Anthropogenic Carbon Dioxide Emissions Research Articles

Forest-floor respiration, N2O fluxes, and CH4 fluxes in a subalpine spruce forest: drivers and annual budgets

Abstract. Forest ecosystems play an important role in the global carbon (C) budget by sequestering a large fraction of anthropogenic carbon dioxide (CO2) emissions and by acting as important methane (CH4) sinks. The forest-floor greenhouse gas (GHG; CO2, CH4, and nitrous oxide (N2O)) flux, i.e., from soil and understory vegetation, is one of the major components to consider when determining the C or GHG budget of forests. Although winter fluxes are essential to determine the annual C budget, only very few studies have examined long-term, year-round forest-floor GHG fluxes. Thus, we aimed to (i) quantify seasonal and annual variations of forest-floor GHG fluxes; (ii) evaluate their drivers, including the effects of snow cover, timing, and amount of snowmelt; and (iii) calculate annual budgets of forest-floor GHG fluxes for a subalpine spruce forest in Switzerland. We measured GHG fluxes year-round during 4 years with four automatic large chambers at the ICOS Class 1 Ecosystem station Davos (CH-Dav). We applied random forest models to investigate environmental drivers and to gap-fill the flux time series. The forest floor emitted 2336 g CO2 m−2 yr−1 (average over 4 years). Annual and seasonal forest-floor respiration responded most strongly to soil temperature and snow depth. No response of forest-floor respiration to leaf area index or photosynthetic photon flux density was observed, suggesting a strong direct control of soil environmental factors and a weak, or even lacking, indirect control of canopy biology. Furthermore, the forest floor was a consistent CH4 sink (−0.71 g CH4 m−2 yr−1), with annual fluxes driven mainly by snow depth. Winter CO2 fluxes were less important for the CO2 budget (6.0 %–7.3 %), while winter CH4 fluxes contributed substantially to the annual CH4 budget (14.4 %–18.4 %). N2O fluxes were very low (0.007 g N2O m−2 yr−1), negligible for the forest-floor GHG budget at our site. In 2022, the warmest year on record with below-average precipitation at the Davos site, we observed a substantial increase in forest-floor respiration compared with other years. The mean forest-floor GHG budget indicated emissions of 2319 ± 200 g CO2 eq. m−2 yr−1 (mean ± standard deviation (SD) over all years), with respiration fluxes dominating and CH4 offsetting a very small proportion (0.8 %) of the CO2 emissions. Due to the relevance of snow cover, we recommend year-round measurements of GHG fluxes with high temporal resolution. In a future with increasing temperatures and less snow cover due to climate change, we expect increased forest-floor respiration at this subalpine site modulating the carbon sink of the forest ecosystem.

Electricity climate-compatibility index: Measuring global progress towards decarbonising the power sector

This paper proposes a novel index, ECI (Electricity Climate-Compatibility Index), to measure global fossil fuel electricity generation alignment with climate targets. Net anthropogenic carbon dioxide emissions (CO2) must approach zero by mid-century to stabilise the mean temperature to well below 2°C. Pursuing carbon neutrality will require immediate action if we are to avoid the economic risks associated with a delayed, more abrupt energy transition. This paper reviewed the existing literature and found insufficient indicators for country-level climate targets in electricity generation. Therefore, the paper proposes a novel electricity climate-compatibility index (ECI) to address the gap. The index computes climate compatibility or incompatibility as the difference between fossil fuel electricity generation permitted in the Integrated Assessment Model (IAM) country-level climate scenarios and that which is generated from operational, under-construction and planned power generation assets. The ECI correlates positively in specific instances with relatable metrics such as Energy Transition Index (ETI) and Climate Change Performance Index (CCPI) but provides a better understanding of the climate-incompatible generation of fossil fuel plants for a decarbonised power sector.

Efficient Selective Carbon Dioxide Separation via Task-Specific Ionic Liquids Incorporated in ZIF-8.

Owing to the rapid increase in anthropogenic emission of carbon dioxide (CO2) in the atmosphere, which has resulted in a number of global climate challenges, a decrease in CO2 emissions is urgently needed in the current scenario. This study focuses on the development and characterization of composites for carbon dioxide (CO2) separation. The composites consist of two task-specific ionic liquids (TSILs), namely, tetramethylgunidinium imidazole [TMGHIM] and tetramethylgunidinium phenol [TMGHPhO], impregnated in ZIF-8. The performance of CO2 separation, including sorption capacity and selectivity, was evaluated for pristine ZIF-8 and composites of TMGHIM@ZIF-8 and TMGHPhO@ZIF-8. To demonstrate the thermal stability of the material, thermogravimetric analysis (TGA) was performed. Additionally, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to showcase the crystal structures and morphology. Fourier transform infrared spectroscopy (FTIR) and BET were also utilized to confirm the successful incorporation of TSILs into ZIF-8. The composite synthesized with TMGHIM@ZIF-8 demonstrated superior CO2 sorption performance as compared with TMGHPhO@ZIF-8. This is attributed to its strong attraction toward CO2, resulting in a higher CO2/CH4 selectivity of 110 while pristine MOFs showed 12 that is 9 times higher than that of the pristine ZIF-8. These TSILs@ZIF-8 composites have significant potential in designing sorbent materials for efficient acid gas separation applications.

Impact of anthropogenic emissions of carbon dioxide and related temperature rise on wildlife population: A modeling study

Climate change is driven by the increase in greenhouse gases in Earth’s atmosphere, especially carbon dioxide (CO2), leading to a rise in the global average temperature. This temperature rise unleash far-reaching and profound consequences on various living organisms. In this research work, we formulate a nonlinear mathematical model to perceive the impact of rising temperature on wildlife species. In formulating the model, we take into account that the escalating CO2 concentration contributes to a rise in the global average temperature, thereby impacting the growth rate of wildlife population. We pinpoint the sufficient conditions for all the dynamic variables to reach their simultaneous equilibrium levels. The model analysis reveals a spectrum of bifurcations, including transcritical, Hopf, saddle–node, and Bogdanov–Takens bifurcations. Further, the examination of transcritical bifurcation led to the identification of a critical reduction rate of wildlife species due to human activities above which the wildlife population may teeter on the brink of extinction under the considered stressor of temperature rise. This extinction of wildlife species can be avoided by increasing the carrying capacity of forest biomass. Also, we have shown that for a specific set of parameter values, there exists a bistability between the forest-wildlife free equilibrium and the coexisting equilibrium.

The Influence of Ozone Depletion Potential Weighted Anthropogenic Emissions of Nitrous Oxide

The effects of anthropogenic emissions of nitrous oxide (N2O), carbon dioxide (CO2), methane (CH4), and halocarbons on stratospheric ozone (O3) over the twentieth and twenty-first centuries are divided using a chemical model of the stratosphere. As halocarbon levels revert to pre-industrial levels, N2O and CO2 will likely play the primary roles in the evolution of ozone in the future. It is unable to distinguish clearly between these gases’ effects on ozone due to nonlinear interactions between them. The work was conducted using the monthly and annual data of the gases in the stratospheric layer to determine the overlap between N2O and O3 for the Iraq station and for the period (2003-2016). The strength of the association between gases was determined using the Spearman rho test (rs). It was found that there is a very high positive relationship between the N2O and O3 in Nasriyah station, which is 0.807 which indicates a strong association. This is because meteorological conditions, climatic fluctuations, and atmospheric location all affect correlation. The ozone layer is destroyed by nitrous oxide at high concentrations through the stratosphere layer and the tropospheric layer, the concentration of ozone increases with an increase in the concentration of nitrogen dioxide.

Trends of Satellite-Derived Thermal Fronts in the Southeast and Southwest of Australia Between 1993 and 2019

Oceanic fronts play a significant role in marine ecosystems by enhancing vertical exchange, promoting the aggregation of plankton, and drawdown of organic carbon. Anthropogenic emission of carbon dioxide and other greenhouse gases in the twentieth century has driven global warming, leading to rising ocean temperatures. Specific regions warming faster than the global average—known as ‘ocean warming hotspots’—have been identified, impacting geophysical and biogeochemical dynamics of local ecosystems. Here, we aim to characterize the variability of sea surface temperature (SST) fronts in the southeast and southwest Australia hotspots. Using a histogram frontal detection method, we derived fronts from AVHRR-only and Multi-sensor 6-day SST composites on a 0.02 × 0.02 grid between January 1993 and December 2019. Our results indicate that frontal frequency and frontal density have increased in both regions in the past three decades, by around 0.2–0.3%. In addition, both regions exhibit higher frequency and density of fronts in austral winter and fewer in austral summer. Our calculations show that changes in frontal frequency/density show some relationship to El Niño-Southern Oscillation and Indian Ocean Dipole. Changes in frontal activity could strongly impact local ocean biogeochemistry and marine ecosystems. A better understanding changing fronts in hotspots will help predict and manage future changes in regional oceans to warming.

Potential of wind turbines on the alteration of carbon dioxide concentration

Anthropogenic carbondioxide (CO2) emissions are a major factor in global warming, requiring significant cuts to combat climate change. A crucial technology to reduce global CO2 concentration is direct air capture (DAC) of CO2. However, existing DAC techniques are expensive because of low CO2 concentrations, and they frequently rely on fossil fuel-based energy. In this article, we investigate how wind turbines can influence local CO2 levels and potentially collaborate with DAC and other technologies. To explore this idea, we performed large-eddy simulations using two 5 MW commercial-scale wind turbines. We incorporated realistic CO2 profiles collected from 13 different global locations across different seasons. The simulations were performed under neutral atmospheric boundary layer conditions. The results demonstrate that the wake recovery mechanism of a wind turbine promotes rapid mixing of CO2 both above and below the turbine blade tips in the wind turbine wake. In cases where the initial concentrations of CO2 were elevated above the turbine, downward entrainment of CO2 occurred. Conversely, when high concentrations of CO2 were present in the lower atmosphere, wind turbines facilitated a decrease in concentration at that layer by up to 138 kg/m within the intermediate wake (within 7 diameters) of the second turbine, T2. These discoveries inspire further investigation into the potential synergies between wind turbines and DAC devices or local CO2 pollutant diverters, depending on the prevailing CO2 profile. Consequently, this article marks the initial showcase of wind turbines' capability to influence CO2 levels by creating an entrainment and removal effect.

Optimisasi Budidaya Rumput Laut sebagai Benteng Alami untuk Mengurangi Asidifikasi Laut

Anthropogenic carbon dioxide emissions are propelling a concerning rise in ocean acidity, posing severe threats to marine ecosystems, especially calcifying organisms like corals and mollusks. In response to this global challenge, seaweed farming has emerged as a promising remedy. Leveraging their remarkable growth rates and carbon sequestration abilities, seaweeds offer a viable solution to counteract the acidifying effects of elevated carbon dioxide levels in the oceans. Through photosynthesis, seaweeds actively absorb carbon dioxide from seawater, thereby mitigating acidity and fostering improved water quality. The potential of seaweed farms extends beyond mere carbon sequestration. These farms play a pivotal role in habitat creation, absorb nitrogen and phosphorus nutrients, and contribute to enhanced biodiversity. The cultivation of seaweed not only addresses the immediate concern of ocean acidification but also provides a holistic ecological approach with far-reaching benefits. As a sustainable and scalable strategy, seaweed farming exemplifies an innovative and multifaceted solution to the complex challenges posed by anthropogenic impacts on the oceans, underlining the importance of nature-based interventions in preserving the health and balance of marine ecosystems.

Industrial by-products-derived binders for in-situ remediation of high Pb content pyrite ash: Synergistic use of ground granulated blast furnace slag and steel slag to achieve efficient Pb retention and CO2 mitigation

Ordinary Portland cement (OPC) is a cost-effective and conventional binder that is widely adopted in brownfield site remediation and redevelopment. However, the substantial carbon dioxide emission during OPC production and the concerns about its undesirable retention capacity for potentially toxic elements strain this strategy. To tackle this objective, we herein tailored four alternative binders (calcium aluminate cement, OPC-activated ground-granulated blast-furnace slag (GGBFS), white-steel-slag activated GGBFS, and alkaline-activated GGBFS) for facilitating immobilization of high Pb content pyrite ash, with the perspectives of enhancing Pb retention and mitigating anthropogenic carbon dioxide emissions. The characterizations revealed that the incorporation of white steel slag efficiently benefits the activity of GGBFS, herein facilitating the hydration products (mainly ettringite and calcium silicate hydrates) precipitation and Pb immobilization. Further, we quantified the cradle-to-gate carbon footprint and cost analysis attributed to each binder-Pb contaminants system, finding that the application of these alternative binders could be pivotal in the envisaged carbon-neutral world if the growth of the OPC-free roadmap continues. The findings suggest that the synergistic use of recycled white steel slag and GGBFS can be proposed as a profitable and sustainable OPC-free candidate to facilitate the management of lead-contaminated brownfield sites. The overall results underscore the potential immobilization mechanisms of Pb in multiple OPC-free/substitution binder systems and highlight the urgent need to bridge the zero-emission insights to sustainable in-situ solidification/stabilization technologies.

A decade of marine inorganic carbon chemistry observations in the northern Gulf of Alaska – insights into an environment in transition

Abstract. As elsewhere in the global ocean, the Gulf of Alaska is experiencing the rapid onset of ocean acidification (OA) driven by oceanic absorption of anthropogenic emissions of carbon dioxide from the atmosphere. In support of OA research and monitoring, we present here a data product of marine inorganic carbon chemistry parameters measured from seawater samples taken during biannual cruises between 2008 and 2017 in the northern Gulf of Alaska. Samples were collected each May and September over the 10 year period using a conductivity, temperature, depth (CTD) profiler coupled with a Niskin bottle rosette at stations including a long-term hydrographic survey transect known as the Gulf of Alaska (GAK) Line. This dataset includes discrete seawater measurements such as dissolved inorganic carbon and total alkalinity, which allows the calculation of other marine carbon parameters, including carbonate mineral saturation states, carbon dioxide (CO2), and pH. Cumulative daily Bakun upwelling indices illustrate the pattern of downwelling in the northern Gulf of Alaska, with a period of relaxation spanning between the May and September cruises. The observed time and space variability impart challenges for disentangling the OA signal despite this dataset spanning a decade. However, this data product greatly enhances our understanding of seasonal and interannual variability in the marine inorganic carbon system parameters. The product can also aid in the ground truthing of biogeochemical models, refining estimates of sea–air CO2 exchange, and determining appropriate CO2 parameter ranges for experiments targeting potentially vulnerable species. Data are available at https://doi.org/10.25921/x9sg-9b08 (Monacci et al., 2023).

Satellite derived trends and variability of CO2 concentrations in the Middle East during 2014–2023

The Middle East has major sources of anthropogenic carbon dioxide (CO2) emissions, but a dearth of ground-based measurements precludes an investigation of its regional and temporal variability. This is achieved in this work with satellite-derived estimates from the Orbiting Carbon Observatory-2 (OCO-2) and OCO-3 missions from September 2014 to February 2023. The annual maximum and minimum column (XCO2) concentrations are generally reached in spring and autumn, respectively, with a typical seasonal cycle amplitude of 3–8 ± 0.5 ppmv in the Arabian Peninsula rising to 8–10 ± 1 ppmv in the mid-latitudes. A comparison of the seasonal-mean XCO2 values with the CO2 emissions estimated using the divergence method stresses the role played by the sources and transport of CO2 in the spatial distribution of XCO2, with anthropogenic emissions prevailing in arid and semi-arid regions that lack persistent vegetation. In the 8-year period 2015–2022, the XCO2 concentration in the United Arab Emirates (UAE) increased at a rate of about 2.50 ± 0.04 ppmv/year, with the trend empirical orthogonal function technique revealing a hotspot over northeastern UAE and southern Iran in the summer where anthropogenic emissions peak and accumulate aided by low-level wind convergence. A comparison of the satellite-derived CO2 concentration with that used to drive climate change models for different emission scenarios in the 8-year period revealed that the concentrations used in the latter is overestimated, with maximum differences exceeding 10 ppmv by 2022. This excess in the amount of CO2 can lead to an over-prediction of the projected increase in temperature in the region, an aspect that needs to be investigated further. This work stresses the need for a ground-based observational network of greenhouse gas concentrations in the Middle East to better understand its spatial and temporal variability and for the evaluation of remote sensing observations as well as climate models.

Valorization of bio-oil distillation residue through co-pyrolysis with moso bamboo to prepare biochar: Optimization study on effects of blend ratio, pyrolysis temperature, and residence time

In view of the high energy consumption and pollutant emissions in the cement production industry, biomass as the renewable carbon-neutrality energy is promisingly conducive to remitting cement carbon dioxide emissions and simultaneously realizing waste-to-energy initiatives. In this study, bio-oil distillation residue (DR), with high carbon content and heat value, is co-pyrolyzed with moso bamboo (MB) to optimize the bulk and combustion properties of biochar, aiming at yielding bio-fuel as an alternative fuel to replace coals for energy and heat supply in cement industry. The impacts of three primary process parameters on the carbonization reaction were investigated, while the parametric interactions were further estimated by using response surface methodology (RSM) to optimize the ultimate, proximate and fuel characteristics of biochars. The results showed the co-pyrolysis synergies between bio-oil distillation residue and moso bamboo endowed the maximum biochar yield of 44.62% and the maximum difference biochar yield of 7.56%. Meanwhile, the experimental carbon content, fixed carbon content and high heat value (HHV) were regulated through coupling parametric distribution and further increased by 1.96%, 2.59% and 1.23 MJ/kg, respectively. The parametric responses on combustion characteristics of biochar based on thermogravimetric analysis were predicted, and the optimal carbonization conditions for biochar production were also summarized. This study would offer an optimal biochar production scheme to adaptively yield coal-like biochar for reducing anthropogenic carbon dioxide emissions in cement industry.

Survival of Nutrient-Starved Diatoms Under Ocean Acidification: Perspective from Nutrient Sensing, Cadmium Detection, and Nitrogen Assimilation.

Increased anthropogenic emissions of carbon dioxide (CO2) have resulted in ocean acidification (OA) that is intertwined with enhanced ocean stratification. Diatoms are assumed to suffer from a more nutrient-limited condition in the future ocean. This study aimed to explore how OA affects the diatom dynamics under nutrient-poor conditions and the ability of diatoms to perceive nutrients (nitrogen, phosphorus, silicon, and trace metals) and cadmium (Cd) stimuli and assimilate nitrogen when receiving nutrients or Cd supplementation. Our study observed that diatom population grown under OA condition declined faster than those grown under ambient condition. Ocean acidification greatly lower intracellular Ca2+ concentration in diatom cells. Intracellular Ca2+ burst was involved in phosphorus accumulation but not in nitrogen, silicon, essential metals, and cadmium uptake. Our data demonstrate slower NO3- assimilation rates of diatoms grown in acidified seawater. Our study also indicates that diatoms have a poor perception of phosphorus availability under OA condition.

A technical and environmental comparison of novel silica PEI adsorbent-based and conventional MEA-based CO2 capture technologies in the selected cement plant

The cement industry accounts for almost 7 % of anthropogenic carbon dioxide emissions globally. Therefore, it is imperative to identify innovative solutions to mitigate carbon dioxide emissions from the cement industry.This study aims to evaluate and compare the technical and environmental aspects of integrating two post-combustion carbon capture processes (CCS) into a cement plant: the conventional monoethanolamine (MEA)-based CCS process and the novel silica-alkoxylated polyethyleneimine (SPEI)-based CCS process. Three scenarios were considered: (i) a reference cement plant without CCS, (ii) the conventional MEA-based CCS system integrated into a cement plant and (iii) the novel SPEI-based CCS system integrated into a cement plant. The technical evaluation results showed that the regeneration energy requirements for the conventional MEA and novel SPEI-based CCS processes were 3.53 GJ/tonne CO2 and 2.36 GJ/tonne CO2, respectively, to achieve a capture rate of 90 %. However, the performance of MEA-based carbon capture processes can be improved by using advanced amine formulations that offer lower regeneration heat requirements at 3.3 GJ/tonne CO2, although this is still higher than the SPEI-based carbon capture processes.The novel SPEI-based CCS process showed superior environmental performance compared to the conventional MEA-based CCS process. The endpoint single score was conducted which showed that the SPEI-based CCS process had a lower impact on human health, ecosystems, and resources (7 %, 9 %, and 26 % lower, respectively) compared to the MEA-based CCS process.

Global Carbon Budget 2023

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land-use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based fCO2 products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. Additional lines of evidence on land and ocean sinks are provided by atmospheric inversions, atmospheric oxygen measurements, and Earth system models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2022, EFOS increased by 0.9 % relative to 2021, with fossil emissions at 9.9±0.5 Gt C yr−1 (10.2±0.5 Gt C yr−1 when the cement carbonation sink is not included), and ELUC was 1.2±0.7 Gt C yr−1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 11.1±0.8 Gt C yr−1 (40.7±3.2 Gt CO2 yr−1). Also, for 2022, GATM was 4.6±0.2 Gt C yr−1 (2.18±0.1 ppm yr−1; ppm denotes parts per million), SOCEAN was 2.8±0.4 Gt C yr−1, and SLAND was 3.8±0.8 Gt C yr−1, with a BIM of −0.1 Gt C yr−1 (i.e. total estimated sources marginally too low or sinks marginally too high). The global atmospheric CO2 concentration averaged over 2022 reached 417.1±0.1 ppm. Preliminary data for 2023 suggest an increase in EFOS relative to 2022 of +1.1 % (0.0 % to 2.1 %) globally and atmospheric CO2 concentration reaching 419.3 ppm, 51 % above the pre-industrial level (around 278 ppm in 1750). Overall, the mean of and trend in the components of the global carbon budget are consistently estimated over the period 1959–2022, with a near-zero overall budget imbalance, although discrepancies of up to around 1 Gt C yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows the following: (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living-data update documents changes in methods and data sets applied to this most recent global carbon budget as well as evolving community understanding of the global carbon cycle. The data presented in this work are available at https://doi.org/10.18160/GCP-2023 (Friedlingstein et al., 2023).

Race to Carbon Neutrality. Prospects of Phasing Out Coal

Abstract Carbon neutrality is necessary to address the global problem of climate change. The International Energy Agency has recognized coal as the largest source of anthropogenic carbon dioxide emissions. This article analyzes carbon dioxide emissions from coal and carbon dioxide emissions from energy for the major emitters of CO2 emissions. As more than half of the world's Carbon dioxide emissions from coal come from China, the authors have analyzed the extreme situation that could arise in the carbon reduction market if China were to postpone its commitments to reduce coal consumption. The article calculates the time frame required for other coal-consuming countries to phase out coal to compensate for China's annual coal consumption. It demonstrates that without China transitioning from coal consumption to zero-carbon energy sources, other countries will not be able to achieve carbon neutrality by 2050. This proves that for the first time in history, the achievement of the goal set by the global community depends on the actions of a single country. The article outlines the goals set by China in its Nationally Determined Contribution and other government documents to reduce greenhouse gas emissions and achieve carbon neutrality. It also presents China's efforts to implement renewable energy sources, nuclear reactors, and energy storage.

Differential reaction norms to ocean acidification in two oyster species from contrasting habitats.

Ocean acidification (OA), a consequence of the increase in anthropogenic emissions of carbon dioxide, causes major changes in the chemistry of carbonates in the ocean with deleterious effects on calcifying organisms. The pH/PCO2 range to which species are exposed in nature is important to consider when interpreting the response of coastal organisms to OA. In this context, emerging approaches, which assess the reaction norms of organisms to a wide pH gradient, are improving our understanding of tolerance thresholds and acclimation potential to OA. In this study, we deciphered the reaction norms of two oyster species living in contrasting habitats: the intertidal oyster Crassostrea gigas and the subtidal flat oyster Ostrea edulis, which are two economically and ecologically valuable species in temperate ecosystems. Six-month-old oysters of each species were exposed in common garden tanks for 48 days to a pH gradient ranging from 7.7 to 6.4 (total scale). Both species were tolerant down to a pH of 6.6 with high plasticity in fitness-related traits such as survival and growth. However, oysters underwent remodelling of membrane fatty acids to cope with decreasing pH along with shell bleaching impairing shell integrity and consequently animal fitness. Finally, our work revealed species-specific physiological responses and highlights that intertidal C. gigas seem to have a better acclimation potential to rapid and extreme OA changes than O. edulis. Overall, our study provides important data about the phenotypic plasticity and its limits in two oyster species, which is essential for assessing the challenges posed to marine organisms by OA.

WAYS TO REDUCE CO<sub>2</sub> EMISSIONS AT THE CONVERSION OF NATURAL GAS INTO CHEMICAL PRODUCTS

One of the most realistic possibilities for reducing anthropogenic carbon dioxide emissions is its involvement as a feedstock in various processes for producing gas chemical products. First of all, it is advisable in the production of the largest-tonnage products, such as syngas, hydrogen and methanol. The paper considers the possibility of involving carbon dioxide in non-catalytic autothermal processes of the production of these products. A combined process for the production of methanol and hydrogen without CO2 emission based on the matrix conversion of natural gas into syngas is presented.

Pore-scale kinetics of calcium dissolution and secondary precipitation during geological carbon storage

Geological carbon storage (GCS) in deep underground formations presents a significant opportunity to mitigate anthropogenic emissions of carbon dioxide in the context of climate change. The injected carbon dioxide may acidify the formation brine and dissolve carbonate minerals in the storage formations. Understanding the dynamics of carbonate dissolution at reservoir conditions is crucial for assessing the integrity and stability of reservoir rocks. Using carbonate-functionalized micromodels we investigate the pore-scale dynamics of carbonate dissolution and shed light on the interplay between surface reactions and mass transfer with relevance for geological carbon storage. Our experimental observations reveal the complex interplay between carbon dioxide exsolution/mineralization and mineral dissolution/precipitation during injection. Local chemical reactions and hydrodynamics impact the dissolution rate, whereas the presence of a free carbon dioxide phase can impede carbonate dissolution. Hence, we provide new experimental data that enhance our fundamental understanding of coupled geochemical GCS reactions that can augment the development of accurate and reliable constitutive models that assess leakage risks and the stability of mitigation techniques such as microbial-induced carbonate precipitation.

Ground granulated iron silicate slag as supplementary cementitious material: Effect of prolonged grinding and granulation temperature

The metallurgical and cement industries contribute significantly to anthropogenic carbon dioxide emissions. Utilizing oxidic by-products from the metallurgical industry as supplementary cementitious materials (SCMs) can improve resource efficiency and reduce emissions from cement production. Iron silicate copper slags have been studied as SCMs, but mainly in systems where Portland cement is used as an activator. There is limited research on the inherent reactivity of the slag under changing processing conditions. The present study offers insight into the effect of granulation temperature and grinding on the inherent reactivity of an industrially produced iron silicate copper slag. The results showed that granulation temperature had an insignificant effect on reactivity, while grinding generated substantial improvements. The latter effect was concluded to stem from the increased specific surface area, increased number of sites for nucleation and growth of hydrates, and changes in the inherent reactivity owing to structural changes induced by the grinding.