Index). Based on the calculation results, the value obtained for the coastal area of Sidoarjo Regency the TCS or total carbon stock ranged from 1.1679468503445e-09 to 84.3344 TonC/hectares. Meanwhile, the results of the mangrove health index calculation show that the condition of mangroves in the coastal area of Sidoarjo Regency has a sufficient mangrove health index, with the highest area being 637.77 hectares, while only 10.80 hectares are available has a good health index. The results of this study are expected to be one of the bases for decision-making and policies in the rehabilitation and conservation of mangrove in Sidoarjo.

Synergistic Effects of Supplemental Lighting and Foliar Phosphorus Application on Flowering in Passion Fruit (Passiflora edulis)

Passion fruit (Passiflora edulis), a commercially vital tropical crop, faces flowering instability due to photoperiod-sensitive flowering patterns, particularly under the cloudy, rainy climates of subtropical regions. To mitigate floral suppression during unfavorable light conditions, this study implemented a dual-modality strategy combining 16 h daily supplementary lighting (460 nm blue + 630 nm red spectrum) and foliar application of a high-phosphorus-containing nutrient, the Plant-Prod (nitrogen–phosphorus–potassium = 10:52:10) grown in field ‘Qinmi No. 9’. The treatment significantly stimulated lateral branch formation, internode elongation, flower retention, stage IV flower bud development, and enhanced photosynthetic efficiency. Physiological analyses revealed that the treatment increased the net photosynthetic rate (Pn), reduced the intercellular carbon dioxide concentration (Ci), and enhanced stomatal conductance (Gs), indicating the improvement of carbon assimilation. Controlled seedling trials further confirmed these effects, with treated groups exhibiting accelerated lateral branching and stress resilience. This integrated approach, combining optimized supplemental lighting and precision phosphorus fertilization, offers a practical and scalable strategy to stabilize passion fruit yields in climate-variable regions, with immediate potential for commercial orchards and greenhouse production.

Co-application of potassium and thiourea for mitigating salinity stress in wheat seedlings

Salt stress disrupts ionic homeostasis and induces oxidative damage, leading to reduced plant growth and development. Determining the lethal dose of NaCl is essential for developing effective mitigation strategies. Potassium and other antioxidant regulatory compounds often prove insufficient in addressing salt-induced toxicity, especially in wheat. This laboratory experiment aimed to determine NaCl concentration that reduces plant growth by 50% and to evaluate the effectiveness of different mitigation approaches involving potassium and thiourea supplementation at 0 mM, 10 mM, and 15 mM under the identified NaCl condition. The experiment followed a factorial arrangement with three biological replications. Results showed that NaCl at 198 mM decreased germination and plant growth by 50%. The combined application of potassium and thiourea at 15 mM significantly improved ionic homeostasis, leading to a 14% increase in overall ion balance. This was achieved by reducing sodium ions concentration by 28.55% and increasing potassium ion concentration by 23.92%. Furthermore, the interactive application enhances various growth parameters, including shoot and root length (by 14.20–32.82%), and shoot/root fresh and dry weight (by 18.56/8.89% to 26.60/25.52%, respectively). These improvements were attributed to enhanced physiological processes, including a 10.23% increase in net photosynthetic rate, a 30.20% increase in stomatal conductance, a 6.70% increase in transpiration rate, an 8.12% increase in internal carbon dioxide concentrations and a 10.13% improvement in relative water content. Additionally, oxidative markers, such as hydrogen peroxide and malonaldeahyde, were reduced by 8.43% and 26.20%, respectively. This reduction was associated with increased antioxidant enzyme activity, including a 13.69% increase in superoxide dismutase, an 8.91% increase in catalase, a 20.18% increase in peroxidase, and a 13.11% increase in ascorbate peroxidase. The decrease in oxidative stress contributed to an 8.48% improvement in membrane stability and a 17.06% enhancement in relative water content. Principle component analysis confirmed the efficacy of the K15 + TU15 treatment in improving wheat salt tolerance. The simultaneous application of K and TU at 15 mM effectively mitigated salt-induced toxicity by enhancing ionic homeostasis and reducing oxidative stress through increased antioxidant enzyme activity in wheat.