Deciphering the roles of organic matter types and hydraulic conditions on the crystal transformation and release behavior of organic matter during floc aging

Influence of organic matter type and content on the intrinsic compressive behavior of sewage sludge

The degradation of organic matter (OM) by microorganisms in thawing permafrost produces greenhouse gases. Terrestrial OM is transported into fjords through hydrological runoff, but it is unclear whether the microbial mechanisms of OM degradation on land persist after soils enter marine environments, which differ greatly in conditions and microbial communities. This question is particularly relevant for low-OM soils, which dominate Arctic landscapes and are more exposed to oxidants. Here, we compared OM-degrading capacity in permafrost-affected active layer soils and adjacent fjord sediments from Kongsfjorden, Svalbard, focusing on carbohydrate-active enzymes (CAZymes), which target some of the most abundant types of organic matter in soils. Using multi-omics approaches-metagenomics, metagenome-assembled genomes (MAGs), metabolomics, metatranscriptomics, and metaproteomics-we examined CAZyme presence, distribution, and activity. Despite environmental differences, both soils and sediments harbored diverse glycoside hydrolases and polysaccharide lyases, most of which showed evidence of activity. Verrucomicrobia expressed the highest number of CAZyme transcripts, indicating that they dominated active carbohydrate degradation in fjord sediments, while Acidobacteria and Actinobacteria were more active in soils. Notably, CAZymes in fjord sediments targeted primarily soil-derived OM, and the proportions of enzymes degrading terrestrial OM, marine OM, and microbial necromass-remnants of dead microbial cells were similar across both environments. These results suggest that microbial communities in both soils and fjord sediments are equipped to degrade carbohydrates, and that burial of terrestrial-derived OM in fjord sediments may not protect it from microbial breakdown under Arctic warming.IMPORTANCEPermafrost thaw may be a critical climate feedback because microbial degradation of organic matter (OM) can release greenhouse gases. While fjords serve as major carbon burial sites, our results show that burial of terrestrial-derived OM in these sediments does not ensure protection from microbial degradation. Microbial communities in both active layer soils and fjord sediments harbor a broad arsenal of carbohydrate-active enzymes, with evidence of activity across diverse taxa. This functional continuity indicates that once terrestrial material is washed into fjords, it remains vulnerable to microbial breakdown despite different environmental conditions. Understanding these cross-system continuities in microbial function is essential for predicting the fate of OM in a rapidly warming Arctic and highlights the importance of including fjord sediments in global carbon cycle models.

This study aims to elucidate the depositional characteristics of the Qingshankou Formation shales in the Qian'an area of the Songliao Basin and establish a new paradigm for organic-matter enrichment governed by the coupled effects of salinity, water depth, and primary productivity. A total of 54 core samples from Well QY2 were analyzed for total organic carbon (TOC), pyrolysis parameters (S1, OSI, Tmax), and trace-element proxies [Sr/Cu, Sr/Ba, Ba/Al, V/(V+Ni), δU], enabling a comparative assessment of oil content, organic-matter type, thermal maturity, and depositional environmental indicators between the first and second members of the formation. The results demonstrate that Member 1 exhibits systematically higher TOC, stronger hydrocarbon-generation potential (reflected by elevated S1 and OSI values), more favorable kerogen compositions (predominantly Type I), and higher thermal maturity. Trace-element signatures reveal that the Qingshankou shales were deposited in a semideep-to-deep lacustrine setting under semihumid-to-semiarid paleoclimatic conditions, characterized by mildly brackish-to-moderately brackish water, relatively great paleowater depth, high lake productivity, and overall weakly oxic-to-reducing conditions. Specifically, Member 1 is marked by higher salinity (Sr/Ba > 1.0-1.5), greater paleowater depth (Ba/Al > 30-35), enhanced primary productivity (EFMo > 3), and slightly stronger reducing conditions, all of which correspond well with its elevated TOC values. In addition, volcanic eruptions and episodic marine incursions strengthened nutrient influxes and promoted water-column stratification, thereby further enhancing the organic-matter preservation. Collectively, the findings indicate that organic-matter enrichment in the Qingshankou shales was jointly controlled by the coupled interplay among salinity, water depth, and productivity superimposed by extrinsic events such as volcanism and marine incursions. This integrated "salinity-water depth-productivity" framework provides a new conceptual basis for evaluating shale-oil sweet spots and predicting favorable target intervals in the region.

Abstract This study provides the first comprehensive organic geochemical evaluation of the Upper Cretaceous Shiranish Formation as a moderate potential source rock in the WZFTB, northern Iraq. A total of 102 cutting rock samples from five wells were analyzed to assess hydrocarbon generation potential, organic matter type, thermal maturity, and depositional environment. Multi-proxy geochemical approach combining Rock-Eval pyrolysis, vitrinite reflectance, GC-MS biomarker analysis, and organic petrography were performed. Total organic carbon (TOC) values range from 0.34 to 2.08 wt%, indicating poor to good organic richness, with an average of 0.72 wt% falling within the low to moderate, based on genetic potential fair category. Hydrocarbon generation potential is considered low to moderate, based on genetic potential (GP) (0.51–11.09 mg HC/g rock) and extractable organic matter (EOM) (48.06 and 445.48 mg HC/g TOC). Kerogen is dominated by Type II/III, supported by HI values (85 to 625 mg HC/g TOC) and liptinite - rich macerals. T max (420–443 °C), and vitrinite reflectance (0.60–0.74% VRr) indicate early to peak thermal maturity. Reworked vitrinite with higher reflectance (0.80–1.10% VRr) suggest allochthonous organic matter input. This interpretation is reinforced by bimodal S2 pyrograms, which demonstrate heterogeneity in organic matter. Furthermore, biomarker maturity proxies (including CPI, Ts/(Ts + Tm), C₃₁ 22 S/(22 S + 22R), C₂₉ 20 S/(20 S + 20R), and ββ/(ββ + αα)) consistently confirm early to peak oil generation conditions. Framboidal pyrite, sulfur enrichment, and biomarker distributions, point to suboxic to anoxic marine carbonate deposition, with episodic terrestrial influence. Spatial variability is notable, with wells CH-3 and TT-22 showing higher source potential. Although the Shiranish Formation exhibits fair TOC content and low to moderate hydrocarbon generation potential compared to major regional source rocks such as the Sargelu and Chia Gara formations, it is classified herein as a secondary source rock. Notably, localized fracturing within its carbonate facies may enhance its capacity as a self-sourcing reservoir. These results advance understanding of petroleum systems in northern Iraq and highlight the value of integrated multi-proxy geochemistry for assessing complex carbonate source units.

This study evaluated the effects of organic matter techniques application (surface pile and subsurface biopore infiltration holes) and organic matter types on the vertical root distribution of oil palm (Elaeis guineensis).The experiment used a factorial randomised block design with two factors: Application technique (pile and biopore infiltration holes) and five organic matter types (no organic matter, fresh empty fruit bunches [EFB], EFB compost, palm fronds and palm leaves).Root depth was measured at the second and fourth months after treatment.Although statistical analysis showed no significant differences (p>0.05),consistent biological trends were observed.Treatments using EFB compost, particularly with the pile method, indicated a tendency to promote root growth closer to the soil surface, with root depth decreasing from 6.33 to 4.17 cm.Pile applications showed faster response of root distribution than biopore infiltration holes, although biopore infiltration holes combined with EFB compost also improved root distribution.Conversely, treatments without organic inputs or with slowly decomposing materials (fresh EFB, palm fronds and palm leaves) resulted in minimal changes in root depth.These findings suggest that using EFB compost with appropriate application techniques may enhance shallow root proliferation, potentially improve nutrient uptake efficiency and support sustainable plantation management.

ABSTRACT The breakup of Gondwana is considered one of the key tectonic events in Tanzania's geological history. These events were accompanied by the deposition of key elements, including the deposition of black shales in the Middle Jurassic that could serve as regional source rocks. Previous local reports suggested poor to good petroleum source potential for these shales. However, no attempts have been made to assess the satial variability of these source intervals across the Tanzanian coastal belt. Here, we present a spatial variability of these source rock intervals, focusing on five sub‐basins within the Tanzania coastal basin. Using rock pyrolysis and gamma ray log data from five boreholes, we aim to assess total organic carbon (TOC) content, determine the type and quality of organic matter (OM), and reconstruct the OM preservation conditions and its syn‐ and post‐diagenetic alteration. Results show that overall TOC content ranges from 0.05 to 3.6 wt% with an average of 1.2 wt%. S 2 and hydrogen index (HI) values also vary, ranging from 0.01 to 4.5 mg HC/g with an average of 1 mg HC/g and from 7 to 191 mg HC/g TOC with an average of 55 mg HC/g TOC, respectively. The OM primarily consists of a mixture of Type III–IV kerogen, with varying degrees of thermal maturation ( T max ). Samples from Well‐1 (Tanga Basin) and a few from Well‐4 (Mandawa Basin) exhibit fair to good source potential compared to samples from other wells. The variation in source potential is attributed to local micro paleoclimate, physiography, and degree of thermal maturation. This work demonstrates the necessity for a regional evaluation of source intervals to identify areas where enriched source rocks may be present.

The reduced fallow period and continuous cultivation of sweet potato on the same land have resulted in the depletion of soil nutrients and poor yields in Papua New Guinea (PNG) highlands, necessitating improved soil fertility management practices. In this study, we conducted a field experiment to understand the roles of organic matter in composted mounds used for sweet potato production in the highlands of PNG, utilizing cogon grass material (high carbon) and fern leaves (high nitrogen). The first treatment was set without amendment and planted as control. The second and third treatments were solely amended, respectively, and the fourth was amended with a combination of the two. All treatments were replicated five times, set up in a randomized complete block design, planted with the same number of vines, and allowed to grow in the field for twelve months. During production, soil and tuber samples were taken after six and twelve months, processed, and subjected to instrumental analysis. The average data from four replicates of each treatment were pooled, averages calculated, and statistically analysed. The results showed that composted mounds improve soil parameters and increase the concentration of nutrients in both the soil and tubers. In almost all cases, nutrient availability in the soil and tissue was dependent on the type of organic matter and the time of production. Nutrient availability was high in the six months and then decreased thereafter, implications for human and livestock consumption of sweet potato, as well as sustainable soil health.

ABSTRACT Organic matter decomposition is a fundamental ecosystem process in streams, which have a large aquatic‐terrestrial interface. The sensitivity of organic matter decomposition to changes in environmental conditions promoted by human activities is relatively well understood at large and local scales. In contrast, less is known about the natural variability of organic matter decomposition along natural gradients, especially at intermediate spatial scales. This gap undermines the use of organic matter decomposition as a tool to assess stream functional integrity in biomonitoring programmes. This study aimed at identifying the main moderators of organic matter decomposition under undisturbed conditions to establish natural baseline variation in organic matter decomposition rates in Portuguese streams. A field study was carried out to assess organic matter decomposition rates in 37 least‐disturbed streams distributed throughout continental Portugal and Madeira Island. This study addressed gaps in empirical research by using poplar organic matter, including wood, and undertaking the incubation in spring, while previous studies were carried out preferably in autumn/winter and used alder and oak leaf litter. A systematic literature review was also conducted to compile organic matter decomposition rates from least‐disturbed streams across continental Portugal and the Azores archipelago. Organic matter type (leaves or wood), shredder access (fine‐mesh or coarse‐mesh bags), season (autumn/winter or spring/summer), water nitrate concentration, the presence of exotic vegetation, distance to the source, and percentage shade emerged as main moderators of organic matter decomposition in the field study. Organic matter type and identity (genus), shredder access, season, stream type (national Water Framework Directive typologies), hydrological regime (permanent or intermittent), water temperature, conductivity, and soluble reactive phosphorus concentrations were also important moderators of organic matter decomposition for the compilation of the field data and literature review data. There was considerable variation in organic matter decomposition across least‐disturbed streams, reflecting differences in organic matter type and identity, shredder access, season, and environmental conditions. Therefore, for organic matter decomposition to be used as a tool to assess stream functional integrity, it is necessary to standardise the protocol by selecting specific organic matter types and species, mesh types, and incubation seasons to minimise variation caused by these factors. Choosing stream typologies relevant for the decomposition process (e.g., as outlined in the Water Framework Directive), along with identifying reference decomposition ranges for each typology, may facilitate the assessment of deviations in stream functioning from reference conditions.

Overlooked role of soil microbial-derived carbon in promoting neurotoxic methylmercury production.

A comprehensive study was conducted on the hydrocarbon generation potential of the deeply buried Permian source rocks with high–over mature in the southwestern part of the Central Depression, Junggar Basin. Using Rock-Eval pyrolysis, carbon-sulfur analysis, kerogen macerals analysis, adamantane quantification, molecular geochemistry, major and trace element analysis, coupled with organic carbon recovery methods. The evaluation primarily focused on thermal maturation, types, and abundance of organic matter, with an emphasis on summarizing methods for evaluating high–over mature source rocks. The results demonstrate that the Permian source rocks in the Shawan Sag (Well Zhengshen-101) and the Penyijingxi Sag (Well Zhuangshen-1) have reached a high–over mature, as evidenced by vitrinite reflectance (Ro), adamantane parameters, methyl phenanthrene indices (MPI), and Laser Raman spectroscopy. Horizontally, for the Fengcheng (P 1 f ) and Lower Wuerhe (P 2 w ) formations, the Well Zhengshen-101 in the Shawan Sag is thermally more matured than the Well Zhuangshen-1 in the Penyijingxi Sag, while vertically, both wells show that the P 1 f is thermally more mature than the P 2 w . Raman and Fourier transform infrared (FTIR) spectroscopy confirm that Type II kerogen is the dominant organic matter type. Through material balance, degradation ratio, and inorganic element methods, obtain the original content of organic carbon (TOC 0 ) and hydrocarbon generation potential (S 1 +S 2 ). After restoration, the P 1 f samples from Well Zhengshen-101 in the Shawan Sag show moderate to high-quality organic matter abundance, predominantly high-quality; the P 2 w samples are classified as high-quality source rocks. The Xiazijie Formation (P 2 x ) and the P 2 w samples from Well Zhuangshen-1 in the Penyijingxi Sag range from poor to high-quality, predominantly good to high-quality. Horizontally, the P 2 w samples from Well Zhengshen-101 in the Shawan Sag exhibit higher organic matter abundance compared to those from Well Zhuangshen-1 in the Penyijingxi Sag. Notably, the P 2 x source rocks in the Penyijingxi Sag demonstrate superior potential compared to the P 2 w , highlighting their underexplored significance. Comprehensive analysis of the depositional environment in the study area indicates that the Well Zhengshen-101 in the Shawan Sag may experience a deeper, stable reducing environment with moderate sedimentation rates, stable water stratification, and a more abundant nutrient supply, all of which favor organic matter enrichment. This systematic evaluation advances methodologies for assessing high–over mature source rocks and underscores the exploration potential of high–over mature Permian source rocks in the Junggar Basin. Meanwhile, comparison with the highly mature marine shales of the Sichuan Basin further accentuates the methodological innovation of this study.

Microbe–mineral interactions in lacustrine environments play a critical role in controlling carbonate diagenesis and preserving organic matter, particularly under the influence of hydrothermal processes. To improve the understanding of such processes, this study focuses on the diagenesis of different types of carbonates from the upper section of the Bayingebi Formation in the Yin’e Basin, revealing the association between lacustrine sedimentation and hydrothermal activity. According to mineralogical and geochemical evidence, the carbonates in the studied interval can be broadly classified into hydrothermal, hydrothermal-biogenic, and sedimentary types on the basis of their dominant genetic signatures. Hydrothermal carbonates are dominated by crystalline dolomite, with associated hydrothermal minerals rich in Fe, Ba, and Mg, while 87Sr/86Sr values are close to mantle source values, indicating substantial mantle hydrothermal fluid contributions. Hydrothermal-biogenic carbonates are dominated by mud-crystalline and spherical dolomite enriched in Mg, Na, and P. The 87Sr/86Sr values fall between the typical mantle-derived and paleolake water ranges, indicating a mixed hydrothermal signal, with possible microbial involvement indicated by mineralogical and textural features. Sedimentary carbonates are predominantly crystalline calcite, with 87Sr/86Sr values close to crustal source values, indicating the influence of terrestrial inputs. Moreover, there are significant relationships between different types of diagenetic carbonates and organic matter. Intense hydrothermal activity is associated with low TOC values and relatively unfavorable conditions for organic matter preservation. In contrast, sections with mild hydrothermal activity have higher TOC contents, and the nutrient contents and water temperatures are more conducive to enrichment with organic matter. Although based on a single fully cored borehole from the upper section of the Bayingebi Formation, this study provides a framework for understanding the coupling between carbonate diagenesis and organic matter enrichment in hydrothermally influenced lacustrine systems, with implications for future studies involving multi-core investigations across the basin.

The second member of the Kongdian Formation (Ek2; also referred to as the Kong 2 Member) in the Cangdong Sag within the Bohai Bay Basin contains a series of high-quality lacustrine shales characterized by high organic matter abundance and significant hydrocarbon shows. However, the mechanisms governing organic matter enrichment in the deep parts of the sag remain poorly understood, and the impacts of depositional environments on organic matter enrichment are yet to be determined. This study investigated shales in the C1, C3, and C5 sublayers of the Kong 2 Member. Specifically, this study examined the mineralogy and petrology, organic geochemistry, and elemental geochemistry of the shales using whole-rock X-ray diffraction (XRD) analysis, total organic carbon (TOC) analysis, pyrolysis experiments, and analyses of macerals, major and trace elements, and stable carbon and oxygen isotopes. Additionally, numerical analyses were conducted. The results indicate that shales in the Kong 2 Member consist primarily of felsic, dolomitic–calcareous, and mixed shales. These shales exhibit high TOC content (average: 3.07%), and favorable organic matter types dominated by liptinite and interbedded with minor planktonic algae and amorphous sapropelinite. These suggest great potential for hydrocarbon exploitation. During the deposition of shales in the Kong 2 Member, substantial terrigenous clasts were deposited at moderate rates under relatively arid climates characterized by frequently alternating dry and humid conditions. In this period, the anoxic to reducing depositional water bodies showed elevated salinity, resulting in saline-to-brackish water environments and moderate paleoproductivity. The organic matter enrichment of shales in the Kong 2 Member was jointly governed by paleoclimate dynamics, terrigenous input, and redox conditions, as demonstrated by multivariate analyses including the correlation analysis of depositional environmental factors, the univariate analysis of TOC content, gray relational analysis (GRA), and robust regression analysis. Two organic matter enrichment patterns were identified: (1) the preservation-dominated pattern under arid climates, governed by intense reducing environments, and (2) the productivity-driven pattern under humid climates, enhanced by terrestrial input.

This study is based on field observations and sample collections from the Panjinbulak, Qiongbulak, and Qunjisayi outcrops in the Yining Sag of the Ili Basin. Using organic geochemical analysis methods, the characteristics and hydrocarbon generation potential of the Permian Xiaoshansayi Formation (P2x) and Tamqisayi Formation (P2t) source rocks in the Yining Sag were compared and analyzed. The results indicate that the Permian source rocks in the Yining Sag of the Ili Basin exhibit high organic matter abundance and good types, among which the P2t source rocks are overall superior to the P2x. The P2t source rocks in the Panjinbulak outcrop section on the northern margin are dominated by Type II1-II2 kerogen, while those in the Qunjisayi and Qiongbulak outcrop sections on the southern margin show a transition to Type II2-III kerogen. The maturity of Permian source rocks presents a pattern of “higher in the south and lower in the north”, and all have reached the hydrocarbon-generation threshold. The northern margin is in the oil window, mainly dominated by oil generation; the southeastern margin has higher maturity, mainly producing oil/condensate gas. The Permian source rocks were deposited in a saline-reducing environment, with mixed input of aquatic organisms and terrestrial plants. During the deposition of P2t source rocks in the northern margin, the water salinity was higher, and plankton such as cyanobacteria made prominent contributions. The P2t source rocks in the Panjinbulak outcrop section on the northern margin have relatively better organic matter abundance and type, making it the main hydrocarbon-generation-potential area. The source rocks in the Qunjisayi outcrop section on the southeastern margin are slightly poorer, but their maturity is higher, currently in the main oil window, representing a secondary hydrocarbon-generation-potential area.

Classifying optical water types (OWTs), particularly concerning different phytoplankton bloom types, is critically important because dominant phytoplankton groups govern key marine ecosystem functions and biogeochemical processes, including nutrient cycling and carbon export. This study refines a recent OWT classification method developed for the Second-Generation Global Imager (SGLI), which was originally proposed to discriminate dinoflagellate and diatom blooms. By employing binary logistic regression (bLR) with independent in situ data from Karenia selliformis (dinoflagellate) blooms off the Kamchatka Peninsula and Skeletonema spp. (diatom) blooms in Tokyo Bay, this study establishes more robust and statistically meaningful boundaries between OWTs. The analysis confirms the diagnostic spectral shapes from SGLI data: a trough at 490 nm for K. selliformis blooms and a peak at 490 nm for diatom blooms, validating the consistency of this spectral criterion. The updated method reliably identifies waters dominated by coloured dissolved organic matter and different phytoplankton functional types in mesotrophic waters, and successfully detected a Karenia mikimotoi bloom in the Gulf St. Vincent, South Australia, demonstrating its potential for the global monitoring of red tides. By providing a reliable, satellite-based tool to distinguish between ecologically distinct phytoplankton groups, this refined OWT classification offers a valuable data product to improve the accuracy of marine ecosystem and carbon cycle models, moving beyond bulk chlorophyll-a parameterizations.

Total organic carbon and organic matter quality estimation based on hyperspectral imaging and Rock-Eval analysis.

Short-term marine heatwaves have a limited impact on the lignocellulose of Thalassia hemprichii seagrass plant.

Introduction/purpose: Black shales are increasingly recognized as significant unconventional hydrocarbon sources due to their organic richness and potential for oil and gas generation. However, their complex geochemical nature, especially in underexplored regions such as Tamtert in southwestern Algeria, poses challenges to accurate evaluation. This study aims to assess the hydrocarbon potential of black shales from the Djebel-Zereg area using advanced organic geochemical methods. Methods: Five black shale samples were collected from Djebel-Zereg, Tamtert region. Total Organic Carbon (TOC) content was determined, and Rock-Eval 6 pyrolysis and elemental analysis were conducted. Parameters measured included TOC, S1, S2, Tmax, Hydrogen Index (HI), Oxygen Index (OI), and vitrinite reflectance (Ro), providing data on organic matter type, thermal maturity, and hydrocarbon generative capacity. Results: TOC values ranged from 0.51 to 2 wt.% with an average of 1.33 wt.%, indicating acceptable to very good source rock quality. S2 values ranged from 0.45 to 4 mg HC/g rock, and the average Production Index (PI) was 2.23. HI values (51-233 mg HC/g TOC), along with OI and Tmax, indicated the presence of type II and III kerogen, suggesting potential for both oil and gas generation. Tmax values (435-465°C, average 447°C) and vitrinite reflectance (0.68%-1.19%) confirmed thermal maturity. A positive correlation between TOC and S1 values supported the presence of indigenous hydrocarbons. Conclusion: The integrated geochemical approach confirms that the Djebel-Zereg black shales are thermally mature, organic-rich rocks with promising oil shale potential. These findings support further exploration and development of unconventional hydrocarbon resources in the Tamtert region.

This study evaluates the petroleum generating potential of the Middle-Late Jurassic Sargelu and Naokelekan Formations across distinct tectonic zones in the Kurdistan Region, Iraq. Source rock quality is assessed through geochemical analyses of organic matter (OM) quantity, type, thermal maturity, and key factors influencing hydro-carbon generation. Rock-Eval pyrolysis was performed on outcrop samples from five sections located within the Imbricated and High Folded Zones of the Zagros Fold-Thrust Belt. Results demonstrate significant variability in total organic carbon (TOC) content, hydro-carbon generation potential (as reflected by S1, S2, and genetic potential values.), and kerogen types across these zones. The Sargelu and Naokelekan formations exhibit excellent source rock potential in the Banik and Gara sections, with TOC values up to 20 wt% and S2 values exceeding 80 g HC/gr rock. Kerogen types in these areas are predominantly oil-prone Type II and mixed Type II/III, with thermal maturity within the oil generation window (Tmax ~439°C in average). Conversely, samples from the Rania, Sargelu, and Chnaran sections demonstrate poor hydrocarbon potential, characterized by lower values TOC (

Unraveling coalification dynamics: a comprehensive spectroscopic study on the chemical and microstructural evolution from lignite to semi-anthracite.