Sequestration Of Atmospheric CO2 Research Articles

Estimating the Greenhouse Gas Emission Potential Due to Construction Work on the 225 kV Segou - Bamako High Voltage BI-Ternal Electric Line in Mali in The Context of Climate Change

The aim of this study is to assess the carbon emissions resulting from the construction of the power line linking Bamako to Ségou. It focuses on direct emissions, more specifically those linked to the degradation and desctruction of the vegetation cover in the project right-of-way. To collect the data, surveys were set up on the project right-of-way, through which 3302 trees were inventoried in situ at the three sites. Circumference was measured at 1.30 m from the ground surface. Allometric equations for direct biomass estimation were used as a predictor o f tree diameter. Emission factors were then used to estimate the potential greenhouse gas emissions resulting from tree felling during power line construction. The standard error associated with the carbon fraction in dry biomass was calculated. In the Ségou, Koulikoro and Dioïla project areas, there are a number of plant species that provide local populations with various ecosystem services, including micro-climate regulation through carbon sequestration or absorption of atmospheric CO2. The implementation of the project will undoubtedly result in the felling of these trees. This felling will generate emissions of 22.11 t.eqCO2/ha in Ségou, 16.56 t.eqCO2/ha in Koulikoro and 15.43 t.eqCO2/ha in Dioïla. Across Ségou, Koulikoro and Dioïla, the trees in the project right-of-way represent a reservoir of 34.04 t/ha of above-ground woody biomass. This biomass represents a carbon stock of around 16.58 t.C/ha. This carbon stock will be transformed into a carbon source with emissions of 60.78 t.eqCO2/ha if the trees in the power line right-of-way are systematically felled. Mitigation measures are therefore urgently needed, with compensatory reforestation areas planted with species with high carbon sequestration potential.

Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration

The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.

Controls on Early Cretaceous South Atlantic Ocean circulation and carbon burial – a climate model–proxy synthesis

Abstract. Black shale sediments from the Barremian to Aptian South Atlantic document the intense and widespread burial of marine organic carbon during the initial stages of seafloor spreading between Africa and South America. The enhanced sequestration of atmospheric CO2 makes these young ocean basins potential drivers of the Early Cretaceous carbon cycle and climate perturbations. The opening of marine gateways between initially restricted basins and related circulation and ventilation changes are a commonly invoked explanation for the transient formation and disappearance of these regional carbon sinks. However, large uncertainties in palaeogeographic reconstructions limit the interpretation of available palaeoceanographic data and prevent any robust model-based quantifications of the proposed circulation and carbon burial changes. Here, we present a new approach to assess the principal controls on the Early Cretaceous South Atlantic and Southern Ocean circulation changes under full consideration of the uncertainties in available boundary conditions. Specifically, we use a large ensemble of 36 climate model experiments to simulate the Barremian to Albian progressive opening of the Falkland Plateau and Georgia Basin gateways with different configurations of the proto-Drake Passage, the Walvis Ridge, and atmospheric CO2 concentrations. The experiments are designed to complement available geochemical data across the regions and to test circulation scenarios derived from them. All simulations show increased evaporation and intermediate water formation at subtropical latitudes that drive a meridional overturning circulation whose vertical extent is determined by the sill depth of the Falkland Plateau. The densest water masses formed in the southern Angola Basin and potentially reached the deep Cape Basin as Walvis Ridge Overflow Water. Palaeogeographic uncertainties are as important as the lack of precise knowledge of atmospheric CO2 levels for the simulated temperature and salinity spread in large parts of the South Atlantic. Overall temperature uncertainties reach up to 15 °C and increase significantly with water depth. The ensemble approach reveals temporal changes in the relative importance of geographic and radiative forcings for the simulated oceanographic conditions and, importantly, nonlinear interactions between them. The progressive northward opening of the highly restricted Angola Basin increased the sensitivity of local overturning and upper-ocean stratification to atmospheric CO2 concentrations due to large-scale changes in the hydrological cycle, while the chosen proto-Drake Passage depth is critical for the ocean dynamics and CO2 response in the southern South Atlantic. Finally, the simulated processes are integrated into a recent carbon burial framework to document the principal control of the regional gateway evolution on the progressive shift from the prevailing saline and oxygen-depleted subtropical water masses to the dominance of ventilated high-latitude deep waters.

Influence of ocean alkalinity enhancement with olivine or steel slag on a coastal plankton community in Tasmania

Abstract. Ocean alkalinity enhancement (OAE) aims to increase atmospheric CO2 sequestration in the oceans through the acceleration of chemical rock weathering. This could be achieved by grinding rocks containing alkaline minerals and adding the rock powder to the surface ocean where it dissolves and chemically locks CO2 in seawater as bicarbonate. However, CO2 sequestration during dissolution coincides with the release of potentially bioactive chemicals and may induce side effects. Here, we used 53 L microcosms to test how coastal plankton communities from Tasmania respond to OAE with olivine (mainly Mg2SiO4) or steel slag (mainly CaO and Ca(OH)2) as alkalinity sources. Three microcosms were left unperturbed and served as a control, three were enriched with olivine powder (1.9 g L−1), and three were enriched with steel slag powder (0.038 g L−1). Olivine and steel slag powders were of similar grain size. Olivine was added in a higher amount than the steel slag with the aim of compensating for the lower efficiency of olivine to deliver alkalinity over the 3-week experiment. Phytoplankton and zooplankton community responses as well as some biogeochemical parameters were monitored. Olivine and steel slag additions increased total alkalinity by 29 and 361 µmol kg−1, respectively, corresponding to a respective theoretical increase of 0.9 % and 14.8 % of the seawater storage capacity for atmospheric CO2. Olivine and steel slag released silicate nutrients into the seawater, but steel slag released considerably more and also significant amounts of phosphate. After 21 d, no significant difference was found in dissolved iron concentrations (>100 nmol L−1) in the treatments and the control. The slag addition increased dissolved manganese concentrations (771 nmol L−1), while olivine increased dissolved nickel concentrations (37 nmol L−1). There was no significant difference in total chlorophyll-a concentrations between the treatments and the control, likely due to nitrogen limitation of the phytoplankton community. However, flow cytometry results indicated an increase in the cellular abundance of several smaller (∼<20 µm) phytoplankton groups in the olivine treatment. The abundance of larger phytoplankton (∼>20 µm) decreased much more in the control than in the treatments after day 10. Furthermore, the maximum quantum yields of photosystem II (Fv/Fm) were higher in slag and olivine treatments, suggesting that mineral additions increased photosynthetic performance. The zooplankton community composition was also affected, with the most notable changes being observed in the dinoflagellate Noctiluca scintillans and the appendicularian Oikopleura sp. in the olivine treatment. Overall, the steel slag used here was more efficient for CO2 removal with OAE than the olivine over the 3-week timescale of the experiment. Furthermore, the steel slag appeared to induce less change in the plankton community than the olivine when comparing the CO2 removal potential of both minerals with the level of environmental impact that they caused.

Release of ballast material during sea-ice melt enhances carbon export in the Arctic Ocean.

Globally, the most intense uptake of anthropogenic carbon dioxide (CO2) occurs in the Atlantic north of 50°N, and it has been predicted that atmospheric CO2 sequestration in the Arctic Ocean will increase as a result of ice-melt and increased primary production. However, little is known about the impact of pan-Arctic sea-ice decline on carbon export processes. We investigated the potential ballasting effect of sea-ice derived material on settling aggregates and carbon export in the Fram Strait by combining 13 years of vertical flux measurements with benthic eDNA analysis, laboratory experiments, and tracked sea-ice distributions. We show that melting sea-ice in the Fram Strait releases cryogenic gypsum and terrigenous material, which ballasts sinking organic aggregates. As a result, settling velocities of aggregates increased ≤10-fold, resulting in ≤30% higher carbon export in the vicinity of the melting ice-edge. Cryogenic gypsum is formed in first-year sea-ice, which is predicted to increase as the Arctic is warming. Simultaneously, less sea-ice forms over the Arctic shelves, which is where terrigenous material is incorporated into sea-ice. Supporting this, we found that terrigenous fluxes from melting sea-ice in the Fram Strait decreased by >80% during our time-series. Our study suggests that terrigenous flux will eventually cease when enhanced sea-ice melt disrupts trans-Arctic sea-ice transport and thus, limit terrigenous-ballasted carbon flux. However, the predicted increase in Arctic primary production and gypsum formation may enhance gypsum-ballasted carbon flux and compensate for lowered terrigenous fluxes. It is thus unclear if sea-ice loss will reduce carbon export in the Arctic Ocean.

Role of sacred groves in southwestern Nigeria in biodiversity conservation, biomass and carbon storage.

Sacred groves are remnants of primary forests with rich biological diversity, protected by indigenous communities. Their role in carbon sequestration and provision of other ecosystem services is being recognized. We investigated four sacred groves (Idanre Hills, Igbo-Olodumare, Ogun-Onire, and Osun-Osogbo) in southwestern Nigeria for biodiversity conservation, biomass production, and carbon storage. A total of 32 temporary sample plots of 800 m2 each were laid across all the sacred groves. Within each plot, all trees with dbh greater or equal to 10cm were identified, and their diameters and heights measured. Saplings and seedlings were assessed within 100m2 and 25m2 sub-plots, respectively. Non-destructive methods were employed in estimating volume, biomass production, and carbon storage. Shannon-Wiener diversity index, Margalef index, and tree species richness in the four groves ranged from 2.63-3.55, 5.64-10.02, and 41-85, respectively, and differed significantly. The four groves were sanctuaries for many indigenous tree species of immense social, religious, ecological, and socio-economic importance. The high densities ofseedling and sapling, together with the inverted-J tree diameter distributions, are indications of active regeneration and healthy ecosystem. Mean volume was high (range 244.99 to 343.08 m3ha-1). The biomass (range 87.8 to 231.85 t ha-1) and carbon stock (range 43.9 to 115.9 t ha-1) of the groves revealed their potentials for climate change mitigation through atmospheric CO2 sequestration. Thus, besides being an effective biodiversity conservation method, sacred groves are important carbon sink. This calls for further conservation of sacred groves to serve as long-term carbon storagemechanism.

Conversion of Marginalized Tea Lands into Timber Plantations and its Impact on Soil Organic Carbon Content: A Case Study in Central Highlands of Sri Lanka

Tea (Camellia sinensis) plantations can be in production for about 100 years under well-managed conditions. However, soil degradation makes the tea lands marginalized and uneconomical. Land use conversion is an option for marginalized tea lands that could gain numerous environmental and economic benefits. This study estimated and compared the soil organic carbon stocks (SOC) in the surface soil layer (0–30 cm) of marginalized tea lands against those converted to timber plantations in the Badulla and Nuwaraeliya districts. Disturbed and undisturbed soil samples were collected from the top layer (0-30 cm) of the selected sites of marginalized tea lands and those converted to timber plantations for analysis. Organic matter percentage in the site-level dry soil samples was analysed using the loss on ignition method. The final carbon stocks (t C ha-1) for samples from both land use types were then estimated using the SOC percentages and bulk density estimates. The carbon stocks for the soil samples collected at marginalized tea lands and the marginalized tea lands converted to timber plantations were then statistically analysed (descriptive statistics, normality tests and two-sample t-tests) using Minitab 21.2 software. The pH of marginal tea lands (5.34±0.14) and the marginal tea lands converted to timber plantations (5.20±0.13) was slightly acidic in nature. The bulk density estimates of marginalized tea lands and marginalized tea lands converted to timber plantations were very close and estimated as 1.15±0.02. The statistical analysis showed that overall mean SOC was significantly higher under the marginalized tea lands converted to timber plantations (155.3±10.0 t C ha-1) compared to the marginalized tea lands (126.7±5.8 t C ha-1). Land use conversion has increased the SOC stocks gradually after forest establishment. The increased carbon stocks could be attributed to consistent addition of litter layer on the soil, less soil disturbance, and retarded soil erosion contributing to the buildup of soil organic matter and SOC. On the other hand, low carbon stocks in the marginalized tea land could be attributed to unsustainable agronomical practices. Our findings suggest that converting marginalized tea lands in central highlands into timber plantations could enhance the sequestration of atmospheric CO2, significantly contributing to climate change mitigation.
 Keywords: Soil organic carbon, Land use change, Climate change, Tea plantations

A pathway to 25% reduction in greenhouse gas emission by 2030 using GIS-Based multi-criteria decision making for renewables, date palm (phoenix dactylifera), and carbon credits: a case for Qatar

Qatar is making concerted efforts at the national level to decrease anthropogenic greenhouse gas emissions. The country has set its National Determined Contribution (NDC) in line with the Paris Agreement to reduce its overall emissions by 25% by the year 2030. This study identifies several pathways, which Qatar can explore to achieve its set goals. It explores Qatar’s potential for renewable energy generation (solar and wind), carbon offset through planting trees, and the purchase of carbon offset credits. The study starts by investigating the available wind and solar energy potential in the country, by considering physical and legal restrictions, which limit the available land to be utilized for RE generation. Multi-criteria Decision is carried out utilizing the Analytic Hierarchy Process (AHP) for variable percentage estimation in ArcMap Geographic Information Systems software. Next, a review based on Qatar’s climate is performed to identify suitable tree species that would promote atmospheric CO2 sequestration in the country. Finally, the cost implication of offsetting emissions using verified carbon credits is considered and compared with other options. Results indicated that while a considerable area is available for both wind (37%) and solar (53%) energy generation, only 6.2% and 13.8% of Qatar are highly suitable for wind and solar energy installations, respectively. Also, while Qatar has the potential to meet 20% of its energy demand by 2030 from renewable sources by using solar PV and wind, this will only account for a 14.28% reduction in overall emissions. Additionally, planting date palm trees (Phoenix dactylifera) would significantly benefit the nation in the area of carbon sequestration and revenue generation as compared to purchasing carbon offset credits.

Atmospheric CO2 Sequestration in Seawater Enhanced by Molluscan Shell Powders.

Carbon capture, utilization, and storage (CCUS) are widely recognized as a promising technology for mitigating climate change. CO2 mineralization using Ca-rich fluids and high-concentration CO2 gas has been studied extensively. However, few studies have reported CO2 mineralization with atmospheric CO2, owing to the difficulty associated with its low concentration. In seawater, the biomineralization process promotes Ca accumulation and CaCO3 precipitation, assisted by specific organic matter. In this study, we examined the conversion of atmospheric CO2 into CaCO3 in seawater using shell powders (Pinctada fucata, Haliotis discus, Crassostrea gigas, Mizuhopecten yessoensis, Turbo sazae, and Saxidomus purpurata). Among the six species, the shell powder of S. purpurata showed the highest rate of CaCO3 formation and recovery of CaCO3. NaClO treatment test revealed that the organic matter in the shells enhanced the CO2 mineralization. All materials used in this study, including atmospheric CO2, seawater, and shells, are economically feasible for large-scale applications. Using shell powder for CO2 mineralization in seawater embodies an innovative technological advancement to address climate change.

Phytoplankton physiology and functional traits under artificial upwelling with varying Si:N

IntroductionArtificial upwelling has been discussed as a nature-based solution to fertilize currently unproductive areas of the ocean to enhance food web productivity and atmospheric CO2 sequestration. The efficacy of this approach may be closely tied to the nutrient stoichiometry of the upwelled water, as Si-rich upwelling should benefit the growth of diatoms, who are key players for primary production, carbon export and food web efficiency.MethodsWith a mesocosm experiment in subtropical waters, we assessed the physiological and functional responses of an oligotrophic phytoplankton community to artificial upwelling under varying Si:N ratios (0.07-1.33).ResultsDeep water fertilization led to strongly enhanced primary productivity rates and net autotrophy across Si scenarios. At the community level, Si-rich upwelling50 temporarily increased primary production and consistently enhanced diatom growth, producing up to 10-fold higher abundances compared to Si-deficient upwelling. At the organism level, contrasting effects were observed. On the one hand, silicification and size of diatom cells remained unaffected by Si:N, which is surprising given the direct dependency of these traits on Si. On the other hand, diatom Chlorophyll a density and carbon density were strongly reduced and particulate matter C:N was elevated under Si-rich upwelling.DiscussionThis suggests a reduced nutritional value for higher trophic levels under high Si:N ratios. Despite these strong qualitative changes under high Si, diatom cells appeared healthy and showed high photosynthetic efficiency. Our findings reveal great physiological plasticity and adaptability in phytoplankton under artificial upwelling, with Si-dependent trade-offs between primary producer quantity and quality.

THE POTENTIAL FOR CARBON SEQUESTRATION IN RECLAIMED MINE SOIL

Mining sector has been the central attention of the business and public policy sustainable development scheme for several years. Reclamation territories are with potential carbon sequestration capacity in degraded mining areas and can be an impeccable option for achieving sustainable development goal-13. This paper made an investigation about the presence of heavy metals in reclaimed area possibilities to improve reclaimed soils with biochar with idea to enhance ecosystem carbon pool and atmospheric CO2 sequestration capacity to offset CO2 emission and soil organic carbon losses. The results show that the carbon content in biochar is 46.6 % and would be classified in class 2 according to the International Biochar Initiative. H/C and O/C atomic ratios could be useful for restoration of degraded poor mine soils through enhanced carbon sequestration. O/C ratio is 0.085 mol mol–1 and half-life of biochar is 2795.65 years, which confirm the biochar stability. For each kilogram of biochar incorporated into the soil, 144 g of carbon were sequestrated 52,8 % CO2 emission reduction. Hence, the biochar developed in this study can be used in carbon-deficient soils with the added benefit of long-term carbon storage.

Carbon reserves in deltaic mangroves of the Colombian Pacific across different disturbance degrees

Mangrove forests occupy less than 1% of tropical forest areas, but account for approximately 3% of global tropical forest carbon sequestration and act as a natural atmospheric CO2 sequestration mechanism, which gives them an important role in climate change mitigation. However, different anthropogenic disturbances continue to negatively impact the structure and function of mangrove ecosystems; therefore, it is important to investigate the effect of specific anthropogenic alterations on the capacity of mangroves to store carbon. The present study aimed to test the hypothesis of a direct relationship between the degree of anthropogenic intervention and the reduction of mangrove carbon stocks. Eight edge forest types with different degrees of anthropogenic intervention and multiple uses were selected. Six 100 m2 plots were established in each forest to determine its structure and evaluate the concentration of sedimentary organic carbon and biomass. The anthropogenic disturbance index (ADI) was used to quantify the degree of specific disturbances in the studied forests. The results supported the proposed hypothesis, showing that the mangroves with the highest anthropogenic disturbance measured through the ADI registered the lowest values in blue carbon. However, it is evident that in addition to anthropogenic disturbances, impacts such as coastal erosion pose a very important threat to some of these forests. Estimated organic carbon losses in the study area were between 8.4% and 49.3%, corresponding to 158 and 929 Mg CO2 eq ha−1, respectively. Logging is one of the main disturbances that affects forests differently according to their structural development. Forests with higher structural development are subject to greater pressure. Carbon losses from logging are not only reflected in aboveground carbon, but are also evident in sedimentary carbon.

Ocean Deserts Could Help Capture CO<sub>2</sub> and Mitigate Global Warming

Various nutrient sources in the upper waters of oceanic subtropical gyres, which are the Earth's largest oligotrophic ecosystems, play a crucial role in governing the sequestration of atmospheric CO2.

Passive carbon sequestration associated with wollastonite mining, Adirondack Mountains, New York

Abstract Crushed ore in Adirondack wollastonite mines (New York) shows textural evidence for wollastonite dissolution and cementation by calcite and opal. The reaction CaSiO3 + CO2 = CaCO3 + SiO2 is a model reaction for silicate weathering and carbonation that has not been characterized in the field until now (outside of controlled experiments). Cemented samples from the Lewis and Fox Knoll mines contain up to 3% and 6% calcite, respectively, and contain modern 14C. Carbon isotope ratios have an organic signature at both mines but more strongly at Lewis (δ13C from –9‰ to –29‰ VPDB), which, along with observed filamentous biofilms, supports a microbial role in mineralization. Differences are seen between wollastonite weathering in these mines vs. wollastonite weathering in lab experiments and field studies of carbonate formation in other rock types. Grains surrounded by reaction products reach complete dissolution here, indicating that passivation by jacketing is not important at the field sites. Also, dissolved ions do not all form in situ reaction products, suggesting that solutes are leaving the system. A key finding of this study is the strong organic δ13C signature of calcite cements at the Lewis mine, which also show higher calcite content per years of exposure compared to cements at the Fox Knoll mine. Although microbial fractionation complicates isotopic assessment of atmospheric CO2 sequestration, our findings suggest sequestration rates are enhanced by geomicrobiological activity.

Assessing soil organic carbon in agroforestry systems in different altitudes of Tehri District, Uttarakhand, India

An agroforestry system that combines trees and shrubs with crops, increases organic carbon accumulation in soil by providing continuous supply of organic matter over time. Soil organic carbon is a key component of terrestrial ecosystem that helps in enhanced sequestration of atmospheric CO2 in the soil. This study was carried out during the year 2017 in Tehri Garhwal of Uttarakhand. Three agroforestry systems selected were Agrihorticulture (AH), Agrisilviculture (AS) and Agrihortisilviculture (AHS) in three altitude viz., Lower altitude (286-1200 m), Middle altitude (1200-2000 m), and Upper altitude (2000-2800 m). Ten sample plots (100m2) were randomly laid out in each agroforestry system on each altitude of each block. Soil organic carbon was determined using the Walkley and Black method. Soil physico-chemical properties revealed that maximum bulk density (1.38 g cm-3) was recorded in the agrisilviculture system and minimum in agrihorticulture system (1.29 g cm-3). Maximum soil organic carbon (2.74%) was found in the agrihorticulture system and minimum in agrisilviculture system (2.48%). The soil organic carbon percent also increased significantly with the ascending altitudes. It was concluded that upper altitude (2000-2800m) and agrihorticulture system had accumulated greater soil organic carbon pool and suggested that, if need be, conversion of agriculture field should be into agrihorticulture system in Northwestern Himalayas for better soil carbon sequestration.

Mitigation of Global Climate Change through Genetic Improvement of Resin Production from Resinous Pines: The Case of Pinus halepensis in Greece

Carbon sequestration by forests and storage in biomass has gained great interest globally in climate change mitigation. Resinous pine forests act as ideal carbon sinks because, in addition to capturing atmospheric CO2 for biomass production, they produce resin (resin concentration in C: 77.17% w/w), contributing further to the mitigation of the greenhouse effect. Greece until the 1970s was considered one of the main resin-producing countries of Europe, due to the quantity and quality of resin products collected from natural populations mainly of Pinus halepensis Mill. Previous and current research has shown that resin production is a genetically controlled trait (h2 > 0.70) that exhibits great variability among trees (resin 0.5–33.0 kg per tree and year). The above led to the genetic selection of P. halepensis genotypes with constant over time high resin yields (≥20 kg per tree and year) and consequently greater atmospheric CO2 sequestration for more effective counteracting climate change but also for economic reasons for the benefit of resin producers. These high-yielding genotypes were cloned through grafting on P. brutia rootstocks and became potential trees for establishing commercial pine plantations. Thus, one hectare of commercial plantation of 500 P. halepensis trees, with a resin yield of 20 kg per tree, is expected to sequester 28.31 tn CO2 per year (instead of 2.82 tn of CO2 per year of a natural stand of 400 P. halepensis trees based on a resin yield of 2.5 kg per tree), at the productive age of 25 years. In this case, commercial plantations with improved genotypes of P. halepensis have great potential not only in mitigating the concentration of CO2 in the atmosphere, but also in restoring degraded marginal areas and arid soils, and at the same time can offer social and economic benefits to the local communities.

Qualitative and Quantitative Changes in Soil Organic Compounds in Central European Oak Forests with Different Annual Average Precipitation

The various climate scenarios consistently predict warming and drying of forests in Hungary. Soils play a significant role in the long-term sequestration of atmospheric CO2, while in other cases they can also become net carbon emitters. Therefore, it is important to know what can be expected regarding future changes in the carbon storage capacity of soils in forests. We used precipitation gradient studies to solve this problem, using a type of “space–time” substitution. In this research, we primarily examined the quality parameters of soil organic matter (SOM) to investigate how climate change transforms the ratio of the main SOM compound groups in soils. For our studies, we applied elemental and 13C and 15N isotopic ratio analysis, NMR analysis, FT-IR spectra analysis, thermogravimetric and differential thermal analyses to measure SOM chemistry in samples from different oak forests with contrasting mean annual precipitation from Central Europe. Our results showed that soil organic carbon (SOC) was lower in soils of humid forests due to the enhanced decomposition processes and the leaching of Ca, which stabilizes SOM; however, in particular, the amount of easily degradable SOM compounds (e.g., thermolabile SOM, O-alkyl carbon, carboxylic and carbonyl carbon) decreased. In dry forest soils, the amount of recalcitrant SOM (e.g., thermostable SOM, alkyl carbon, aromatic and phenolic carbon and organo–mineral complexes stabilized by Ca increased, but the amount of easily degradable SOM increased further. The main conclusion of our study is that SOC can increase in forests that become drier, compensating somewhat for the decrease in forest plant biomass.

Multiple controls on carbon dioxide sequestration in the beagle channel (Southern Patagonia) in early fall

Subpolar coastal waters are key hotspots in the global carbon cycle. However, the small-scale distribution of partial pressure of carbon dioxide (pCO2) in these environments and the physical and biological controls underlying this variability are still poorly understood. Here, we examine simultaneous high-resolution spatial measurements of wind speed and pCO2, temperature, salinity, and in-vivo chlorophyll-a fluorescence (chl-a fluo, a proxy of phytoplankton biomass) in surface waters that were obtained during an oceanographic survey in the Argentinian Beagle Channel (subantarctic Atlantic Patagonian) in early fall 2017. The 240 km study transect (centered at 55°S - 67°W) was divided into two zones: (A1) The Beagle Channel innermost portion, semi-enclosed and subject to strong continental influence and (A2) its eastern outlet towards the open Southwest Atlantic. Discrete seawater samples were also collected for apparent oxygen utilization (AOU), nutrients and pH measurements. High-resolution spatial measurements revealed the persistence of pCO2 below atmospheric equilibrium, increasing in median (interquartile range 25–75%) from 314 μatm in the inner Beagle Channel (A1) to 348 μatm towards the adjacent open sea (A2). A decrease in atmospheric CO2 sequestration was associated with an increase in water temperature from 9.5 °C to 10.7 °C, salinity from 30.8 to 32.5, and chl-a fluo from 2.24 to 2.91 mg m−3 along the coastal-offshore gradient. Low AOU and nutrient levels were found in regions inside the channel. Indeed, the relationships between CO2 and temperature or salinity were significantly different from those expected from the theoretical solubility effect, indicating a dominance of metabolic over physicochemical controls on this gas. Moreover, physical factors such as vertical stratification contributed to the variable surface pCO2 values. These findings reveal the existence of short-scale spatial variability of CO2 in the Beagle Channel, improving our understanding of the multiple controls on atmospheric carbon sequestration in extensive subpolar continental shelves.

Direct CO2 Capture by Alkali-Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures.

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, an effective pathway is offered that addresses climate action by atmospheric CO2 sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO2 absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 102 to 107 mPas and storage modulus from 10 to 105 Pa). CO2 absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5gCO2 gcellulose -1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration.

Nanoscale Mg-Depleted Layers Slow Carbonation of Forsterite (Mg2SiO4) When Water Is Limited

Passivation of silicate surfaces by accumulated reaction products is an obstacle to efficient CO2 mineralization. In this study, we investigate a unique passivation effect during the carbonation of the basalt mineral forsterite (Mg2SiO4) in humid supercritical CO2 (50 °C, 90 bar). Using in situ high-pressure infrared spectroscopy, we demonstrate that dissolution of forsterite into a thin water film slows significantly after reaction for ≈24 h, even under far-from-equilibrium conditions. 29Si magic angle spinning nuclear magnetic resonance spectroscopy detects a highly polymerized amorphous silica at this stage. On the basis of transmission electron microscopy and energy dispersive X-ray spectroscopy, we show that the silica is present as a Mg-depleted layer that is just 2–3 nm thick on the reacted forsterite particles. The decrease in the level of forsterite dissolution in the presence of an extraordinarily thin Mg-depleted layer can be strongly linked to properties of the thin fluid film at the surface, highlighting the importance of water during mineral carbonation. This study furthers our understanding of silicate mineral carbonation under select low-water, humidified fluid conditions relevant to basaltic geologic reservoirs, recovery of critical elements by carbonation of mafic ores, and sequestration of atmospheric CO2 by enhanced rock weathering.