Ultra‐High Surface Area Activated Porous Asphalt for CO2 Capture through Competitive Adsorption at High Pressures

This study reports an improved method for activating asphalt to produce ultra‐high surface area porous carbons. Pretreatment of asphalt (untreated Gilsonite, uGil ) at 400 °C for 3 h removes the more volatile organic compounds to form pretreated asphalt ( uGil‐P ) material with a larger fraction of higher molecular weight π‐conjugated asphaltenes. Subsequent activation of uGil‐P at 900 °C gives an ultra‐high surface area (4200 m² g^?1) porous carbon material ( uGil‐900 ) with a mixed micro and mesoporous structure. uGil‐900 shows enhanced room temperature CO₂ uptake capacity at 54 bar of 154 wt% (35 mmol g^?1). The CH₄ uptake capacity is 37.5 wt% (24 mmol g^?1) at 300 bar. These are relevant pressures in natural gas production. The room temperature working CO₂ uptake capacity for uGil‐900 is 19.1 mmol g^?1 (84 wt%) at 20 bar and 32.6 mmol g^?1 (143 wt%) at 50 bar. In order to further assess the reliability of uGil‐900 for CO₂ capture at elevated pressures, the authors study competitive sorption of CO₂ and CH₄ on uGil‐900 at pressures from 1 to 20 bar at 25 °C. CO₂/CH₄ displacement constants are measured at 2 to 40 bar, and found to increase significantly with pressure and surface area.     

Photosynthetic downregulation in leaves of the Japanese white birch grown under elevated CO2 concentration does not change their temperature‐dependent susceptibility to photoinhibition

To determine the effects of elevated CO₂ concentration ([CO₂]) on the temperature‐dependent photosynthetic properties, we measured gas exchange and chlorophyll fluorescence at various leaf temperatures (15, 20, 25, 30, 35 and 40°C) in 1‐year‐old seedlings of the Japanese white birch (Betula platyphylla var. japonica), grown in a phytotron under natural daylight at two [CO₂] levels (ambient: 400 µmol mol^?1 and elevated: 800 µmol mol^?1) and limited N availability (90 mg N plant^?1). Plants grown under elevated [CO₂] exhibited photosynthetic downregulation, indicated by a decrease in the carboxylation capacity of Rubisco. At temperatures above 30°C, the net photosynthetic rates of elevated‐CO₂‐grown plants exceeded those grown under ambient [CO₂] when compared at their growth [CO₂]. Electron transport rates were significantly lower in elevated‐CO₂‐grown plants than ambient‐CO₂‐grown ones at temperatures below 25°C. However, no significant difference was observed in the fraction of excess light energy [(1 ? q_P)× F_v′/F_m′] between CO₂ treatments across the temperature range. The quantum yield of regulated non‐photochemical energy loss was significantly higher in elevated‐CO₂‐grown plants than ambient, when compared at their respective growth [CO₂] below 25°C. These results suggest that elevated‐CO₂‐induced downregulation might not exacerbate the temperature‐dependent susceptibility to photoinhibition, because reduced energy consumption by electron transport was compensated for by increased thermal energy dissipation at low temperatures.     

Responses of a new isolated <Emphasis Type="Italic">Cyanobacterium aponinum</Emphasis> strain to temperature,pH, CO<Subscript>2</Subscript> and light quality

A new strain of cyanobacteria was isolated from seawater samples collected near Jimo hot springs, Qingdao, China, and was identified as Cyanobacterium aponinum by 16S rDNA analysis. This study examined the effects of temperature, pH, light quality and high CO₂ concentration on the growth of the cyanobacteria. Results showed that the strain exhibited a higher growth rate (about 168.4 mg L^?1 day^?1) at 35 °C than other temperatures (surviving at up to 50 °C) and a wide growth tolerance to acidic stress (pH 3.0 to 4.0) resulting from either H₂SO₄ or HNO₃. The four light qualities, ranked by greatest to least biomass effect, were as follows: LED white light (LW) > LED red light (LR) > fluorescent white light (FW) > LED blue light (LB), achieving a higher lighting effect at a LW light intensity (60 μmol photons m^?2 s^?1) lower than other light qualities, which implied less energy consumption therewith. This strain demonstrates excellent CO₂ tolerance at least 10% CO₂ with the highest productivity in biomass (about 337.8 mg L^?1 day^?1) measured at 1% CO₂ level. Results indicate that this strain is a promising candidate for use in biofixation of CO₂ from flue gases emitted by thermoelectric plants.     

Effect of temperature on ion content, ion fluxes and energy metabolism in Chara corallina

Abstract Effects of temperature on the ionic relations and energy metabolism of Chara corallina were investigated. Measurements were made of the ionic content, tracer ion fluxes, and photosynthetic and dark CO₂ fixation in isolated cells, and of O₂ exchange in photosynthesis and respiration in isolated shoot apices. The total intracellular concentration of K⁺, Na⁺ and Cl^? was the same in cells held for 5 days in non-growing medium at 15°C (the growth temperature) as in those held at 25°C or 5°C. The tracer influx in the light of all ions tested (Rb⁺, Na⁺, CH₃NH₃⁺, Cl^? and H₂PO₄^?) was lower at 5°C than at 15°C in experiments in which cells were subjected to 5°C for less than 24 h in toto. The influx at 25°C was greater than that at 15°C for H₂PO^?₄, there was no difference between the two temperatures for Na⁺, while the influx at 25°C was less than that at 15°C for Cl^?, Rb⁺ and CH₃NH₃⁺ For Cl^? and H₂PO^?₄ similar results were found in later experiments with cells grown at 20—23°C. Photosynthetic CO₂ fixation and O₂ evolution, and respiratory O₂ uptake, are greater at 25°C, and lower at 5°C, than they are at the growth temperature of 15°C. In longer-term pretreatments at the different temperatures, tracer Cl^? influx at 15°C and particularly at 25°C were lower than in short-term experiments, while the influx at 5°C was higher. It was concluded from these experiments, and from previous data on H⁺ free energy differences across the plasmalemma, that (1) the maintenance of internal ion concentrations involves a close balancing of influx and efflux of K⁺, Na⁺ and Cl^? at all experimental temperatures; (2) the regulation of the tracer fluxes of the ions is kinetic rather than thermodynamic and (3) that the tracer fluxes at low temperatures are not restricted by the rate at which respiration or photosynthesis can supply energy to them.     

The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest‐wetland landscape

At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus (‘forest’) lead to expansion of permafrost‐free wetlands (‘wetland’). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH₄) emissions. Here, we quantify the thaw‐induced increase in CH₄ emissions for a boreal forest‐wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long‐term net carbon dioxide (CO₂) exchange. Using nested wetland and landscape eddy covariance net CH₄ flux measurements in combination with flux footprint modeling, we find that landscape CH₄ emissions increase with increasing wetland‐to‐forest ratio. Landscape CH₄ emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10 °C warmer than forest soils. The cumulative growing season (May–October) wetland CH₄ emission of ~13 g CH₄ m^?2 is the dominating contribution to the landscape CH₄ emission of ~7 g CH₄ m^?2. In contrast, forest contributions to landscape CH₄ emissions appear to be negligible. The rapid wetland expansion of 0.26 ± 0.05% yr^?1 in this region causes an estimated growing season increase of 0.034 ± 0.007 g CH₄ m^?2 yr^?1 in landscape CH₄ emissions. A long‐term net CO₂ uptake of >200 g CO₂ m^?2 yr^?1 is required to offset the positive radiative forcing of increasing CH₄ emissions until the end of the 21st century as indicated by an atmospheric CH₄ and CO₂ concentration model. However, long‐term apparent carbon accumulation rates in similar boreal forest‐wetland landscapes and eddy covariance landscape net CO₂ flux measurements suggest a long‐term net CO₂ uptake between 49 and 157 g CO₂ m^?2 yr^?1. Thus, thaw‐induced CH₄ emission increases likely exert a positive net radiative greenhouse gas forcing through the 21st century.     

A High‐Power Na3V2(PO4)3‐Bi Sodium‐Ion Full Battery in a Wide Temperature Range

Sodium‐ion batteries (SIBs) that operate in a wide temperature range are in high demand for practical large‐scale electric energy storage. Herein, a novel full SIB is composed of a bulk Bi anode, a Na₃V₂(PO₄)₃/carbon nanotubes composite (NVP‐CNTs) cathode and a NaPF₆‐diglyme electrolyte. The Bi anode gradually evolves into a porous network in the ether‐based electrolyte during initial cycles, and in the NVP‐CNTs cathode the NVP is cross linked by CNTs to show large exchange current density. These unique features merit the full SIB of Bi//NVP‐CNTs with high Na⁺ diffusion coefficient and low reaction activation energy, and hence fast Na⁺ transport and facile redox reaction kinetics. The resultant full SIB presents high power density of 2354.6 W kg^?1 and energy density of 150 Wh kg^?1 and superior cycling stability in a wide temperature range from ?15 to 45 °C. This will shed light on battery design, and promote their development for practical applications in various weather conditions.     

Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.)

It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO₂) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO₂ on photosynthesis, pollen production, pollen viability, seed‐set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO₂ levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol^?1) or elevated (700 µmol mol^?1) CO₂ levels. There were strong negative relations between temperature over a range of 28/18–40/30 °C and seed‐set (slope, ? 6.5% °C^?1) and seed number per pod (? 0.34 °C^?1) under both ambient and elevated CO₂ levels. Exposure to temperature > 28/18 °C also reduced photosynthesis (? 0.3 and ? 0.9 µmol m^?2 s^?1 °C^?1), seed number (? 2.3 and ? 3.3 °C^?1) and seed yield (? 1.1 and ? 1.5 g plant^?1 °C^?1), at both the CO₂ levels (ambient and elevated, respectively). Reduced seed‐set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO₂ did not affect seed size but temperature > 31/21 °C linearly reduced seed size by 0.07 g °C^?1. Elevated CO₂ increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO₂ and temperature, and CO₂ enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO₂ enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development.     

Solar‐Light‐Driven CO2 Reduction by CH4 on Silica‐Cluster‐Modified Ni Nanocrystals with a High Solar‐to‐Fuel Efficiency and Excellent Durability

Catalytic CO₂ reforming of CH₄ (CRM) to produce syngas (H₂ and CO) provides a promising approach to reducing global CO₂ emissions and the extensive utilization of natural gas resources. However, the rapid deactivation of the reported catalysts due to severe carbon deposition at high reaction temperatures and the large energy consumption of the process hinder its industrial application. Here, a method for almost completely preventing carbon deposition is reported by modifying the surface of Ni nanocrystals with silica clusters. The obtained catalyst exhibits excellent durability for CRM with almost no carbon deposition and deactivation after reaction for 700 h. Very importantly, it is found that CRM on the catalyst can be driven by focused solar light, thus providing a promising new approach to the conversion of renewable solar energy to fuel due to the highly endothermic characteristics of CRM. The reaction yields high production rates of H₂ and CO (17.1 and 19.9 mmol min^?1 g^?1, respectively) with a very high solar‐to‐fuel efficiency (η, 12.5%). Even under focused IR irradiation with a wavelength above 830 nm, the η of the catalyst remains as high as 3.1%. The highly efficient catalytic activity arises from the efficient solar‐light‐driven thermocatalytic CRM enhanced by a novel photoactivation effect.     

Temperature response of photosynthetic light‐ and carbon‐use characteristics in the red seaweed Gracilariopsis lemaneiformis (Gracilariales,Rhodophyta)

The red seaweed Gracilariopsis is an important crop extensively cultivated in China for high‐quality raw agar. In the cultivation site at Nanao Island, Shantou, China, G. lemaneiformis experiences high variability in environmental conditions like seawater temperature. In this study, G. lemaneiformis was cultured at 12, 19, or 26°C for 3 weeks, to examine its photosynthetic acclimation to changing temperature. Growth rates were highest in G. lemaneiformis thalli grown at 19°C, and were reduced with either decreased or increased temperature. The irradiance‐saturated rate of photosynthesis (P_max) decreased with decreasing temperature, but increased significantly with prolonged cultivation at lower temperatures, indicating the potential for photosynthesis acclimation to lower temperature. Moreover, P_max increased with increasing temperature (~30 μmol O₂ · g^?1FW · h^?1 at 12°C to 70 μmol O₂ · g^?1FW · h^?1 at 26°C). The irradiance compensation point for photosynthesis (I_c) decreased significantly with increasing temperature (28 μmol photons · m^?2 · s^?1 at high temperature vs. 38 μmol photons · m^?2 · s^?1 at low temperature). Both the photosynthetic light‐ and carbon‐use efficiencies increased with increasing growth or temperatures (from 12°C to 26°C). The results suggested that the thermal acclimation of photosynthetic performance of G. lemaneiformis would have important ecophysiological implications in sea cultivation for improving photosynthesis at low temperature and maintaining high standing biomass during summer. Ongoing climate change (increasing atmospheric CO₂ and global warming) may enhance biomass production in G. lemaneiformis mariculture through the improved photosynthetic performances in response to increasing temperature.     

Predicting long‐term carbon mineralization and trace gas production from thawing permafrost of Northeast Siberia

The currently observed Arctic warming will increase permafrost degradation followed by mineralization of formerly frozen organic matter to carbon dioxide (CO₂) and methane (CH₄). Despite increasing awareness of permafrost carbon vulnerability, the potential long‐term formation of trace gases from thawing permafrost remains unclear. The objective of the current study is to quantify the potential long‐term release of trace gases from permafrost organic matter. Therefore, Holocene and Pleistocene permafrost deposits were sampled in the Lena River Delta, Northeast Siberia. The sampled permafrost contained between 0.6% and 12.4% organic carbon. CO₂ and CH₄ production was measured for 1200 days in aerobic and anaerobic incubations at 4 °C. The derived fluxes were used to estimate parameters of a two pool carbon degradation model. Total CO₂ production was similar in Holocene permafrost (1.3 ± 0.8 mg CO₂‐C gdw^?1 aerobically, 0.25 ± 0.13 mg CO₂‐C gdw^?1 anaerobically) as in 34 000–42 000‐year‐old Pleistocene permafrost (1.6 ± 1.2 mg CO₂‐C gdw^?1 aerobically, 0.26 ± 0.10 mg CO₂‐C gdw^?1 anaerobically). The main predictor for carbon mineralization was the content of organic matter. Anaerobic conditions strongly reduced carbon mineralization since only 25% of aerobically mineralized carbon was released as CO₂ and CH₄ in the absence of oxygen. CH₄ production was low or absent in most of the Pleistocene permafrost and always started after a significant delay. After 1200 days on average 3.1% of initial carbon was mineralized to CO₂ under aerobic conditions while without oxygen 0.55% were released as CO₂ and 0.28% as CH₄. The calibrated carbon degradation model predicted cumulative CO₂ production over a period of 100 years accounting for 15.1% (aerobic) and 1.8% (anaerobic) of initial organic carbon, which is significantly less than recent estimates. The multiyear time series from the incubation experiments helps to more reliably constrain projections of future trace gas fluxes from thawing permafrost landscapes.     

Photosynthetic performance at low temperature of Bouteloua gracilis Lag., a high-altitude C4 grass from the Rocky Mountains, USA

The mechanisms controlling the photosynthetic performance of C₄ plants at low temperature were investigated using ecotypes of Bouteloua gracilis Lag. from high (3000 m) and low (1500 m) elevation sites in the Rocky Mountains of Colorado. Plants were grown in controlled‐environment cabinets at a photon flux density of 700 μ mol m^?2 s^?1 and day/night temperatures of 26/16 °C or 14/7 °C. The thermal response of the net CO₂ assimilation rate (A) was evaluated using leaf gas‐exchange analysis and activity assays of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPCase) and pyruvate,orthophosphate dikinase (PPDK). In both ecotypes, a reduction in measurement temperature caused the CO₂‐saturated rate of photosynthesis to decline to a greater degree than the initial slope of A versus the intercellular CO₂ response, thereby reducing the photosynthetic CO₂ saturation point. As a consequence, A in normal air was CO₂‐saturated at sub‐optimal temperatures. Ecotypic variation was low when grown at 26/16 °C, with the major difference between the ecotypes being that the low‐elevation plants had higher A; however, the ecotypes responded differently when grown at cool temperature. At temperatures below the thermal optimum, A in high‐elevation plants grown at 14/7 °C was enhanced relative to plants grown at 26/16 °C, while A in low‐elevation plants grown at 14/7 °C was reduced compared to 26/16 °C‐grown plants. Photoinhibition at low growth temperature was minor in both ecotypes as indicated by small reductions in dark‐adapted F_v/F_m. In both ecotypes, the activity of Rubisco was equivalent to A below 17 °C but well in excess of A above 25 °C. Activities of PEPCase and PPDK responded to temperature in a similar proportion relative to Rubisco, and showed no evidence for dissociation that would cause them to become principal limitations at low temperature. Because of the similar temperature response of Rubisco and A, we propose that Rubisco is a major limitation on C₄ photosynthesis in B. gracilis below 17 °C. Based on these results and for theoretical reasons associated with how C₄ plants use Rubisco, we further suggest that Rubisco capacity may be a widespread limitation upon C₄ photosynthesis at low temperature.     

Modelling carbon balances of coastal arctic tundra under changing climate

Rising air temperatures are believed to be hastening heterotrophic respiration (R_h) in arctic tundra ecosystems, which could lead to substantial losses of soil carbon (C). In order to improve confidence in predicting the likelihood of such loss, the comprehensive ecosystem model ecosys was first tested with carbon dioxide (CO₂) fluxes measured over a tundra soil in a growth chamber under various temperatures and soil‐water contents (θ). The model was then tested with CO₂ and energy fluxes measured over a coastal arctic tundra near Barrow, Alaska, under a range of weather conditions during 1998–1999. A rise in growth chamber temperature from 7 to 15 °C caused large, but commensurate, rises in respiration and CO₂ fixation, and so no significant effect on net CO₂ exchange was modelled or measured. An increase in growth chamber θ from field capacity to saturation caused substantial reductions in respiration but not in CO₂ fixation, and so an increase in net CO₂ exchange was modelled and measured. Long daylengths over the coastal tundra at Barrow caused an almost continuous C sink to be modelled and measured during most of July (2–4 g C m^?2 d^?1), but shortening daylengths and declining air temperatures caused a C source to be modelled and measured by early September (～1 g C m^?2 d^?1). At an annual time scale, the coastal tundra was modelled to be a small C sink (4 g C m^?2 y^?1) during 1998 when average air temperatures were 4 °C above normal, and a larger C sink (16 g C m^?2 y^?1) during 1999 when air temperatures were close to long‐term normals. During 100 years under rising atmospheric CO₂ concentration (C_a), air temperature and precipitation driven by the IS92a emissions scenario, modelled R_h rose commensurately with net primary productivity (NPP) under both current and elevated rates of atmospheric nitrogen (N) deposition, so that changes in soil C remained small. However, methane (CH₄) emissions were predicted to rise substantially in coastal tundra with IS92a‐driven climate change (from ～20 to ～40 g C m^?2 y^?1), causing a substantial increase in the emission of CO₂ equivalents. If the rate of temperature increase hypothesized in the IS92a emissions scenario had been raised by 50%, substantial losses of soil C (～1 kg C m^?2) would have been modelled after 100 years, including additional emissions of CH₄.     

Effects of seasonality,transport pathway,and spatial structure on greenhouse gas fluxes in a restored wetland

Wetlands can influence global climate via greenhouse gas (GHG) exchange of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Few studies have quantified the full GHG budget of wetlands due to the high spatial and temporal variability of fluxes. We report annual open‐water diffusion and ebullition fluxes of CO₂, CH₄, and N₂O from a restored emergent marsh ecosystem. We combined these data with concurrent eddy‐covariance measurements of whole‐ecosystem CO₂ and CH₄ exchange to estimate GHG fluxes and associated radiative forcing effects for the whole wetland, and separately for open‐water and vegetated cover types. Annual open‐water CO₂, CH₄, and N₂O emissions were 915 ± 95 g C‐CO₂ m^?2 yr^?1, 2.9 ± 0.5 g C‐CH₄ m^?2 yr^?1, and 62 ± 17 mg N‐N₂O m^?2 yr^?1, respectively. Diffusion dominated open‐water GHG transport, accounting for >99% of CO₂ and N₂O emissions, and ~71% of CH₄ emissions. Seasonality was minor for CO₂ emissions, whereas CH₄ and N₂O fluxes displayed strong and asynchronous seasonal dynamics. Notably, the overall radiative forcing of open‐water fluxes (3.5 ± 0.3 kg CO₂‐eq m^?2 yr^?1) exceeded that of vegetated zones (1.4 ± 0.4 kg CO₂‐eq m^?2 yr^?1) due to high ecosystem respiration. After scaling results to the entire wetland using object‐based cover classification of remote sensing imagery, net uptake of CO₂ (?1.4 ± 0.6 kt CO₂‐eq yr^?1) did not offset CH₄ emission (3.7 ± 0.03 kt CO₂‐eq yr^?1), producing an overall positive radiative forcing effect of 2.4 ± 0.3 kt CO₂‐eq yr^?1. These results demonstrate clear effects of seasonality, spatial structure, and transport pathway on the magnitude and composition of wetland GHG emissions, and the efficacy of multiscale flux measurement to overcome challenges of wetland heterogeneity.     

Advanced Electrolytes for Fast‐Charging High‐Voltage Lithium‐Ion Batteries in Wide‐Temperature Range

LiNi_xMn_yCo_1?x?yO₂ (NMC) cathode materials with Ni ≥ 0.8 have attracted great interest for high energy‐density lithium‐ion batteries (LIBs) but their practical applications under high charge voltages (e.g., 4.4 V and above) still face significant challenges due to severe capacity fading by the unstable cathode/electrolyte interface. Here, an advanced electrolyte is developed that has a high oxidation potential over 4.9 V and enables NMC811‐based LIBs to achieve excellent cycling stability in 2.5–4.4 V at room temperature and 60 °C, good rate capabilities under fast charging and discharging up to 3C rate (1C = 2.8 mA cm^?2), and superior low‐temperature discharge performance down to ?30 °C with a capacity retention of 85.6% at C/5 rate. It is also demonstrated that the electrode/electrolyte interfaces, not the electrolyte conductivity and viscosity, govern the LIB performance. This work sheds light on a very promising strategy to develop new electrolytes for fast‐charging high‐energy LIBs in a wide‐temperature range.     

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH4 flux

Tropical peatlands hold about 15%–19% of the global peat carbon (C) pool of which 77% is stored in the peat swamp forests (PSFs) of Southeast Asia. Nonetheless, these PSFs have been drained, exploited for timber and land for agriculture, leading to frequent fires in the region. The physico‐chemical characteristics of peat, as well as the hydrology of PSFs are affected after a fire, during which the ecosystem can act as a C source for decades, as C emissions to the atmosphere exceed photosynthesis. In this work, we studied the longer‐term impact of fires on C cycling in tropical PSFs, hence we quantified the magnitude and patterns of C loss (CO₂, CH₄ and dissolved organic carbon) and soil‐water quality characteristics in an intact and a degraded burnt PSF in Brunei Darussalam affected by seven fires over the last 40 years. We used natural tracers such as ¹⁴C to investigate the age and sources of C contributing to ecosystem respiration (R_eco) and CH₄, while we continuously monitored soil temperature and water table (WT) level from June 2017 to January 2019. Our results showed a major difference in the physico‐chemical parameters, which in turn affected C dynamics, especially CH₄. Methane effluxes were higher in fire‐affected areas (7.8 ± 2.2 mg CH₄ m^?2 hr^?1) compared to the intact PSF (4.0 ± 2.0 mg CH₄ m^?2 hr^?1) due to prolonged higher WT and more optimal methanogenesis conditions. On the other hand, we did not find significant differences in R_eco between burnt (432 ± 83 mg CO₂ m^?2 hr^?1) and intact PSF (359 ± 76 mg CO₂ m^?2 hr^?1). Radiocarbon analysis showed overall no significant difference between intact and burnt PSF with a modern signature for both CO₂ and CH₄ fluxes implying a microbial preference for the more labile C fraction in the peat matrix.     

Three physiological parameters capture variation in leaf respiration of Eucalyptus grandis,as elicited by short‐term changes in ambient temperature,and differing nitrogen supply

We used instantaneous temperature responses of CO₂‐respiration to explore temperature acclimation dynamics for Eucalyptus grandis grown with differing nitrogen supply. A reduction in ambient temperature from 23 to 19 °C reduced light‐saturated photosynthesis by 25% but increased respiratory capacity by 30%. Changes in respiratory capacity were not reversed after temperatures were subsequently increased to 27 °C. Temperature sensitivity of respiration measured at prevalent ambient temperature varied little between temperature treatments but was significantly reduced from ~105 kJ mol^?1 when supply of N was weak, to ~70 kJ mol^?1 when it was strong. Temperature sensitivity of respiration measured across a broader temperature range (20–40 °C) could be fully described by 2 exponent parameters of an Arrhenius‐type model (i.e., activation energy of respiration at low reference temperature and a parameter describing the temperature dependence of activation energy). These 2 parameters were strongly correlated, statistically explaining 74% of observed variation. Residual variation was linked to treatment‐induced changes in respiration at low reference temperature or respiratory capacity. Leaf contents of starch and soluble sugars suggest that respiratory capacity varies with source‐sink imbalances in carbohydrate utilization, which in combination with shifts in carbon‐flux mode, serve to maintain homeostasis of respiratory temperature sensitivity at prevalent growth temperature.     

Soil-atmospheric exchange of CO2, CH4, and N2O in three subtropical forest ecosystems in southern China

The magnitude, temporal, and spatial patterns of soil‐atmospheric greenhouse gas (hereafter referred to as GHG) exchanges in forests near the Tropic of Cancer are still highly uncertain. To contribute towards an improvement of actual estimates, soil‐atmospheric CO₂, CH₄, and N₂O fluxes were measured in three successional subtropical forests at the Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. Soils in DNR forests behaved as N₂O sources and CH₄ sinks. Annual mean CO₂, N₂O, and CH₄ fluxes (mean±SD) were 7.7±4.6 Mg CO₂‐C ha^?1 yr^?1, 3.2±1.2 kg N₂O‐N ha^?1 yr^?1, and 3.4±0.9 kg CH₄‐C ha^?1 yr^?1, respectively. The climate was warm and wet from April through September 2003 (the hot‐humid season) and became cool and dry from October 2003 through March 2004 (the cool‐dry season). The seasonality of soil CO₂ emission coincided with the seasonal climate pattern, with high CO₂ emission rates in the hot‐humid season and low rates in the cool‐dry season. In contrast, seasonal patterns of CH₄ and N₂O fluxes were not clear, although higher CH₄ uptake rates were often observed in the cool‐dry season and higher N₂O emission rates were often observed in the hot‐humid season. GHG fluxes measured at these three sites showed a clear increasing trend with the progressive succession. If this trend is representative at the regional scale, CO₂ and N₂O emissions and CH₄ uptake in southern China may increase in the future in light of the projected change in forest age structure. Removal of surface litter reduced soil CO₂ effluxes by 17–44% in the three forests but had no significant effect on CH₄ absorption and N₂O emission rates. This suggests that microbial CH₄ uptake and N₂O production was mainly related to the mineral soil rather than in the surface litter layer.     

Temperature and peat type control CO2 and CH4 production in Alaskan permafrost peats

Controls on the fate of ~277 Pg of soil organic carbon (C) stored in permafrost peatland soils remain poorly understood despite the potential for a significant positive feedback to climate change. Our objective was to quantify the temperature, moisture, organic matter, and microbial controls on soil organic carbon (SOC) losses following permafrost thaw in peat soils across Alaska. We compared the carbon dioxide (CO₂) and methane (CH₄) emissions from peat samples collected at active layer and permafrost depths when incubated aerobically and anaerobically at ?5, ?0.5, +4, and +20 °C. Temperature had a strong, positive effect on C emissions; global warming potential (GWP) was >3× larger at 20 °C than at 4 °C. Anaerobic conditions significantly reduced CO₂ emissions and GWP by 47% at 20 °C but did not have a significant effect at ?0.5 °C. Net anaerobic CH₄ production over 30 days was 7.1 ± 2.8 μg CH₄‐C gC^?1 at 20 °C. Cumulative CO₂ emissions were related to organic matter chemistry and best predicted by the relative abundance of polysaccharides and proteins (R² = 0.81) in SOC. Carbon emissions (CO₂‐C + CH₄‐C) from the active layer depth peat ranged from 77% larger to not significantly different than permafrost depths and varied depending on the peat type and peat decomposition stage rather than thermal state. Potential SOC losses with warming depend not only on the magnitude of temperature increase and hydrology but also organic matter quality, permafrost history, and vegetation dynamics, which will ultimately determine net radiative forcing due to permafrost thaw.     

Effect of culturing parameters on the vegetative growth of Haematococcus alpinus (strain lcr‐cc‐261f) and modeling of its growth kinetics

The present study investigated the effect of different culture conditions on the vegetative growth of a new species, Haematococcus alpinus (strain LCR‐CC‐261f) using airlift photobioreactors. The influence of culture medium, aeration rates, CO₂ concentration in air‐gas mixture, temperature, light intensities, and wavelengths were investigated to achieve sustainable high cell density cultures. Growth parameters were determined by fitting the data to a form of the logistic equation that included a lag phase. The shear‐sensitive vegetative cells favored lower aeration rates in the photobioreactors. MLA medium increased to 40 mM nitrate produced high density cultures. Temperatures between 12°C and 18°C, 3% (v/v) CO₂ concentration and a narrow photon flux density ranging between 37 and 48 μmol photons · m^?2 · s^?1 were best suited for growth. The wavelength of the light source also impacted growth and a high cell density of 9.6 × 10⁵ cells · mL^?1 was achieved using a mixture of red and blue compared to warm white, red, or blue LEDs.     

Tunable Polyaniline‐Based Porous Carbon with Ultrahigh Surface Area for CO2 Capture at Elevated Pressure

Natural gas is the cleanest fossil fuel source. However, natural gas wells typically contain considerable amounts of CO₂, with on‐site CO₂ capture necessary. Solid sorbents are advantageous over traditional amine scrubbing due to their relatively low regeneration energies and non‐corrosive nature. However, it remains a challenge to improve the sorbent's CO₂ capacity at elevated pressures relevant to natural gas purification. Here, the synthesis of porous carbons derived from a 3D hierarchical nanostructured polymer hydrogel, with simple and effective tunability over the pore size distribution is reported. The optimized surface area reaches 4196 m² g^?1, which is among the highest of carbon‐based materials, with abundant micro‐ and narrow mesopores (2.03 cm³ g^?1 with d < 4 nm). This carbon exhibits a record‐high CO₂ capacity among reported carbons at elevated pressure (i.e., 28.3 mmol g^?1 total adsorption at 25 °C and 30 bar). This carbon also shows good CO₂/CH₄ selectivity and excellent cyclability. Molecular simulations suggest increased CO₂ density in micro‐ and narrow mesopores at high pressures. This is consistent with the observation that these pores are mainly responsible for the material's high‐pressure CO₂ capacity. This work provides insights into material design and further development for CO₂ capture from natural gas.