CO2 Enrichment Research Articles

CupAR negatively controls the key protein CupA in the carbon acquisition complex NDH–1MS in Synechocystis sp. PCC 6803

The low CO2-inducible NDH complex (NDH-1MS) plays a crucial role in the cyanobacterial CO2-concentrating mechanism. However, the components in this complex and the regulation mechanism are still not completely understood. Using a mutant only with NDH-1MS as active Ci sequestration system, we identified a functional gene sll1736 named as cupAR (CupA Regulator). The cupAR deletion mutant, ΔcupAR, grew faster than the WT under high CO2 (HC) condition, more evidently at low pH. The activities of O2 evolution, CO2 uptake，NDH-1, and the building up of a transthylakoid proton were stimulated in this mutant under HC conditions. The cupAR gene is cotranscribed with the NDH-1S operon (ndhF3-ndhD3-cupA) and encoded protein, which specifically suppresses the transcription level of this operon under HC conditions. Mutation of cupAR significantly upregulated the accumulation of CupA, the key protein of NDH-1MS, under HC condition. CupAR interacted with NdhD3 and NdhF3, the membrane components of NDH-1MS, while accumulation of CupAR was reduced in the ΔndhD3 mutant. Furthermore, CupAR was colocated with CupA in both NDH-1MS complex and NDH-1S subcomplex. On the other hand, deletion of ndhR, a negative regulator of the NDH-1S operon, increased the accumulation of CupAR, whereas deletion of cupAR significantly lowered NdhR. Based on these results, we concluded that CupAR is a novel subunit of NDH-1MS, negatively regulating the activities of CupA and CO2 uptake dependent on NDH-1MS by positive regulation of NdhR under enriched CO2 conditions.

Getting allometry right at the Oak Ridge free‐air CO2 enrichment experiment: Old problems and new opportunities for global change experiments

Societal Impact StatementFree‐air CO2 enrichment (FACE) experiments provide essential data on forest responses to increasing atmospheric CO2 for evaluations of climate change impacts on humanity. Understanding and reducing the uncertainty in the experimental results is critical to ensure scientific and public confidence in the models and policy initiatives that derive therefrom. One source of uncertainty is the estimation of tree biomass using mathematical relationships between biomass and easily obtained and non‐destructive measurements (allometry). We evaluated the robustness of the allometric relationships established at the beginning of a FACE experiment and discuss the challenges and opportunities for the new generation of FACE experiments.Summary Long‐term field experiments to elucidate forest responses to rising atmospheric CO2 concentration require allometric equations to estimate tree biomass from non‐destructive measurements of tree size. We analyzed whether the allometric equations established at the beginning of a free‐air CO2 enrichment (FACE) experiment in a Liquidambar styraciflua plantation were still valid at the end of the 12 year experiment. Aboveground woody biomass was initially predicted by an equation that included bole diameter, taper, and height, assuming that including taper and height as predictors would accommodate changes in tree structure that might occur over time and in response to elevated CO2. At the conclusion of the FACE experiment, we harvested 23 trees, measured dimensions and dry mass of boles and branches, and extracted and measured the woody root mass of 10 trees. Although 10 of the harvested trees were larger than the trees used to establish the allometric relationship, measured aboveground woody biomass was well predicted by the original allometry. The initial linear equation between bole basal area and woody root biomass underestimated final root biomass by 28%, but root biomass was just 21% of total wood mass, and errors in aboveground and belowground estimates were offsetting. The allometry established at the beginning of the experiment provided valid predictions of tree biomass throughout the experiment. New allometric approaches using terrestrial laser scanning should reduce an important source of uncertainty in decade‐long forest experiments and in assessments of centuries‐long forest biomass accretion used in evaluating carbon offsets and climate mitigation.

Enhanced woody biomass production in a mature temperate forest under elevated CO2

Enhanced CO2 assimilation by forests as atmospheric CO2 concentration rises could slow the rate of CO2 increase if the assimilated carbon is allocated to long-lived biomass. Experiments in young tree plantations support a CO2 fertilization effect as atmospheric CO2 continues to increase. Uncertainty exists, however, as to whether older, more mature forests retain the capacity to respond to elevated CO2. Here, aided by tree-ring analysis and canopy laser scanning, we show that a 180-year-old Quercus robur L. woodland in central England increased the production of woody biomass when exposed to free-air CO2 enrichment (FACE) for 7 years. Further, elevated CO2 increased exudation of carbon from fine roots into the soil with likely effects on nutrient cycles. The increase in tree growth and allocation to long-lived woody biomass demonstrated here substantiates the major role for mature temperate forests in climate change mitigation.

Effects of enriched CO2, temperature, and irrigation on soil properties in greenhouse apple tree cultivation

The significant contributions of anthropogenic activity to global warming are evidenced by the increasing average atmospheric temperatures and CO2 concentration. To date, data on the impact of global warming on crops, particularly field-scale fruit growth and the soil environment, remain lacking. Therefore, we conducted a 4-year monitoring experiment on semi-closed apple tree populations cultivated under the present or near-future climate to assess the effects of atmospheric temperature and CO2 concentrations on soil moisture, temperature, and inorganic ion concentration. Apple saplings were grown in three independent environment-controlled greenhouses, namely greenhouses A (GH_A; control), B (GH_B; high-temperature), and C (GH_C; high-temperature and high CO2), representing climate modification experiments. The pH increased by 0.02, 0.20, and 0.12/year for GH_A, GH_B, and GH_C, respectively. In particular, GH_B (standard irrigation plot; STD) showed a significant pH increase of 0.25/year. The EC increased by 0.014 mS/cm/year for GH_A, decreased by -0.010 mS/cm/year for GH_B, and increased by 0.006 mS/cm/year for GH_C, showing no clear overall increasing or decreasing trend. The NO3 concentration increased by 1.2 mg/L/year for GH_A, decreased by 10.2 mg/L/year for GH_B and decreased by 0.7 mg/L/year for GH_C. The apparent activation energy (Ea) ranged from 85.3 to 214.4 (kJ/mol NH4+) and, regardless of watering treatment, GH_A > GH_B > GH_C. The values in STD plots were 1.4 to 1.7 times those in abundant irrigation plots. Using GH_A (STD) as a standard, the soil temperature dependence of the nitrification rate did not change overall at high or low air temperatures with increasing watering (Ea = 150.5 kJ/mol) or heating (Ea = 154.1 kJ/mol). The soil temperature dependence of the nitrification rate did not vary under heating and increased watering (Ea = 89.5 kJ/mol) or under heating, increased watering, and increased CO2 (Ea = 85.3 kJ/mol). This study provides novel insights into determining the environmental impacts of apple tree community soils under near-future climatic conditions.

Enhanced CO2 Adsorption and Conversion in Diethanolamine‐Cu Interfaces Achieving Stable Neutral Ethylene Electrosynthesis

AbstractMolecular modifications have shown tremendous potential in boosting the electrochemical CO2 reduction (CO2RR) to ethylene. However, the key mechanisms of modulation at the molecular level remain unclear, especially for the adsorption and activation of key intermediates (e.g., *CO2 and *CO). Here, report that a diethanolamine (DEA)‐modified Cu catalyst can reduce CO2 to ethylene with a faradaic efficiency of ≈50.5% with a partial current density of ≈155.7 mA cm−2 in the neutral conditions, which surpasses the Cu catalyst without molecular modification (≈28.5% and ≈95.6 mA cm−2). Density functional theory calculations demonstrate that DEA on the Cu surface boosts the adsorption and activation of CO2 and the following C–C coupling processes during the CO2RR‐to‐ethylene process. Molecular dynamics simulations suggest that the molecules distant from the Cu site have a CO2 enrichment effect. Operational stability achieved via the introduction of DEA molecules onto ketjen black, which then successively immobilized on the Cu nanoparticles and polytetrafluoroethylene electrodes to obtain a stable tripe‐phase boundary, realizing constant ethylene selectivity for 100 operating hours in a flow cell.

Research progress on the effects of elevated atmospheric CO2 concentration on CH4 emission and related microbial processes in paddy fields.

Paddy fields are recognized as significant sources of methane (CH4) emissions, playing a pivotal role in global climate change. Elevated atmospheric carbon dioxide (CO2) concentrations (e[CO2]) exert a profound influence on the carbon cycling of paddy fields. Understanding the effects of e[CO2] on CH4 emissions, as well as the underlying microbial processes, is crucial for enhancing carbon sequestration and reducing emissions in paddy fields. We reviewed the impacts of e[CO2] on CH4 emission in paddy fields, focusing on the activity, abundance, community structure, and diversity of carbon-cycling-related microbes. We also delineated the roles of various microbial processes in mitigating CH4 emissions under e[CO2], as well as the primary environmental determinants. Overall, the type of e[CO2] experimental platforms, duration of fumigation, concentration gradients, and the methods of CO2 enrichment all influence CH4 emissions from paddy fields. e[CO2] initially stimulates CH4 emissions, which may decrease over time, indicating an adaptability of the methane-emitting microbial community to e[CO2]. This response exhibits a trend of initial attenuation followed by an intensification of the positive effects on CH4 emissions. Experiments with abrupt increase of CO2 concentration might overestimate CH4 emissions. The impact of e[CO2] on microbial processes is predominantly characterized by enhanced activities and abundance of methanogens, aerobic and anaerobic methanotrophs. It significantly alters the community composition and diversity of methanotrophs, with minimal effects on methanogens and anaerobic methanotrophic communities. Finally, we outlined future research directions: 1) Integrated investigations into the effects of e[CO2] on CH4 emissions, methanogenesis, and both aerobic and anaerobic methanotrophs in paddy fields could elucidate the mechanisms underlying the impacts of climate change on CH4 emissions; 2) Long-term studies are essential to understand the mechanisms of e[CO2] on CH4 emissions and associated microbial processes more accurately and realistically; 3) Multi-scale (temporal and spatial), multi-factorial (CO2 concentration, temperature, atmospheric nitrogen deposition, and water management practices), and multi-methodological (observational, data, and model integration) research is necessary to effectively reduce the uncertainties in assessing the response of CH4 emissions in paddy fields and related microbial processes to e[CO2] under future climate change scenarios.

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment

The increasing atmospheric CO2 concentration is a global concern that affects the plant-bacteria-soil system. Previous studies have investigated plant growth and bacteria activity under CO2 enrichment. However, the effects of coupled elevated CO2 and biochar amendment on the interactions of soil and medicinal plants are not well understood. This study aims to investigate the medicinal plant-soil hydraulic interactions and rhizosphere bacteria communities under coupled CO2 enrichment and biochar conditions. Two levels of CO2 concentration (400, 1000 ppm) and two biochar dosages (3%, 5% by mass) were considered. Pseudostellaria heterophylla was used as the tested medicinal plant. During plant growth, coupled CO2 enrichment and biochar at 3% and 5% dosage increased the volumetric water content at a matric suction of 33 kPa by 97% and 82% respectively, which indicates enhanced water retention. The transpiration rate of P. heterophylla was slightly reduced by 11–30% with an increase in biochar dosage due to higher total suction, while it was significantly reduced by up to 57% due to CO2 enrichment. In the rhizosphere of P. heterophylla, elevated CO2 (1000 ppm) coupled with 3% biochar dramatically increase the relative abundance of Thaumarchaeota, which played an important role in C and N cycles. Moreover, coupled CO2 enrichment and biochar addition resulted in the highest bacterial richness, while 3% biochar at ambient CO2 induced the highest bacterial diversity. This study provides a basis for understanding the medicinal plant-bacteria-soil system under CO2 enrichment and biochar conditions.

Forage legume responses to climate change factors

AbstractIncorporating forage legumes into grasslands is a recommended climate change mitigation strategy, but accruing desired benefits from legumes is contingent upon their resilience when exposed to climate change factors (CCF). Our objective was to synthesize literature describing responses to CCF of a broad array of forage legume species, including annuals and perennials from both temperate and tropical/subtropical regions. Most‐represented species in the related literature include alfalfa (Medicago sativa L.), various Trifolium and Lotus species, rhizoma peanut (Arachis glabrata Benth.), and capitata stylo (Stylosanthes capitata Vogel). The data indicate that while CCF effects on forage legumes can be generalized, interactions among CCF, species, and site‐specific soil/climate conditions may cause variation from expected responses. In most instances, exposing forage legumes to CO2 enrichment (eCO2) increased forage accumulation (FA), but elevated temperature (eT) often reduced the magnitude of the positive response to eCO2. Photosynthetic acclimation to eCO2 occurs in non‐N‐fixing plants, but legume nodules are large C sinks and drive sustained increases in legume FA to eCO2. Legume N2 fixation and the proportion of legume N derived from N2 fixation increase with eCO2, but the magnitude of the increases lessens with eT. Legume nutritive value (NV) responses to eCO2 are less pronounced than FA responses, but decreased herbage N and greater nonstructural carbohydrate concentrations are common. Exposure to eT negatively affects NV unless intervals between defoliation events are shortened. Limited data on reproductive performance show CCF affect flower number, pollen grain morphology and viability, and behavior of pollinators, potentially influencing legume reproductive success.

Response of photosynthetic characteristics and yield of grape to different CO2 concentrations in a greenhouse.

Due to the enclosed environment of greenhouse grape production, the supply of CO2 required for photosynthesis is often insufficient, leading to photosynthetic downregulation and reduced yield. Currently, the optimal CO2 concentration for grape production in greenhouses is unknown, and the precise control of actual CO2 levels remains a challenge. This study aims to investigate the effects of different CO2 concentrations on the photosynthetic characteristics and yield of grapes, to validate the feasibility of a CO2 gas irrigation system, and to identify the optimal CO2 concentration for greenhouse grape production. In this study, a CO2 gas irrigation system combining CO2 enrichment and gas irrigation techniques was used with a 5-year-old Eurasian grape variety (Vitis vinifera L.) 'Flame Seedless.' Four CO2 concentration treatments were applied: 500 ppm (500 ± 30 µmol·mol-1), 700 ppm (700 ± 30 µmol·mol-1), 850 ppm (850 ± 30 µmol·mol-1), and 1,000 ppm (1,000 ± 30 µmol·mol-1). As CO2 concentration increased, chlorophyll a, chlorophyll b, and carotenoids in grape leaves all reached maximum values at 700 ppm and 850 ppm during the same irrigation cycle, while the chlorophyll a/b ratio was lower than at other concentrations. The net photosynthetic rate (Pn) and water use efficiency (WUE) of grape leaves were the highest at 700 ppm. The transpiration rate and stomatal conductance at 700 ppm and 850 ppm were significantly lower than those at other concentrations. The light saturation point and apparent quantum efficiency reached their maximum at 850 ppm, followed by 700 ppm. Additionally, the maximum net photosynthetic rate, carboxylation efficiency, electron transport rate, and activities of SOD, CAT, POD, PPO, and RuBisCO at 700 ppm were significantly higher than at other concentrations, with the highest yield recorded at 14.54 t·hm-2. However, when the CO2 concentration reached 1,000 ppm, both photosynthesis and yield declined to varying degrees. Under the experimental conditions, the optimal CO2 concentration for greenhouse grape production was 700 ppm, with excessive CO2 levels gradually inhibiting photosynthesis and yield. The results provide a theoretical basis for the future application of CO2 fertilization and gas irrigation techniques in controlled greenhouse grape production.

Combined effects of heatwaves and atmospheric CO₂ levels on Brassica juncea phytoremediation

Heatwaves, expected to become more frequent, pose a significant threat to plant biomass production. This experiment was designed to estimate heatwave influence on Brassica juncea phytoremediation when superimposed on different CO2 levels. A 7-day heatwave was generated during the species flowering stage. Heatwaves decreased all B. juncea dry weights. The lowest species dry weight was recorded when the heatwave was accompanied by 250 ppm CO2, in which the biomass significantly decreased by 40.0% relative to that of no heatwave under the same atmospheric CO2 conditions. Heatwave superposition with 250 ppm CO2 reduced the Cd content in B. juncea aerial parts by 28.1% relative to that of identical environmental conditions without heatwave, whereas the opposite result was observed under 550 ppm CO2 conditions. The heatwave caused oxidative damage to B. juncea under all CO2 conditions, as manifested by increased malondialdehyde levels in the plant shoots. With heatwave superposition, antioxidant enzyme activity was enhanced by exposure to 400 and 550 ppm CO2. Considering biomass yield generation and Cd uptake capacity, heatwave superposition decreased the B. juncea phytoremediation effects, and high atmospheric CO2 conditions could alleviate detrimental effects to a certain extent. This study uniquely examines the combined effects of heatwaves and varying CO2 levels on phytoremediation, providing microscopic insights into oxidative damage and enzyme activity, highlighting the potential for CO2 enrichment to mitigate heatwave impacts, and offering comprehensive analysis for future agricultural practices and environmental management.

Mass transfer at vapor-liquid interfaces of H2O + CO2 mixtures studied by molecular dynamics simulation

Abstract In many industrial applications as well as in nature, the mass transfer of CO2 at vapor-liquid interfaces in aqueous systems plays an important role. In this work, this process was studied on the atomistic level using non-equilibrium molecular dynamics simulations. In a first step, a molecular model of the system water + CO2 was developed that represents both bulk and interfacial equilibrium properties well. This system is characterized by a very large adsorption and enrichment of CO2 at the vapor-liquid interface. Then, non-equilibrium mass transfer simulations were carried out using a method that was developed recently: CO2 is inserted into the vapor phase of a simulation box which contains a liquid slab. Surprising effects are observed at the interface such as a net repulsion of CO2 particles from the interface and a complex time dependence of the amount of CO2 adsorbed at the interface.

Local microenvironment modulation of zirconium-porphyrinic frameworks for CO2 reduction

Solar-powered photocatalysis offers a sustainable strategy to convert carbon dioxide into valuable fuels, which mitigates the energy crisis and the greenhouse effect. Nevertheless, exploring efficient, selective, stable, and environmentally friendly photocatalysts for CO2 reduction continues to meet a significant challenge. Herein, two iron-porphyrinic zirconium-based metal–organic frameworks, Zr6O4(OH)4(FeTCBPP)3 (MOF-526-H) and Zr6O4(OH)4(FeTCBPP-NH2)3 (MOF-526-NH2) were achieved by the integration of the light-harvesting sites and catalytic centers into one phase (FeTCBPP = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)phenyl]-porphyrin, FeTCBPP-NH2 = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)-2-aminophenyl]-porphyrin), which were employed as a couple of models for CO2 photoreduction. MOF-526-NH2 exhibited excellent CO2 reduction with a CO yield of 21.2 mmol·g−1 in the absence of any photosensitizer under visible light, which was 4-fold higher than that of MOF-526-H. Additionally, MOF-526-NH2 showed no significant reduction in CO production during the four rounds, indicating that MOF-526-NH2 possessed good stability. The presence of amino groups in MOF-526-NH2 played an important role in adjusting the micro-environment and electronic structure, which was beneficial to CO2 enrichment and light absorption, and thus improved CO2 photoreduction performance. Based on the density functional theory calculations, a possible mechanism of photocatalytic CO2 reduction over porphyrinic MOFs was proposed.

Soil organic carbon under decadal elevated CO2: Pool size unchanged but stability reduced

Soil organic carbon (SOC) dynamics under elevated atmospheric CO2 concentration has been widely reported, however, in which the behaviors of active and passive fractions remain inadequately explored. Here we studied this issue using three pairs of active and passive fractions of SOC under a 10-year free-air CO2 enrichment experiment (550 ​± ​17 ​ppm) in a cropland in the North China Plain. We found that decadal elevated CO2 increased the root biomass, root exudation rate and microbial biomass, but had little effects on SOC pool size. Elevated CO2 increased the readily oxidizable organic carbon (ROOC) and particulate organic carbon (POC) due to the increments of root C input, but decreased their paired passive fractions possibly because of the carbon input-induced positive priming effect. Our results indicate the reduced stability of SOC pool under elevated CO2. This is significant for better predicting SOC feedback to future climate change.

Carbon-phosphorus cycle models overestimate CO2 enrichment response in a mature Eucalyptus forest.

The importance of phosphorus (P) in regulating ecosystem responses to climate change has fostered P-cycle implementation in land surface models, but their CO2 effects predictions have not been evaluated against measurements. Here, we perform a data-driven model evaluation where simulations of eight widely used P-enabled models were confronted with observations from a long-term free-air CO2 enrichment experiment in a mature, P-limited Eucalyptus forest. We show that most models predicted the correct sign and magnitude of the CO2 effect on ecosystem carbon (C) sequestration, but they generally overestimated the effects on plant C uptake and growth. We identify leaf-to-canopy scaling of photosynthesis, plant tissue stoichiometry, plant belowground C allocation, and the subsequent consequences for plant-microbial interaction as key areas in which models of ecosystem C-P interaction can be improved. Together, this data-model intercomparison reveals data-driven insights into the performance and functionality of P-enabled models and adds to the existing evidence that the global CO2-driven carbon sink is overestimated by models.

Individual grain mass of inbred rice cultivars does not benefit from elevated [CO2]

Climate warming has led to a reduction of global crop yields. Elevated atmospheric [CO2] is believed to promote crop production by increasing photosynthesis, and thus partly offset the yield losses due to climate warming. However, photosynthetic acclimation may occur when the plant is exposed to long-term high [CO2] conditions, suggesting that elevated [CO2] (e[CO2]) might not bring benefits for cereal crops as the growing season proceeds. To assess the effect of long-term e[CO2] on rice yield, particularly on individual grain mass determined post-heading, we synthesized existing data from FACE (free-air CO2 enrichment) experiments across four locations in Japan and China. We also conducted a five-year field experiment with different [CO2] treatments using OTC (open-top chamber) facility. A novel experiment of pot replacement at heading was conducted in 2018 to evaluate the effect of post-heading e[CO2] on individual grain mass of rice. Meanwhile, we measured net photosynthetic rates under ambient [CO2] (a[CO2]) and e[CO2] (ambient + 200 μmol mol−1) at different developmental stages to identify the occurrence of photosynthetic acclimation. We show that FACE condition did not increase individual grain mass across thirty-six inbred rice cultivars at various rates of nitrogen application, and that the replacement of potted plants either from a[CO2] to e[CO2] or from e[CO2] to a[CO2] did not impact the individual grain mass. The yield benefit from e[CO2] was primarily attributed to an increase in the spikelet density determined pre-heading. We conclude that the individual grain mass of inbred rice does not benefit from e[CO2], which is most likely attributed to a loss of the advantage in CO2 gain induced by photosynthetic acclimation. Our findings suggest the necessity for selective breeding strategies to make better use of post-heading e[CO2] and for crop modelers to incorporate updated knowledge into models in the context of elevated [CO2].

Effects of experimental CO2 enrichment on the PSII photochemical efficiency of Symbiodinium sp. in Acropora millepora

Enrichment of seawater with CO2 decreases the concentration of the carbonate ion while increasing that of hydrogen and bicarbonate ions. We use pulse-amplitude-modulation (PAM) fluorometry to investigate whether, in the absence of warming, and in sub-saturating light, these changes affect the PSII photochemical efficiency of _Symbiodinium_ sp. in the reef-building coral _Acropora millepora_. We assessed this experimentally with 30-min-interval saturation pulse analyses at 25 °C, a daily peak in the intensity of the photosynthetically active radiation (PAR) at ~65 µmol quanta m–2 s–1, and a seawater _p_CO2 that we gradually increased over nine days from ~496 to ~1290 μatm by injection of CO2-enriched air. Nine 14-day time series, which, except one, were recorded at the growing apices of a coral branch, revealed diel oscillations in the PSII photochemical efficiency characterized by a steep nocturnal decrease followed by a steep increase and peak in the morning, a daily minimum at midday (∆F/Fm’,midday), and a daily maximum at the onset of darkness at 19:00 h (Fv/Fm,19:00 h). An inadvertent shift in the position of one of the PAM fluorometer measuring heads revealed differences between the basal part and the growing coral apices of a coral branch in ∆F/Fm’midday and Qm. In ambient seawater (Control) _Symbiodinium_ sp. exhibited a gradual decrease, over the course of the experiment, in ∆F/Fm’,midday, Fv/Fm,19:00 h, and the slope of the linear regression between the relative electron transport rate and the intensity of PAR (rETR/PAR). Although two of three successive experiments indicated that CO2 enrichment counteracted these trends, statistical analyses failed to confirm an influence of _p_CO2 on ∆F/Fm’,midday, Fv/Fm,19:00 h, and Qm, rendering this experiment inconclusive.

Boosting Interfacial Electron Transfer and CO2 Enrichment on ZIF-8/ZnTe for Selective Photoelectrochemical Reduction of CO2 to CO.

Artificial photosynthesis is an effective way of converting CO2 into fuel and high value-added chemicals. However, the sluggish interfacial electron transfer and adsorption of CO2 at the catalyst surface strongly hamper the activity and selectivity of CO2 reduction. Here, we report a photocathode attaching zeolitic imidazolate framework-8 (ZIF-8) onto a ZnTe surface to mimic an aquatic leaf featuring stoma and chlorophyll for efficient photoelectrochemical conversion of CO2 into CO. ZIF-8 possessing high CO2 adsorption capacity and diffusivity has been selected to enrich CO2 into nanocages and provide a large number of catalytic active sites. ZnTe with high light-absorption capacity serves as a light-absorbing layer. CO2 molecules are collected in large nanocages of ZIF-8 and delivered to the ZnTe surface. As evidenced by scanning electrochemical microscopy, the interface can effectively boost interfacial electron transfer kinetics. The ZIF-8/ZnTe photocathode with unsaturated Zn-Nx sites exhibits a high Faradaic efficiency for CO production of 92.9% and a large photocurrent of 6.67 mA·cm-2 at -2.48 V (vs Fc/Fc+) in a nonaqueous electrolyte at AM 1.5G solar irradiation (100 mW·cm-2).

Performance Evaluation of Three Peanut Cultivars Grown under Elevated CO2 Concentrations

This study explored the performance and physiological responses of three commercially used peanut cultivars in Australian farming systems under ambient and elevated CO2 conditions, aiming to identify the most suitable genotype for dual-purpose (grain and graze) cropping experiments. The experiment utilized an open-top chamber (OTC) facility to regulate CO2 concentrations. The elevated CO2 (EC) treatment targeted approximately 650 ± 50 µmol mol−1, while both ambient CO2 (AC) and control plots operated at a concentration of approximately 400 µmol mol−1. Notably, control plots without chambers served as a reference for current CO2 and environmental conditions. In contrast, despite having the same ambient CO2 concentration, AC plots were enclosed in chambers, allowing for plant growth comparisons with EC plots with the same environmental conditions aside from CO2 levels. The analyses revealed significant effects of CO2 enrichment on peanut plants. In particular, the EC treatment led to enhanced photosynthetic rates (20% in Kairi, 31% in Holt, and 19% in Alloway), alongside reduced stomatal conductance (−55% in Kairi, −32% in Holt, and −40% in Alloway), transpiration, and increased water use efficiency compared to AC conditions. Elevated CO2 levels positively influenced pod yields in Kairi (+41%) and Alloway (+36%). However, CO2 enrichment did not significantly alter the protein content, total phenolic content, cupric-reducing antioxidant capacity, and ferric-reducing antioxidant power of peanut plant material. Furthermore, no significant differences were observed in the phytochemical composition among the three cultivars under ambient or elevated CO2 conditions. On the other hand, analysis of the fibre structure conducted on peanut stover harvested at plant maturity suggested potential declines in feedstock quality. Based on the findings of this research, further investigations and testing, including simulated grazing trials, will be carried out to identify a single breed line suitable for dual-purpose management under future elevated CO2 conditions.

Five decades of ecological and meteorological data enhance the mechanistic understanding of global change impacts on the treeline ecotone in the European Alps

Understanding the dynamics of treeline ecotones under global change requires long-term ecological and environmental data. The Stillberg ecological treeline research site in the Swiss Alps was established in 1975 by planting 92,000 seedlings of Larix decidua, Pinus cembra and Pinus mugo ssp. uncinata, and has been continuously monitored since then. Here, we present curated long-term data acquired over almost 50 years at the Stillberg site, and we synthesise the major research findings. The long-term datasets comprise 6.5 million ecological and environmental records from the 40-year afforestation experiment, as well as from a 9-year free-air CO2 enrichment experiment crossed with a 6-year soil warming experiment, a 12-year nutrient addition experiment and an 8-year multifactorial tree seedling recruitment experiment. Our datasets further include 38 million records of 25 meteorological parameters measured at an hourly resolution from 1975 to 1996, and at a 10 min resolution since 1997. We provide all datasets and the corresponding metadata as open research data. Almost five decades of research in this treeline ecotone showed high mortality after tree establishment that was closely related to microclimatic variability. The two Pinus species survived at a much lower rate than L. decidua, due to indirect pathogen interactions. Furthermore, CO2 enrichment only increased growth of L. decidua, while warming increased growth of P. mugo ssp. uncinata and two Vaccinium shrub species. Enhanced nutrient availability stimulated growth in tree and understorey shrub species. In addition, soil warming and CO2 enrichment stimulated microbial activity and decreased soil carbon stocks. These findings improve our understanding of ecological processes in the treeline ecotone under global change and confirm the importance of tree growth and establishment limitations. The enhanced availability and quality of these long-term data are expected to foster whole-system approaches and transdisciplinary research syntheses, supporting the development of effective global change adaptation strategies.

Variability in the responses of rice ecotypes to elevated CO2 based on data from FACE studies in China and Japan: Implications for climate change adaptation

Elevated CO2 increases rice yields, and the response level varies across locations and genotypes. Previous analyses of genotypic variations from diverse Free-Air CO2 Enrichment (FACE) studies lacked specificity, limiting their applicability in simulating the responses of crop growth to elevated CO2. Using meta-analysis approach and the ORYZA (v3) model with historical and projected climatic data, this study evaluated the differences in the responses of rice ecotypes to elevated CO2 and identified adaptive measures. Meta-analytical findings indicated that Chinese inbred indica (indicai) and hybrid indica (indicah) rice exhibited comparable yield response rates (28.4% and 31.1%, respectively) to elevated CO2, surpassing those of Chinese japonica rice and Japanese indicai and japonica rice. Achieving higher adaptation to elevated CO2, exemplified by Chinese indicah rice, necessitates the consideration of balanced yield components, with individual contributions to yield responses ranging from 9.8% to 36.2%. This study highlighted the susceptibility of japonica rice to adverse effects of maximum temperatures on yield component responses to elevated CO2 compared to indicai or indicah rice. Strategic adjustments in sowing dates can enhance rice production under climate change, with high-response genotypes benefiting more from optimal sowing periods. Furthermore, for genotypes with less responsiveness to elevated CO2, augmenting nitrogen application in conjunction with sowing date adjustments was beneficial for yield optimization. This research not only advances our understanding of the diverse adaptation strategies of rice genotypes under varying climatic conditions but also enhances the precision of crop growth simulations by accounting for the varied responses to CO2 enrichment. These insights are pivotal for developing targeted breeding and management practices aimed at enhancing climate resilience in rice production.