Carbonate Deposits Research Articles

Prospects for the use of flow diverter technologies at the Alibekmola oil field

Background: The process of oil production from low-permeability reservoirs has some features and is associated with a number of problems. The main problem is the lack of involvement in the active development of oil reserves in low-permeability zones. Most design documents for the development of low-permeability carbonate reservoirs recommend conventional water injection, which leads to rapid water encroachment of production wells due to water breakthrough from the injection well to the production well through the high-permeability layers or fractures.
 Aim: In the conditions of low-permeability reservoirs of carbonate deposits, there is a need to search for new technologies and development methods that will ensure the economic viability of field development at a late stage.
 Materials and methods: One of the promising technologies that help reduce the level of water cut and involve in the development of an inactive matrix zone low-permeability fractured reservoirs are flow diverter technologies aimed at increasing the sweeping efficiency of productive formations by redistributing filtration flows, reducing or stabilizing water cut, reducing the volume of produced water, obtaining additional oil production.
 Results: This article presents the results of laboratory studies on the selection of optimal flow diverter chemical compositions for the conditions of the Alibekmola oil field.
 Conclusion: Conducted laboratory studies prove the applicability and effectiveness of flow diverter compositions for the conditions of carbonate fractured reservoirs.

Experimental study of carbonate samples dissolution using X-ray microcomputer-based tomography

Background: The study of the interaction of hydrochloric acid with carbonate materialsis important in the oil and gas industry. Carbonate rocks are common rock types, and half of all petroleum reserves worldwide are found in carbonate deposits. Understanding the mechanisms and characteristics of dissolution of carbonate rocks is of great practical importance in the production of hydrocarbons and the injection of carbon dioxide into formations.
 Aim: The purpose of this article is to study the dissolution processes of carbonate samples in laboratory conditions using X-ray microcomputer-based tomography.
 Materials and methods: The study used 5 cylindrical carbonate samples, which were tested during the injection of hydrochloric acid solutions. Additional experimental and digital data from 8 samples are also used. The three-dimensional pore space of the samples was obtained using specialized software based on tomographic images.
 Results: The results obtained demonstrate the significance of the use of X-ray computed tomography for a deeper understanding of dissolution processes in geological and engineering studies. The study highlighted the complexity of the rock dissolution process, which depends on many factors. The created three-dimensional models of the samples allowed us to visualize wormholes, including branched and dominant wormholes. 3D imaging provided valuable information about changes in the pore structure of the samples before and after acid exposure.
 Conclusion: The results of this study highlight the importance of considering physical and structural properties when analyzing dissolution processes in carbonate samples. These data can have practical applications in the oil and gas industry, contributing to a more accurate understanding and optimization of the processes of interaction of acid solutions with carbonate samples.

Immobilized Tetraalkylammonium Cations Enable Metal-free CO2 Electroreduction in Acid and Pure Water.

Carbon dioxide reduction reaction (CO2 RR) provides an efficient pathway to convert CO2 into desirable products, yet its commercialization is greatly hindered by the huge energy cost due to CO2 loss and regeneration. Performing CO2 RR under acidic conditions containing alkali cations can potentially address the issue, but still causes (bi)carbonate deposition at high current densities, compromising product Faradaic efficiencies (FEs) in present-day acid-fed membrane electrode assemblies. Herein, we present a strategy using a positively charged polyelectrolyte-poly(diallyldimethylammonium) immobilized on graphene oxide via electrostatic interactions to displace alkali cations. This enables a FE of 85 %, a carbon efficiency of 93 %, and an energy efficiency (EE) of 35 % for CO at 100 mA cm-2 on modified Ag catalysts in acid. In a pure-water-fed reactor, we obtained a 78 % CO FE with a 30 % EE at 100 mA cm-2 at 40 °C. All the performance metrics are comparable to or even exceed those attained in the presence of alkali metal cations.

Immobilized Tetraalkylammonium Cations Enable Metal‐free CO2 Electroreduction in Acid and Pure Water

AbstractCarbon dioxide reduction reaction (CO2RR) provides an efficient pathway to convert CO2 into desirable products, yet its commercialization is greatly hindered by the huge energy cost due to CO2 loss and regeneration. Performing CO2RR under acidic conditions containing alkali cations can potentially address the issue, but still causes (bi)carbonate deposition at high current densities, compromising product Faradaic efficiencies (FEs) in present‐day acid‐fed membrane electrode assemblies. Herein, we present a strategy using a positively charged polyelectrolyte—poly(diallyldimethylammonium) immobilized on graphene oxide via electrostatic interactions to displace alkali cations. This enables a FE of 85 %, a carbon efficiency of 93 %, and an energy efficiency (EE) of 35 % for CO at 100 mA cm−2 on modified Ag catalysts in acid. In a pure‐water‐fed reactor, we obtained a 78 % CO FE with a 30 % EE at 100 mA cm−2 at 40 °C. All the performance metrics are comparable to or even exceed those attained in the presence of alkali metal cations.

Local deposition characteristics of calcium carbonate fouling in different enhanced tubes

With the development and advancements of modern industry, the application of enhanced tubes is becoming more and more extensive in various engineering domains and technological applications. When water is used as the working fluid for thermal energy utilization, there is a large chance of accumulating a large amount of fouling on the surface of the enhanced tubes. This paper establishes a mathematical model of the local fouling deposition of calcium carbonate in enhanced tubes. The model is used to simulate and compare the local fouling characteristics of CaCO3 in different tubes. In addition, a study is conducted on the effects of different inlet flow rates, water temperature, and calcium carbonate concentrations on the local fouling resistance of bellows tubes. The results showed that the local fouling resistance (average) and local fouling resistance of enhanced tubes is smaller than that of circular tubes. Additionally, the bellows tubes yielded the best scale inhibition effect. The obtained local fouling resistance is also found to change periodically along the length of the tube. The local fouling resistance decrease with an increase in the inlet flow rate and wall temperature, and increases with an increase in the calcium carbonate solution concentration.

The role of electrical current mode in calcium carbonate deposition on conductive carbon nanofiber–epoxy coating

AbstractCalcium carbonate is one of the most common scaling minerals. In this paper we have used different electrical current modes (direct current [DC], pulsed DC, and alternating current [AC]) to control the amount, morphology, and distribution of calcium carbonate deposit on electroconductive epoxy/carbon nanofiber (CNF) coating. The effect of different current modes on surface scaling was visualized using scanning electron microscopy. It has been shown that both AC and DC anodic polarization limited scale deposition on epoxy/CNF coated surfaces, although the mechanisms of scale inhibition during AC and DC polarization were different. DC polarization of the coating at +2 V resulted in the smallest scale buildup without leading to coating degradation, while DC polarization at potentials as high as +5 V caused the coating to degrade. Interestingly, application of pulsed DC with high pulse frequency (50 Hz) inhibited the degradation. The type of current applied affected also the morphology of the precipitate at the cathode. The results presented in this work show, for the first time, how different modes of electrical current applied to electroconductive composite coatings can be used to control the morphology and distribution of calcium carbonate scale, and how the organic coating degradation at high polarization potentials can be avoided.

Assessing the performance of metakaolin-enriched bio-mineralized concrete

This research paper delves into an innovative approach leveraging pozzolanic material, particularly Metakaolin (MK), as a sustainable substitute for cement in concrete production. The study explores the integration of MK at various ratios, examining its impact on the creation of eco-friendly bio-mineralized concrete. By assessing MK ratios up to 15% by weight of cement, this work identifies a threshold—10% MK—that significantly enhances concrete properties, notably reducing permeability by 23.63% at 28 days. Incorporating bacteria at a concentration of 10^5 cfu/ml further amplifies these benefits, showcasing a 19% increase in compressive strength and a remarkable 43.23% reduction in permeability through calcium carbonate deposition. This synergy between MK and bio-mineralization not only fortifies concrete but also curtails cement content while maintaining or even enhancing its durability and strength. The research underscores the potential of MK and bio-mineralization as game-changing, eco-conscious solutions for concrete manufacturing, advocating for their adoption in construction to mitigate cement's environmental impact and address waste disposal, ultimately fostering sustainable growth in the industry. The study's findings spotlight a paradigm shift toward integrating biological processes into construction engineering, paving the way for a greener, more resilient built environment.

Discriminating organic carbon from endokarstic moonmilk-type deposits by LIBS. The case of a natural carbonated Martian analogue

Moonmilk-type deposits exemplify carbonated Martian analogues existing in the subsurface of Earth, an endokarstic speleothem with a possible biochemical origin composed principally by carbonates, mainly huntite and dolomite. In this work, samples of moonmilk located in Nerja Cave (southern Spain) have been studied by LIBS with the aim of identifying carbon of biogenic origin by establishing a relationship between a molecular emission indicator, CN signal, and the organic carbon content. The characterization of this kind of carbonate deposit with a multiple mineralogical composition has been completed using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction techniques for qualitative and semi-quantitative analysis. The information attained from LIBS regarding energy thresholds and time-resolved kinetics of CN emissions provides useful insight into the identification of different molecular emitters, namely organic and inorganic CN, depending on the laser irradiance and time settings conditions. These promising results are of application in the search and identification of biosignatures in upcoming planetary missions with astrobiological purposes.

CPPD and Associated Crystals in Clinically Diagnosed Chondrocalcinosis: A Clinicopathological Study of 20 Patients

Introduction: Chondrocalcinosis (Ch-C), induced by calcium pyrophosphate dihydrate crystals (CPPD) [Ca2P2O7.2H2O] is considered as a distinct metabolic disease and a well-defined clinical entity, with characteristic clinical manifestations and symptoms. This study used previously found method by the author .i.e, non-staining approach to discover crystal deposits in patients with clinically diagnosed Ch-C, to find a possible correlation between coexisting crystals, and to assess the role of coexistent crystals in inflammatory cellular processes of joints. Patients and methods: There were forty (40) surgical specimens that had been traditionally processed from 16 patients who had been clinically diagnosed with Ch-C. Results: In unstained tissue sections CPPD crystals were found in 22 of 40 samples of all 16 patients. Beside the CPPD crystals calcium hydroxyapatite (HA) [Ca5(PO4)3(OH)] crystals were found in 26 tissue samples of all 16 patients, cholesterol (CC) [C27H46O] in 23 tissue samples of 12 patients, and crystalline liquid lipid droplets (CL) in 11 tissue samples of 5 patients. More or less amorphous deposits of calcium carbonate [CaCO3] and/or calcium phosphate [Ca3(PO4)2] were present alongside CPPD and the contemporaneous crystals. There was a significant and positive correlation between prevalence of CPPD and HA. The connection between inflammatory cellular infiltration and CPPD, HA, CC or CL crystals surrounded by mineral deposits was not significant. Conclusions: The non-staining approach is a practical, low-tech way to find CPPD, HA, CC, and other crystals (with or without CL). The positive and significant correlation between CPPD and HA support the earlier premise that CPPD and HA represent basically an identical metabolic disorder). CPPD and/or HA crystals can provoke inflammatory processes responsible for the clinical symptoms, but the variable amounts of amorphous minerals enclose (isolate) the crystals, and can reduce or eliminate the inflammatory reaction. The authors assume that CC (with or without CL) is an associated phenomenon (concomitant fat metabolic malady) without direct cause of inflammation, and is not responsible for clinical symptoms of crystal induced arthropathies.

Climate monitoring in the Caumont cave and quarry system (northern France) reveal near oxygen isotopic equilibrium conditions for carbonate deposition

The study of modern cave deposits forming under near isotopic equilibrium conditions can potentially help disentangle the processes influencing the oxygen isotope system and suitability of stalagmites as archives of past hydrological or thermal changes. We used cave monitoring to evaluate the impact of kinetic isotope fractionation and assess the conditions under which modern cave carbonates form in the Caumont cave and quarry system, located in Normandy, northwest France. Over 20 months, we collected climatological data, dripwater, and modern carbonate samples at 2–4-week intervals at three different stations inside the Caumont cave and quarry system. We find highly stable (10.4 ± 0.3°C – 11.3 ± 0.1°C) temperature in the deeper sections of the Caumont cave and quarry system. The temporal dynamics of δ18Odrip indicates that the drip water composition in Caumont reflects the original (though subdued) signal of precipitation, rather than the impact the seasonal to interannual cave air temperature has on isotopic fractionation. The monitoring reveals that δ13C of modern carbonate is influenced by prior carbonate precipitation that occurs during the summer season when evapotranspiration can minimize effective infiltration. Comparison of δ18O from dripwater and modern calcite, precipitated on glass plates and collected every two to four weeks, reveals that modern calcite forms near oxygen isotope equilibrium. A Hendy test on modern carbonate deposited on a stalagmite-shaped glass flask over 20 months confirms this finding because neither does δ13C increase with distance from the apex, nor are δ13C and δ18O positively correlated. We conclude that the δ13C signal in speleothems reflect summer (and longer-term) prior carbonate precipitation in response to effective infiltration dynamics, and that the δ18O signal likely reflects annual to multi-annual changes in the composition of precipitation above the cave.

Brazil Margin Stable Isotope Profiles for the Last Glacial Cycle: Implications for Watermass Geometry and Oceanic Carbon Storage

AbstractVertical profiles of benthic foraminiferal oxygen and carbon isotopes (δ18O and δ13C) imply the volume of southern source water (SSW) in the Atlantic basin expanded during the Last Glacial Maximum. Shoaling of the boundary between SSW and northern source water (NSW) may reduce mixing between the two watermasses, thereby isolating SSW and enhancing its ability to store carbon during glacial intervals. Here we test this hypothesis using profiles of δ18O and δ13C from the Brazil Margin spanning the last glacial cycle (0–150 ka). Shoaling of the SSW‐NSW boundary occurred during Marine Isotope Stage (MIS) 2, 4, and 6, consistent with expansion of SSW and greater carbon sequestration in the abyss. But the watermass boundary also shoaled during MIS 5e, when atmospheric CO2 levels were comparable to MIS 1. Additionally, we find there was little change in watermass structure across the MIS 5e‐d transition, the first major decline in CO2 of the last glacial cycle. Thus, the overall pattern in glacial‐interglacial geometry is inconsistent with watermass mixing acting as a primary control on atmospheric pCO2. We also find that δ13C values for MIS 5e are systematically lower than MIS 1, with the largest difference (∼1‰) occurring in the upper water column. Low δ13C during MIS 5e was most likely due to a long‐term imbalance in weathering and deposition of calcium carbonate or input of 13C‐depleted carbon from a reservoir external to the ocean‐atmosphere system.

Seismic and stratigraphic characterization of karstogenic horizons in a sequence of carbonate deposits: Example of the Dogger limestones of the Poitou threshold

The Deffend Hydrogeological Experimental Site (HES), near Poitiers, has been the site of numerous studies that have shown that the Bajocian and Aalenian limestones were modified by the horizontal development of multiple karstification planes. These investigations have demonstrated the occurrence of stacked circulation. The origin of the structures that generated these sub-horizontal flows has not been specifically explained. Geophysical investigations were conducted at the site, both at the surface (3D seismic) and in wells (vertical seismic profile (PSV) and acoustic logging). Comparison of the geophysical data, mainly acoustic logs, and a stratigraphic interpretation of cuttings and borehole wall imaging makes it possible to propose a coherent karstogenesis scheme that does not involve tectonic constraints. This article offers an explanation based on gaps recorded in the sequence of Dogger deposits. The karstogenic horizons are linked to sedimentary discontinuities that geologists have identified on the Poitou threshold.

Dasycladalean algae from Middle-Upper Triassic limestones of North Dobrogea (SE Romania)

The Triassic carbonate deposits are widely distributed in North Dobrogea (SE Romania) mainly within the Tulcea Nappe. Within this structural unit, the carbonate facies reveals an eastward-westward transition from shallow-water to basin facies. The shallow-water limestones were studied in three areas (Murighiol-Dealul Duna, Dunavatu de Sus and Enisala) in order to identify and describe the algal flora. In this paper we describe the assemblage of dasycladalean green algae. Thirteen species were identifi ed, out of which nine are also known from other parts of the Alpine-Carpathian or Dinaric areas (Macroporella alpina, Poncetella hexaster, Neophysoporella lotharingica, Ardeiporella cf. karrerioidea, Poikiloporella duplicata, Probolocuspis cf. hydrae, Salpingoporella sturi, S. cf. triasica and Clypeina besici). Three species are new (Pseudodiplopora ioanaletitiae n. sp., Julpiaella baltresi n. sp. and Acicularia claudiopolitana n. sp.) and one species (Ioanella dobrogiaca) was already the subject of a previous work. This is the richest assemblage of calcareous dasycladalean algae described so far from the Triassic of Dobrogea. In addition, the Clypeina besici-Poikiloporella duplicata association is also important for age constraints because it is characteristic for the Carnian stage.

ОПРЕДЕЛЕНИЕ ПРОИЗВОДИТЕЛЬНОСТИ КАРЬЕРОВ ЦЕМЕНТНОЙ ПРОМЫШЛЕННОСТИ, РАЗРАБАТЫВАЮЩИХ МИНЕРАЛЬНОЕ СЫРЬЕ С ИСПОЛЬЗОВАНИЕМ КОМБАЙНОВ ПОСЛОЙНОГО ФРЕЗЕРОВАНИЯ SM

Introduction. The relevance of the study is due to the need to optimize technological processes in quarries for cement raw materials and increase the reliability and economic efficiency of deposit development. Surface Miner (SM) layer milling machines, allow carrying out thin-layer mining of deposits, to conduct rational use of subsoil, to increase industrial safety. During open-cast mining of cement raw materials deposits using layer milling machines (SM), the increase of economic efficiency of mining works may be achieved by determining rational values of parameters and indicators of the open cast mine. The main aim. To determinate the optimum productivity of cement industry quarries developed with layer milling machines (SM) ensuring increased reliability and economic efficiency of deposit development. Methodology. As the basic methods of research, we used monitoring of technological processes of the quarry, systematic analysis of the structure, characteristics, properties of technological complexes and links of quarries of cement plant Beocin (Serbia) developing complex structure carbonate deposits with the use of layer-milling machines. Dependence of duration of dump truck rides, number of rides per shift and number of dump trucks for 1 milling machine on the distance of rock mass transportation for mining-technical conditions of the quarries at the cement plant Beocin (Serbia) has been determined. Conclusions. Application of (SM) surface miners at cement industry open-pit mines ensures thin-layer mining of rock mass, reduction of ore losses and emissions of pollutants, rational use of subsoil, increase of industrial safety. Number of factors influences Surface Miner productivity: speed of the machine moving in the process of milling, width of the milling band, thickness of the mined layer, physical and mechanical characteristics of the mined rock and applied technological scheme. It is shown that the increase of Surface Miner productivity is achieved when the length of the front is increased, when the cyclic-continuous and continuous technology of deposit mining is used, and the auxiliary technological processes are minimized.

Assessment of inhibitor protection efficiency of oilfield equipment from salt deposits

In the field development practice, the most common method for protecting oilfield equipment and pipeline surfaces from inorganic salt deposits is inhibitor protection. To enhance prevention efficiency, a salt deposit inhibitor has been developed, which contains a surfactant, acid, and anionic polymer. The aim of this development is to eliminate the need for scarce and expensive reagents, increase formation productivity by preventing the formation of inorganic deposits during the treatment of carbonate and terrigenous productive formations, and eliminate contamination of formation and downhole equipment by insoluble salts, as well as salt deposits in pipeline systems. Samples prepared at a flow rate of 10-30 g/t demonstrated a high inhibitor effect in preventing calcium sulphate and carbonate deposition. Field tests of the developed salt deposition inhibitor yielded positive results. Keywords: Salt deposition inhibitor; Adsorptiondesorption properties; Inhibition efficiency; Calcium sulfate; Calcium carbonate; Field tests.

Study of vertical electrical resistance changes in reservoir beds of Tournaisian oil deposits

The article proposes a method for rapid assessment of the initial position of oil-water contacts, oxidized oil zones, transition zones, zones of high and decreasing resistance in the Lower Carboniferous Tournaisian oil deposits at one of the oilfields of the Republic of Tatarstan. As initial data, the values of electrical resistivity of effective interlayers from the catalog of geological and geophysical data, determined from induction logging curves, were used. Well log data for more than 200 wells drilled in elevation areas were used in analysis. The change in the electrical properties of deposits vertically is considered using the average resistivity values of effective interlayers averaged over all wells. Conclusions are based on the results of the done work: according to the resistivity values in massive carbonate deposits of the Tournaisian age, it is possible to distinguish various zones of oil saturation along the vertical; initial oil saturation does not grow exponentially, as in the Leverett function, but linearly in each zone.

Enhancing concrete resilience and sustainability through fly ash-assisted microbial biomineralization for self-healing: From waste to greening construction materials

This study presents a pioneering approach that enables remarkable crack closure up to 0.8 mm through stimulated biomineralization aiming to enhance the self-healing capacity of concrete. The innovative synergy tackles the pressing environmental challenges head-on investigates the intriguing germination process of endospores in a cementitious environment and underscores the function of calcareous fly ash in promoting Microbially Induced Calcium Carbonate Precipitation (MICP) by providing additional Ca2+ ions, that are converted into carbonate phases through bacterial metabolic processes. These phenomena are thoroughly examined using an in-situ model particularly concerning MICP in bio-concrete, and thermodynamic modelling is performed to forecast the influence of fly ash on the quantity of Ca-bearing (carbonation sensitive) phases present in the hydrated phases of fly ash-blended cement system. Incorporating 30 % class C fly ash significantly amplifies the biomineralization activity, with 6.5 % calcium carbonate deposition in bio-concrete leds to significant healing activity. Concurrently, MICP contributes to a significant reduction in pore sizes, thereby enhancing the overall durability of concrete. Beyond structural improvements, this innovative bio-concrete formulation showcases an impressive 39 % reduction in CO2 emissions, aligning with sustainability goals. Additionally, repurposing fly ash, typically consigned to landfills, seamlessly adheres to the tenets of a circular economy, despite incurring a 7 % rise in the initial production cost. That promising advanced methodology can deliver transformative environmental benefits, ushering in a paradigm shift in sustainable construction practices, and finding the synergistic interplay between microbial activity and calcium-dependent fly ash.

The deposition of lanthanum carbonate may activate macrophages to induce gastrointestinal mucosal injury in patients with chronic kidney disease: an in vitro caco-2/THP-1 macrophage coculture model study.

The aim of this study was to investigate the effect and possible underlying mechanism of La2(CO3)3 deposition on GI mucosal inflammation. Our results showed that La2(CO3)3 can dissolve in artificial gastric fluids and form lanthanum phosphate (LaPO4) precipitates with an average size of about 1μm. To mimic the intestinal mucosa and epithelial barrier, we established a Caco-2/THP-1 macrophage coculture model and a Caco-2 monoculture model, respectively. Our findings demonstrated that the medium of THP-1 macrophages stimulated by LaPO4 particles can damage the Caco-2 monolayer integrity in the coculture model, while the particles themselves had no direct impact on the Caco-2 monolayer integrity in the monoculture model. We measured values of trans-epithelial electrical resistance and detected images using a laser scanning confocal microscope. These results indicate that continuous stimulation of LaPO4 particles on macrophages can lead to a disruption of intestinal epithelium integrity. In addition, LaPO4 particles could stimulate THP-1 macrophages to secrete both IL-1β and IL-8. Although LaPO4 particles can also promote Caco-2 cells to secrete IL-8, the secretion was much lower than that produced by THP-1 macrophages. In summary, the deposition of La2(CO3)3 has been shown to activate macrophages and induce damage to intestinal epithelial cells, which may exacerbate inflammation in patients with chronic kidney disease. Therefore, patients taking lanthanum carbonate, especially those with gastrointestinal mucosal inflammation, should be mindful of the potential for drug deposition in the GI system.

Mass Transport in a Gas-Fed CO2 Electrolyzer with a Forward-Bias Bipolar Membrane

In the context of synthetic fuel and chemical production, CO2 electrolyzers using bipolar membranes (BPM) in forward bias have proven to overcome current limitations in state-of-the-art alkaline CO2 electrolyzers. These limitations are CO2 cross-over and carbonate deposition in the cathode catalyst layer, which limit the large-scale development of alkaline CO2 electrolyzers. Devices with a BPM in forward bias (Figure 1) solve these issues by setting the anode under acidic conditions while keeping the cathode alkaline. This configuration prevents carbonate ions to reach the anode and thus suppresses CO2 cross-over. Moreover, it allows pure water as an anolyte. Pure water eradicates unwanted cation cross-over and thus prevents carbonate deposition at the cathode. However, the use of a BPM for CO2 also has limitations. The most prominent ones are low stability and high over-voltage. These are partly caused by the complex and unexplored water transport.This work presents efforts to characterize and optimize different water transport phenomena. For this, we study cells of different complexity. It implies understanding first the water diffusion across the membrane, by setting a water concentration gradient between the electrodes and analyzing water transport by dew point measurement. The membrane hydration state can be determined with the simultaneously measured ion conductivity. Then, the water transport of a full cell is measured in parallel to its electrochemical performance. In this setup, a gas chromatograph and a mass spectrometer measure the selectivity of the cathode reaction.The optimal conditions at the cathode are a subtle balance between excess and scarcity of water. Water is a reactant in the CO2 reduction reaction and helps to humidify the membrane, ensuring good ionic conductivity. Additionally, water is formed by ion recombination at the BPM junction affecting the membrane hydration state. Still, we observe that the water supply at the cathode can be insufficient, especially at high current density. However, too much water can flood the cathode and block CO2 transport to the catalyst layer.In summary, we deliver a clearer picture of the water paths and demonstrate that optimized material and operating conditions help to overcome current limitations. Figure 1

Late Cretaceous (Cenomanian-Turonian) temperature evolution and biotic response in the Adriatic Carbonate Platform region of Friuli, northeast Italy

Climate modelling and palaeotemperature reconstructions derived from several proxies (TEX86, δ18O) suggest that the Late Cretaceous was one of the warmest intervals in Earth history. The greenhouse climate reached its acme near the Cenomanian-Turonian boundary (CTB) interval with sea surface temperatures over 35 °C in low and mid- palaeolatitudes, coinciding with the highest sea level stands of the Phanerozoic. Following this warming phase, a general cooling trend punctuated by short-term hot snaps characterized the rest of the Cretaceous. Palaeotemperature and palaeoenvironmental changes are well documented in deep-water carbonate deposits based on variations in geochemical proxies and distribution patterns of macro- and microfauna. However, such climatic and environmental fluctuations severely impacted carbonate platforms, sedimentary environments that are particularly sensitive to external perturbations. Palaeontological data show major changes within the main carbonate platform producers (rudists and benthic foraminifera) during the early Late Cretaceous. Both groups experienced major taxonomic turnovers at the CTB, followed by a further re-radiation in the middle/late Turonian. The lack of detailed palaeoclimatic reconstructions in shallow water carbonate succession hampers the possibility to investigate a possible causal relationship between temperature changes and faunal evolution. In this paper, we report integrated geochemical, sedimentological, and palaeontological data from the Adriatic Carbonate Platform (Friuli, north-east Italy). Benthic foraminifera biostratigraphy and isotope stratigraphy (δ13C and 87Sr/86Sr) were used to precisely constrain the stratigraphy of the late Cenomanian-middle Turonian interval. δ18O analysis on both well-preserved rudist shells and bulk rock samples enabled the construction of high-resolution palaeotemperature curves. The resulting temperature trends are comparable with those from the deep-water record across the late Cenomanian-Turonian interval. The warmest phase was in the Early Turonian with sea surface palaeotemperatures as high as 41–45 °C recorded in rudist shells. Data show temperature fluctuation from the late Cenomanian to the Early Turonian with a magnitude >7 °C. Benthic foraminifera and rudist evolution responded to these palaeotemperature fluctuations, and their decline in the late Cenomanian and full recovery in the Turonian suggest a strong link with temperature changes.