Effects Of CO2 Levels Research Articles

The effects of CO2 levels and body temperature on brain interstitial pH alterations during the induction of hypoxic-ischemic encephalopathy in newborn pigs

Brain interstitial pH (pHbrain) alterations play a crucial role in the development of hypoxic-ischemic (HI) encephalopathy (HIE) caused by asphyxia in neonates. The newborn pig is one of the most suitable large animal models for studying HIE, however, compared to rats, experimental data on pHbrain alterations during HIE induction are limited. The major objective of the present study was thus to compare pHbrain changes during HIE development induced by experimental normocapnic hypoxia (H) or asphyxia (A), elicited with ventilation of a gas mixture containing 6%O2 or 6%O2/20%CO2, respectively for 20 min, under either normothermia (NT) or hypothermia (HT) (38.5 ± 0.5 °C or 33.5 ± 0.5 °C core temperature, respectively) in anesthetized piglets yielding four groups: H-NT, A-NT, H-HT, and A-HT. pHbrain changes during HI stress and the 60 min reoxygenation period were measured using a pH-selective microelectrode inserted into the parietal cortex through an open cranial window. In all groups, the pHbrain response to HI stress was acidosis, at the nadir pHbrain values dropped from the baseline of 7.27 ± 0.02 to H-NT:5.93 ± 0.30, A-NT:5.90 ± 0.52, H-HT:6.81 ± 0.27, and A-HT:6.27 ± 0.24 indicating that (1) H and A elicited similar, severe brain acidosis under NT greatly exceeding pH changes in arterial blood (pHa dropped to 7.24 ± 0.07 and 6.78 ± 0.03 from 7.52 ± 0.06 and 7.50 ± 0.05, respectively), and (2) HT ameliorated more the brain acidosis induced by H than by A. In all four groups, pHbrain was restored to baseline values without an alkalotic overshoot during the observed reoxygenation, Our findings suggest that under NT either H or A – both commonly employed HI stresses to elicit HIE in piglet models – would result in a similar acidotic pHbrain response without an alkalotic component either during the HI stress or the early reoxygenation period.

Interaction of Light Intensity and CO2 Concentration Alters Biomass Partitioning in Chrysanthemum

Abstract Biomass partitioning is one of the pivotal determinants of crop growth management, which is influenced by environmental cues. Light and CO2 are the main drivers of photosynthesis and biomass production in plants. In this study, the effects of CO2 levels: ambient 400 ppm (a[CO2]) and elevated to 1,000 ppm (e[CO2]) and different light intensities (75, 150, 300, 600 μmol·m−2·s−1 photosynthetic photon flux density – PPFD) were studied on the growth, yield, and biomass partitioning in chrysanthemum plants. The plants grown at higher light intensity had a higher dry weight (DW) of both the vegetative and floral organs. e[CO2] diminished the stimulating effect of more intensive light on the DW of vegetative organs, although it positively influenced inflorescence DW. The flowering time in plants grown at e[CO2] and light intensity of 600 μmol·m−2·s−1 occurred earlier than that of plants grown at a[CO2]. An increase in light intensity induced the allocation of biomass to inflorescence and e[CO2] enhanced the increasing effect of light on the partitioning of biomass toward the inflorescence. In both CO2 concentrations, the highest specific leaf area (SLA) was detected under the lowest light intensity, especially in plants grown at e[CO2]. In conclusion, elevated light intensity and CO2 direct the biomass toward inflorescence in chrysanthemum plants.

Long-Term Effect of Elevated CO2 on the Development and Nutrition Contents of the Pea Aphid (Acyrthosiphon pisum).

It is predicted that the current atmospheric CO2 level will be doubled by the end of this century. Here, we investigate the impacts of elevated CO2 (550 and 750 μL/L) on the development and nutrition status of the green pea aphid for six generations, which is longer than previous studies. All seven examined physiological parameters were not affected over six generations under the ambient CO2 level (380 μL/L). However, the elevated CO2 levels (550 and 750 μL/L) prolonged nymph duration, decreased adult longevity, female fecundity and protein content, and increased the contents of total lipid, soluble sugar and glycogen. There was a significant interaction between the effect of CO2 levels and the effect of generations on nymph duration, female fecundity and adult longevity. The elevated CO2 had immediate effects on the female fecundity and the contents of total protein, total lipid and soluble sugar, starting within F0 generation. The adult longevity decreased, and the glycogen content increased from the F1 generation. However, the significant effect on the nymph development was only observed after three generations. Our study indicates that the elevated CO2 levels first influence the reproduction, the nutrition and the energy supply, then initiate aphid emergency responses by shortening lifespan and increasing glucose metabolism, and finally result in the slow development under further persistent elevated CO2 conditions after three generations, possibly leading to population decline under elevated CO2 conditions. Our results will guide further field experiments under climate change conditions to evaluate the effects of elevated CO2 on the development of the pea aphids and other insects, and to predict the population dynamics of the green pea aphid.

Perceived indoor air quality in naturally ventilated primary schools in the UK: Impact of environmental variables and thermal sensation.

Indoor air quality (IAQ) in classrooms has a significant impact on children's academic performance, health, and well-being; therefore, understanding children's perception of IAQ is vital. This study investigates how children's perception of IAQ is affected by environmental variables and thermal sensation. In total, 29 naturally ventilated classrooms in eight UK primary schools were selected and 805 children were surveyed during non-heating and heating seasons. Results show that air sensation votes (ASVs) are more correlated to CO2 levels than to operative temperatures (Top ) during non-heating seasons and more correlated to Top than CO2 levels during heating seasons. The impact of Top on ASVs decreases with an increase in CO2 levels, and the effect of CO2 levels on ASVs decreases with increase in Top . The most favorable ASVs are given when children feel "cool" and have "as it is" preference. By keeping CO2 <1000ppm and Top within children's thermal comfort band, ASVs are improved by 43%. The study recommends that standards should consider the impact of both temperature and CO2 levels on perceived IAQ. Perception of IAQ also affects children's overall comfort and tiredness levels; however, this influence is more significant on tiredness level than that on overall comfort level.

Soil properties and not high CO2 affect CH4 production and uptake in periodically waterlogged arable soils

Several studies related to CH4 cycling focus on the effect of elevated atmospheric CO2 levels on soil methanogenesis and methanotrophy. However, periodically waterlogged soils are characterized by much higher CO2 concentrations, while aggregates forming in arable soils due to traditional cultivation may be a natural CH4 source for low-affinity methanotrophs. We present a comprehensive laboratory investigation into both methanogenesis and methanotrophy in three different soils under ambient and high CO2 concentrations. The tested materials were agricultural soils widely distributed in Europe: Eutric Cambisol, Haplic Podzol and Mollic Gleysol with determined properties: Corg, Ntot, clay, silt, sand, pH, NO3−, NH4+. We conducted two independent experiments on methanogenesis (flooded conditions) and methanotrophy (non-flooded conditions). All samples for both studies were divided into three sets which differed in the initial CO2 concentration in headspace: ambient CO2 (0.03% v/v ± 0.005), and two high CO2 levels (5% ± 0.4 and 10% ± 0.5 v/v CO2). Moreover, 1% (v/v) of CH4 was added to all sets prepared for the methanotrophy test since low-affinity methanotrophy in the tested soils had been reported previously. Gas concentrations (CH4, CO2, O2) in headspace were measured using gas chromatography method. We observed that the examined soils differed in their ability to produce CH4 as follows: Haplic Podzol = Eutric Cambisol > Mollic Gleysol, as well as to consume CH4: Mollic Gleysol > Haplic Podzol > Eutric Cambisol. The CH4 emissions started faster in Gleysol, but the final CH4 concentration and CH4 production rate in this soil were significantly lower than in the two other soils. The CH4 uptake rate significantly differed among the tested soils. The MANOVA confirmed the significance of the soil-type factor in determining both process rates, whereas the effect of CO2 level and the interaction between both factors were not significant. The amount of consumed O2 during CH4 oxidation was also characteristic for examined soil, but did not differ significantly between CO2 variants. CH4 production and consumption in three different soils (Eutric Cambisol, Haplic Podzol and Mollic Gleysol) collected from periodically waterlogged arable fields were more strongly affected by soil properties than by high CO2 concentration. In contrast, the high CO2 level significantly decreased CO2 production accompanying tested the CH4-related processes.

Effect of CO2 on acid-base regulation and growth performance of basa catfish (Pangasius bocourti)

This study aims to evaluate the effects of different carbon dioxide levels on blood physiological parameters and growth performance of basa catfish (Pangasius bocourti). The study included two experiments, (1) change of fish blood physiological parameters at different CO2 levels such as 1%, 2%, 3% CO2;and (2) effect of CO2 levels on fish growth performance. In the first experiment, blood samples were collected at 0, 1, 6, 24, 48, 72, 96 and 168 hrs. after equilibration to investigate pHe, pCO2, [HCO3-] and [Cl-] in plasma. The grow-out experiment was set up for 60 days and fish was weighed at the day 0, 30 and 60. The results showed that, after 1 hr. of CO2 exposure, pHe wassignificantly decreased (7.51±0.01 in control fish and 7.28±0.02 in the fish exposed to CO2 3%, this parameter was recovered after 6 hrs. pCO2 and [HCO3-] increased at all CO2 exposed groups. After 168 hrs., pCO2 and [HCO3-] in plasma of 3% CO2 exposed fish were significantly increased and reached the values of 20.7±1.35 mmHg and 22.2±1.16 mM, respectively; those pCO2 and [HCO3-] values were 2.7 and 3.2 fold as high as the values of control fish. [Cl-] concentration in plasma of fish in 2% and 3% CO2 treatments were significantly decreased after 48 hrs. of CO2 exposure in comparison with control treatment (p2 concentrations (p

Modeling the Effect of Elevated CO2 and Climate Change on Reference Evapotranspiration in the Semi-Arid Central Great Plains

Changes in evapotranspiration demand due to global warming will have a profound impact on irrigation water demand and agricultural productivity. In this study, the effects of possible future anthropogenic climate change on reference evapotranspiration (ETo) were evaluated using the Penman-Monteith equation. The combined effect of temperature and elevated CO2 concentrations on ETo was the major focus of this study. The ETo under the General Circulation Model (GCM) projected climate change scenarios was estimated for a location in Colorado. Multi-model ensemble climate change scenarios were generated from 112 Bias Corrected and Spatially Disaggregated (BCSD) projections from the World Climate Research Program (WCRP) archive, which cover different levels of greenhouse gas emissions. Results showed a decrease in ETo demand with increases in CO2 levels, which greatly moderated the increase in ETo due to increasing temperature. The effect of increases in CO2 levels up to 450 ppm offset the effect of about 1C rise in temperature. Simulation results with projected climate change scenarios, without considering the effects of CO2 levels, showed an 8.3%, 14.7% and 21.0% increase in annual ETo during the 2020s, 2050s, and 2080s, respectively, when simulation was carried out using an ensemble of the 112 projections. When the effect of elevated CO2 levels was also considered in combination with projected changes in temperature, changes in annual ETo demand varied from -1.5% to 5.5%, -10.4% to 6.7%, and -19.7% to 6.6% during the 2020s, 2050s, and 2080s, respectively, depending on the different climate change scenarios considered and the relationship or equation used for estimating the effect of elevated CO2 on stomatal resistance term in the Penman-Monteith equation.