Carbonate Buildups Research Articles

Development of a medium-duty stoichiometric diesel micro-pilot natural gas engine

Fueling a compression-ignition engine with premixed natural gas offers the potential to combine a clean-burning, low-carbon fuel with a high compression ratio, high-efficiency engine. This work describes the development of a multi-cylinder 6.7 L diesel engine converted to run stoichiometric diesel micro-pilot/ natural gas premix combustion with a maximum diesel contribution target of 5% of the total fuel energy and a three-way catalyst aftertreatment system. Results are given by comparing the stoichiometric combustion to the diesel baseline operation, showing combustion characteristics differences, including the rapid two stage heat release. A high load output of 23 bar brake mean effective pressure was obtained with diesel-like brake thermal efficiency of 41%. This operating condition enabled a brake specific CO2 emissions reduction of up to 25% when compared to diesel. It was observed that the low load output is limited by combustion stability when operated at stoichiometric condition. The three-way catalyst is observed to run at peak efficiency with an equivalence ratio of 1.01. Injector fouling was observed through the inspection of the nozzle and its internal parts, indicating carbon build-up similar to that seen in injector coking mechanisms. A comparison of the developed engine to other engine technologies is given, showing that the diesel micro-pilot natural gas engine performance is in good standing among other diesel and gas engines in the market.

Correction to: Imaging of a possible isolated carbonate build-up (ICB) in Penobscot Bay at anomalous low frequencies

Correction to: Imaging of a possible isolated carbonate build-up (ICB) in Penobscot Bay at anomalous low frequencies

Long-term Effect of Different Cropping Systems on Carbon Sequestration in a Sandy Loam Soil of Telangana

Background: Rice, maize and Bt cotton are the predominant crops which are either grown solely or in rotation with other crops in Telangana state. As all these crops are exhaustive, non leguminous in nature and may lead to fast soil degradation. Therefore, a major agricultural research priority is needed to sustain soil productivity through carbon sequestration by including legume component in cropping systems. The present study was undertaken to investigate effect of cropping systems on carbon sequestration in the ongoing long-term field trial. Methods: This field investigation was initiated during the year 2017 at an experimental farm located at College of Agriculture, Rajendranagar, Hyderabad. The surface soil samples were collected at 0-15 cm depth in various treatments within different cropping systems after harvest of Kharif and Rabi crops, 2019-2020 at the completion of third year of the experiment and analysed for soil organic carbon (SOC) and soil inorganic carbon (SIC) status by following standard procedures. Data were subjected to statistical analysis by adopting RBD statistical tool and analysis of variance was worked by adopting operational statistics (OP STAT) software programme. Result: The results indicated the improvement in soil organic carbon over the initial status due to the effect of efficient cropping systems. Significantly highest build-up of organic carbon was noticed in the following cropping sequence: CS5: maize + pigeon pea (1:3) (1.25 Mg ha-1) and CS4: pigeon pea + green gram (1:3) - sesame (1.22 Mg ha-1) but the lowest value of SOC was recorded in CS1: rice-maize (7.51 Mg ha-1) and CS2: Bt cotton-fallow (7.24 Mg ha-1), respectively. During the study, it was also observed that in one of the cropping systems i.e., CS10: bhendi-marigold-beetroot showed the negative impact on the level of SOC stock (6.77 Mg ha-1) fell below the initial value (7.53 Mg ha-1) after third year of trial. However, the highest carbon sequestration rate was recorded in CS5: maize + pigeon pea (0.42 Mg ha-1 yr-1) and CS4: pigeon pea + green gram (1:3) - sesame (0.41 Mg ha-1 yr-1). The salient findings of this study showed that cropping systems involving legumes and fodder crops had improved soil organic carbon on long term basis.

Effect of Organic Manure and Moisture Regimes on Soil Physiochemical Properties, Microbial Biomass Cmic:Nmic:Pmic Turnover and Yield of Mustard Grains in Arid Climate.

(1) Background: Arid conditions occur due to climate abnormality in the different biogeography regions of the world. The aim of this research is to investigate the stoichiometry of manure and moisture regimes on soil properties, microbial biomass C:N:P turnover, and the grain yield of mustard crops under stress in arid conditions; (2) Methods: The field experiment was carried out for 2 years at the farms of the agriculture college of SKN, Jobner (SKRAU Bikaner, Rajasthan). The effects of organic manure, moisture regimes, and saline water treatment on soil properties, such as the soil microbial biomass build-up, loss, turnover, and recycling of carbon (Cmic), nitrogen (Nmic), and phosphorus (Pmic) in the mustard crop were investigated. The twenty-seven treatments studied are described as follows: organic manures (control, FYM @ 10 t ha−1 and vermicompost @ 5 t ha−1), moisture regimes (0.4, 0.6, and 0.8 IW/CPE ratio), and saline irrigation water (control, 6, 12 dSm−1); (3) Results: Our findings indicate that vermicompost @ 5 t ha−1 significantly increases moisture retention and the available water in soil at 33 kPa and 1500 kPa. The microbial biomass build-up of Cmic increases by 43.13% over the control and 14.36% over the FYM. Similarly, the soil microbial biomass of Nmic, and Pmic also increase considerably. The SHC of the soil is enhanced by the application of farmyard fertilizer and vermicompost. The BD and pH decrease significantly, while the SHC, OC, CEC, and ECe of the soil increase significantly. The build-up, losses, and fluxes of the soil microbial biomass of Cmic, Nmic, and Pmic increase significantly, and the turnover rate decreases under vermicompost @ 5 t ha−1. A significant increase in grain yield was observed. Irrigation with a 0.8 IW/CPE moisture regime significantly decreases the pH of the SHC; (4) Conclusions: We hypothesized the interactive outcomes of the moisture regime and found that organic manure significantly influenced grain and stover yield. The treatments of quality irrigation water and the addition of organic manure are efficient enough to improve soil properties, water holding capacity, and soil microbial biomass C:N:P in stress climatic conditions.

The impact of alcohol admixture with gasoline on carbon build-up and fuel injectors performance

The operating conditions of injectors in spark ignition engines with direct fuel injection make them susceptible to coking, which leads to a reduced quality of fuel atomization. This can be observed by a drop in performance and an increase in exhaust emissions, especially particulate matter. One effective method of reducing injector coking is by using detergentdispersing gasoline additives. The article describes the effect of using an admixture with a varied alcohol content on the quantitative and qualitative fuel atomization indicators. The research consisted of a 48-hour engine test, done in accordance with the CEC F-113-KC procedure (CEC-F-113 test). After each test cycle, the injectors underwent optical tests with the use of an isochoric chamber. The spray penetration and surface area were analyzed at a set of different fuel injection parameter values. The research performed resulted in determining the influence of each tested admixture on the change of injection time and on the geometric indicators of the fuel spray. The obtained characteristics of the engine in operation and conducted stationary tests enabled the operational evaluation of the impact an alcohol admixture with gasoline fuels had on key engine parameters.

Responses of soil organic carbon, aggregate diameters, and hydraulic properties to long‐term organic and conventional farming on a Vertisol in India

AbstractOrganic matter management can improve soil structural properties. This is crucial for agricultural soils in tropical regions threatened by high rainfall intensities. Compared to conventional farming, organic farming is usually deemed to increase organic carbon and improve soil structural properties such as stability and permeability. However, how much, if any, buildup of organic carbon is possible or indeed occurring also depends on soil type and environmental factors. We compared the impact of seven years of organic farming (annually 13.6 t ha−1 of composted manure) with that of conventional practices (2 t ha−1 of farmyard manure with 150–170 kg N ha−1 of mineral fertilizers) on soil structural properties. The study was conducted on a Vertisol in India with a two‐year crop rotation of cotton soybean wheat. Despite large differences in organic amendment application, organic carbon was not significantly different at 9.6 mg C g−1 on average in the topsoil. However, the size distribution of water‐stable aggregates shifted toward more aggregates <137 μm in the organic systems. Cumulative water intake was lower compared to the conventional systems, leading to higher runoff and erosion. These changes might be related to the lower pH and higher exchangeable sodium in the organic systems. Our results indicate that higher application of organic amendments did not lead to higher soil organic carbon and associated improvement in soil structures properties compared to integrated fertilization in this study. Chemical properties may dominate soil aggregation retarding the uptake and integration of organic amendments for sustainable agricultural intensification in tropical, semiarid climates.

Imaging of a possible isolated carbonate build-up (ICB) in Penobscot Bay at anomalous low frequencies

Imaging of a possible isolated carbonate build-up (ICB) in Penobscot Bay at anomalous low frequencies

Spatial self-organization of marine agglutinated microbial carbonate build-ups: Insights from stratigraphic forward modelling using Stromatobyte3D

Microbialites span a substantial fraction of Earth history, and have important meanings for understanding long-term history of life and environment. Key controls on microbialite morphology and distribution include substrate topography, hydrodynamic conditions, water depth, salinity, light intensity, and sedimentation rates. This leads to potentially complex combinations of control by internal spatial feedbacks and also external factors. This complexity is explored here using Stromatobyte3D, a new numerical stratigraphic forward model that calculates microbialite accumulation due to in-situ precipitation, sediment trapping and binding, and sedimentation from suspension, controlled by evolving topography and water flow due to waves, tides or other currents. Results show that with increasingly strong spatial interactions of microbialite growth with water and suspended sediment, particularly the influence of hydrodynamics on in-situ microbialite growth and suspended sediment deposition patterns, three distinct microbialite morphologies are produced, from isolated columns, through elongated mounds, to ridges elongated in the dominant flow direction. Quantitative analysis demonstrates a dominant antecedent substrate topographic control on microbialite nucleation and growth in the absence of water flow, declining as hydrodynamic processes and strong spatial interactions are introduced causing mounds to accrete and coalesce laterally in the flow direction. Formation of coherent morphological patterns, produced by spatial interactions between topography, hydrodynamics, microbialite growth, and sedimentation from suspension, and independent of initial condition, is evidence of spatial self-organization. Modelled morphologies are strikingly similar to observations from modern marine agglutinated microbialite strata, suggesting modelled processes and their behaviours are realistic, and can therefore be useful to assist field interpretations of observed microbialite morphologies where similar processes were operating together.

Chemical looping steam reforming of glycerol for hydrogen production over NiO-Fe2O3/Al2O3 oxygen carriers.

Fe-based oxygen carriers (OCs) are widely used in chemical looping steam reforming (CLSR) due to excellent resistance to carbon buildup, low toxicity, and high activity. In this study, a type of nano NiO–Fe2O3/Al2O3 Fe-based OC that can easily be reduced by fuels and re-oxidized by air was developed for use in glycerol CLSR. It was synthesized by co-precipitation and impregnation. Based on the quadratic regression orthogonal model, a quadratic polynomial function was established to investigate the effects of temperature (T), water/carbon ratio (S/C), and loading (M) on hydrogen content (HL) and hydrogen selectivity (S). The OCs were characterized by XRD, XPS, SEM/EDX-mapping, TEM, and H2-TPR to determine their physicochemical properties. XPS shows the Fe phase highly interacted with the Al2O3 supporting matrix by forming Fe aluminates in NiO–Fe2O3/Al2O3. The S (85.33%) and HL (78.41%) were obtained under the optimal conditions T = 600 °C, S/C = 1.0 mol mol−1 and M = 0. A hydrogen content fluctuation within 4% was obtained under T = 700 °C, S/C = 1.0 mol mol−1, and M = 2.5%, which means the cycle stability is perfect because of the addition of Ni. This study provides a basis for the development of efficient oxygen carriers in the CLSR system.

Performance of Leguminous Crops under Different Tillage Practices in Silty Loam Soil of Balochistan

Balochistan is the province of Pakistan that facing serious issues such assoil erosion, structural instability, and nutrient depletion, and water scarcity, accumulation of excessive salts in soil and low contents of organic matter. Unfortunately, the current exhaustive cropping system and intensive ploughing further promoting the mentioned problems. The following study was designed with the objective i) to evaluate the effects of different tillage and legumes on soil organic carbon dynamic in upland of Balochistan. ii) To compare the outcomes of various tillage practices on legume crop manufacturing in upland of Balochistan. Treatments consist of zero tillage (ZT), minimal tillage (MT) and traditional tillage (CT) and crop become gram develop at some point of summer time season. Experimental results revealed that soil pH under ZT (8.1) MT (8) CT (8); EC under ZT (1.3dsm-1) MT (0.84 dsm-1) CT (0.87 dsm-1); MOC under ZT (0.27%) MT (0.24%) CT (0.25%); POC under ZT (0.45%) MT (0.42%) CT (0.4%), TOC under ZT (0.84%) MT (0.82%) CT (0.78%); OM under ZT (0.7%) MT (0.7%) CT (0.64%); MBC under ZT (0.53%) MT (0.52%) CT (0.46%); Moisture Content under ZT (16.51) MT (15.87) CT (15.16); temperature Under ZT (23.067) MT (22.867) CT (22.733) Plant emergence Under ZT (81.6%) MT (80%) CT (79%); Biological yield Under ZT (0.3933kgm-2) MT (0.38 kgm-2) CT (0.38 kgm-2); Grain Yield under ZT (0.14 kgm-2) MT (0.13 kgm-2) CT (0.12 kgm-2). It is concluded that guar crop germination was a serious problems under all the tillage practices. However, soil properties were improved with reduction of tillage practices especially buildup of organic carbon was observed under zero tillage practices.

Long-Term Integrated Nutrient Management in the Maize–Wheat Cropping System in Alluvial Soils of North-Western India: Influence on Soil Organic Carbon, Microbial Activity and Nutrient Status

Integrated nutrient management (INM) is a widely recognized tool to ensure sustainable crop productivity while preserving soil fertility. The addition of organic manures in soil has been evidenced to improve soil characteristics, in addition to improving nutrient availability. The soil samples, with five treatment combinations of chemical fertilizers with farmyard manure (FYM), were collected from a 17-year-old field experiment conducted at PAU, Ludhiana to investigate the effect of INM on the buildup of organic carbon (OC), microbial community, soil nutrient status and improvement in soil physical properties under the maize–wheat cropping system. The INM technique enhanced the OC content (0.44 to 0.66%), available N (152.8 to 164.9 kg ha−1), P (22.8 to 31.4 kg ha−1) and K (140.6 to 168.0 kg ha−1) after 17 years. The DTPA-extractable and total micronutrients (Zn, Cu, Fe, and Mn) status also improved significantly with FYM supplementation. The organic source, coupled with inorganic fertilizers, improved the water holding capacity, total porosity, soil respiration, microbial biomass C, microbial biomass N, and potentially mineralizable N. However, pH, EC, and bulk density of soil decreased with the addition of FYM, coupled with chemical fertilizers.

Soil carbon-food synergy: sizable contributions of small-scale farmers

BackgroundBenefits to agricultural yield improvement, soil degradation prevention, and climate mitigation are central to the synergies of soil organic carbon (SOC) build-up. However, the contributions of small-scale farmers, the main target of recent agricultural and rural development policies, to SOC enhancement are understudied. Here, we present a global analysis of small-scale farmers’ contributions to the potential of additional SOC stocks and the associated increase in crop production.MethodsWe applied random forest machine learning models to global gridded datasets on crop yield (wheat, maize, rice, soybean, sorghum and millet), soil, climate and agronomic management practices from the 2000s (n = 1808 to 8123). Using the established crop-specific SOC-yield relationships, the potentials of additional SOC build-up and crop production increase were simulated. The estimated SOC increase was converted into global decadal mean temperature change using the temperature sensitivity to cumulative total anthropogenic CO2 emissions from preindustrial levels. The amount of inorganic nitrogen (N) input that would result in the same yield outcome as the SOC build-up was derived from the crop-specific N-yield relationships.ResultsSOC contributes to yields in addition to management and climatic factors. Additional SOC sums up to 12.78 GtC (11.55–14.05 GtC) of global SOC stock, which earns 38.24 Mt (22.88–57.48 Mt) of additional crop production and prevents warming by 0.030 °C (0.019–0.041 °C). This production increase equates to what would be achieved by an inorganic N input of 5.82 Mt N (3.89–7.14 Mt N). Small-scale farmers account for 28% (26–30%) of the additional SOC build-up and 17% (15–20%) of the production increase. Key crops and regions in terms of small-scale farmers’ contributions include Sub-Saharan African maize and rice, Latin American and Caribbean soybean and maize, and South Asian rice and wheat.ConclusionsThe contribution of small-scale farmers to the potential increase in SOC stock and crop production is sizable, which in theory further leads to saving inorganic N input. These findings emphasize the importance of linking soil management to sustainable land and climate mitigation with institutions and policy for small-scale farmers. Such a joint policy would assist multiple development goals.

Fabrication and Characterization of Thin-Film SOFC Supported by Microchannel-Structured Zirconia Substrate for Direct Methane Operation

Ni-cermet anode demonstrates excellent catalytic activity and electrical conductivity but suffers from carbon deposition issue. To utilize Ni-cermet anode while preventing carbon deposition, a synergic strategy is employed to design anode electrode. In particular, Zr is incorporated into Ce0.8Sm0.2O2-δ lattice to tailor oxygen storage and catalytic properties of Ni-Ce0.8-xSm0.2ZrxO2-δ anode for improving electrochemical oxidizations of various fuel species. An inert thick YSZ microtubular substrate with radially well-aligned microchannels open at the inner surface is used to support multi thin functional layers of solid oxide cell, i.e., Ni current collector, Ni-Ce0.8-xSm0.2ZrxO2-δ anode, YSZ/SDC electrolyte, and LSCF cathode. The thick YSZ substrate is able to inhibit the ratio of fuel to product gases in the thin anode functional layer, which favors the prevention of carbon buildup in the thin anode layer when synergistically combined with Ni-Ce0.8-xSm0.2ZrxO2-δ anode material. The microchannels embedded in the YSZ substrate can also avoid too much dilutions of the fuel in the anode functional layer. The cell is fabricated and tested with both hydrogen and methane as the fuel. A short-term test is conducted with methane as fuel and good stability is obtained. The fundamental mechanisms for the prevention of carbon buildup in anode functional layer are also discussed.

Pull-Up Effect Correction and Oil In Place Sensitivity Test by Comparing Velocity Model Method in JAX-Field, Offshore North West Java

The pull-up effect is the condition of lithology elevated in seismic imaging because of rapid seismic wave propagation through carbonate build-up on it. Pull-up effect conditions can lead to misinterpretation, so it needs to be corrected until the actual geological conditions are obtained. This research was conducted in the JAX-field working area of PT Pertamina Hulu Energi ONWJ. The target reservoirs of this study are in the Main (Upper Cibulakan) Formation under the Carbonate Parigi Formation. The reflectors of the target reservoirs show pull-up effect in time domain seismic data. Thus, building a velocity model for velocity anomaly correction is needed to reduce uncertainty for structure maps and oil in place calculation. The method of correcting the pull-up effect in this study uses three variations of the velocity model: variation structurally controlled model, variation RMS velocity with well control, variation calibrated RMS velocities model. The three variations of the velocity model result can correct the pull-up effect on JAX-Field. Velocity model with variation RMS velocity with well control had the lowest error with 17,31 feet average of depth difference with actual depth from well. Based on three velocity models, the value of original oil in place on the JAX-32 reservoir surface had a range of 59,14-84,59 mmbo, while on the JAX-35A surface has a range of 27,77-31,23 mmbo. These values can be considered in reserve calculation sensitivity.

Deep Directional Electromagnetic Technique Improves Well-Drilling Efficiency

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202265, “Leap of Faith From Conventional to EM Look-Ahead: A Game-Changing Technology To Improve Well Efficiency,” by Muhamad Yanuar Mahardi, Hendarsyah Hendarsyah, and Kharisma Endarmoyo, PT Pertamina, et al., prepared for the 2020 SPE Asia Pacific Oil and Gas Conference and Exhibition, originally scheduled to be held in Perth, Australia, 20–22 October. The paper has not been peer reviewed. The structure in the Matindok block in Central Sulawesi operated by Pertamina has proven producible gas reserves in the Minahaki formation. One of the main challenges in this area is the low resolution of seismic data, leading to a high depth uncertainty. The complete paper describes a technology developed to meet these challenges with the capability to map and detect lithology changes ahead of the bit in real time. Geological Background A first exploration well, PEP-001, was drilled in 2018. The structure has a Miocene carbonate buildup play, and the target reservoir is the M pinnacle carbonate reef. The PEP-001 well was planned to set the 9⅝-in. casing point above the top of the M formation. Offset wells did not show any clear markers in the thick shale above the M formation that could have been used for log correlation. In previously drilled offset wells, correlation was performed convention-ally by examination of cutting samples and on drilling breaks. However, when Well PEP-001 was drilled, no apparent drilling break was observed. By the time cuttings reached the surface, the bit had drilled into 20 m of the M formation. Because the casing covered most of the upper carbonate formation, openhole logging and well-testing data were not acquired to delineate the target formation optimally. The second exploration well, PEP-002, was planned with an objective of setting 9⅝-in. casing approximately 5 m above the top of M to acquire full-interval coverage of coring, openhole wireline logging, and well testing. This information was critical for optimal reservoir delineation to allow for accurate reserves calculation and future development. Conventional correlation methods have proven insufficient for casing point placement. The presence of limestone stringers in offset wells within proximity of the top of M presented an additional challenge. The stringers could have been misinterpreted as the main carbonate body, if interpretation were based solely on cutting samples. Real-Time Electromagnetic (EM) Look-Ahead Technology

The multidisciplinary approaches on facies developments and depositional systems of the Bahçecik travertines, Gümü!hane, NE-Turkey

The Bahçecik travertines, located in Gümüşhane (NE-Turkey) have been investigated for the first time using a multidisciplinary approach, which included sedimentological (lithofacies, depositional system), petrographic, radiometric 230Th dating, geochemical analysis (stable isotopes), palynomorphs and geophysics (GPR). A carbonate build-up, 12 m thick, was formed with some interruptions, through the middle Pleistocene period. For this study, two travertine sections (F and D) were extensively used to figure out palaeoenvironmental and palaeoclimatic proxies. The main precipitation cycles, separated by palaeosol levels, have been described and interpreted from a sedimentological perspective. The carbonate deposits consist of shrubs, crystalline crust, reed, laminated (micritic), pisoids, oncoids, calcite thin rafts and coated gas bubbles, lithoclasts, and palaeosol levels. The sedimentological fieldwork and petrographic analysis show that the Bahçecik travertines formed in depression depositional and slope depositional systems. Moreover, the first 230Th ages, stable isotopic results and palynofloral data in this study, prove that the Bahçecik travertines might have been affected by climatic and tectonic interruptions. According to dating results, the travertine occurrences began to precipitate during the 353 ka and continued into the 263 ka. Based on the palynological data, an abundance of herbaceous plants species was recorded in the warming period of climate. The thickness ranges from 2 to 12 m of the Bahçecik travertines. This precise thickness and also the presence of two different travertine formations, separated by a palaeosol erosional surface, were recorded by the ground penetrating radar (GPR) geophysical method.

'Ten Years After'-a long-term settlement and bioerosion experiment in an Arctic rhodolith bed (Mosselbukta, Svalbard).

Rhodolith beds and bioherms formed by ecosystem engineering crustose coralline algae support the northernmost centres of carbonate production, referred to as polar cold-water carbonate factories. Yet, little is known about biodiversity and recruitment of these hard-bottom communities or the bioeroders degrading them, and there is a demand for carbonate budgets to include respective rates of polar carbonate build-up and bioerosion. To address these issues, a 10-year settlement and bioerosion experiment was carried out at the Arctic Svalbard archipelago in and downslope of a rhodolith bed. The calcifiers recorded on experimental settlement tiles (56 taxa) were dominated by bryozoans, serpulids and foraminiferans. The majority of the bioerosion traces (30 ichnotaxa) were microborings, followed by attachment etchings and grazing traces. Biodiversity metrics show that calcifier diversity and bioerosion ichnodiversity are both elevated in the rhodolith bed, if compared to adjacent aphotic waters, but these differences are statistically insignificant. Accordingly, there were only low to moderate dissimilarities in the calcifier community structure and bioerosion trace assemblages between the two depth stations (46 and 127m), substrate orientations (up- and down-facing) and substrate types (PVC and limestone), in that order of relevance. In contrast, surface coverage as well as the carbonate accretion and bioerosion rates were all significantly elevated in the rhodolith bed, reflecting higher abundance or size of calcifiers and bioerosion traces. All three measures were highest for up-facing substrates at 46m, with a mean coverage of 78.2% (on PVC substrates), a mean accretion rate of 24.6gm-2 year-1 (PVC), and a mean bioerosion rate of -35.1gm-2 year-1 (limestone). Differences in these metrics depend on the same order of factors than the community structure. Considering all limestone substrates of the two platforms, carbonate accretion and bioerosion were nearly in balance at a net rate of -2.5gm-2 year-1 . A latitudinal comparison with previous settlement studies in the North Atlantic suggests that despite the harsh polar environment there is neither a depletion in the diversity of hard-bottom calcifier communities nor in the ichnodiversity of grazing traces, attachment etchings and microborings formed by organotrophs. In contrast, microborings produced by phototrophs are strongly depleted because of limitations in the availability of light (condensed photic zonation, polar night, shading by sea ice). Also, macroborings were almost absent, surprisingly. With respect to carbonate production, the Svalbard carbonate factory marks the low end of a latitudinal gradient while bioerosion rates are similar or even higher than at comparable depth or photic regime at lower latitudes, although this might not apply to shallow euphotic waters (not covered in our experiment), given the observed depletion in bioeroding microphytes and macroborers. While echinoid grazing is particularly relevant for the bioerosion in the rhodolith bed, respective rates are far lower than those reported from tropical shallow-water coral reefs. The slow pace of carbonate production but relatively high rates of bioerosion (both promoted by low carbonate supersaturation states in Arctic waters), in concert with high retention of skeletal carbonates on the seafloor and no calcite cements forming in open pore space created by microborers, suggest a low fossilisation potential for polar carbonates, such as those formed in the Mosselbukta rhodolith beds.

Influence of extensional faults and relay ramp on palaeo‐topography and lacustrine carbonate facies: Purbeck Limestone Group (Upper Jurassic – Lower Cretaceous), Wessex Basin, UK

AbstractLacustrine carbonate facies distribution is controlled by multiple environmental parameters including climate, hydrology, and tectonic setting, but few published models address this complexity. In this study, seismic and borehole data, integrated with outcrop logging, correlations, and facies models, are used to create a new tectono‐sedimentary model demonstrating how extensional faults, linked by a relay ramp, control distribution of lacustrine carbonate facies in the Upper Jurassic to Lower Cretaceous Purbeck Limestone Group (Wessex Basin, UK). Accumulation occurred in half‐graben sub‐basins south of two extensional east‐west faults, with widespread subaerial emergence of footwall blocks to the north. The lacustrine limestones of the lowest unit of this Group are characterised by in‐situ microbial mounds within bedded inter‐mound packstones‐grainstones. Mounds occur in three depositional intervals separated by paleosols. The distribution of facies indicates more brackish‐water conditions shoreward to the west, and more hypersaline conditions basinward to the east. The relay ramp hosts extensive microbial carbonate buildups formed in response to carbonate‐rich waters sourced from the northern limestone footwall blocks that fed into extensive shallow‐water areas on the low‐angle relay ramp slope.

Delineation of Carbonate Buildups Using Advanced Seismic Attributes, NW Sirte Basin, Libya

The Paleocene reservoir formations of the Northwest Sirte Basin in North-central, Libya contains chaotic and mound-shaped seismic geometries that may have an impact on the performance of the reservoirs. It is crucial to characterize and interpret these complex geometries for future field development. Therefore, this study was utilized numerous seismic attributes to characterize and enhance the interpretation of the chaotic and mounded geometries. Data conditioning represented by spectral whitening and median filter was first applied to enhance the quality of the seismic data and remove random noise resulted from data acquisition and processing. It provided high-resolution seismic data and better-displayed edges and sedimentological features. Variance, root mean square (RMS), curvature, and envelope attributes were computed from the post-stack 3D seismic data to better visualize and interpret the chaotic and mound-like seismic geometries. Based on the seismic attribute analysis, the chaotic facies were interpreted as barrier reefs forming the margins of an isolated carbonate platform, whereas the small-scale mound-shaped facies was interpreted as patch reefs developed on the platform interior. Data conditioning methods and seismic attribute analysis that were applied to the 3-D seismic data have effectively improved the detection and interpretation of the chaotic and mounded facies in the study area. Keywords: Carbonate buildup, data conditioning, seismic attributes, Sirte Basin, Libya

Highly Dispersed Indium Oxide Nanoparticles Supported on Carbon Nanorods Enabling Efficient Electrochemical CO2 Reduction

Indium‐based materials can selectively reduce CO2 to formate, but their activities still fall short of expectations to be considered for practical applications. Structural engineering at the nanoscale offers a promising solution. However, it is challenging to directly prepare nanostructures of metallic indium because of its low melting point and high oxophilicity. Herein, a strategy to prepare highly dispersed indium oxide nanoparticles as the precatalyst supported on conductive carbon nanorods from annealing the MIL‐68 (In) precursor is proposed. When assessed in an H‐cell, the product enables CO2 reduction to formate with great faradaic efficiency of around 90% over a wide potential window in 0.5 m KHCO3. When applied in a gas‐diffusion‐electrode‐based flow cell, the catalyst delivers large current density of up to 300 mA cm−2 in 1 m KOH, great formate faradaic efficiency and decent stability. These results indicate the commercial viability of the catalyst even though the carbonate buildup at the gas diffusion electrode remains an issue of future research.