Heavy Fraction Research Articles

Soil–Plant Carbon Pool Variations Subjected to Agricultural Drainage in Xingkai Lake Wetlands

This study examines the responses of soil organic carbon (SOC) pools and their components to agricultural water drainage in paddy fields, with a focus on the wetland–paddy field ecotone of Xingkai Lake, a transboundary lake shared by China and Russia. Field investigations targeted three representative wetland vegetation types: Glyceria spiculosa (G), Phragmites australis (P), and Typha orientalis (T), across drainage durations ranging from 0 to over 50 years. SOC fractions, including light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC), were systematically analyzed. The results revealed that SOC components in T and P wetlands steadily increased with drainage duration, whereas those in G wetlands exhibited a fluctuating pattern. SOC dynamics were primarily driven by LFOC, while MBC displayed species-specific variations. Correlation analyses and structural equation modeling (SEM) demonstrated that soil physicochemical properties, such as total nitrogen and moisture content, exerted a stronger influence on SOC fractions than microbial biomass. Overall, water drawdown significantly altered SOC dynamics, with distinct responses observed across vegetation types and wetland ages. This study provides critical data and theoretical insights for optimizing carbon sequestration and hydrological management in wetland–paddy field systems.

Features of chromite-containing placers of the Lukoyanovsky Placer district (Nizhny Novgorod region) and conditions of their formation

Chromites are a common component of the heavy fraction of sedimentary deposits of the cover of the platform areas, while their contents usually do not exceed the first percent. Placers of chromites of economic importance, as a rule, are formed in close connection of indigenous sources. Within the Lukoyanovsky placer area (Nizhny Novgorod region), high chromite contents (up to 100 kg/m3) were found in complex coastal-marine rare metal-titanium placers of the Middle Jurassic system, which is of economic importance. Placer bodies are localized on the periphery of the domed structures of the sedimentary cover. A possible source is the Upper Permian and Lower Jurassic sediments, which were eroded in the zone of positive tectonic structures of the cover and foundation of the platform and within the adjacent land. The studied patterns can serve as a basis for forecasting similar deposits within promising areas.

Coconut residues increase light fraction of organic matter and water retention in semi-arid sandy soil under irrigated cultivation

ABSTRACT Coconut palm cultivation is associated with the generation of a large amount of residues, mainly from coconut shells, and their utilization in agriculture can represent an opportunity in the context of circular economy and climate change. This study aimed to determine the effect of coconut shell deposition on carbon (C) stocks, organic matter quality, and soil water retention in coconut palm cultivation in the Brazilian semi-arid region. The study was conducted in a commercial coconut palm cultivation area in Petrolina, Pernambuco State, Brazil, forming a chronosequence with 0, 2, 4, 5 and 6 years of coconut shells or coconut leaves application on soil surface. Carbon contents and stocks up to 0.40 m deep, the physical quality of soil organic matter, and soil water retention were evaluated. Coconut leaves and coconut shells increased organic C content in the surface layers of the soil, but the addition of residues did not influence soil C stocks. The light fraction of organic matter (>53 µm) was more sensitive to the management studied, while the heavy fraction of organic matter (<53 µm) was not significantly changed by the evaluated treatments. Coconut shells deposition on the surface increased the available water content to 8.5 % in the soil up to 0.40 m deep, but the effects were more significant on the surface. The highest C contents in the fraction >53 µm and the highest soil water retention were observed three years after the deposition of coconut shells on the surface, which suggests the need for reapplying the residues after this period to maintain the benefits.

Catalytic conversion of the heavy fraction of bio-oil into phenol-rich oils using an Fe-carbon catalyst during straw pyrolysis

This study examines the catalytic cracking of the heavy fraction of bio-oil to produce phenol-rich oils, emphasizing the enhancement of biochar-based catalysts through the incorporation of metallic iron (Fe) species. Results indicate that the Fe-carbon catalyst significantly enhances the conversion of heavy oil constituents into phenolic compounds, increasing the relative content of phenolics from 41 % to over 76 %, compared to unenhanced co-pyrolysis, which primarily yielded methylphenols, phenol, 2-methylphenol, and 3-methylphenol. These findings suggest that the heavy fraction of bio-oil, typically abundant in macromolecular compounds, offers viable opportunities for the targeted production of phenolic oils utilizing Fe-carbon catalysts. The findings suggest a viable pathway for the conversion of bio-oil heavy fractions into valuable phenolic compounds, highlighting the potential for industrial applications and the optimization of biorefinery processes.

The functional dominance and metabolic diversity of comammox Nitrospira in recirculating aquaculture systems.

As a newly discovered group of ammonia-oxidizing microorganisms, complete ammonia oxidizing (comammox) Nitrospira has been widely found in various oligotrophic ecosystems. However, their activity and ecological niche is still unclear in recirculating aquaculture systems (RAS). This study aimed to compare the abundance and activity of comammox Nitrospira, ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), and elucidate metabolic versatility of comammox Nitrospira in RAS. Quantitative PCR (qPCR) results showed that either comammox Nitrospira or AOB numerically predominated, while comammox Nitrospira and AOA shared similar low ammonia niches. Specifically, DNA-based stable isotope probing in conjunction with high-throughput 16S rRNA gene amplicon sequencing revealed that comammox Nitrospira accounted for 79.1 %, 97.5 %, 91.9 % and 97.6 % in the active ammonia-oxidizing community in four selected typical samples representing high abundance of comammox, AOA, and AOB, respectively. Phylogenetic analysis of heavy fraction DNA further identified novel comammox species from Nitrospira nitrificans cluster and clade A.2 acting as active species in different freshwater aquariums. Moreover, metagenome-assembled genome analysis revealed them as novel species with stress resistance and metabolic diversity compared with known comammox Nitrospira. This study underscores the dominant role of comammox Nitrospira as active ammonia-oxidizers in RAS and presents two novel comammox MAGs with metabolic flexibility, enriching our understanding of the nitrification process in oligotrophic artificial ecosystems.

First field application of functionalized nanoparticles-based nanofluids in thermal enhanced oil recovery: From laboratory experiments to cyclic steam stimulation process

The increasing global demand for fossil fuels and the depletion of light crude oil reserves have driven the petroleum industry to focus on exploiting heavy crude oils, which present significant challenges in recovery and processing. To address these challenges, enhanced oil recovery (EOR) technologies are being developed, with a strong emphasis on advances in catalysis and nanomaterials science. This research significantly contributes to developing new technologies for petroleum exploitation by introducing a novel nanofluid designed to facilitate in-situ upgrading of heavy oil, improving its quality for downstream refining and fuel production. The nanofluid, engineered to enhance the productivity of a heavy oil reservoir under cyclic steam stimulation, targets improvements in oil recovery and fuel-quality indicators such as API gravity and viscosity. Laboratory tests demonstrated the nanofluid’s capability to reduce oil viscosity, improve oil mobility, and selectively interact with heavy oil fractions like resins and asphaltenes. Displacement tests simulating steam injection conditions showed an improvement in oil recovery, increasing from 56 % to 76 % after nanofluid application. The treatment also led to a notable increase in API gravity, from 11.6° to 29.2°, and a significant reduction in viscosity, from 39,987 cP to 104 cP, indicating enhanced crude oil quality, critical for refining and fuel production. Field trials in two wells in Colombia demonstrated the nanofluid’s practical effectiveness, with production increases averaging 97 % and incremental yields of 11,966 barrels in well A and 3213 barrels in well B. Post-treatment, the crude oil exhibited sustained improvements in quality, with API gravity increasing from 11.6° to 13.4° and viscosity decreasing from 39,987 cP to 11,734 cP. These results confirm the long-term durability of the nanofluid’s effects and its potential to enhance fuel production from heavy oil reservoirs. Additionally, the field trial indicated a 48 % reduction in operational costs, primarily due to decreased steam generation and lower CO2 emissions, highlighting the environmental and economic benefits of nanofluid technology for petroleum exploitation.

Characteristics of soil organic carbon fractions and influencing factors in different understory mosses in karst urban parks

The impact of different vegetation types on soil organic carbon (SOC) is a key focus in global warming research. Bryophytes, commonly found in karst urban forests, significantly contribute to carbon accumulation in surface soil. However, the changes in soil organic carbon fractions under moss and the influencing factors remain unclear. To address this knowledge gap, the study examined the organic carbon content, soil physicochemical properties, and associated environmental factors in both moss-covered soil and bare soil under six different forest species within an urban park. The results showed that the SOC contents under moss cover in evergreen coniferous forest (127.28 g/kg), bamboo forest (144.70 g/kg), deciduous broad-leaved forest (87.63 g/kg), and evergreen shrub (109.28 g/kg) were significantly higher compared to bare soil. Moss cover also had a significant impact on soil readily oxidizable carbon (ROC), particulate organic carbon (POC), mineral-associated organic carbon (MOC), and heavy fraction organic carbon (HFOC) (P < 0.01). The soil under moss had a higher content of stable organic carbon fraction, which is conducive to the stability of the soil organic carbon pool. The interaction between moss cover and stand type had the most significant effect on soil organic carbon, especially in bamboo forests. Canopy density, moss biomass, and soil moisture were the main environmental factors affecting the content of soil organic carbon and its fractions, while soil organic carbon content was mainly affected by soil nitrogen and phosphorus. This study establishes a theoretical framework for investigating the carbon cycle in karst urban underforest ecosystems, offering a scientific basis for the management and preservation of urban green space ecosystems. Future studies should include bryophytes in the assessment of dynamic factors affecting the soil carbon pool under forest cover and further explore the function and ecological significance of bryophytes in understory ecosystems.

Using geochemical and geophysical data to characterise inter-aquifer connectivity and impacts on shallow aquifers and groundwater dependent ecosystems

Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia's Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable 3H (0.43 TU), and activities of radiocarbon a14C (14.1 – 95.3 pMC) and chlorine-36 R36Cl (78.1 × 10−15 – 161 × 10−15) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO3 and F concentrations and heavy fraction hydrocarbons (>100 μg/L C10–C40) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine's groundwater impacts, which was the basis of the mine's approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.

Rice husk biochar resuscitates the microecological functions of heavy–metal contaminated soil after washing by enriching functional bacteria

Biochar has great potential for simultaneously improving soil ecological functions and eliminating environmental pollutants. However, studies on this strategy in the restoration of ecological functions in chelator–washed soil are lacking, and the effect of biochar on the structure, functions, and microbial interactions of washed soil microbiomes are unclear. Hence, the effect of rice husk biochar (RHB, 2 %) on the physicochemical properties, heavy metal fractions, and microbial community structure of glutamate–N, N–diacetic acid (GLDA)– and ethylenediaminetetraacetic acid (EDTA)– washed remediated soil were investigated. Results showed that the RHB addition restored the washed soil physical structure (pores and agglomerates) and meanwhile, the soil colloidal sheet sweeps increased by 20.49 % and 102.07 % in the z–axis, respectively. Additionally, RHB significantly increased washed soil pH (P < 0.05) and alkaline phosphatase and urease activities, while decreased acid phosphatase and glucosidase activities. The Observed–species and Shannon index were significantly higher in soil treated by RHB combined with GLDA and EDTA than those treated with GLDA and EDTA alone (P < 0.05). GLDA washing coupled RHB treatment enriched key bacterial groups such as MND1, Chelativorans, and Ellin6067, while EDTA washing coupled RHB treatment enriched Sreroidobacter, Micromonospora, and Reyranella, that both related to C–, N–, and P– cycles. Importantly, RHB addition could enrich functional bacteria by increasing bacterial resistance, including glucose metabolic homeostasis and metal ion resistance. The observed enrichment of functional bacteria provided evidence for the enhancement of soil nutrient cycles, indicative of improved soil functions by combination of chelator washing and biochar amended.

Effect of iron-based nanomaterials on organic carbon dynamics and greenhouse gas emissions during composting process

Iron-based nanomaterials as effective additives can enhance the quality and safety of compost. However, their influence on organic carbon fractions changes and greenhouse gas emissions during composting remains unclear. This study demonstrated that iron-based nanomaterials facilitate the conversion of light organic carbon fraction into heavy organic carbon fraction, with the iron-based nanomaterials group showing a significantly higher heavy organic carbon fraction content (41.88%) compared to the control group (35.71%). This shift led to an increase in humic substance content (77.5 g/kg) and a reduction in greenhouse gas emissions, with CO2, CH4, and N2O emissions decreasing by 20.5%, 39.7%, and 55.4%, respectively. Additionally, CO2-equivalent emissions were reduced by 42.9%. Microbial analysis revealed that iron-based nanomaterials increased the abundance of Bacillus and reduced the abundance of methane-producing archaea such as Methanothermobacter and Methanomassiliicoccus. These results indicated that the role of iron-based nanomaterials in regulating reactive oxygen species production and specific microbial communities involved in humification process. This study provides a practical strategy for improving waste utilization efficiency and mitigating climate change.

Determinants of rhizospheric organic carbon fractions and accumulation in four different vegetations of coastal saline-alkali soils

Rhizosphere processes are key pathways through which plants influence the carbon cycling of diverse ecosystems and are closely associated with vegetation types. However, the environmental responses of rhizospheric soil organic carbon (SOC) mediated by the interaction between rhizospheric effect and vegetation type remain uncertain, severely limiting our assessment of the carbon sequestration potential of different coastal vegetation. Here, we identified the core factors driving changes in various soil carbon fractions in the rhizosphere of four coastal vegetation types by testing the contents of the reactive, dissolved, particulate, mineral-associated, heavy and light fractions of SOC and their relationships with physicochemical properties and enzyme activities. It was found that the rhizosphere effect significantly influenced SOC, with rhizospheric SOC contents varying significantly among vegetation types, ranging from 2.12 to 9.04 g/kg. Besides, rhizospheric soil pH was found to contribute significantly to SOC fractions (except for light organic carbon) and exert significant inhibitory effects on SOC, reactive organic carbon, mineral-associated organic carbon and heavy organic carbon. Despite the different responses of various SOC fractions to physicochemical properties and enzyme activities, soil available phosphorus and alkaline phosphatase activity emerged as core environmental factors influencing rhizospheric SOC accumulation across different coastal vegetation types. This study presents a promising framework for understanding the determinants of SOC fractions in rhizospheric soil, and their accumulation in the vegetation of coastal saline-alkali soils. In addition to alkalinity, phosphorus acquisition capacity can be a key predictor of coastal SOC fractions and their accumulation.

Process swing adsorption with selective purge gas recirculation (PSA-SPUR): Adsorption process technology optimised for separation of heavy component from a gas mixture and its design for CO2 capture through Equilibrium Theory analysis

PSA-SPUR (Pressure Swing Adsorption with Selective Purge Gas Recirculation) has been developed aimed at separating the most strongly adsorbing component from a gas mixture at high product purity and recovery. The innovative strategy for designing a Pressure Swing Adsorption system features recycling its purge gas stream exiting the column and mixing it back into the feed. This operation enriches the mixed feed with an elevated fraction of the heavy component during the adsorption step, thus enhancing the PSA’s performance greatly. Reusing the purge gas helps significantly increase the product recovery compared to conventional methods where purge gas is simply discarded or taken as a low-quality product. For theoretical analysis of a PSA-SPUR system, a bespoke Equilibrium Theory model was developed and solved successfully, providing valuable insights into the performance of the PSA-SPUR system designed for capturing CO2 from a flue gas. The study revealed that there exists an optimum extent of purging that maximises the heavy component mole fraction in the mixed feed, leading to the best possible feed throughput of the adsorption system. Furthermore, the effects of the desorption pressure and feed composition on the PSA-SPUR system’s performance were investigated. The results indicate that the CO2 capture PSA-SPUR system using commercial zeolite 13X has excellent potential to achieve very high product purity and recovery, being allowed to operate at moderate vacuum pressures without having to compress the flue gas feed, even when the gas feed contains less than 10 mol% CO2.

Innovations in residue upgrading for the Niger delta by transforming heavy oil fractions into high-value products: A state of the art review

This review discusses new innovations in residue upgrading technologies for the conversion of heavy oil fractions into high-value products, especially for Delta and Rivers States of the Niger Delta region. Recent works within the 2020-2024 period show that upgrading methods have been significantly developed; however, no prior work has been done regarding applying those upgrading techniques to the peculiar nature of crude oil from this region. The paper probes the environmental impacts of these technologies, emphasizing the need for localized assessment that would take into consideration the fragile ecosystems of Delta and Rivers States. It further assesses the economic viability of scaling up the implementation of advanced upgrading processes within the current refining infrastructure. The discussion covers variable quality heavy oil in these regions and what that does to upgrading efficiency, how to integrate these technologies into the current refining practices, underlines the potential socio-economic advantages for the local communities through the creation of jobs and enhancing the skills of those communities to underscore the importance of these innovations for sustainable development. The review establishes that in such siamese twin areas, further research is needed to ensure that heavy oil resources in Delta and Rivers States are utilized effectively while ensuring that there is a minimal environmental impact from the extraction process.

State of atmospheric pollution between vulnerabilities and criticalities from 2007 to 2022 and a projection in 2030 focused on the proliferation of gasoline sales in the city of N'Djamena

According to the World Health Organization (2008), 1.3 million annual deaths worldwide are attributable to air pollution, and that the latter is the cause of 16% of the total number of deaths. Among air pollutants, particles play an important role in worsening air quality in urban areas. The city of Ndjamena has recorded an increased proliferation of hydrocarbon stations since 2007 to the present day. The analysis of the vulnerability and criticality of pollutants from 2007 to 2022 and a projection to 2030 were made. For a response relating to the subject of our research, we chemically characterized two types of gasoline by following the recommended parameters. The result obtained following these analyses shows that street gasoline has a more or less negative result compared to gasoline produced, stored and sold in accordance with standards and regulations in Chad. We note that the analyzed contraband gasolines have negative results unlike other types of gasoline sold at the pump (some service stations) in terms of: - ASTM distillation, confirming the presence of significant heavy fractions, the Octane Index, presenting a minimum limit required by the standard for super 90 gasoline. Total sulfur, which reaches the maximum limit required and finally, Corrosion giving the maximum limit required by the standard in terms of corrosion. We also noted the presence of traces of water and unidentified solid debris at the bottom of most of our contraband samples.

Understanding how corn-yellow melilot intercropping combined with straw return increased stable organic carbon pool in Mollisols by reducing the application of chemical fertilizer

Long-term cultivation with persistent use of chemical fertilizers causes a rapid decline in organic matter content of Mollisols. But practicing intercropping along with straw return instead of the use of chemical fertilizer have the potential to reverse the decline and improve soil organic carbon (SOC) content. A field experiment with five treatments at two sites of Songnen Plain of Northeast China included the following treatments (1) corn monoculture with no chemical fertilizers and no straw return (c), (2) corn monoculture with chemical fertilizers and no straw return (c + F), (3) corn-yellow melilot intercropping and straw return combined with full application of chemical fertilizers (c&m + S + F), (4) corn-yellow melilot intercropping and straw return combined with half dose of chemical fertilizers (c&m + S + F/2), and (5) corn-yellow melilot intercropping and straw return without chemical fertilizers (c&m + S). The results showed that c&m + S + F, c + F, and c&m + S + F/2 decreased specific gravity and c&m + S + F increased water content. The c&m + S + F, c&m + S + F/2, and c&m + S improved SOC with 18.7%, 7.95%, and 8.17% (P < 0.05), respectively. The c&m + S + F and c&m + S + F/2 increased mineral-associated organic carbon, humus organic carbon, and heavy fraction organic carbon content. These findings provide a method for utilizing intercropping and straw return to replace chemical fertilizers to improve SOC and stable organic carbon content to ameliorate soil quality.

Spatial distribution of remaining movable and non-movable oil fractions in a depleted Maastrichtian chalk reservoir, Danish North Sea: Implications for CO2 storage

Depleted oil and gas fields constitute potentially important storage sites for CO2 in the subsurface, but large-scale injection of supercritical (sc) CO2 in chalk has not yet been attempted. One of the risks is the adverse effect of the substantial amount of remaining oil in the chalk reservoirs on scCO2 injection. In order to counter an undesired effect on injectivity, a fundamental understanding of the spatial distribution and quantity of the movable, semi-movable, and non-movable oil, and solid bitumen/asphaltenes fractions of the remaining oil is critical. In this study a combination of organic geochemistry (gas chromatography of the saturated fraction and programmed pyrolysis), and reflected light microscopy was applied to evaluate and measure the spatial distribution, volume, and saturation of different oil fractions in a well-defined reservoir interval of a waterflooded Maastrichtian chalk reservoir in the Danish Central Graben, North Sea. A total of 127 samples from a slightly deviated vertical well and two ∼5 km-long horizontal wells from the Halfdan and Dan fields were analyzed. An original uneven distribution of oil saturation and composition or different production efficiency of different levels in the reservoir may account for variations in the total oil and oil fraction saturations. Gas chromatography shows that the solvent extractable oil is quite similar in composition, characterized by a dominance of polar compounds and a high content of asphaltenes. Extended slow heating (ESH) pyrolysis reveals that most of the remaining oil saturation consists of semi-movable oil and total non-movable oil (non-movable oil plus solid bitumen/asphaltenes). Reduced oil gravity values (API) are related to evaporation loss of the lightest hydrocarbon fraction during core storage and increase of the relative proportion of the heavier oil fractions by waterflooding during production. Microscopy disclosed three forms of oil: i) Patchy distributed lighter, movable oil showing a bluish fluorescence, ii) Brownish staining with a dark orange to brownish fluorescence, and iii) Dark brown non-fluorescing oil and black solid bitumen/asphaltenes occurring in microfossils and along deformation bands and stylolites, constituting the heavy non-movable oil fractions. There is a general correlation between bulk rock porosity and the total non-movable oil saturation. It thus appears that the heavy non-movable oil fractions preferentially occur in association with low-permeability heterogeneities within high-permeability stratigraphic intervals. These intervals appear to favor accumulation of non-movable oil and solid bitumen/asphaltenes and may carry a higher risk for impeding scCO2 flow.

COMPLICATED THERMAL HISTORY OF THE LITHOSPHERIC MANTLE OF THE ANABAR REGION: RECONSTRUCTIONS BASED ON XENOCRYSTS FROM KIMBERLITES

The thermal history and thickness of the lithospheric mantlebeneath the kimberlite fields of the Eastern Anabar shield and adjacent territories of the Siberian craton were reconstructed based on the composition of clinopyroxene xenocrysts from the concentrate of kimberlite heavy fraction and mantle xenoliths. Garnet and spinel peridotites are most abundant in the lithospheric mantle beneath the five studied fields of the Siberian craton. Almost in all fields, the Mg# index of clinopyroxene decreases through depth. In the oldest Chomurdakh kimberlite field, both TiO2 and FeO contents vary slightly. The titanium oxide values markedly vary from 0 to 0.6 wt. % in the Triassic fields. The high titanium oxide contents in minerals are indicative of deep­seated metasomatic transformations of lithospheric mantle blocks in the northern Yakutia kimberlite province. The geotherm was fitted to the PT data set in the Gtherm program with the model involved D. Hasterok and D. Champan. The thermal lithosphere beneath the studied fields retained the thermal thickness up to 260 km. In the period between 430 and 230 Ma, it underwent a significant metasomatic transformation resulting in the formation of high­Fe and high­Ti blocks. It appears, that the thermal thickness declined to 190–200 km only in the north of the Siberian craton during the Jurassic period. This assumption is verified by the values of lithosphere thickness beneath the northern Kuoika field.

Enhanced hydrothermal liquefaction of tires using zinc and MoS2

This study introduces a novel approach for tire liquefaction employing zinc and unsupported catalyst MoS2 to mitigate oxygen, nitrogen, and sulfur content, while inhibiting poly-aromatic formation. Autoclave experiments were conducted under subcritical water conditions at 360 and 410 °C. Comprehensive characterization of char and oil was performed, encompassing elemental analysis, functional-group assessment, and composition analysis using gas chromatography-mass spectrometry (GC-MS) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). During the liquefaction, zinc metal pellets react with water to form ZnO and hydrogen, aiding hydrogenation, and MoS2 preserves its catalytic stability. ZnO shows a catalytic effect on deoxygenation, desulfurization, and denitrification reactions. However, the reaction between ZnO and H2S is not favorable under hydrothermal conditions. Zinc and MoS2 synergistically promote cracking of heavier compounds into lighter ones, particularly evident at higher temperatures, without diminishing the overall oil yield. Incorporating zinc pellets and MoS2 slightly facilitates sulfur and oxygen migration from liquid to solid and gas phases. FT-ICR MS analysis reveals oxygen, sulfur, and nitrogen-containing compounds in heavy fraction of oils. The oxygen-containing compounds, predominantly comprised of stearic acid and its derivatives, are identified. Concurrently, the nitrogen-containing compounds manifest primarily as basic nitrogen compounds. MoS2 possesses the capability of forming more N-containing compounds, leading to the generation of a broader spectrum of N-containing compounds. This work elucidates the synergistic role of zinc-assisted catalysis and MoS2, offering insights into tire liquefaction mechanisms and product composition, vital for sustainable waste management and resource recovery.

Use of In-Situ ESR Measurements for Mechanistic Studies of Free Radical Non-Catalytic Thermal Reactions of Various Unconventional Oil Resources and Biomass

The exhaustion of conventional light oils necessitates the shift towards unconventional sources such as biomass, heavy oil, oil shale, and coal. Non-catalytic thermal cracking by a free radical mechanism is at the heart of the upgrading, prior to refining into valuable products. However, thermal pyrolysis is hindered by the formation of asphaltenes, precursors to coke, limiting cracking, causing equipment fouling, and reducing product stability. Free radicals are inherently present in heavy fractions and are generated during thermal processes. This makes these reactive intermediates central to understanding these mechanisms and limiting coking. Electron spin resonance (ESR) spectroscopy facilitates such mechanistic studies. Over the past decade, there has been no review of using in-situ ESR for studying thermal processes. This work begins with a brief description of free radicals’ chain reactions during thermal reactions and the wealth of information ESR provides. We then critically review the literature that uses ESR for mechanistic studies in thermal pyrolysis of biomass, heavy oil, shales, and coal. We conclude that limited literature exist, and more investigations are necessary. The key findings from existing literature are summarized to know the current state of knowledge. We also explicitly highlight the research gaps.

Rapid screening of indigenous degrading microorganisms for enhancing in-situ bioremediation of organic pollutants-contaminated soil

Organic pollutants (OPs) have caused severe environmental contaminations in the world and aroused wide public concern. Autochthonous bioaugmentation (ABA) is considered a reliable bioremediation approach for OPs contamination. However, the rapid screening of indigenous degrading strains from in-situ environments remains a primary challenge for the practical application of ABA. In this study, 3,5,6-Trichloro-2-pyridinol (TCP, an important intermediate in the synthesis of various pesticides) was selected as the target OPs, and DNA stable isotope probing (DNA-SIP) combined with high-throughput sequencing was employed to explore the rapid screening of indigenous degrading microorganisms. The results of DNA-SIP revealed a significant enrichment of OTU557 (Cupriavidus sp.) in the 13C-TCP-labeled heavy DNA fractions, indicating that it is the key strain involved in TCP metabolism. Subsequently, an indigenous TCP degrader, Cupriavidus sp. JL-1, was rapidly isolated from native soil based on the analysis of the metabolic substrate spectrum of Cupriavidus sp. Furthermore, ABA of strain JL-1 demonstrated higher remediation efficacy and stable survival compared to the exogenous TCP-degrading strain Cupriavidus sp. P2 in in-situ TCP-contaminated soil. This study presents a successful case for the rapid acquisition of indigenous TCP-degrading microorganisms to support ABA as a promising strategy for the in-situ bioremediation of TCP-contaminated soil.