The central Congo Basin hosts the world's largest tropical peatland complex, storing 29.0 Pg of carbon, the equivalent to three years of global CO₂ emissions. These peatlands are significant natural sources of greenhouse gases (GHGs), including CO₂, CH₄ and N₂O, but the environmental controls on their emissions remain poorly understood. To address this, we collected surface peat samples from six regional landscapes, spanning palm- and hardwood-dominated sites, and incubated them under three hydrological regimes: flooded aerobic, flooded anoxic and mesic (aerobic and no surface water). This allowed us to quantify how hydrology and peat chemistry (carbon, nutrients and organic chemistry) influence GHG dynamics. We observed strong differences in GHG production between vegetation types, and high sensitivity to hydrological change. Using random forest models, we assessed 27 potential drivers of GHG fluxes, identifying distinct controls across GHGs and hydrological regimes. Incubation of deeper peat samples (up to 1.5 m) highlighted that surface layers dominate peat GHG production. Taken together, our findings demonstrate that hydrology, vegetation, nutrients and peat organic chemistry shape regional GHG emissions, driving substantial spatial variability. Changes to peatland hydrology, for example from land use or climate change, could significantly shift GHG balances, with important implications for global climate feedbacks. A French translation of this abstract is available in the supplementary material. This article is part of the discussion meeting issue 'African tropical peatlands: function, value and vulnerability'.

Biomarkers are powerful tools to assess thermal maturity of oil and rock extracts and for oil-source rock correlation. While temperature effects on biomarker evolution have been widely studied, the impact of pressure remains largely underexplored. This study examines the effect of high water pressure (up to 900 bar) on biomarker maturation in expelled oil and extracted bitumen from pyrolysis experiments on a rock sample from the Campanian-Maastrichtian Duwi Formation, Red Sea Basin, Egypt. Extracted bitumens exhibited higher maturity under anhydrous conditions compared to low-pressure hydrous samples, and this was more pronounced at 350 degrees C. The extracted bitumen displayed higher biomarker maturity ratios than the corresponding expelled oil at 350 degrees C, likely due to prolonged interactions of the bitumen with the rock mineral matrix. In contrast, delta 13C values were similar for extracted bitumen and the corresponding expelled oil. At 320 degrees C, high pressure reduced values of biomarker maturity ratios, particularly C31-C35 homohopane isomerisation, Ts/Tm, Ts/H30, and C29Ts/ H29 ratios, whereas sterane ratios remained unaffected. At 350 degrees C, pressure effects were less significant, with some anomalous variations, suggesting a non-systematic influence on biomarker maturation at higher temperatures. These findings demonstrate the complex role of pressure in biomarker evolution, emphasising the need to consider pressure in biomarker-based maturity assessment, particularly in overpressured basins and deep petroleum systems, where high pressure may be a dominant factor. Based on 12 source-related biomarker and isotopic ratios, chemometric analysis reveals that artificially generated oils and South Malak-1 oils from southwestern onshore Gulf of Suez are quite different, and both groups differ significantly from other natural oils from the central and northern parts of the basin. This may be due to facies variations and the effects of mixing from multiple source horizons under natural subsurface conditions.

The presence of soil hydrocarbon parameters (SHPs), including total petroleum hydrocarbons (TPHs), total organic carbon (TOC; %), and soil toxicity (EC50; mg L-1), can affect vegetation in several ways. This study assessed the impact of SHPs on vegetation in the Niger Delta using field-measured, leaf-scale hyperspectral data acquired across the region. Red-edge position (REP) and four hyperspectral vegetation indices (HVIs)-mND705, photochemical reflectance index (PRI), Normalised Difference Vegetation Vigour Index (NDVVI844,447; a vegetation vigour index), and modified DATT (MDATT; a chlorophyll-sensitive red-edge index)-were used to quantify chlorophyll content in the vegetation types of Awolowo grass, elephant grass, mango trees, oil palm trees, and mangrove vegetation and to explore their variation with SHPs. The results show that mangrove vegetation was the most impacted by TPHs (R = -0.683), while mango vegetation was the most impacted by TOC (R = -0.725), based on Pearson correlation coefficients derived from the mND705 index. Similarly, mango and mangrove vegetation showed the strongest responses to soil toxicity (EC50; mg L-1), based on Spearman correlation coefficients (rs = 0.657 and rs = 0.870, respectively) using the MDATT index. These findings highlight species-specific physiological responses to soil hydrocarbon contamination and demonstrate the applicability of red-edge-based hyperspectral techniques for assessing vegetation stress in complex coastal ecosystems such as the Niger Delta.

Accurately predicting the evolution of pore networks under realistic thermo-hydro-mechanical conditions remains a critical challenge, limiting the reliable identification of hydrocarbon "sweet spots" in mature shale basins. This study aims to decouple the synergistic controls of thermal maturity, shale composition, water, and pressure on pore development. We conducted systematic, sequential high-pressure hydrous pyrolysis experiments on two compositionally distinct lacustrine shales, immature Huadian (Type II kerogen, high TOC, illite-smectite mixed-layer clay-rich) and Fushun (Type I kerogen, low TOC, siderite-rich) shales. Integrated geochemical analyses (vitrinite reflectance, Rock-Eval pyrolysis, TOC) and pore structure characterization (lowpressure N2/CO2 adsorption, SEM) revealed that thermal maturity is the primary driver for pore development, but its expression is fundamentally mediated by composition. Kerogen type dictates the evolutionary pathway, and TOC dominates the porosity magnitude. Minerals further modulate pore evolution, with carbonate dissolution regenerating porosity and clay stability determining pore integrity. Water is the most critical environmental factor, enhancing porosity by facilitating hydrocarbon expulsion, inhibiting pore-filling, and promoting mineral dissolution. Pressure exerts a dual role, with internal pore pressure promoting porosity, outweighing external compaction in our closed system. Notably, water pressure results in an additional 1.9-4.5-fold increase in pore volume during the wet gas cracking stage compared to non-hydrous conditions. These results establish a novel, integrated shale-water-pressure framework that advances beyond traditional maturity-centric models by quantitatively distinguishing the roles of and interactions between key controlling factors, providing a mechanistic basis for predicting reservoir quality, although its field application requires calibration to account for basin-specific geological complexity.

Five sediment cores of 40 cm length were collected from the Singapore Strait and analysed for emerging and persistent contaminants to assess changing pollutant trends and risk to benthic ecology. Data on the sedimentary accumulation of pharmaceuticals are currently lacking and yet present a potential threat to Singapore's coastal ecosystem. Pharmaceuticals occurred in the order hormones>non-steroidal anti-inflammatory>antibiotics and were highest at the sediment surface then decreased down-core. Similar trends were observed for individual antibiotics, azithromycin 0.18-0.51 ng/g-1, clarithromycin 0.02-0.44 ng/g-1 and erythromycin-H2O 0.01-0.04 ng/g-1 as well as anti-inflammatory drug ibuprofen 0.19-8.59 ng/g-1. The non-systematic variation in the hormone estradiol (E2) 3.41-13.83 ng/g-1 and drink/food ingredient caffeine 1.27-9.19 ng/g-1 was attributed to greater mobility and or post depositional degradation. In contrast, polyaromatic hydrocarbons (∑16PAH) 0.322-32.569 mg/kg-1 as well as trace metal mercury (Hg) 0.039-1.022 mg/kg-1 were invariant, except for one core which showed a clear-rise and near surface fall tracking TOC% and clay-silt particles. PAH source ratios and parent to alkylated profiles conferred mainly petroleum combustion sources with minor petroleum inputs. Sedimentary PAH and Hg were mostly below established non-statutory sediment quality benchmarks and deemed unlikely to negatively impact benthic ecology. Together PCA and HCA evaluation confirmed similar physico-chemical association for pharmaceuticals and persistent contaminants except for antibiotics. Sediments from Singapore Strait record a recent shift from predominantly hydrocarbon pollution to more complex mixtures spanning pharmaceuticals and caffeine that are suggested but not unequivocally proven to be from on-shore industrial or waste-water discharge sources.

Water, sediments, fish and invertebrates were collected along two English rivers (R. Tone, Sommerset and R. Wensum, Norfolk) and analysed for 52 pesticides to assess source to sea spatial distribution and track bioaccumulation within wildlife. Chemical risk assessments, using Toxic Units, Risk Quotients, and Microtox® solid phase tests were applied to understand threats to river health. Widespread pesticide pollution was detected in the water and sediments of both rivers, often forming complex mixtures containing numerous pesticides. Hydrophobic pesticides, such as Fipronil and Propiconazole, were also observed widely bioaccumulating in fish. The veterinary pesticide Fipronil was measured in the highest concentrations, up to 87.7 ng/g in fish muscle and 322 ng/g in invertebrates. Of particular concern were neonicotinoids in water, which frequently exceeded environmental quality standards (detected ranges: Imidacloprid <1.2-97.1 ng/L; Clothianidin <28.7-63.4 ng/L) and presented a significant risk to aquatic invertebrates and overall river health. Chronic sub-lethal risks to fish resulting from pesticide exposure were also identified. In sediments, Fipronil regularly exceeded likely-effect benchmarks by up to 256 % (0-0.355 ng/g OC; 0-12.6 ng/g). The findings highlight the potentially negative impact of pesticide pollution on river health in England, and emphasise the need for stricter regulation of the most high-risk pesticides, particularly those used in veterinary care.

Savannahs cover 20 % of the global land surface, but there have been few studies of greenhouse gas (GHG) dynamics from savannah soils. Here, we assess potential turnover of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from surface (0-10 cm) and subsurface (20-30 cm) soils from two contrasting tropical savannah sites in the Republic of Congo, Central Africa, under dry (40 % water-filled-pore-space, WFPS) and wet (70 % WFPS) conditions. Under baseline conditions (25 degrees C), we found soils were sources of CO2 and N2O, but a sink for CH4. Assessment of the temperature response of GHG fluxes between 20 and 35 degrees C revealed variable temperature dependences. That is, CO2 fluxes showed a strong temperature response, whereas the temperature response of N2O fluxes was only significant under dry conditions, and no significant temperature response of CH4 fluxes was observed. The temperature quotient (Q10) of soil respiration increased from 1.58 +/- 0.004 to 1.92 +/- 0.006 at sites with lower soil organic carbon contents. The relative increase in N2O with CO2 fluxes across temperatures was significantly influenced by moisture conditions at both sites. No temperature or soil moisture response was observed for CH4 fluxes, collectively implying divergent GHG responses to changing climatic conditions. Using Rock-Eval pyrolysis we assessed the organic chemistry of all soil types, which indicated contrasting degrees of stability of carbon sources between sites and with depth which, alongside significant differences in a range of other soil parameters (including organic matter content, total carbon, total nitrogen, electrical conductivity, and pH), may account for site-specific differences in baseline GHG emissions. Taken together, our results are amongst the first measures of GHG temperature sensitivity of tropical savannah soils, and demonstrate that soil CO2 emissions are more sensitive to warming and changes in moisture than the emissions of other GHGs, although relatively low compared to responses reported for soils from other tropical ecosystems. This implies that GHG fluxes form savannah soils in the region may be at least partially resilient to climate-induced soil warming compared to other ecosystems.

Understanding kerogen transformation under geological conditions is critical for optimizing the in-situ conversion (ISC) process of organic-rich unconventional resources. Sequential high-pressure hydrous pyrolysis was employed to investigate the geological thermal evolution and hydrocarbon generation mechanisms of organic matter in immature Huadian (Type II1 kerogen) and Fushun (Type I kerogen) shales. Experiments progressed through four thermal stages, that is Stage 1 (350 degrees C, 6 h), Stage 2 (350 degrees C, 24 h), Stage 3 (380 degrees C, 24 h), and Stage 4 (420 degrees C, 24 h), with comprehensive analysis of hydrocarbon products by gas-chromatography massspectrometry and solid residues by vitrinite reflectance (Ro) and Rock-Eval pyrolysis. The results revealed that the hydrocarbon-generation potential of these two shales declined sharply with a Ro of 0.78-1.23 %, correlating with peak oil generation. Type I kerogen (Fushun) exhibited higher reactivity, generating twice the cumulative oil yield (normalized by TOC) compared to Type II1 (Huadian) and transitioning earlier to oil dominance. Biomarker evolution (OEP decline, sterane/hopane isomerization) in expelled oil and declining gas dryness index (C1/Sigma C1-C5) correlated strongly with the maturity of organic matter, enabling non-destructive ISC monitoring. Compared to typical temperatures used in ex-situ retorting (520 degrees C), the kerogen conversion was completed at lower temperatures of 350-420 degrees C in this study, validating prolonged heating as a viable low-energy ISC strategy. However, high-pressure conditions in geological formations may impede hydrocarbon expulsion efficiency, leading to the retention of viscous bitumen and thus necessitating engineered solutions for effective oil recovery. This research enriches the understanding of high-pressure pyrolysis mechanisms of immature/low-maturity unconventional resources and establishes a geochemical framework for optimizing ISC in recovering the oil from these source rocks, ultimately contributing to advancing sustainable exploitation of unconventional resources.

This study examines the effect of high water pressure (up to 900 bar) on hydrocarbon generation from Type-I kerogen-rich source rocks and compares the results with previously observed effects on Type-II and Type-III kerogens. An immature Type-I oil shale sample from the Duwi Formation, Egypt, was pyrolysed under anhydrous, low-pressure hydrous, and high water-pressure conditions at 320 degrees C (end of bitumen generation) and 350 degrees C (oil window) for 6 and 24 h, respectively. Pyrolysis at 320 degrees C showed that bitumen generation was promoted in the presence of water under lowpressure hydrous compared to anhydrous conditions but retarded at high water pressures. At 350 degrees C, oil generation was also retarded by increasing pressure, with maximum oil yield at 500 bar before dropping by 72% at 900 bar. Lower bitumen yields at 500 bar and higher yields at 900 bar confirm more retention of oil and bitumen in the rock at higher pressure. High water pressure systematically decreased hydrocarbon gas yields, with a more prominent effect at 320 degrees C because of temperature's dominant impact over pressure at 350 degrees C. Similarly, non- hydrocarbon gas yields decreased as water pressure increased, with maximum yields under anhydrous and low-pressure hydrous conditions. The retardation effect on bitumen generation was less significant than that on oil and gas generation. This study highlights pressure's impact on petroleum generation, particularly in overpressured basins. Elevated pressures on Type-I kerogen source rocks retard oil expulsion, and the retained oil and bitumen within the rock can be directly cracked to gas, suggesting that under such conditions, oil yields may be lower, while unconventional gas resources are likely to be more abundant.

A set of unused virgin polystyrene coffee cup lids were distributed in the environment (Sutton Bonington, UK) for a period of 24 months to compare monthly degradation rates across four treatments with variable degrees of exposure to natural UV irradiance (full or reduced exposure) and soil (surface or buried). Analysis of monthly samples (hole-punched discs) from three lids of each treatment via FTIR-ATR indicated that the lids in each treatment displayed varying levels of degradation, ranked as follows: exposure on the ground surface, no shading > exposure on the ground surface, shading> both buried treatments. Principal component analyses (PCAs) and the carbonyl index indicated that photooxidation via sunlight exposure was the primary degradation mechanism for polystyrene under these environmentally relevant conditions. Monthly variations in spectra for each treatment (particularly surface treatments) also indicated that degradation rate was not a continuous process, with a multiple regression establishing correlation between monthly carbonyl index for the first 12 months of the experiment, and both UV irradiance and temperature (p = 0.058). This demonstrated that environmental polystyrene degradation rate was closely related to seasonal cycles in the temperate environment.

Nairobi River sediments from locations adjacent to the Kawangware and Kiambio slums were analyzed via Fourier transform ion cyclotron resonance mass spectrometry with atmospheric pressure photoionization (APPI-FT-ICR-MS). The data from these ultrahigh resolution, untargeted measurements provided new insights into the impacts of local anthropogenic activity, which included likely benzo- and dibenzothiophene pollution with a suspected petrogenic origin, and prominent surfactant-like compositions. Other features in the data included highly abundant tetra-oxygenated compounds, and oxygenated nitrogen compounds with sphingolipid interpretations. Most notably, several hydrocarbon and oxygenated compound classes in the sediment data featured intensity patterns consistent with steroid molecular formulas, including those associated with sewage contamination investigatory work. In support of this interpretation, standards of cholesterol, beta-sitosterol, stigmasterol, coprostanol, cholestanol, and 5 alpha-sitostanol were analyzed via APPI, to explore steroid ionization behavior. Generally, these analytes produced radical molecular ions ([M](center dot+)), and water-loss pseudo molecular ion species ([M-H2O](center dot+) and [M+H-H2O](+)), among various other less intense contributions. The absence of pseudo molecular protonated species ([M+H](+)) was notable for these compounds, because these are often assumed to form with APPI. The standard measurements demonstrated how steroids can create the observed intensity patterns in FT-ICR-MS data, and hence these patterns have the potential to indicate sewage contamination in the analysis of other complex environmental samples. The steroid interpretation for the Kawangware and Kiambio data was further verified by subjecting the steroid standard radical molecular ions to collision-induced dissociation and comparing the detected fragments to those for the corresponding isolated ions from a Kawangware sediment sample.

Microplastics at 10 sites along a 77 km transect of the river Thames estuary (UK) and 5 sites along 29 km of the Medway estuary were separated from sediment and analysed by ATR-FTIR spectroscopy. Microplastics were observed at all sites. Highest Thames concentrations were in urban London between Chelsea and West Thurrock (average 170.80 particles kg(-1) +/- 46.64, 3.36 mg kg(-1) +/- 1.79 by mass), mid-outer estuary sites were two to three times lower. Microplastics were slightly dominated by particles (54 %) over fibres (45 %), including polymer types ranked: polyethylene > PET > polypropylene > polyamide. Medway microplastics decreased seaward, with one urban-municipal site impacted by a combined-sewer-overflow containing a high proportion of fibres (Rochester, 484 particles kg(-1), 7.39 mg kg(-1) by mass). Microplastic abundance was correlated to organic carbon (TOC %) (R-2 of 0.71 Thames and 0.96 Medway), but not sediment particle size. Sedimentary microplastics accumulation in the Thames was controlled by urbanisation-distance, and site hydrodynamics.

Polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and heteroatom-containing analogues, constitute an important environmental contaminant class. For decades, limited numbers of priority PAHs have been routinely targeted in pollution investigations, however, there is growing awareness for the potential occurrence of thousands of PACs in the environment. In this study, untargeted Fourier transform ion cyclotron resonance mass spectrometry was used for the molecular characterisation of PACs in a sediment core from Chiswick Ait, in the River Thames, London, UK. Using complex mixture analysis approaches, including aromaticity index calculations, the number of molecular PAC components was determined for eight core depths, extending back to the 1930s. A maximum of 1676 molecular compositions representing PACs was detected at the depth corresponding to the 1950s, and a decline in PAC numbers was observed up the core. A case linking the PACs to London’s coal consumption history is presented, alongside other possible sources, with some data features indicating pyrogenic origins. The overall core profile trend in PAC components, including compounds with oxygen, sulfur, nitrogen, and chlorine atoms, is shown to broadly correspond to the 16 priority PAH concentration profile trend previously determined for this core. These findings have implications for other industry-impacted environments.

An enhanced in vitro human dermal bioavailability method was developed to measure the release of twenty parent and seven alkylated high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAHs) from contaminated soils collected from five former manufactured Gas Plants (MGP) in England. GC-MS/MS was used to quantify HMW PAHs in soil, Strat-M artificial membrane representing skin, and synthetic receptor solution (RS) representing systemic circulation at 1-h, 10-h, and 24-h timesteps. Fluoranthene and pyrene exhibited the highest fluxes from soils to membrane (ranging from 9.5 - 281 ng/cm 2 /h) and soil to RS ( 16.9 ng/cm 2 / h). Chrysene, benzo[ a ]anthracene, benzo[ b ]fluoranthene and the alkylated C1-fluoranthene/pyrene homologue series demonstrated fluxes higher than other HMW PAHs. The dermal fluxes were generally lower than those reported in previous investigations and suggests that dermal absorption varies between both HMW parent and alkylated PAHs and individual PAHs. The utilisation of real -world contaminated soils allowed for a more realistic representation; this is important because current risk assessment guidance is baseed on results from experiments that used artificially spiked soils. This research shows that the the ranges of dermal fluxes are PAH dependent and impact the mass of absorbed from soil after dermal exposure and therefore the potential risk contaminated soil poses to human health.

We evaluated the unconventional hydrocarbon potential of the Holywell Shale Formation, a lateral equivalent of the Bowland Shale Formation deposited in the Blacon Basin. Two cores with ArnsbergianChokierian and Kinderscoutian (Namurian, Late Mississippian-Early Pennsylvanian) ages from the Ellesmere Port 1 borehole were sampled for palynological, stable isotope, Rock-Eval 6 pyrolysis and ichnofacies analyses. The study was designed to provide boundary conditions for parameters that are under-represented in the public domain and hamper accurate resource assessments: thermal maturity (through mean random vitrinite reflectance, Rr), present-day organic matter content, kerogen type, original hydrogen index and original organic matter content. Our results show that the Arnsbergian Core 2 has been buried to a depth equivalent to the bottom of the oil window to the top of the gas window (%Rr = 1.15%-1.29%). The Kinderscoutian Core 1 is too immature to have generated any natural gas (%Rr = 0.91-1.03%). Furthermore, kerogen typing and ichnofacies analysis show that the Bowland Shale Formation is very heterogeneous, with organic matter originating from terrestrial and marine sources. Five palynofacies assemblages are described that range in basin setting from proximal and oxic to distal and anoxic with evidence of episodic connections to the open ocean. The combination of heterogeneity and low thermal maturity restricts the thickness of the Bowland Shale Formation in the Blacon Basin that is prospective for unconventional hydrocarbons. Our results show that these Carboniferous mudstones should not be treated as uniform units with uniform composition and maturity in basin modelling and resource estimates. This undoubtedly has repercussions for future exploration because the contrasting composition and density of the materials making up the Bowland Shale Formation may complicate extraction, while the thermal maturity window significantly narrows the prospective interval.

Mangrove sediments are valuable archives of relative sea-level change if they can be distinguished in the stratigraphic record from other organic-rich depositional environments (e.g., freshwater swamps). Proxies for establishing environment of deposition can be poorly preserved (e.g., foraminifera) in mangrove sediment. Consequently, differentiating mangrove and freshwater sediment in the stratigraphic record is often subjective. We explore if biomarkers can objectively identify mangrove sediment with emphasis on their utility for reconstructing relative sea level. Our approach is specific to identifying in situ sediment, which has received less attention than identifying allochthonous mangrove organic matter. To characterize mangrove and non-mangrove (freshwater) environments, we measured n-alkane, sterol, and triterpenoid abundances in surface sediments at three sites in the Federated States of Micronesia. Elevated taraxerol abundance is diagnostic of sediment accumulating in mangroves and taraxerol is particularly abundant beneath monospecific stands of Rhizophora spp. Taraxerol was undetectable in freshwater sediment. Other triterpenoids are more abundant in mangrove sediment than in freshwater sediment. Using cores from Micronesian mangroves, we examine if biomarkers in sediments are indicative of in situ deposition in a mangrove, and have utility as a relative sea-level proxy. Taraxerol concentrations in cores are comparable to surface mangrove sediments, which indicates deposition in a mangrove. This interpretation is supported by pollen assemblages. Downcore taraxerol variability may reflect changing inputs from Rhizophora spp. rather than diagenesis. We propose that taraxerol is a proxy that differentiates between organic sediment that accumulated in mangrove vs. freshwater environments, lending it utility for reconstructing relative sea level.

The Bowland sub-basin is a target for hydrocarbon exploration, but to a large extent it remains unexplored. To determine the economic potential of the Bowland sub-basin, it is important to identify the oceanographic processes involved in the deposition of the Bowland Shale Formation in the Late Mississippian ( c. 330 Ma). Palaeoceanographic processes are known to be a major control on the development of hydrocarbon source rocks. This study investigates core (Preese Hall-1 and Becconsall-1Z) materials from the Upper Bowland Shale, and makes a comparison with previously published data (outcrop Hind Clough), all from the Bowland sub-basin, Lancashire, UK. The sedimentology and geochemistry of this formation were determined via a multi-technique approach including X-ray fluorescence, sedimentology, gamma-ray spectra, X-ray diffraction and Rock-Eval pyrolysis. Key trace metal abundances and enrichment factors were used to assess sediment provenance and to determine the bottom-water redox conditions during the deposition of the Upper Bowland Shale. Our results support interpretations of contemporaneous anoxia developing in bottom waters in at least three sites in the Bowland sub-basin. In a comparison with the Fort Worth Basin (Barnett Shale, USA), the Bowland sub-basin was apparently less restricted and deposited under a much higher mean sediment accumulation rate. Knowledge from this study will improve future resource estimates of the Bowland Shale Formation, and challenge the early assumptions that the Barnett Shale is an analogue of the Bowland Shale.

We conducted a high-resolution multi-disciplinary analysis of two core sections in the borehole Ellesmere Port-1, Cheshire, UK. Biostratigraphic analysis indicates that the core sections are Kinderscoutian and late Arnsbergian-Chokierian in age, respectively. Both cores are assigned to the Bowland Shale Formation (Holywell Shale). Coupled core scan and discrete geochemical analysis enables interpretation of syngenetic processes at a high stratigraphic resolution. Both cores exhibit the classic cyclicity of limestones, calcareous to non-calcareous mudstones and siltstones, interpreted to represent sediment deposition during fourth-order sea-level fluctuation. Machine learning of the well log data coupled to the core scan data enabled prediction of the key lithofacies through the entire Bowland Shale interval in Ellesmere Port-1. The machine predictions show that the Bowland Shale is interfingered with three turbiditic leaves of the Cefn-y-Fedw Sandstone Formation and contains at least 12 complete fourth-order cycles. The Bowland Shale exhibits high radiogenic heat productivity in comparison with other sedimentary rocks, due primarily to relative U enrichment under intermittently euxinic conditions. Thermal modelling, however, shows that the radiogenic heat productivity of the Bowland Shale contributes a negligible source of additional heat at the scale of hundreds of metres.

Shale rock core from the Bowland Shale Formation, UK, was analysed in the laboratory using Rock-Eval pyrolysis and Fourier transform infrared spectroscopy (FTIR). These methods are used to characterize the organic constituents of soil and rock. This research is a proof-of-concept study to investigate whether regression models developed using FTIR and Rock-Eval data for the same length of core can be used to estimate selected Rock-Eval parameters. The accuracy of the regression models was assessed using statistical methods, the results of which were used to choose preferred models for each Rock-Eval parameter. The models produced were shown to have an acceptable level of uncertainty for total organic carbon and S1, S2 and S3 outputs, which led us to conclude that these are potentially suitable for estimating unknown down-core Rock-Eval parameter values. Conversely, the model for the temperature of the maximum rate of hydrocarbon generation ( T max ) had higher variability in the cross-validation data above the acceptable level of uncertainty, which could lead to erroneous estimates. Down-core interpolations of selected Rock-Eval parameters could be practically achieved by modelling FTIR data by maintaining standard sample frequencies for Rock-Eval while supplementing with higher frequencies for FTIR and chemometric analysis.

The regional character of organic matter types and depositional conditions of Pendleian, Brigantian and Arnsbergian mudstones between the Craven Basin and the Widmerpool Gulf was compared through interpretation of biomarker and pyrolysis data from 201 samples recovered from nine boreholes. The Carboniferous seaways have been determined to commonly host dysoxic conditions, enabling the preservation of a mixture of marine and terrestrial organic matter types. Photic zone anoxia, established by the presence of aryl isoprenoids, was determined to be persistent during 'marine' conditions represented by marine band, high-sea-level and carbonate facies. The observation and correlation of diasteranes and trisnorneohopane/trisnorhopane ratios within the samples and to other maturity parameters highlighted a significant clay mineral catalytic and/or hydrocarbon retention effect in the samples. This influenced both biomarkers and programmed pyrolysis thermal maturity indices such as T-max, reducing the reliability of such results for interpreting the burial depth, and ultimately reserve potential.