CO2 Treatment Research Articles

Supercritical CO2 as a potential tool for the eco-friendly printing of meta-aramid

Large degree of orientation, crystallinity, and high glass transition temperature of aramid make the fibers exhibit ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and other excellent properties. However, the resulting poor dyeability and water pollution problems of aramid greatly limits its application in protective areas. An eco-friendly supercritical CO2 assisted printing strategy for meta-aramid was developed firstly in this study. The effects of treatment temperature, time, pressure and dye concentration on the printing properties were investigated. The obtained results showed that the K/S values of the printed meta-aramid increased with the enhancing of CO2 temperature, treatment time and CO2 pressure. Compared to tradition printing, higher color depth can be obtained by supercritical CO2 assisted printing with 40% sodium carboxymethyl cellulose and 20% guar gum as original paste. The K/S values of the meta-aramid with Cationic Pink X-FG in supercritical CO2 was 12.18 while that of the samples with Cationic Yellow 5GL was 5.42. Washing and rubbing colorfastness rated above 4 were reached at 180 °C for Cationic Pink X-FG and at 160 °C for Cationic Yellow 5GL in supercritical CO2. In addition, up to 99% outline sharpness and acceptable stiffness, air permeability and mechanical properties was obtained, which demonstrated that the meta-aramid fabrics with supercritical assisted printing could better meet the wearability requirements.

Statement of Retraction: Metal-organic framework with dual functional sites for CO2 catalytic fixation and treatment on COPD by down-regulating the tlr3 expression on the lung mucosal epithelial cells

Statement of Retraction: Metal-organic framework with dual functional sites for CO2 catalytic fixation and treatment on COPD by down-regulating the tlr3 expression on the lung mucosal epithelial cells

Expansion deformation and permeability characteristics of bituminous coal with different moisture content after CO2 adsorption

Injecting CO2 into deep unexploitable coal seams is a means with dual benefits of enhanced coalbed methane exploitation (CO2-ECBM) and CO2 geological storage (CGS). The permeability change of the coal seam after CO2 injection is an important factor for the CO2-ECBM and CGS. However, the impact of the interaction of CO2–H2O-coal in the coal seam on the adsorption swelling and permeability characteristics is poorly understood. In this study, we quantitatively analyzed the adsorption characteristics, permeability characteristics, and microstructure changes of coal samples under CO2–H2O-coal interaction by Geotechnical Consulting & Testing Systems (GCTS), nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). The results show that the increase of moisture content inhibits the adsorption of CO2 due to the clusters formed by water molecules occupy the position of adsorption pores, reducing the expansion rate of coal samples. The reaction rate content of carbonate minerals in coal samples increases with the increase of moisture content after subcritical CO2 treatment, leading to an increase in the relative content of clay minerals, which can enlarge the pore volume. However, the subcritical CO2 treatment cannot completely eliminate the negative impact of loading and unloading processes on the mesopore and macropore, and therefore show a decrease of the pore volume and permeability. The dissolution of carbonate mineral in coal samples is more severe after supercritical CO2 (ScCO2), which can effectively enlarge seepage pores and thus improves the permeability. The clay mineral content increases slightly at 5.6% moisture content, indicating that it also reacts significantly after ScCO2 treatment. For instance, the permeability growth rate of 2.8% moisture content coal sample reaches 421.74% at 8 MPa effective stress, which is the best moisture content for permeability enhancement. In addition, the coal samples with 5.6% moisture content show the transformation from mesopores and macropores to micropores and small pores after subcritical CO2 and ScCO2 treatment, which provides more adsorption sites for CGS.

Leaf Gas Exchange and Photosystem II Fluorescence Responses to CO2 Cycling.

Experimental systems to simulate future elevated CO2 conditions in the field often have large, rapid fluctuations in CO2. To examine possible impacts of such fluctuations on photosynthesis, the intact leaves of the field-grown plants of five species were exposed to two-minute cycles of CO2 between 400 and 800 μmol mol-1, lasting a total of 10 min, with photosynthesis, stomatal conductance and PSII fluorescence measured at the end of each half-cycle and also 10 min after the end of the cycling. Prior to the cyclic CO2 treatments, the steady-state responses of leaf gas exchange and fluorescence to CO2 were determined. In four of the five species, in which stomatal conductance decreased with increasing CO2, the cyclic CO2 treatments reduced stomatal conductance. In those species, both photosynthesis and the photochemical efficiency of PSII were reduced at limiting internal CO2 levels, but not at saturating CO2. In the fifth species, there was no change in stomatal conductance with CO2 and no change in either photosynthesis or PSII efficiency at any CO2 level with CO2 cycling. It is concluded that in many, but not all, species, fluctuations in CO2 may reduce photosynthesis at low CO2, partly by decreasing the photochemical efficiency of photosystem II as well as by decreasing stomatal conductance.

Experimental Investigation of Mafic Rocks for Carbon Mineralization Prospect

Carbon capture and storage by mineralization (CCSM) in mafic rock is a viable technology to store captured gaseous carbon dioxide (CO2) into carbonate minerals by chemical reaction with rocks. Here, we investigate the interaction of CO2 with four outcrop mafic rock samples of the Saudi Arabian region for their CCSM potential. Samples interacted with CO2 at 8.27 MPa and 343 K in a batch reactor system for 2 months, and petrophysical and geomechanical properties were analyzed before and after CO2 treatment. The results indicate that the initial state of samples is compromised after exposure to CO2. X-ray diffaction and scanning electron microscopy analyses confirm the reactivity of CO2 with samples. Petrophysical and mechanical parameters also changed after interaction with CO2; i.e., porosity decreased, while Young’s modulus and hardness increased. The results of this study thus shed light on rapid carbon mineralization in the mafic rocks of Saudi Arabia, which can have direct implications for CO2 geo-sequestration in the region.

Ocean acidification alters the benthic biofilm communities in intertidal soft sediments

Microphytobenthos (MPB) and bacterial biofilms play crucial roles in primary and secondary production, nutrient cycling and invertebrate settlement in coastal ecosystems, yet little is known of the effects of ocean acidification (OA) on these communities in intertidal soft sediments. To fill in this gap, a 28-day CO2 enhancement experiment was conducted for the benthic biofilms in soft intertidal sediments (muds and sands) from Qingdao, China. This experiment included three CO2 treatments: 400 ppm CO2 (control), 700 ppm CO2 and 1000 ppm CO2 (IPCC predicted value in 2100), which were established in a three-level CO2 incubator that can adjust the CO2 concentration in the overlying air. The effects of OA on benthic biofilms were assessed in the following three aspects: MPB biomass, biofilm community structure and microbial biogeochemical cycling (e.g., C-cycle, N-cycle and S-cycle). This study found that the 700 ppm CO2 treatment did not significantly affect the benthic biofilms in intertidal soft sediments, but the 1000 ppm CO2 treatment significantly altered the biofilm community composition and potentially their role in microbial biogeochemical cyc\ling in sediments (especially in sandy sediments). For the bacterial community in biofilms, the 1000 ppm CO2 enhancement increased the relative abundance of Alteromonadales and Bacillales but decreased the relative abundance of Rhodobacterales and Flavobacteriales. For microbial biogeochemical cycling, the 1000 ppm CO2 treatment enhanced the potential of chemoheterotrophic activity, nitrate reduction and sulfur respiration in sediments, likely resulting in a more stressful environment (hypoxic and enriched H2S) for most benthic organisms. Even though incubations in this study were only 28 days long and thus couldn’t fully accommodate the range of longer-term adaptions, it still suggests that benthic biofilms in intertidal sandy sediments are likely to change significantly near the end of the century if anthropogenic CO2 emissions unmitigated, with profound implications on local ecosystems and biogeochemical cycling.

Analysis of CO2 effects on porosity and permeability of shale reservoirs under different water content conditions

CO2 technology has been the key technology to enhance oil and gas recovery for shale oil and gas reservoir development. After injection, CO2 can react with water and generate carbonic acid, which then can react with various minerals in shale, leading to changes of porosity and permeability. However the specific research conclusions remain controversial on whether the effect of CO2 is improvement or damage for porosity and permeability. In CO2 hybrid fracturing, The areas with varied water content are formed due to the difference in mobility. So in this article, we carried out systematic research to clarify the interaction between CO2 and shale in different water content conditions (sufficient water, deficient water and water-free) and draw a pertinent conclusion. And the results show that the effects of CO2 treatment on shale have significant differences among different water content. Under sufficient water conditions, CO2 fully dissolves into water to generate carbonic acid, and large dissolved pores are generated by the massive dissolution of minerals such as feldspar and carbonates in the shale matrix, leading to the increase of porosity and permeability. Under deficient water conditions, only a small amount of carbonic acid is formed after the reaction of CO2 and water, leading to a significant decrease of porosity and permeability. Under water-free conditions, no dissolution is observed on the shale matrix, while some soluble components of organic matter may be extracted by CO2 to form organic pores, leading to slight changes in porosity and permeability. In large scales, although both porosity and permeability in the near-wellbore water-sufficient area is improved, the CO2-affected region presents the overall decline of porosity and permeability, due to the negative effects on the water-deficient area. So, it is necessary to enlarge the volume of water-sufficient areas to get a better effect of enhanced oil and gas recovery.

Modification of construction waste derived recycled aggregate via CO2 curing to enhance corrosive freeze-thaw durability of concrete

Although the utilization of construction waste derived recycled aggregate (CWDRA) has been reported as a promising way to reduce carbon emission and energy consumption for construction industry, the resistance of reinforced concrete containing CWDRA to corrosion and freeze-thaw (F-T) cycles are usually inferior than that containing natural aggregate. This study aims to provide a clean and efficient strategy (CO2 curing) for the modification of CWDRA to enhance corrosive F-T durability of such green concrete, and thus promote its application to marine or offshore structures under cold environment. Some experiments are conducted on specimens exposed to NaCl F-T cycles to verify the improvement effect of CO2 curing, including the mass loss, relative dynamic modulus of elasticity (RDME), mechanical properties, chloride migration coefficient (CMC) of plain concrete as well as the corrosion degradation of steel bar reinforced concrete. Results show that the concrete damage caused by NaCl F-T cycles can be significantly alleviated by CO2 treatment on CWDRA. The compressive and flexural strength of concrete after exposure to NaCl F-T cycles are enhanced by 40.1% and 25.9%, while the CMC value is reduced by 66.1%. Besides, incorporating CO2-cured CWDRA decreases the corrosion speed of reinforced concrete (by 42.4%) and particularly inhibits the progress of rust generation from steel bar (by 48.4%). The phase transformation inside material during CO2 curing makes the loose interface between mortar matrix and CWDRA grows to be rougher, which significantly promotes the improvement effect on the corrosive freeze-thaw resistance. Therefore, CO2 curing technology for CWDRA is highly recommended for the cleaner production of durable concrete in cold region offshore structures.

Climate drivers alter nitrogen availability in surface peat and decouple N2 fixation from CH4 oxidation in the Sphagnum moss microbiome.

Peat mosses (Sphagnum spp.) are keystone species in boreal peatlands, where they dominate net primary productivity and facilitate the accumulation of carbon in thick peat deposits. Sphagnum mosses harbor a diverse assemblage of microbial partners, including N2 -fixing (diazotrophic) and CH4 -oxidizing (methanotrophic) taxa that support ecosystem function by regulating transformations of carbon and nitrogen. Here, we investigate the response of the Sphagnum phytobiome (plant + constituent microbiome + environment) to a gradient of experimental warming (+0°C to +9°C) and elevated CO2 (+500 ppm) in an ombrotrophic peatland in northern Minnesota (USA). By tracking changes in carbon (CH4 , CO2 ) and nitrogen (NH4 -N) cycling from the belowground environment up to Sphagnum and its associated microbiome, we identified a series of cascading impacts to the Sphagnum phytobiome triggered by warming and elevated CO2 . Under ambient CO2 , warming increased plant-available NH4 -N in surface peat, excess N accumulated in Sphagnum tissue, and N2 fixation activity decreased. Elevated CO2 offset the effects of warming, disrupting the accumulation of N in peat and Sphagnum tissue. Methane concentrations in porewater increased with warming irrespective of CO2 treatment, resulting in a ~10× rise in methanotrophic activity within Sphagnum from the +9°C enclosures. Warming's divergent impacts on diazotrophy and methanotrophy caused these processes to become decoupled at warmer temperatures, as evidenced by declining rates of methane-induced N2 fixation and significant losses of keystone microbial taxa. In addition to changes in the Sphagnum microbiome, we observed ~94% mortality of Sphagnum between the +0°C and +9°C treatments, possibly due to the interactive effects of warming on N-availability and competition from vascular plant species. Collectively, these results highlight the vulnerability of the Sphagnum phytobiome to rising temperatures and atmospheric CO2 concentrations, with significant implications for carbon and nitrogen cycling in boreal peatlands.

A carbon dioxide huff and puff project at a mature heavy oil Field in Dagang, China

AbstractCarbon dioxide has been proved an effective agent to enhance recovery for relatively light crude oil, but its applications in heavy oil are very limited. This short communication presents field trials of CO2 huff and puff at Dagang, a heavy oil field in Northeast China. Two wells received CO2 injection, and both wells saw higher oil output and lower water‐cut after CO2 treatment. This project proves CO2 is effective for heavy oil recovery. Recommendations are also made for future CO2 huff and puff projects. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

The impact of ocean acidification on the eye, cuttlebone and behaviors of juvenile cuttlefish (Sepiella inermis)

The cuttlefish (Sepiella inermis) is an economically important species in the coastal seas of China. The impacts of ocean acidification on the ability of juvenile cuttlefish to select a suitable habitat, its hunting and swimming behavior, remains unknown. We examined behavior-related responses and the eye and cuttlebone structure of juvenile cuttlefish following short-term exposure to CO2-enriched seawater. The predation success rate decreased with the elevation in CO2 concentration. In the CO2 treatment groups, cuttlefish spent more time in the dark zone and the average swimming speed and total swimming distance significantly decreased. The structure of the retina and cuttlebone was affected by seawater acidification. Moreover, apoptotic cells were significantly increased in the eyes. In the wild, the impairment of the eye and cuttlebone may decrease the predation ability of juvenile cuttlefish and negatively affect their ability to select a suitable habitat, which would be detrimental to its population.

Norfloxacin-CO2 crystal formed under supercritical CO2 and enhanced Norfloxacin dissolution properties

A molecular crystal of Norfloxacin coupled with CO2, was produced after the supercritical CO2 treatment of Norfloxacin form B. The effects of pressure and temperature on Norfloxacin-CO2 crystal formation are studied semi-quantitatively using on powder XRD and TGA. The higher pressure and temperature conditions result in the formation of more Norfloxacin-CO2 crystals for a limited time. Based on these results, pure Norfloxacin-CO2 crystals are fabricated. Through further studies, we found out that CO2 is fixed in Norfloxacin-CO2 crystal through the formation of a paired carbamic acid structure with two piperazine groups from two adjacent Norfloxacin molecules. The fixed CO2 can be released during dissolution, improving the equilibrium solubility of Norfloxacin from 0.28 mg g−1 water to 0.64 mg g−1 water at 25 ºC. Since no toxic organic solvent used, this research offers a new pathway for greener and safer enhancement for the dissolution properties of poorly soluble APIs.

Metabolomics Approach to Reveal the Effects of Ocean Acidification on the Toxicity of Harmful Microalgae: A Review of the Literature

Climate change has been associated with intensified harmful algal blooms (HABs). Some harmful microalgae produce toxins that accumulate in food webs, adversely affecting the environment, public health and economy. Ocean acidification (OA) is a major consequence of high anthropogenic CO2 emissions. The carbon chemistry and pH of aquatic ecosystems have been significantly altered as a result. The impacts of climate change on the metabolisms of microalgae, especially toxin biosynthesis, remain largely unknown. This hinders the optimization of HAB mitigation for changed climate conditions. To bridge this knowledge gap, previous studies on the effects of ocean acidification on toxin biosynthesis in microalgae were reviewed. There was no solid conclusion for the toxicity change of saxitoxin-producing dinoflagellates from the genus Alexandrium after high CO2 treatment. Increased domoic acid content was observed in the diatom Pseudo-nitzschia. The brevetoxin content of Karenia brevis remained largely unchanged. The underlying regulatory mechanisms that account for the different toxicity levels observed have not been elucidated. Metabolic flux analysis is useful for investigating the carbon allocations of toxic microalgae under OA and revealing related metabolic pathways for toxin biosynthesis. Gaining knowledge of the responses of microalgae in high CO2 conditions will allow the better risk assessment of HABs in the future.

Strong Ferromagnetic Manipulation of SrTiO3 from CO2 -Straining Effect on Electronic Structure Modulation.

2D magnetic materials are ideal to fabricate magneto-optical, magneto-electric, and data storage devices, which are proposed to be critical to the next generation of information technologies. Benefited from their labile structures, 2D perovskites are amenable for magnetic manipulation through structural optimization. In this work, 2D room-temperature ferromagnetic SrTiO3 is achieved through straining effect induced by supercritical carbon dioxide (SC CO2 ). According to experimental results, the cubic phase of SrTiO3 is converted to tetragonal with exposure of (110), (200), (111), and (211) planes over the SC CO2 treatment, leading to significant ferromagnetic enhancement. Theoretical calculations illustrate that over the conversion from cubic to tetragonal, the electronic structure of SrTiO3 is significantly modulated. Specifically, the spin density of planes of (200), (111), and (211) is enhanced, presumably due to the stabilization of the highest occupied molecular orbital over straining by SC CO2 , leading to magnetic optimizations. This work suggests that magnetic optimization can be achieved from SC CO2 -induced electronic structure modulation.

Loss of peroxisomal NAD kinase 3 (NADK3) affects photorespiration metabolism in Arabidopsis

Nicotinamide adenine dinucleotides (NAD+ and NADP+) are electron mediators involved in various metabolic pathways. NADP(H) are produced by NAD kinase (NADK) through the phosphorylation of NAD(H). The Arabidopsis NADK3 (AtNADK3) is reported to preferentially phosphorylate NADH to NADPH and is localized in the peroxisome. To elucidate the biological function of AtNADK3 in Arabidopsis, we compared metabolites of nadk1, nadk2 and nadk3 Arabidopsis T-DNA inserted mutants. Metabolome analysis revealed that glycine and serine, which are intermediate metabolites of photorespiration, both increased in the nadk3 mutants. Plants grown for 6 weeks under short-day conditions showed increased NAD(H), indicating a decrease in the phosphorylation ratio in the NAD(P)(H) equilibrium. Furthermore, high CO2 (0.15%) treatment induced a decrease in glycine and serine in nadk3 mutants. The nadk3 showed a significant decrease in post-illumination CO2 burst, suggesting that the photorespiratory flux was disrupted in the nadk3 mutant. In addition, an increase in CO2 compensation points and a decrease in CO2 assimilation rate were observed in the nadk3 mutants. These results indicate that the lack of AtNADK3 causes a disruption in the intracellular metabolism, such as in amino acid synthesis and photorespiration.

The effect of elevated CO2 on photosynthesis is modulated by nitrogen supply and reduced water availability in Picea abies.

It is assumed that the stimulatory effects of elevated CO2 concentration ([CO2]) on photosynthesis and growth may be substantially reduced by co-occurring environmental factors and the length of CO2 treatment. Here, we present the study exploring the interactive effects of three manipulated factors ([CO2], nitrogen supply and water availability) on physiological (gas-exchange and chlorophyll fluorescence), morphological and stoichiometric traits of Norway spruce (Picea abies) saplings after 2 and 3 years of the treatment under natural field conditions. Such multifactorial studies, going beyond two-way interactions, have received only limited attention until now. Our findings imply a significant reduction of [CO2]-enhanced rate of CO2 assimilation under reduced water availability which deepens with the severity of water depletion. Similarly, insufficient nitrogen availability leads to a down-regulation of photosynthesis under elevated [CO2] being particularly associated with reduced carboxylation efficiency of the Rubisco enzyme. Such adjustments in the photosynthesis machinery result in the stimulation of water-use efficiency under elevated [CO2] only when it is combined with a high nitrogen supply and reduced water availability. These findings indicate limited effects of elevated [CO2] on carbon uptake in temperate coniferous forests when combined with naturally low nitrogen availability and intensifying droughts during the summer periods. Such interactions have to be incorporated into the mechanistic models predicting changes in terrestrial carbon sequestration and forest growth in the future.

Oxidation of metallic Cu by supercritical CO2 and control synthesis of amorphous nano-metal catalysts for CO2 electroreduction

Amorphous nano-metal catalysts often exhibit appealing catalytic properties, because the intrinsic linear scaling relationship can be broken. However, accurate control synthesis of amorphous nano-metal catalysts with desired size and morphology is a challenge. In this work, we discover that Cu(0) could be oxidized to amorphous CuxO species by supercritical CO2. The formation process of the amorphous CuxO is elucidated with the aid of machine learning. Based on this finding, a method to prepare Cu nanoparticles with an amorphous shell is proposed by supercritical CO2 treatment followed by electroreduction. The unique feature of this method is that the size of the particles with amorphous shell can be easily controlled because their size depends on that of the original crystal Cu nanoparticles. Moreover, the thickness of the amorphous shell can be easily controlled by CO2 pressure and/or treatment time. The obtained amorphous Cu shell exhibits high selectivity for C2+ products with the Faradaic efficiency of 84% and current density of 320 mA cm−2. Especially, the FE of C2+ oxygenates can reach up to 65.3 %, which is different obviously from the crystalline Cu catalysts.

Balance dysfunction in large yellow croaker in response to ocean acidification

Large yellow croaker (Larimichthys crocea) is a coastal-dwelling soniferous, commercially important fish species that is sensitive to sound. An understanding of how ocean acidification might affect its auditory system is therefore important for its long-term viability and management as a fisheries resource. We tested the effects of ocean acidification with four CO2 treatments (440 ppm (control), 1000 ppm, 1800 ppm, and 3000 ppm) on the inner ear system of this species. After exposure to acidified water for 50 d, the impacts on the perimeter and mass of the sagitta, asteriscus, and lapillus otoliths were determined. In the acidified water treatments, the shape of sagittal otoliths became more irregular, and the surface became rougher. Similar sound frequency ranges triggered startle responses of fish in all treatments. In the highest CO2 treatment (3000 ppm CO2), significant asymmetry of the left and right lapillus perimeter and weight was apparent. Moreover, in the higher CO2 treatments (1800 ppm and 3000 ppm CO2), the fish were unable to maintain a balanced dorsal-up posture and tilted to one side. This result suggested that the balance functions of the inner ear might be affected by ocean acidification, which may threaten large yellow croaker individuals and populations. The molecular response to acidification was analyzed by RNA-Seq. The differentially expressed genes (DEGs) between right and left sensory epithelia of the utricle in each CO2 treatment group were identified. In higher CO2 concentration groups, nervous system function and regulation of bone mineralization pathways were enriched with DEGs. The comparative transcriptome analyses provide valuable molecular information about how the inner ear system responds to an acidified environment.

Effect of different anaesthesia treatments on the onset of oviposition by virgin queen honey bees

Treating instrumentally inseminated honey bee queens with carbon dioxide accelerates egg laying. This treatment also activates the ovaries of virgins. The aim of the study was to compare the effect of three different treatments: (1) anaesthesia with carbon dioxide, (2) anaesthesia with nitrogen, and (3) oxygen deprivation by submersion in water, on the onset of oviposition in virgin queens. The effect of the number and duration of CO2 treatments was also investigated. No significant differences were found in the onset of egg laying in queens treated with CO2, or N2, or water. The beginning of oviposition after the CO2 treatment for 0.1, 1, 2, and 10 min, did not differ significantly. Whether a CO2 treatment was performed twice or three times, the effect was the same, but oviposition was accelerated compared to when only one anaesthesia treatment was used. I speculate that ovary activation in queens is not the effect of CO2 or any other gases but rather the effect of a lack of oxygen, i.e., anoxia.

Photosynthetic Physiological Response of Porphyra yezoensis to Light Change at Different CO2 Concentrations

The effect of different CO2 concentrations and their subsequent light changes on the photosynthetic characteristics of Porphyra yezoensis are not well understood. The relationship between the availability of CO2 and light to physiological traits of the thalli could help understand the response and adaptation mechanisms of P. yezoensis to extreme weather changes. In this study, the photosynthetic response of P. yezoensis to light changes at different CO2 concentrations was determined. Under low light intensity, the high CO2 concentration promoted the relative growth rate (RGR) of P. yezoensis by 22.79% compared to that of ambient CO2 treatment. The net photosynthetic rate and phycoerythrin (PE) content under high CO2 were also significantly greater than those under ambient CO2 treatment at low light therapy. Under high light intensity, high CO2 exacerbated the inhibitory effect of light on the RGR of thalli. The net photosynthetic rate and PE content were significantly reduced by 12.53% and 14.06% at elevated CO2 concentration under a high light intensity, respectively. Furthermore, the net photosynthetic rate was significantly decreased when the light intensity was rapidly reduced, especially under simultaneously elevated CO2 concentrations. These findings indicate that elevated CO2 concentration increased the RGR and PE content at low light intensity of P. yezoensis. In addition, this study provides a theoretical basis for the response and adaptation mechanism of P. yezoensis to extreme weather changes.