The Eocene was a critical period of global climate transition from the warm “greenhouse” to the cooling “icehouse” state, during which high-quality source rocks developed in several coastal basins in eastern China, with paleoclimatic conditions playing a significant controlling role. During the deposition of the Second Member of the Liushagang Formation in the Weixi’nan Sag of the Beibuwan Basin, the rifting process reached its peak; however, organic-rich shales only developed in the lower submember, suggesting that paleoclimatic conditions played a key role in their formation. This study integrates organic and inorganic geochemical analyses to investigate the development mechanism of organic-rich shales in the Eocene Liushagang Formation driven by paleoclimatic conditions, providing insights into source rock development in the Eocene coastal basins of eastern China. The results show that: (1) The organic-rich shales have total organic carbon (TOC) contents ranging from 2.7% to 10.3% (average 5.66%), significantly higher than conventional mudstones (0.59%–10.34%, average 3.01%) and shales (1.26%–6.03%, average 2.40%). (2) The Beibuwan Basin, located in the tropical monsoon region, experienced increased precipitation and a more humid environment during periods of temperature rise. The chemical weathering index indicates that the source rocks of the Liushagang Formation underwent intense weathering, corresponding to a hot and humid paleoclimate. The high Sr/Cu ratios in the lower submember of the Second Member suggest a hotter and more humid climate during the deposition of organic-rich shales, consistent with the Early Eocene Climatic Optimum (EECO). (3) During the deposition of organic-rich shales, the hot and humid climate intensified the weathering of parent rocks, supplying abundant nutrients to the lake basin and promoting algal proliferation, which led to high paleoproductivity. Meanwhile, strong evaporation created a freshwater to brackish environment that enhanced bottom-water anoxia, providing favorable conditions for organic matter preservation. The combination of high paleoproductivity and superior preservation conditions jointly controlled the development of organic-rich shales.

How to cite: Meng, X., Liu, H., and Cheng, B.: Development Mechanism of Organic-rich Shales in the Eocene under the Influence of Paleoclimatic Conditions in the Weixi’nan Sag, Beibuwan Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6746, https://doi.org/10.5194/egusphere-egu25-6746, 2025.

Over the past decade raman spectroscopy has been used to investigate an increasing range of geological challenges. It’s application in fault zones to track strain is an emerging area. Difficulties in the applications of raman spectroscopy to fault zones stem from deciphering the effects of the multitude of processes occurring in a fault zone on carbon structure and hence raman spectroscopy. Here we consider a range of raman data acquired from fault zones, the processes occurring in the fault zones and how these could influence the raman spectroscopy signal. Our samples include carbonaceous material from natural brittle and ductile fault zones as well as synthetic fault gouge and show that if we are to successfully use raman spectroscopy to determine strain in fault zones we need to better understand fault zone processes and their interaction with carbonaceous material.   

How to cite: Bond, C., O'Donnell, A., Robertson, R., Muirhead, D., and Menzies, C.: In a Spin: Raman spectroscopy on organic-carbon in fault zones, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16667, https://doi.org/10.5194/egusphere-egu25-16667, 2025.

Microbes make the carbon cycle function in the biosphere. Their use in human industries; utilization of organic compounds, transformation of Organic Matter (OM), accumulation of biomaterials and carbon sequestration make a life-maintaining contribution to our societies. This is provided that we learn to understand and integrate the circulation of carbon in anthropogenic systems into natural ecosystems. Microbes are a key to understanding these mechanisms. We investigated the industrial side stream utilization by mixed microbial cultures in non-aseptic conditions. This gave us industrial processes that operated like ecosystems. They provided up to three-fold productivities and yields compared to the microbial pure cultures. The products were analyzed using NMR spectroscopy (https://www.chemadder.com), which covered both the raw material composition and product manifestation most broadly and accurately. The microbiological bioprocess comprised the natural microflora of the side streams in question, additional industrial strains, and various enzymes as biocatalysts. It was operated and steered by the "Industry Like Nature®" principle (www.finnoflag.fi). Chemical products depend on the sidestream of raw materials, which could originate from various industries, agriculture, or communities. Some of these sources were environmentally deposited, as in the case of P&P factory zero fibre sediments. The commodities or bulk chemicals included organic acids, such as acetic, propionic, butyric and lactic acids, longer-chain acids (hydrocarbons), and various alcohols and sugar alcohols.

In some cases, the mixtures were usable as industrial fuels, but value-added chemicals as ultimate products could make the overall process more feasible. They enabled the development of novel product entities. Sustainability was readily demonstrable, as carbon was consolidated into industrial ecosystems instead of directly emitted into air, water, or soil. The produced substances were purified as bulk or fine chemicals for food, feed, cosmetics, polymer, medical, and other industries. They could be used as preservatives or substitutes in many product chains, which still increase the binding of carbon (and many other elements or molecules) into the cycles. This increased the adhesion of various molecules into the products and the duration of this integration into the product streams. Many of the products also replaced or complemented the fossil sources in a climate-friendly way. The final residues of the chemical-making processes were useful soil improvement agents, as demonstrated in the "Zero waste from zero fibre project" in 2018-19 in Tampere, Finland, funded by the Finnish Ministry of Agriculture and Forestry (Blue bioeconomy program) and in 2023-24 in the EU funded BioResque project (CircInWater call). Chemical production was thus the most critical step in the return of the organics and their carbon residues into the total circulation. The fate of various molecules could be followed by NMR-based surveillance and microbiological communities characterized by tools such as PMEU (Portable Microbe Detection Unit).

How to cite: Hakalehto, E. and Laatikainen, R.: Multistage biochemical refinery unit in complementing fossil hydrocarbons, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20692, https://doi.org/10.5194/egusphere-egu25-20692, 2025.

Carbon capture and storage has emerged as a crucial strategy for mitigating global warming. Ex situ mineralization, which converts CO₂ into stable carbonate minerals aboveground, promises to store carbon safely for geological timescales. However, this approach typically requires mining and processing rocks that contain calcium and magnesium, making it both costly and environmentally damaging.

To reduce quarrying demands, industrial waste streams, such as gypsum and coal fly ash, have been proposed as alternative feedstocks. While studies have demonstrated the feasibility of converting these waste materials into carbonate minerals through reaction with CO₂, the process is limited by stoichiometry: each cation can sequester only one carbon atom. However, the efficiency of carbon mineralization could be doubled by instead forming oxalate minerals, such as glushinskite (MgC₂O₄·2H₂O) and whewellite (CaC₂O₄·H₂O).

These minerals form through reactions between Ca and Mg-bearing phases and oxalic acid (H₂C₂O₄). While oxalic acid is typically produced through expensive electrochemical CO₂ reduction, we propose sourcing it directly from plants. Oxalate occurs naturally in nearly 80% of plant families, comprising up to 80% of dry weight in some species. Since plants produce oxalate through photosynthetic CO₂ fixation, this represents a net atmospheric carbon removal pathway.

Our study demonstrates a proof-of-concept that oxalic acid can be extracted from agricultural waste and reacted with industrial waste to mineralize carbon. Through experiments that react gypsum and fly ash with oxalic acid extracted from two common plants, we quantify Ca oxalate formation efficiency and estimate the carbon storage potential. Our findings have significant implications for integrating waste management with carbon removal and storage at a global scale.

How to cite: Emmanuel, S. and Grayevsky, R.: Converting industrial and agricultural waste streams into carbon-storing oxalate minerals, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10587, https://doi.org/10.5194/egusphere-egu25-10587, 2025.

Enzymes are natural catalysts. They play an important role in a series of biological processes by catalysing reactions with high degree of specificity and efficiency. Inspired by the high degree of selectivity, modified enzymes or their peptide mimics have been used in recent times for applications across different fields, including biotechnology, pharmacology and environmental science. The peptide sequence as possible alternative essentially mimics the enzyme active site. Their diversity in sequence selection and flexibility of structure have shown to be a promising alternative for enzymes, especially in harsh conditions such as high temperature and extreme pH.

Natural carbonic anhydrases catalyze the reversible conversion of CO₂ and water to bicarbonate (HCO₃⁻) and protons (H⁺). The goal is to design synthesize and characterize synthetic catalysts mimicking enzymes that can catalyse reaction even at extreme conditions, potentially aiding in the capture of CO₂ from the atmosphere or industrial emissions. In this work, we attempt to mimic human carbonic anhydrase II enzyme, with four heptapeptides, Ac-HyHyHfF-CONH₂, Ac-HPhYhFf-CONH₂, Ac-HhHfFyF-CONH₂ and Ac-HhYfHfF-CONH₂. Its catalytic activity was found to have remarkably increased with increase in pH and temperature. The conversion of carbon dioxide to bicarbonate was monitored by evaluating the change in pH in the presence of different catalysts and control. The results indicate that Ac-HyHyHfF-CONH2 exhibited the best catalytic performance among the four Zn-heptapeptide. This resulted in investigating further to employ such peptides for potential applications in carbon dioxide sequestration.

Capturing and storing atmospheric carbon dioxide either ‘geologic’ or ‘biologic’ processes is the need of the hour.  In this work we explored the possibility of hybridizing these diverse disciplines by making use of molecules of ‘biological’ origin for storing carbon dioxide in ‘geological’ formations. 

How to cite: Ramakrishnan, V. and Kumari, K.: De novo Design of Peptide Catalyst as Enzyme-mimic for Carbon Dioxide Sequestration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17919, https://doi.org/10.5194/egusphere-egu25-17919, 2025.

Biochar is produced by the thermal decomposition of carbon-rich materials in a limited oxygen atmosphere. A wide source of raw materials can be used, and depending on the source material and pyrolysis conditions, outstanding features can be obtained, such as high specific area, porosity, functional groups, and high-stable carbon. Thus, biochar properties make it suitable for various applications for pollutant sorption, energy storage, carbon sequestration, and soil improvement. The significance of biochar as a soil amendment is attributed to the improvement of both the physical and biochemical properties of soil, the increase of soil fertility and productivity, the rise in water retention, and the improvement of microbial activities. Water retention in soil is affected by adding biochar, which interacts with soil particles and could result in the formation of macroaggregates with higher specific surface and porosity. This results in the formation of more binding sites for water molecules and thus increases the water retention of soil. Except for the interactions of biochar-soil mixture, biochar-self properties could affect water holding capacity. Specific surface, particle size sphericity, and surface functionality have been shown to affect water-holding capacity. In this study, biochars were produced using coffee spent grains and crushed olive grains under different pyrolysis conditions (300 to 900^oC). Biochar was characterized for the specific surface, pore volume and size, and surface functional groups.

How to cite: Manarioti, M.-V., Pelekis, P., and Manariotis, I.: Effect of pyrolysis conditions on biochar characteristics and water evaporation  , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7955, https://doi.org/10.5194/egusphere-egu25-7955, 2025.

Peat has traditionally and widely served as a growing medium. However, peatlands are important carbon sinks, and peat extraction contributes significantly to GHG emissions [1]. Consequently, research into alternative materials to peat is imperative, along with careful consideration of feedstock characteristics and processing techniques for production of peat substitutes [2]. This study studied the potential of biochar and compost from different agro-waste as viable alternatives by assessing their effects on agronomic properties.

The materials studied included peat, green compost, and two types of biochar. Ten treatments were designed as follows: a control using only peat, and nine mixtures incorporating 10% or 20% biochar, compost, or combinations of both with peat. A germination test was conducted in Petri dishes using seeds of Medicago polymorpha, Lolium perenne, Lolium rigidum, and Festuca arundinacea. Following this, two pot experiments were performed to evaluate the effects on soil physical properties, elemental composition, and plant growth. The addition of biochar and/or compost improved the physical properties of the substrates. Biochar significantly increased the total carbon content, whereas compost additions at 10% and 20% resulted in a reduction in carbon content. However, biochar produced from olive pomace, which exhibited high electrical conductivity, negatively impacted germination and plant development. In summary, biochar, whether used alone or in combination with compost, shows promise as a substrate amendment. However, careful selection of feedstock and production conditions is crucial to ensure its effectiveness.

Acknowledgements: The funding of the AGRORES and RES2SOIL projects (PID2021-126349OB-C21 and PID2021-126349OB-C22) by MCIN/AEI/10.13039/501100011033 is gratefully acknowledged. P. Campos thanks MICIU/AEI/10.13039/501100011033 and FSE+ for funding the grant PTA2023-023661-I.

References:

[1] Krüger et al., 2018. Computers and Electronics in Agriculture 154, 265-275. https://doi.org/10.1016/j.compag.2018.09.001

[2] Rozas et al., 2023. Horticulturae 9(2), 168. https://doi.org/10.3390/horticulturae9020168 

How to cite: Campos, P., Sánchez-Martín, Á. M., Santa-Olalla, A., Lucas, M., Rosales, M. A., and De la Rosa, J. M.: Exploring sustainable alternatives to peat: A focus on biochar and compost, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15561, https://doi.org/10.5194/egusphere-egu25-15561, 2025.

Biochar is a heterogeneous, aromatic-rich organic material obtained from the thermal degradation of plant or animal biomass in the absence of oxygen, and could be exploited for a variety of uses, such as in soil amendment, as sorbent or feed additive. A convenient source of lignocellulosic materials for biochar production is represented by pruning residues, which would be otherwise discarded or burnt. In the project “Novel materials for bioinspired metal-airbatteries”, biochar from various pruning residues is valorised by exploiting it as electrode materials in electrochemical devices such as fuel cells, electrolyzes and metal-air batteries, which play a key role in many technological sectors.  In particular, wood-derived cathodes are tested in innovative electrochemical energy storage and conversion devices, namely aluminum-air batteries which, due to their high theoretical gravimetric capacity, are considered promising alternative to the lithium-ion batteries in terms of electrochemical performances, cost and eco-sustainability.

A key point of the project is the thorough elucidation of the original wood both from the chemical and morphological viewpoint. Indeed, the efficiency of the derived biochar-derived cathodes significantly depends on the molecular composition and anatomical structure of the used wood. Therefore, the amount and type of lignin of the selected lignocellulosic biomasses, together with the morphology of their internal wood structure will be assessed via different analytical tools, such as infrared spectrometry, nuclear magnetic resonance spectroscopy, as well as light, epifluorescent and scanning electron microscopy. Then, electrochemical polarization studies will allow evaluating the electrochemical performance of the prepared materials. Furthermore, the effect of different pyrolysis temperatures, as well as the addition of heteroatoms via biochar impregnation in nitrogen-rich solutions will be assessed in order to optimise the synthesis preparation of biochar-based cathodes. Finally, the electrochemical properties of biochar-based batteries will be correlated with the chemical and morphological features of biochar itself, as well as with that of the starting raw lignocellulosic pruning residues, so to unravel the chemical and anatomical properties underlying the observed electrochemical properties of biochar-derived batteries. Overall, the production of electrodes from made of biochar from pruning residues is expected to represent a novel and sustainable way to valorise precious lignocellulosic byproducts, which could in turn reduce our dependence from Li-based batteries, therefore, limiting the negative environmental consequences of their massive exploitation.

How to cite: Rao, M. A., Amitrano, C., Califano, V., Gaele, M. F., Gargiulo, P., Gherardelli, M., Savy, D., Costantini, A., De Micco, V., and Di Palma, T.: Biochar from pruning byproducts applied as electrode material in bioinspired metal-air batteries, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16270, https://doi.org/10.5194/egusphere-egu25-16270, 2025.

Biochar is defined as a solid material derived from the thermochemical degradation of biomass and has been proposed for many applications. A source of biomass for biochar production is represented by branch wood as forestry or fruit crop byproduct. Wood-derived biochar has been proposed as cathode material for metal-air batteries replacing other non-environmentally friendly or non-renewable materials. The electrocatalytic activity of the carbonaceous materials derived from wood depends on the structural and chemical characteristics of the raw materials, which can be preserved during the pyrolysis process.

In this study, we performed a characterisation of anatomical and chemical traits of wood from different softwood and hardwood species to identify suites of traits favoring the development of efficient air cathodes to be used in electrochemical energy conversion devices. Both softwood and hardwood species were considered, the first type being evolutionary younger and structurally simpler (relying on tracheids for both water flow and mechanical support) than hardwoods (having vessels and tracheids for water flow and fibres mainly for mechanical strength). Among the hardwoods, crop species including Vitis vinifera, Citrus, Pyrus, and Prunus species were analyzed considering the huge amount of wood waste produced worldwide from pruning activities. The different organization of the cell types in the various woods and quantitative traits (e.g. conduits lumen size, cell wall thickness, relative incidence and spatial distribution of the various cell types, density, etc.), the different ultrastructure and chemical composition of the cell walls (e.g. cellulose microfibrils arrangement, lignin content/type/distribution, etc.), and the occurrence of occlusions (e.g. tyloses and gums) are species-specific, vary within the tree architecture, with specific rules and trends (age-, size- and stress-related), and are responsible for the different properties of wood including porosity and mechanical strength. Therefore, a deep knowledge of the quantitative traits of the original wood material is crucial to achieving the desired final properties of the derived carbonaceous materials. Wood anatomy of the branch wood was analyzed through light-, epi-fluorescence, and scanning electron microscopy, as well as functional traits were quantified through digital image analysis. Chemical analyses were also performed to highlight the lignin content and elemental composition of the woody biomass. The woods were treated with pyrolysis cycles and impregnation of nitrogen-rich aqueous solutions, then cathodes for metal-air batteries were prepared. Polarization studies performed on wood-derived cathodes assembled in aluminum-air batteries have highlighted electrochemical performances sufficient for practical applications.

All analyzed parameters were integrated and elaborated through multivariate statistical methods to evaluate the relations among wood traits and the technological properties of the cathodes obtained from the biochar of the various species. The utilization of pruning residues for producing bio-inspired metal-air batteries thus represents a novel and sustainable way to valorize precious lignocellulosic byproducts in the framework of a circular economy.

How to cite: De Micco, V., Mara, G., Davide, S., Chiara, A., Valeria, C., Maria Felicia, G., Pasquale, G., Tonia Mariarosaria, D. P., Aniello, C., and Maria Antonietta, R.: Influence of wood anatomical and chemical traits on the properties of derived biochar for technological applications as cathode material in metal-air batteries, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17420, https://doi.org/10.5194/egusphere-egu25-17420, 2025.

The long-term stability of biochar is of great importance for its capacity to serve as a carbon dioxide removal (CDR) method. However, not all pyrolysis techniques result in thermochemically stable biochar with a large fraction of condensed carbon. Moreover, for some applications the best biochars are those made at moderate highest treatment temperatures (HTT) but with highest fractions of functional groups on the carbon surface. Methodologies to quantify the relative amount of ‘stable’ and ‘labile’ biochar in one sample are currently either complex or unprecise. At present, the bulk H/C ratio is used as an easy-to-measure proxy for thermochemical, and by inference biological reactivity/stability of biochar, where a decreasing H/C ratio reflects the loss of functional groups and subsequent aromatization and condensation upon increasing pyrolysis temperature. However, different feedstocks and pyrolysis techniques may result in a large spread of H/C irrespective of the actual carbon structures, introducing significant uncertainty.

This study investigates the potential of quantifying exchangeable (‘labile’) versus non-exchangeable (‘stable’) hydrogen as a complementary proxy for biochar reactivity/stability. Hydrogen in organic substances like biochar is either bound weakly onto functional groups forming a pool of exchangeable hydrogen (H_ex), or is directly and strongly bound to carbon atoms, constituting a non-exchangeable hydrogen pool. The relative amount of H_ex (%H_ex) has previously been found to decrease with increasing maturity of coals, together with decreasing H/C ratio, and increasing vitrinite reflectance (R₀) that reflects an increase in condensed structures. Given the similarities between biochar and coal, %H_ex may be an informative and quantitative proxy of biochar reactivity and stability in conjunction with bulk H/C. %H_ex is determined by means of dual equilibration with H₂O with two different hydrogen isotopic compositions (deuterium:hydrogen ratio, expressed as δ²H) and subsequent comparison of the two resulting δ²H values of the treated material. The analysis is performed using thermal conversion / element analysis - isotope ratio mass spectrometry (TC/EA-IRMS), a common technique in isotope-related research and applied sciences, for instance for food authentication and environmental research. The %H_ex of several series of biochars pyrolyzed with HTT between 250°C - 1000°C were compared with other data on the carbon composition of biochars, in particular the degree of aromatization and condensation. %H_ex was found to respond sensitively to ongoing aromatization in the lower half of the HTT gradient, reaching lowest values once condensation starts to become more prevalent at higher pyrolysis temperatures. The method also allows for the determination of the δ²H value of the non-exchangeable hydrogen (δ²H_n), which was found to become higher with decreasing %H_ex, most likely due to isotope fractionation during pyrolysis. %H_ex and potentially δ²H_n may thus serve as a method to determine the relative amount of reactive and stable biochar, especially in biochars made at lower pyrolysis temperatures.

How to cite: Smittenberg, R.: Percent non-exchangeable hydrogen as reactivity-stability proxy of biochar, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3288, https://doi.org/10.5194/egusphere-egu25-3288, 2025.