Articles de revues : « CO2 vents »

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Zitoun, R., S. D. Connell, C. E. Cornwall, K. I. Currie, K. Fabricius, L. J. Hoffmann, M. D. Lamare et al. « A unique temperate rocky coastal hydrothermal vent system (Whakaari–White Island, Bay of Plenty, New Zealand) : constraints for ocean acidification studies ». Marine and Freshwater Research 71, n^o 3 (2020) : 321. http://dx.doi.org/10.1071/mf19167.

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In situ effects of ocean acidification are increasingly studied at submarine CO2 vents. Here we present a preliminary investigation into the water chemistry and biology of cool temperate CO2 vents near Whakaari–White Island, New Zealand. Water samples were collected inside three vent shafts, within vents at a distance of 2m from the shaft and at control sites. Vent samples contained both seawater pH on the total scale (pHT) and carbonate saturation states that were severely reduced, creating conditions as predicted for beyond the year 2100. Vent samples showed lower salinities, higher temperatures and greater nutrient concentrations. Sulfide levels were elevated and mercury levels were at concentrations considered toxic at all vent and control sites, but stable organic and inorganic ligands were present, as deduced from Cu speciation data, potentially mediating harmful effects on local organisms. The biological investigations focused on phytoplankton, zooplankton and macroalgae. Interestingly, we found lower abundances but higher diversity of phytoplankton and zooplankton at sites in the direct vicinity of Whakaari. Follow-up studies will need a combination of methods and approaches to attribute observations to specific drivers. The Whakaari vents represent a unique ecosystem with considerable biogeochemical complexity, which, like many other vent systems globally, require care in their use as a model of ‘future oceans’.

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Lauritano, C., M. Ruocco, E. Dattolo, M. C. Buia, J. Silva, R. Santos, I. Olivé, M. M. Costa et G. Procaccini. « Response of key stress-related genes of the seagrass Posidonia oceanica ; in the vicinity of submarine volcanic vents ». Biogeosciences Discussions 12, n^o 6 (30 mars 2015) : 4947–71. http://dx.doi.org/10.5194/bgd-12-4947-2015.

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Abstract. Submarine volcanic vents are being used as natural laboratories to assess the effects of CO2 on marine organisms and communities, as this gas is the main component of emissions. Seagrasses should positively react to increased dissolved carbon, but in vicinity of volcanic vents there may be toxic substances, that can have indirect effects on seagrasses. Here we analysed the expression of 35 stress-related genes in the Mediterranean keystone seagrass species P. oceanica in the vicinity of submerged volcanic vents located in the Islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR) was used to characterize the expression levels of genes. Fifty one per cent of genes analysed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls both in Ischia and Panarea locations, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The expression levels of genes involved in free radical detoxification indicate that, in contrast with Ischia, P. oceanica at the Panarea vent face stressors that result in the production of reactive oxygen species triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. Overall, our study reveals that P. oceanica is generally under higher stress in the vicinity of the vents at Panarea than at Ischia, possibly resulting from environmental and evolutionary differences existing between the two volcanic sites. This is the first study analysing gene responses in marine plants living near natural CO2 vents and our results call for a careful consideration of factors, other than CO2 and acidification, that can cause stress to seagrasses and other organisms near volcanic vents.

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Sharma, S., et D. G. Williams. « Carbon and oxygen isotope analysis of leaf biomass reveals contrasting photosynthetic responses to elevated CO2 ; near geologic vents in Yellowstone National Park ». Biogeosciences Discussions 5, n^o 5 (17 septembre 2008) : 3825–43. http://dx.doi.org/10.5194/bgd-5-3825-2008.

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Abstract. In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP) in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C) analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine) and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax) was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate photosynthetic responses of these plants to naturally elevated atmospheric CO2 concentrations. The coupled shifts in carbon and oxygen isotope values suggest that dalmation toadflax responded to elevated CO2 exposure by increasing stomatal conductance with no change in photosynthetic capacity and lodgepole pine apparently responded by decreasing stomatal conductance and photosynthetic capacity. Lodgepole pine saplings exposed to elevated levels of CO2 likewise had reduced leaf nitrogen concentrations compared to plants with no enhanced CO2 exposure, further suggesting that this widespread and dominant conifer down-regulated photosynthetic capacity under elevated CO2 levels near geologic vents.

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Sharma, S., et D. G. Williams. « Carbon and oxygen isotope analysis of leaf biomass reveals contrasting photosynthetic responses to elevated CO2 ; near geologic vents in Yellowstone National Park ». Biogeosciences 6, n^o 1 (7 janvier 2009) : 25–31. http://dx.doi.org/10.5194/bg-6-25-2009.

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Abstract. In this study we explore the use of natural CO2 emissions in Yellowstone National Park (YNP) in Wyoming, USA to study responses of natural vegetation to elevated CO2 levels. Radiocarbon (14C) analysis of leaf biomass from a conifer (Pinus contortus; lodgepole pine) and an invasive, non-native herb (Linaria dalmatica; Dalmation toadflax) was used to trace the inputs of vent CO2 and quantify assimilation-weighted CO2 concentrations experienced by individual plants near vents and in comparable locations with no geologic CO2 exposure. The carbon and oxygen isotopic composition and nitrogen percent of leaf biomass from the same plants was used to investigate photosynthetic responses of these plants to naturally elevated atmospheric CO2 concentrations. The coupled shifts in carbon and oxygen isotope values suggest that dalmation toadflax responded to elevated CO2 exposure by increasing stomatal conductance with no change in photosynthetic capacity and lodgepole pine apparently responded by decreasing stomatal conductance and photosynthetic capacity. Lodgepole pine saplings exposed to elevated levels of CO2 likewise had reduced leaf nitrogen concentrations compared to plants with no enhanced CO2 exposure, further suggesting widespread and dominant conifer down-regulated photosynthetic capacity under elevated CO2 levels near geologic vents.

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Nike Bianchi, Carlo, Paul R. Dando et Carla Morri. « Increased diversity of sessile epibenthos at subtidal hydrothermal vents : seven hypotheses based on observations at Milos Island, Aegean Sea ». Advances in Oceanography and Limnology 2, n^o 1 (17 juin 2011) : 1. http://dx.doi.org/10.4081/aiol.2011.5314.

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Research on subtidal hydrothermal vent ecosystems at Milos, Hellenic Volcanic Arc (Aegean Sea), suggested that vent activity increased the species richness of sessile epibenthic assemblages. Based on 303 species found in 6 sites (3 close to vents, 3 farther away), the present paper uses correspondence analysis and species/samples curves to examine the species composition and richness of these assemblages. Differences due to vent proximity were more important than those due to bottom depth and distance from the shore. Diversity was confirmed to be higher near the vents, although none of the 266 species found at the vent sites can be considered as obligate vent-associated species. Seven different, although not mutually exclusive, hypotheses are discussed to explain the pattern of increased epibenthic species diversity at the vent sites, namely: (i) vents represent an intermediate disturbance, inducing mortality by the emission of toxic fluids; (ii) higher winter temperature allows for the occurrence of warm-water species, which add to the regional background; (iii) venting disrupts the homogeneity of the water bottom layer, increasing bottom roughness and hence habitat heterogeneity; (iv) deposition of minerals and enhanced bioconstruction by Ca enrichment increment habitat provision; (v) fluid emission induces advective mechanisms that favour recruitment; (vi) vents emit CO2, nutrients and trace elements that enhance primary productivity; and (vii) bacterial chemosynthesis add to photosynthesis to provide a diversity of food sources for the fauna.

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Nurmalisa, Moliya, Takayuki Tokairin, Tadashi Kumazaki, Kotaro Takayama et Takanobu Inoue. « CO2 Distribution under CO2 Enrichment Using Computational Fluid Dynamics Considering Photosynthesis in a Tomato Greenhouse ». Applied Sciences 12, n^o 15 (1 août 2022) : 7756. http://dx.doi.org/10.3390/app12157756.

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This study validated the CO2 distribution predicted by a computational fluid dynamics model considering CO2 absorption by photosynthesis in a chamber and greenhouse. The effect of photosynthesis with CO2 emission from a perforated tube remains not fully understood, although previous studies on CO2 distribution in greenhouses have been conducted. Moreover, comparisons between CO2 concentration measurement and simulation were obtained in the chamber and greenhouse model. Cases with open and closed side vents of the greenhouse showed that closed side vents have slightly more even of CO2 concentration than those with open side vents inside the greenhouse. In contrast, the coefficient of variance (CV) of CO2 inside the plant, open (8.8%) and closed (8.7%) side vents, induced almost no significant improvement. Additionally, cases of a rainy- and sunny-day model showed that photosynthetically active radiation possibly compensated CO2 absorption through photosynthesis to be low at low light (rainy day) and higher at high light (sunny day). Nonetheless, the variability of CO2 concentration inside the plant between rainy and sunny days determined almost no significant difference. Thus, this research shows characteristics of CO2 distribution, assessing photosynthesis and the variability of CO2 concentration that leads to the efficiency of CO2 enrichment in the greenhouse.

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Lauritano, C., M. Ruocco, E. Dattolo, M. C. Buia, J. Silva, R. Santos, I. Olivé, M. M. Costa et G. Procaccini. « Response of key stress-related genes of the seagrass Posidonia oceanica ; in the vicinity of submarine volcanic vents ». Biogeosciences 12, n^o 13 (15 juillet 2015) : 4185–94. http://dx.doi.org/10.5194/bg-12-4185-2015.

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Abstract. Submarine volcanic vents are being used as natural laboratories to assess the effects of increased ocean acidity and carbon dioxide (CO2) concentration on marine organisms and communities. However, in the vicinity of volcanic vents other factors in addition to CO2, which is the main gaseous component of the emissions, may directly or indirectly confound the biota responses to high CO2. Here we used for the first time the expression of antioxidant and stress-related genes of the seagrass Posidonia oceanica to assess the stress levels of the species. Our hypothesis is that unknown factors are causing metabolic stress that may confound the putative effects attributed to CO2 enrichment only. We analyzed the expression of 35 antioxidant and stress-related genes of P. oceanica in the vicinity of submerged volcanic vents located in the islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) was used to characterize gene expression patterns. Fifty-one percent of genes analyzed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls at both Ischia and Panarea, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The up-regulation of genes involved in the free radical detoxification response (e.g., CAPX, SODCP and GR) indicates that, in contrast with Ischia, P. oceanica at the Panarea site faces stressors that result in the production of reactive oxygen species, triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. These proteins are activated to adjust stress-accumulated misfolded proteins and prevent their aggregation as a response to some stressors, not necessarily high temperature. This is the first study analyzing the expression of target genes in marine plants living near natural CO2 vents. Our results call for contention to the general claim of seagrasses as "winners" in a high-CO2 world, based on observations near volcanic vents. Careful consideration of factors that are at play in natural vents sites other than CO2 and acidification is required. This study also constitutes a first step for using stress-related genes as indicators of environmental pressures in a changing ocean.

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Brinkman, T. J., et A. M. Smith. « Effect of climate change on crustose coralline algae at a temperate vent site, White Island, New Zealand ». Marine and Freshwater Research 66, n^o 4 (2015) : 360. http://dx.doi.org/10.1071/mf14077.

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Natural CO2 vents allow study of the effects of climate change on marine organisms on a different scale from laboratory-based studies. This study outlines a preliminary investigation into the suitability of natural CO2 vents near White Island, Bay of Plenty, New Zealand (37°31.19′S, 117°10.85′E) for climate change research by characterising water chemistry from two vent and three control locations on a seasonal basis, as well as examining their effects on skeletons of the local calcifying crustose coralline algae. pH measurements at vent sites, calculated from dissolved inorganic carbon and alkalinity, showed reduced mean pH levels (7.49 and 7.85) relative to background levels of 8.06, whereas mean temperatures were between 0.0 and 0.4°C above control. Increases in sulfur and mercury at sites near White Island were probably a result of volcanic unrest. Crustose coralline algae did not show significant variability in skeletal Mg-calcite geochemistry, but qualitative comparisons of calcite skeletons under scanning electron microscopy saw greater deformation and dissolution in coralline algae calcite crystals from vent sites compared to controls. Although additional monitoring of pH fluctuations and hydrogen sulphides is still needed, the low pH and increased temperatures indicate potential for studying multistressor effects of projected climate changes in a natural environment.

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de Beer, D., M. Haeckel, J. Neumann, G. Wegener, F. Inagaki et A. Boetius. « Saturated CO2 ; inhibits microbial processes in CO2-vented deep-sea sediments ». Biogeosciences 10, n^o 8 (26 août 2013) : 5639–49. http://dx.doi.org/10.5194/bg-10-5639-2013.

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Abstract. This study focused on biogeochemical processes and microbial activity in sediments of a natural deep-sea CO2 seepage area (Yonaguni Knoll IV hydrothermal system, Japan). The aim was to assess the influence of the geochemical conditions occurring in highly acidic and CO2 saturated sediments on sulfate reduction (SR) and anaerobic methane oxidation (AOM). Porewater chemistry was investigated from retrieved sediment cores and in situ by microsensor profiling. The sites sampled around a sediment-hosted hydrothermal CO2 vent were very heterogeneous in porewater chemistry, indicating a complex leakage pattern. Near the vents, droplets of liquid CO2 were observed emanating from the sediments, and the pH reached approximately 4.5 in a sediment depth > 6 cm, as determined in situ by microsensors. Methane and sulfate co-occurred in most sediment samples from the vicinity of the vents down to a depth of 3 m. However, SR and AOM were restricted to the upper 7–15 cm below seafloor, although neither temperature, low pH, nor the availability of methane and sulfate could be limiting microbial activity. We argue that the extremely high subsurface concentrations of dissolved CO2 (1000–1700 mM), which disrupt the cellular pH homeostasis, and lead to end-product inhibition. This limits life to the surface sediment horizons above the liquid CO2 phase, where less extreme conditions prevail. Our results may have to be taken into consideration in assessing the consequences of deep-sea CO2 sequestration on benthic element cycling and on the local ecosystem state.

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Rezanejadzanjani, Behdad, et Paul G. O’Brien. « EVALUATION OF SMART BOOSTER FANS AND DAMPERS FOR ADVANCED HVAC SYSTEMS ». Journal of Green Building 16, n^o 2 (1 mars 2021) : 115–27. http://dx.doi.org/10.3992/jgb.16.2.115.

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ABSTRACT There is potential to significantly reduce CO2 emissions by increasing the efficiency and reducing the duty cycle of HVAC systems by using smart booster fans and dampers. Smart booster fans fit in the vents within a home, operating quietly on low power (2W) to augment HVAC systems and improve their performance. In this study, a prototype duct system is used to measure and evaluate the ability for smart booster fans and dampers to control airflow to different vents for the purpose of increasing the efficiency of HVAC systems. Four case studies were evaluated: an HVAC system (1) without any fans or dampers, (2) with a fan installed in one vent, but without any dampers, (3) with dampers installed at the vents, but without any fans, and (4) with both fan and dampers installed. The results from both the experimental and numerical evaluation show that the smart booster fan and dampers can significantly improve the airflow at a vent that is underperforming. For example, the airflow at the last vent in a ducting branch was increased from 17 to 37 CFM when a smart booster fan was installed at this vent. Results from the numerical analysis show that for the case of an underperforming vent during the winter season the HVAC running time may be reduced from 24 hr/day to 5.6 hr/day. Furthermore, results from the numerical analysis show the HVAC running time is further reduced to 4.5 hr/day for cases 3 and 4.

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de Beer, D., M. Haeckel, J. Neumann, G. Wegener, F. Inagaki et A. Boetius. « Saturated CO2 ; inhibits microbial processes in CO2-vented deep-sea sediments ». Biogeosciences Discussions 10, n^o 2 (1 février 2013) : 1899–927. http://dx.doi.org/10.5194/bgd-10-1899-2013.

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Abstract. This study focused on biogeochemical processes and microbial activity in sediments of a natural deep-sea CO2 seepage area (Yonaguni Knoll IV hydrothermal system, Japan). The aim was to assess the influence of the geochemical conditions occurring in highly acidic and CO2 saturated sediments on sulphate reduction (SR) and anaerobic methane oxidation (AOM). Porewater chemistry was investigated from retrieved sediment cores and in situ by microsensor profiling. The sites sampled around a sediment-hosted hydrothermal CO2 vent were very heterogeneous in porewater chemistry, indicating a complex leakage pattern. Near the vents, droplets of liquid CO2 were observed to emanate from the sediments, and the pH reached approximately 4.5 in a sediment depth >6 cm, as determined in situ by microsensors. Methane and sulphate co-occurred in most sediment samples from the vicinity of the vents down to a depth of at least 3 m. However, SR and AOM were restricted to the upper 7–15 cm below seafloor, although neither temperature, low pH, nor the availability of methane and sulphate could be limiting microbial activity. We argue that the extremely high subsurface concentrations of dissolved CO2 (1000–1700 mM), through the ensuing high H2CO3 levels (approx. 1–2 mM) uncouples the proton-motive-force (PMF) and thus inhibits biological energy conservation by ATPase-driven phosphorylation. This limits life to the surface sediment horizons above the liquid CO2 phase, where less extreme conditions prevail. Our results may have to be taken into consideration in assessing the consequences of deep-sea CO2 sequestration on benthic element cycling and on the local ecosystem state.

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He, Runtian, Baoyun Hu, Heng Zhong, Fangming Jin, Junjie Fan, Yun Hang Hu et Zhenzi Jing. « Reduction of CO2 with H2S in a simulated deep-sea hydrothermal vent system ». Chemical Communications 55, n^o 8 (2019) : 1056–59. http://dx.doi.org/10.1039/c8cc08075e.

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CO₂ can be reduced to organic molecules, such as formic and acetic acids in a yield of approximately 67% with metal sulfides catalysts, using H₂S as a reductant and with S_xO_y²⁻ as oxidative products in a simulated hydrothermal vent system. These results are significant for understanding abiotic organic synthesis from dissolved CO₂ in deep sea hydrothermal vents.

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Gugliandolo, Concetta, et Teresa L. Maugeri. « Phylogenetic Diversity of Archaea in Shallow Hydrothermal Vents of Eolian Islands, Italy ». Diversity 11, n^o 9 (5 septembre 2019) : 156. http://dx.doi.org/10.3390/d11090156.

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Shallow hydrothermal systems (SHS) around the Eolian Islands (Italy), related to both active and extinct volcanism, are characterized by high temperatures, high concentrations of CO2 and H2S, and low pH, prohibitive for the majority of eukaryotes which are less tolerant to the extreme conditions than prokaryotes. Archaea and bacteria are the key elements for the functioning of these ecosystems, as they are involved in the transformation of inorganic compounds released from the vent emissions and are at the basis of the hydrothermal system food web. New extremophilic archaea (thermophilic, hyperthermophilic, acidophilic, alkalophilic, etc.) have been isolated from vents of Vulcano Island, exhibiting interesting features potentially valuable in biotechnology. Metagenomic analyses, which mainly involved molecular studies of the 16S rRNA gene, provided different insights into microbial composition associated with Eolian SHS. Archaeal community composition at Eolian vent sites results greatly affected by the geochemistry of the studied vents, principally by hypersaline conditions and declining temperatures. Archaeal community in sediments was mostly composed by hyperthermophilic members of Crenarchaeota (class Thermoprotei) and Euryarchaeota (Thermococci and Methanococci) at the highest temperature condition. Mesophilic Euryarchaeota (Halobacteria, Methanomicrobia, and Methanobacteria) increased with decreasing temperatures. Eolian SHS harbor a high diversity of largely unknown archaea, and the studied vents may be an important source of new isolates potentially useful for biotechnological purposes.

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Scarponi, Daniele, Arianna Mancuso, Stefano Goffredo et Michał Kowalewski. « Mollusk Response Under Ocean Acidification in Shallow Marine Settings of Sicily (Central Mediterranean) ». Bulletin of the Florida Museum of Natural History 60, n^o 2 (16 février 2023) : 113. http://dx.doi.org/10.58782/flmnh.tbsm5836.

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Anthropogenic CO2 is a major driver of change in most marine ecosystems, as the consequent ocean acidification is threatening marine calcifying organisms. In this respect, long-term analyses on ocean acidification effects on marine ecosystems acclimated to high pCO2, as found around CO2 vents, are needed. Here we tackle mollusk assemblages from acidified shallow marine settings off the Aeolian archipelago (Central Mediterranean). The detected gradient manifests along a 34 m long transect (9.6 m and 11.4 m water depth), mostly in a Posidonia oceanica matte from normal (site 1) to high levels (site 3) of pCO2 (405 μatm, pH 8.1 and 715 μatm, pH 7.8; respectively). The strongest acidified condition at the vent crater (site 4, pCO2 1110 μatm, pH 7.7). At the vent site gaseous emissions are characterized by ~99% in volume of CO2 and ~0.6% of H2S. However, water dissolved H2S was below detection limit and the sulphate content along the transect does not show significant variations with respect to normal seawater values. Preliminary paleoecologic surveys on diversity structure (diversity profiles) and taphonomic degradation (NMDS, z scored % values) were conducted on mollusk remains collected along the natural pH gradient (sites 1-4). Along the P. oceanica matte (sites 1-3), overall mollusk taxon diversity (alpha and beta) decreased, mollusk in site 3 were mostly juveniles and had higher overall taphonomic damages than those retrieved at normal pH conditions. Within the vent crater only fewer and highly taphonomically altered gastropod specimens were retrieved on the pebbly seafloor, suggesting a very short residence time of shell material and rapid dissolution. Even if vents are not exact predictors of the anthropogenic-designed future of marine settings, due to their limited spatial and temporal extent, they can act as natural laboratories where to evaluate the output of ecosystem processes under rising pCO2 and the effects on the creation of the future fossil record.

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Nagelkerken, Ivan, Tiphaine Alemany, Julie M. Anquetin, Camilo M. Ferreira, Kim E. Ludwig, Minami Sasaki et Sean D. Connell. « Ocean acidification boosts reproduction in fish via indirect effects ». PLOS Biology 19, n^o 1 (19 janvier 2021) : e3001033. http://dx.doi.org/10.1371/journal.pbio.3001033.

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Ocean acidification affects species populations and biodiversity through direct negative effects on physiology and behaviour. The indirect effects of elevated CO2 are less well known and can sometimes be counterintuitive. Reproduction lies at the crux of species population replenishment, but we do not know how ocean acidification affects reproduction in the wild. Here, we use natural CO2 vents at a temperate rocky reef and show that even though ocean acidification acts as a direct stressor, it can indirectly increase energy budgets of fish to stimulate reproduction at no cost to physiological homeostasis. Female fish maintained energy levels by compensation: They reduced activity (foraging and aggression) to increase reproduction. In male fish, increased reproductive investment was linked to increased energy intake as mediated by intensified foraging on more abundant prey. Greater biomass of prey at the vents was linked to greater biomass of algae, as mediated by a fertilisation effect of elevated CO2 on primary production. Additionally, the abundance and aggression of paternal carers were elevated at the CO2 vents, which may further boost reproductive success. These positive indirect effects of elevated CO2 were only observed for the species of fish that was generalistic and competitively dominant, but not for 3 species of subordinate and more specialised fishes. Hence, species that capitalise on future resource enrichment can accelerate their reproduction and increase their populations, thereby altering species communities in a future ocean.

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Gheibzadeh, Mohammad Sadegh, Colleen Varaidzo Manyumwa, Özlem Tastan Bishop, Hossein Shahbani Zahiri, Seppo Parkkila et Reza Zolfaghari Emameh. « Genome Study of α-, β-, and γ-Carbonic Anhydrases from the Thermophilic Microbiome of Marine Hydrothermal Vent Ecosystems ». Biology 12, n^o 6 (25 mai 2023) : 770. http://dx.doi.org/10.3390/biology12060770.

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Carbonic anhydrases (CAs) are metalloenzymes that can help organisms survive in hydrothermal vents by hydrating carbon dioxide (CO2). In this study, we focus on alpha (α), beta (β), and gamma (γ) CAs, which are present in the thermophilic microbiome of marine hydrothermal vents. The coding genes of these enzymes can be transferred between hydrothermal-vent organisms via horizontal gene transfer (HGT), which is an important tool in natural biodiversity. We performed big data mining and bioinformatics studies on α-, β-, and γ-CA coding genes from the thermophilic microbiome of marine hydrothermal vents. The results showed a reasonable association between thermostable α-, β-, and γ-CAs in the microbial population of the hydrothermal vents. This relationship could be due to HGT. We found evidence of HGT of α- and β-CAs between Cycloclasticus sp., a symbiont of Bathymodiolus heckerae, and an endosymbiont of Riftia pachyptila via Integrons. Conversely, HGT of β-CA genes from the endosymbiont Tevnia jerichonana to the endosymbiont Riftia pachyptila was detected. In addition, Hydrogenovibrio crunogenus SP-41 contains a β-CA gene on genomic islands (GIs). This gene can be transferred by HGT to Hydrogenovibrio sp. MA2-6, a methanotrophic endosymbiont of Bathymodiolus azoricus, and a methanotrophic endosymbiont of Bathymodiolus puteoserpentis. The endosymbiont of R. pachyptila has a γ-CA gene in the genome. If α- and β-CA coding genes have been derived from other microorganisms, such as endosymbionts of T. jerichonana and Cycloclasticus sp. as the endosymbiont of B. heckerae, through HGT, the theory of the necessity of thermostable CA enzymes for survival in the extreme ecosystem of hydrothermal vents is suggested and helps the conservation of microbiome natural diversity in hydrothermal vents. These harsh ecosystems, with their integral players, such as HGT and endosymbionts, significantly impact the enrichment of life on Earth and the carbon cycle in the ocean.

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Moussallam, Y., N. Peters, C. Ramírez, C. Oppenheimer, A. Aiuppa et G. Giudice. « Characterisation of the magmatic signature in gas emissions from Turrialba volcano, Costa Rica ». Solid Earth Discussions 6, n^o 2 (8 août 2014) : 2293–320. http://dx.doi.org/10.5194/sed-6-2293-2014.

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Abstract. The equilibrium composition of volcanic gases with their magma is often overprinted by interaction with a shallow hydrothermal system. Identifying the magmatic signature of volcanic gases is critical to relate their composition to properties of the magma (temperature, fO2, gas-melt segregation depth). We report measurements of the chemical composition and flux of the major gas species emitted from Turrialba volcano during March 2013. Measurements were made of two vents in the summit region; one of which opened in 2010 and the other in 2012. We determined an average SO2 flux of 2.40 ± 0.75 kg s−1 using scanning ultraviolet spectroscopy, and molar proportions of H2O, CO2, SO2, HCl, CO and H2 gases of 94.16, 4.03, 1.56, 0.23, 0.003 and 0.009%, respectively, by open-path Fourier transform infrared (FTIR) spectrometry and a multi-species gas sensing system. Together, these data imply fluxes of 41, 4, 0.2, 2 × 10−3 and 5 × 10–4 kg s−1 for H2O, CO2, HCl, CO and H2 respectively. Although H2S was detected, its concentration could not be resolved. HF was not detected. The chemical signature of the gas from both vents was found to be broadly similar. Following the opening of the 2010 and 2012 vents we found limited to negligible interaction of the magmatic gas with the hydrothermal system has occurred and the gas composition of the volcanic plume is broadly representative of equilibrium with the magma. The time evolution of the gas composition, the continuous emission of large quantities of SO2 and the physical evolution of the summit area with new vent opening and more frequent eruptions all point towards a continuous drying of the hydrothermal system at Turrialba's summit at an apparently increasing rate.

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Moussallam, Y., N. Peters, C. Ramírez, C. Oppenheimer, A. Aiuppa et G. Giudice. « Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica ». Solid Earth 5, n^o 2 (20 décembre 2014) : 1341–50. http://dx.doi.org/10.5194/se-5-1341-2014.

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Abstract. The equilibrium composition of volcanic gases with their magma is often overprinted by interaction with a shallow hydrothermal system. Identifying the magmatic signature of volcanic gases is critical to relate their composition to properties of the magma (temperature, fO2, gas-melt segregation depth). We report measurements of the chemical composition and flux of the major gas species emitted from Turrialba Volcano during March 2013. Measurements were made of two vents in the summit region, one of which opened in 2010 and the other in 2012. We determined an average SO2 flux of 5.2 ± 1.9 kg s-1 using scanning ultraviolet spectroscopy, and molar proportions of H2O, CO2, SO2, HCl, CO and H2 gases of 94.16, 4.03, 1.56, 0.23, 0.003 and 0.009% respectively by open-path Fourier transform infrared (FTIR) spectrometry and a multi-species gas-sensing system. Together, these data imply fluxes of 88, 8, 0.44, 5 × 10-3 and 1 × 10-3 kg s-1 for H2O, CO2, HCl, CO and H2 respectively. Although H2S was detected, its concentration could not be resolved. HF was not detected. The chemical signature of the gas from both vents was found to be broadly similar. Following the opening of the 2010 and 2012 vents we found limited to negligible interaction of the magmatic gas with the hydrothermal system has occurred and the gas composition of the volcanic plume is broadly representative of equilibrium with the magma. The time evolution of the gas composition, the continuous emission of large quantities of SO2, and the physical evolution of the summit area with new vent openings and more frequent eruptions all point towards a continuous drying of the hydrothermal system at Turrialba's summit at an apparently increasing rate.

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Jones, Christopher. « Brownfield modifications to convert existing gas production facilities for CCS operations ». Australian Energy Producers Journal 64, n^o 2 (16 mai 2024) : S143—S147. http://dx.doi.org/10.1071/ep23061.

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In recent years, traditional oil and gas operators have found novel means of extending the life of their assets and deferring onerous decommissioning costs by converting their facilities from gas production into carbon dioxide (CO2) injection. While the task of designing for CO2 may sound simple, CO2 injection works in counter-intuitive ways, with previously established heuristics derived from years of experience in gas condensate systems being quickly challenged as potentially dangerous. The world of designing CO2 systems is back-to-front compared with hydrocarbons; it isn’t simply a case of a change in flow direction. Some of the design challenges explored in this paper include: large density variability in CO2 systems where a small change in the ambient temperature can significantly impact the pressure of a shut-in system; optimal pressure ratings of the vents and drains systems and how previous safety margins may be unsafe; pipeline hydraulic modelling focussed on new areas outside of the traditional suite of analysis, such as assurance of the supercritical phase; understanding liquid water dropout being more of a concern than hydrate formation; injection wells counter-intuitively flowing from low pressure to high pressure; whether to vent CO2 above or below an offshore platform; and optimal liquefied CO2 storage vessel conditions and safeguarding.

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Samaranayake, Premaratne, Chelsea Maier, Sachin Chavan, Weiguang Liang, Zhong-Hua Chen, David T. Tissue et Yi-Chen Lan. « Energy Minimisation in a Protected Cropping Facility Using Multi-Temperature Acquisition Points and Control of Ventilation Settings ». Energies 14, n^o 19 (22 septembre 2021) : 6014. http://dx.doi.org/10.3390/en14196014.

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Energy management in protected cropping is critical due to the high cost of energy use in high-tech greenhouse facilities. The main purpose of this research was to investigate the optimal strategy to reduce cooling energy consumption, by regulating the settings (opening/closing) of either vents or curtains during the day, at the protected cropping facility at Western Sydney University. We measured daily changes in air temperature and energy consumption under four treatments (open/closed combinations of vents and shade screens) and developed an optimal cooling strategy for energy management using multi-temperature acquisition points at different heights within a greenhouse compartment. The optimal treatment (vents open/curtains closed) reduced energy load at the rooftop, thereby maintaining a desirable plant canopy temperature profile, and reducing cooling energy. Daily energy consumption was lowest for vents open/curtains closed (70.5 kWh) and highest for vents closed/curtains open (121 kWh). It was also found that delaying the operation of opening and closing of vents and curtains until the plant canopy temperature reached 25 °C reduced cooling energy consumption and decreased heating energy consumption in the morning (e.g., 08:00 to 10:00). The estimated savings of 1.83 kWh per 1 °C cooling between the optimal (vents open/curtains closed) and least optimal (vents closed/curtains open) conditions had the potential for significant energy savings at 494 kWh per °C over a crop cycle of nine months in warm weather conditions. However, selection of the optimal cooling strategy utilising control of vents and curtains must also account for the impact from other greenhouse environmental factors, including light, humidity, and CO2 concentration, which may be crop specific.

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Goffredi, S., J. Childress, N. Desaulniers, R. Lee, F. Lallier et D. Hammond. « Inorganic carbon acquisition by the hydrothermal vent tubeworm Riftia pachyptila depends upon high external PCO2 and upon proton-equivalent ion transport by the worm ». Journal of Experimental Biology 200, n^o 5 (1 mars 1997) : 883–96. http://dx.doi.org/10.1242/jeb.200.5.883.

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Riftia pachyptila is the most conspicuous organism living at deep sea hydrothermal vents along the East Pacific Rise. To support its large size and high growth rates, this invertebrate relies exclusively upon internal chemosynthetic bacterial symbionts. The animal must supply inorganic carbon at high rates to the bacteria, which are far removed from the external medium. We found substantial differences in body fluid total inorganic carbon (CO2) both within and between vent sites when comparing freshly captured worms from a variety of places. However, the primary influence on body fluid CO2 was the chemical characteristics of the site from which the worms were collected. Studies on tubeworms, both freshly captured and maintained in captivity, demonstrate that the acquisition of inorganic carbon is apparently limited by the availability of CO2, as opposed to bicarbonate, and thus appears to be accomplished via diffusion of CO2 into the plume, rather than by mediated transport of bicarbonate. The greatly elevated PCO2 measured at the vent sites (up to 12.6 kPa around the tubeworms), which is a result of low environmental pH (as low as 5.6 around the tubeworms), and elevated CO2 (as high as 7.1 mmol l-1 around the tubes) speeds this diffusion. Moreover, despite large and variable amounts of internal CO2, these worms maintain their extracellular fluid pH stable, and alkaline, in comparison with the environment. The maintenance of this alkaline pH acts to concentrate inorganic carbon into extracellular fluids. Exposure to N-ethylmaleimide, a non-specific H+-ATPase inhibitor, appeared to stop this process, resulting in a decline in extracellular pH and CO2. We hypothesize that the worms maintain their extracellular pH by active proton-equivalent ion transport via high concentrations of H+-ATPases. Thus, Riftia pachyptila is able to support its symbionts' large demand for inorganic carbon owing to the elevated PCO2 in the vent environment and because of its ability to control its extracellular pH in the presence of large inward CO2 fluxes.

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Fanelli, Emanuela, Simone Di Giacomo, Cristina Gambi, Silvia Bianchelli, Zaira Da Ros, Michael Tangherlini, Franco Andaloro, Teresa Romeo, Cinzia Corinaldesi et Roberto Danovaro. « Effects of Local Acidification on Benthic Communities at Shallow Hydrothermal Vents of the Aeolian Islands (Southern Tyrrhenian, Mediterranean Sea) ». Biology 11, n^o 2 (17 février 2022) : 321. http://dx.doi.org/10.3390/biology11020321.

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The Aeolian Islands (Mediterranean Sea) host a unique hydrothermal system called the “Smoking Land” due to the presence of over 200 volcanic CO2-vents, resulting in water acidification phenomena and the creation of an acidified benthic environment. Here, we report the results of a study conducted at three sites located at ca. 16, 40, and 80 m of depth, and characterized by CO2 emissions to assess the effects of acidification on meio- and macrobenthic assemblages. Acidification caused significant changes in both meio- and macrofaunal assemblages, with a clear decrease in terms of abundance and a shift in community composition. A noticeable reduction in biomass was observed only for macrofauna. The most sensitive meiofaunal taxa were kinorhynchs and turbellarians that disappeared at the CO2 sites, while the abundance of halacarids and ostracods increased, possibly as a result of the larger food availability and the lower predatory pressures by the sensitive meiofaunal and macrofaunal taxa. Sediment acidification also causes the disappearance of more sensitive macrofaunal taxa, such as gastropods, and the increase in tolerant taxa such as oligochaetes. We conclude that the effects of shallow CO2-vents result in the progressive simplification of community structure and biodiversity loss due to the disappearance of the most sensitive meio- and macrofaunal taxa.

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Tamburello, Moune, Allard, Venugopal, Robert, Rosas-Carbajal, Deroussi et al. « Spatio-Temporal Relationships between Fumarolic Activity, Hydrothermal Fluid Circulation and Geophysical Signals at an Arc Volcano in Degassing Unrest : La Soufrière of Guadeloupe (French West Indies) ». Geosciences 9, n^o 11 (15 novembre 2019) : 480. http://dx.doi.org/10.3390/geosciences9110480.

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： Over the past two decades, La Soufrière volcano in Guadeloupe has displayed a growing degassing unrest whose actual source mechanism still remains unclear. Based on new measurements of the chemistry and mass flux of fumarolic gas emissions from the volcano, here we reveal spatio-temporal variations in the degassing features that closely relate to the 3D underground circulation of fumarolic fluids, as imaged by electrical resistivity tomography, and to geodetic-seismic signals recorded over the past two decades. Discrete monthly surveys of gas plumes from the various vents on La Soufrière lava dome, performed with portable MultiGAS analyzers, reveal important differences in the chemical proportions and fluxes of H2O, CO2, H2S, SO2 and H2, which depend on the vent location with respect to the underground circulation of fluids. In particular, the main central vents, though directly connected to the volcano conduit and preferentially surveyed in past decades, display much higher CO2/SO2 and H2S/SO2 ratios than peripheral gas emissions, reflecting greater SO2 scrubbing in the boiling hydrothermal water at 80–100 m depth. Gas fluxes demonstrate an increased bulk degassing of the volcano over the past 10 years, but also a recent spatial shift in fumarolic degassing intensity from the center of the lava dome towards its SE–NE sector and the Breislack fracture. Such a spatial shift is in agreement with both extensometric and seismic evidence of fault widening in this sector due to slow gravitational sliding of the southern dome sector. Our study thus provides an improved framework to monitor and interpret the evolution of gas emissions from La Soufrière in the future and to better forecast hazards from this dangerous andesitic volcano.

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Emerson, David, et Craig L. Moyer. « Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition ». Applied and Environmental Microbiology 68, n^o 6 (juin 2002) : 3085–93. http://dx.doi.org/10.1128/aem.68.6.3085-3093.2002.

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ABSTRACT A number of hydrothermal vent sites exist on the summit of the Loihi Seamount, a shield volcano that is part of the Hawaiian archipelago. The vents are 1,100 to 1,325 m below the surface and range in temperature from slightly above ambient (10°C) to high temperature (167°C). The vent fluid is characterized by high concentrations of CO2 (up to 17 mM) and Fe(II) (up to 268 μM), but there is a general paucity of H2S. Most of the vents are surrounded by microbial mats that have a gelatinous texture and are heavily encrusted with rust-colored Fe oxides. Visually, the Fe oxides appeared homogeneous. However, light microscopy revealed that the oxides had different morphologies, which fell into three classes: (i) sheaths, (ii) twisted or irregular filaments, and (iii) amorphous oxides. A morphological analysis of eight different samples indicated that the amorphous oxides were overall the most abundant; however, five sites had >50% sheaths and filamentous oxides. These latter morphologies are most likely the direct result of microbial deposition. Direct cell counts revealed that all of the oxides had abundant microbial populations associated with them, from 6.9 × 107 to 5.3 × 108 cells per ml of mat material. At most sites, end point dilution series for lithotrophic Fe oxidizers were successful out to dilutions of 10−6 and 10−7. A pure culture was obtained from a 10−7 dilution tube; this strain, JV-1, was an obligate, microaerophilic Fe oxidizer that grew at 25 to 30°C. A non-cultivation-based molecular approach with terminal-restriction fragment length polymorphism also indicated the common presence of Fe-oxidizing bacteria at Loihi. Together, these results indicate that Fe-oxidizing bacteria are common at the Loihi Seamount and probably play a major role in Fe oxidation. A review of the literature suggests that microbially mediated Fe oxidation at hydrothermal vents may be important globally.

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Porras, Manuel E., Pilar Lorenzo, Evangelina Medrano, María J. Sánchez-González, Ginés Otálora-Alcón, María C. Piñero, Francisco M. del Amor et M. Cruz Sánchez-Guerrero. « Photosynthetic acclimation to elevated CO2 concentration in a sweet pepper (Capsicum annuum) crop under Mediterranean greenhouse conditions : influence of the nitrogen source and salinity ». Functional Plant Biology 44, n^o 6 (2017) : 573. http://dx.doi.org/10.1071/fp16362.

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In many plant species, long-term exposure to elevated CO2 concentration results in a reduction in photosynthetic capacity, known as acclimation. This process is mainly explained by a feedback inhibition mechanism. The supply of a fraction of the nitrogen (N) in the nutrient solution as NH4+ can play an important role in the maintenance of photosynthetic activity and could mitigate the acclimation process. The aims of the present work were to study the photosynthetic response of sweet pepper (Capsicum annuum L.) to CO2 enrichment in Mediterranean greenhouse conditions, throughout the crop growth cycle and to evaluate the supply of NH4+ in the nutrient solution as a strategy to enhance the long-term response to CO2 at different levels of salinity. The experiment was conducted in two identical greenhouses: one with CO2 enrichment according to the ventilation, maintaining a high concentration when the vents were closed and a near-atmospheric level when the vents were open and one without. Sweet pepper plants were grown in both greenhouses, being irrigated with two levels of water salinity and two N sources: (i) NO3– and (ii) NO3– plus NH4+. A reduction in the response of photosynthesis to high CO2 concentration was found in the enriched plants after 135 days of CO2 supply, with respect to the reference plants. The leaf photosynthesis rate measured at high CO2 concentration showed a closer relationship with the leaf N concentration than the non-structural carbohydrate concentration. The relative yield gain of the CO2-enriched plants progressively decreased after reaching a maximum value; this was probably associated with the photosynthetic acclimation process. This decrease was delayed by the use of NH4+ in the nutrient solution at low salinity. Knowledge of the crop phase when acclimation to high CO2 concentration occurs can be the basis for deciding when to impose an early cessation of CO2 application, as a strategy to improve the economic efficiency of CO2 supply in Mediterranean conditions.

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Smith, C. « Chemosynthesis in the deep-sea : life without the sun ». Biogeosciences Discussions 9, n^o 12 (4 décembre 2012) : 17037–52. http://dx.doi.org/10.5194/bgd-9-17037-2012.

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Abstract. Chemosynthetic communities in the deep-sea can be found at hydrothermal vents, cold seeps, whale falls and wood falls. While these communities have been suggested to exist in isolation from solar energy, much of the life associated with them relies either directly or indirectly on photosynthesis in the surface waters of the oceans. The sun indirectly provides oxygen, a byproduct of photosynthesis, which aerobic chemosynthetic microorganisms require to synthesize organic carbon from CO2. Planktonic life stages of many vent and cold seep invertebrates also directly feed on photosynthetically produced organic matter as they disperse to new vent and seep systems. While a large portion of the life at deep-sea chemosynthetic habitats can be linked to the sun and so could not survive without it, a small portion of anaerobically chemosynthetic microorganisms can persist in its absence. These small and exotic organisms have developed a way of life in the deep-sea which involves the use of resources originating in their entirety from terrestrial sources.

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Cigliano, M., M. C. Gambi, R. Rodolfo-Metalpa, F. P. Patti et J. M. Hall-Spencer. « Effects of ocean acidification on invertebrate settlement at volcanic CO2 vents ». Marine Biology 157, n^o 11 (16 juillet 2010) : 2489–502. http://dx.doi.org/10.1007/s00227-010-1513-6.

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Tan, Felicia, Vincent Tam et Chris Savvides. « Elevated LNG Vapour Dispersion—Effects of Topography, Obstruction and Phase Change ». Eng 2, n^o 2 (15 juin 2021) : 249–66. http://dx.doi.org/10.3390/eng2020016.

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The dispersion of vapour of liquefied natural gas (LNG) is generally assumed to be from a liquid spill on the ground in hazard and risk analysis. However, this cold vapour could be discharged at height through cold venting. While there is similarity to the situation where a heavier-than-air gas, e.g., CO2, is discharged through tall vent stacks, LNG vapour is cold and induces phase change of ambient moisture leading to changes in the thermodynamics as the vapour disperses. A recent unplanned cold venting of LNG vapour event due to failure of a pilot, provided valuable data for further analysis. This event was studied using CFD under steady-state conditions and incorporating the effect of thermodynamics due to phase change of atmospheric moisture. As the vast majority of processing plants do not reside on flat planes, the effect of surrounding topography was also investigated. This case study highlighted that integral dispersion model was not applicable as key assumptions used to derive the models were violated and suggested guidance and methodologies appropriate for modelling cold vent and flame out situations for elevated vents.

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Lee, Hyun Sook, Sung Gyun Kang, Seung Seob Bae, Jae Kyu Lim, Yona Cho, Yun Jae Kim, Jeong Ho Jeon et al. « The Complete Genome Sequence of Thermococcus onnurineus NA1 Reveals a Mixed Heterotrophic and Carboxydotrophic Metabolism ». Journal of Bacteriology 190, n^o 22 (12 septembre 2008) : 7491–99. http://dx.doi.org/10.1128/jb.00746-08.

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ABSTRACT Members of the genus Thermococcus, sulfur-reducing hyperthermophilic archaea, are ubiquitously present in various deep-sea hydrothermal vent systems and are considered to play a significant role in the microbial consortia. We present the complete genome sequence and feature analysis of Thermococcus onnurineus NA1 isolated from a deep-sea hydrothermal vent area, which reveal clues to its physiology. Based on results of genomic analysis, T. onnurineus NA1 possesses the metabolic pathways for organotrophic growth on peptides, amino acids, or sugars. More interesting was the discovery that the genome encoded unique proteins that are involved in carboxydotrophy to generate energy by oxidation of CO to CO2, thereby providing a mechanistic basis for growth with CO as a substrate. This lithotrophic feature in combination with carbon fixation via RuBisCO (ribulose 1,5-bisphosphate carboxylase/oxygenase) introduces a new strategy with a complementing energy supply for T. onnurineus NA1 potentially allowing it to cope with nutrient stress in the surrounding of hydrothermal vents, providing the first genomic evidence for the carboxydotrophy in Thermococcus.

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Álvaro, Jose Javier, Mónica Sánchez-Román, Klaas G. J. Nierop et Francien Peterse. « Multiscale Microbial Preservation and Biogeochemical Signals in a Modern Hot-Spring Siliceous Sinter Rich in CO2 Emissions, Krýsuvík Geothermal Field, Iceland ». Minerals 11, n^o 3 (4 mars 2021) : 263. http://dx.doi.org/10.3390/min11030263.

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The microbial communities inferred in silica sinter rocks, based on multiscale morphological features (fabrics and textures) and the presence of lipid biomarkers and their carbon isotopic composition, are evaluated in the Krýsuvík geothermal area of Iceland. Close to vent environments (T > 75 °C and pH 1.7‒3), stream floors are capped with homogeneous vitreous crusts and breccia levels, with no distinct recognizable silicified microbes. About 4 m far from the vents (T 75‒60 °C and pH 3‒6) and beyond (T < 60 °C and pH 6‒7.6), microbial sinters, including wavy and palisade laminated and bubble fabrics, differ between abandoned meanders and desiccated ponds. Fabric and texture variances are related to changes in the ratio of filament/coccoid silicified microbes and associated porosity. Coatings of epicellular silica, less than 2 µm thick, favor identification of individual microbial filaments, whereas coalescence of opal spheres into agglomerates precludes recognition of original microbial textures and silicified microbes. Episodic fluctuations in the physico-chemical conditions of surface waters controlled the acidic hydrolysis of biomarkers. Wavy laminated fabrics from pond margins comprise fatty acids, mono- and dialkyl glycerol, mono- and diethers, monoalkyl glycerol esters and small traces of 10-methyl branched C16 and C18 fatty acids and archaeol, indicative of intergrowths of cyanobacteria, Aquificales, and sulfate reducing bacteria and methanogenic archaea. In contrast, wavy laminated fabrics from abandoned meanders and palisade laminated fabrics from ponds differ in their branched fatty acids and the presence vs. absence of bacteriohopanetetrol, reflecting different cyanobacterial contributions. δ13C values of biomarkers range from −22.7 to −32.9‰, but their values in the wavy (pond) and bubble fabrics have much wider ranges than those of the wavy (meander), palisade, and vitreous fabrics, reflecting dissolved inorganic carbon (DIC) sources and a decrease in 13C downstream outflow channels, with heavier values closer to vents and depleted values in ponds.

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Queißer, Manuel, Domenico Granieri, Mike Burton, Fabio Arzilli, Rosario Avino et Antonio Carandente. « Increasing CO2 ; flux at Pisciarelli, Campi Flegrei, Italy ». Solid Earth 8, n^o 5 (29 septembre 2017) : 1017–24. http://dx.doi.org/10.5194/se-8-1017-2017.

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Abstract. The Campi Flegrei caldera is located in the metropolitan area of Naples (Italy) and has been undergoing different stages of unrest since 1950, evidenced by episodes of significant ground uplift followed by minor subsidence, increasing and fluctuating emission strengths of water vapor and CO2 from fumaroles, and periodic seismic crises. We deployed a scanning laser remote-sensing spectrometer (LARSS) that measured path-integrated CO2 concentrations in the Pisciarelli area in May 2017. The resulting mean CO2 flux is 578 ± 246 t d−1. Our data suggest a significant increase in CO2 flux at this site since 2015. Together with recent geophysical observations, this suggests a greater contribution of the magmatic source to the degassing and/or an increase in permeability at shallow levels. Thanks to the integrated path soundings, LARSS may help to give representative measurements from large regions containing different CO2 sources, including fumaroles, low-temperature vents, and degassing soils, helping to constrain the contribution of deep gases and their migration mechanisms towards the surface.

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Bowatte, Saman, R. Andrew Carran, Paul C. D. Newton et Phil Theobald. « Does atmospheric CO2 concentration influence soil nitrifying bacteria and their activity ? » Soil Research 46, n^o 7 (2008) : 617. http://dx.doi.org/10.1071/sr07214.

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Ammonia oxidising bacteria (AOB) are important soil microorganisms that carry out the first step in nitrification, the oxidation of ammonia to nitrite. In this paper we investigated the impact of long-term elevated CO2 on soil nitrification and soil AOB community composition. Soil samples were taken from Hakanoa natural CO2 springs, Kamo, Northland, New Zealand. This site has been exposed to elevated CO2 for several decades. Soils were collected from different points near to CO2-emitting vents where the CO2 concentration at canopy height had been characterised. Nitrification activity was measured using a short-term nitrification assay, and AOB community composition was characterised using polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE). A principal component analysis of the DGGE banding pattern was carried out to identify the effect of CO2 on AOB community composition. Soil nitrification activity was markedly decreased with increasing CO2. The variation in DGGE banding patterns revealed differences in the composition of the soil AOB community that were related to CO2 concentration. Principal component analysis showed that the changes in community composition and nitrifying activity were linked and that these changes were related to atmospheric CO2 concentration.

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Rizzo, Carmen, Erika Arcadi, Rosario Calogero, Valentina Sciutteri, Pierpaolo Consoli, Valentina Esposito, Simonepietro Canese, Franco Andaloro et Teresa Romeo. « Ecological and Biotechnological Relevance of Mediterranean Hydrothermal Vent Systems ». Minerals 12, n^o 2 (16 février 2022) : 251. http://dx.doi.org/10.3390/min12020251.

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Marine hydrothermal systems are a special kind of extreme environments associated with submarine volcanic activity and characterized by harsh chemo-physical conditions, in terms of hot temperature, high concentrations of CO2 and H2S, and low pH. Such conditions strongly impact the living organisms, which have to develop adaptation strategies to survive. Hydrothermal systems have attracted the interest of researchers due to their enormous ecological and biotechnological relevance. From ecological perspective, these acidified habitats are useful natural laboratories to predict the effects of global environmental changes, such as ocean acidification at ecosystem level, through the observation of the marine organism responses to environmental extremes. In addition, hydrothermal vents are known as optimal sources for isolation of thermophilic and hyperthermophilic microbes, with biotechnological potential. This double aspect is the focus of this review, which aims at providing a picture of the ecological features of the main Mediterranean hydrothermal vents. The physiological responses, abundance, and distribution of biotic components are elucidated, by focusing on the necto-benthic fauna and prokaryotic communities recognized to possess pivotal role in the marine ecosystem dynamics and as indicator species. The scientific interest in hydrothermal vents will be also reviewed by pointing out their relevance as source of bioactive molecules.

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Lombardi, Chiara, Maria Cristina Gambi, Claudio Vasapollo, Paul Taylor et Silvia Cocito. « Skeletal alterations and polymorphism in a Mediterranean bryozoan at natural CO2 vents ». Zoomorphology 130, n^o 2 (26 mai 2011) : 135–45. http://dx.doi.org/10.1007/s00435-011-0127-y.

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Capano, Manuela, Simona Altieri, Fabio Marzaioli, Carmina Sirignano, Olivia Pignatelli, Nicoletta Martinelli, Isabella Passariello et al. « Widespread Fossil CO2 in the Ansanto Valley (Italy) : Dendrochronological, 14C, and 13C Analyses on Tree Rings ». Radiocarbon 55, n^o 3 (2013) : 1114–22. http://dx.doi.org/10.1017/s0033822200048025.

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The Ansanto Valley (southern Italy) is characterized by vents and boiling mud lakes that emit typical volcanic exhalations (mostly fossil CO2). This fossil dilution spreads over the Ansanto Valley and its impact on local trees is investigated in this study. Six trees at increasing distance from the emitting sources and 2 aliquots of gas were sampled. Dendrochronological analysis was performed on tree cores in order to check the accuracy of the tree-ring sequences; the results indicate no anomalies in the curves of the analyzed trees. δ13C and radiocarbon (14C) analyses were performed on the α-cellulose extracted from some selected tree rings. The main aim of δ13C analysis was to gain information about the origin of CO2 arising from the source; the results support the hypothesis of a carbonatic origin, with respect to a volcanic origin. 14C analysis was performed to evaluate the influence and to quantify the percentage of fossil dilution characterizing the local atmosphere and affecting the trees at different distances from the source during the years. The results show the presence of a strong fossil dilution affecting the trees, increasing toward the sources (from ∼6% at 80 m distance to ∼30% at 20 m from the nearest vent) with quite stable values over the examined period.

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Meinke, Troy T., Douglas A. Hopper et Virginia S. Story. « LEAF, STEM, AND FLOWER CHARACTERISTICS OF ROSA HYBRIDA L. UNDER DIFFERENT CO2 CONCENTRATIONS ». HortScience 28, n^o 5 (mai 1993) : 574b—574. http://dx.doi.org/10.21273/hortsci.28.5.574b.

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Two greenhouses received ambient CO2 and two were enriched between 1000 and 1200 ppm CO2 when vents were closed. Two-year-old Rosa hybrida L. `Royalty', `Emblem', and `Samantha' plants growing in each house were pinched 20 Oct. and 28 Dec. 1992 for Christmas and Valentine's Day crops. All temperature set points were 22C/17C day/night. At flowering, 5 shoots from each bench location were destructively sampled for stem diameter, stem length, and fresh and dry weights of stem, leaves, and flower bud.At flowering for the Christmas 1992 crop, shoots in the enriched houses tended to have larger stem, leaf, and flower fresh weights, and larger stem diameters. Analysis of variance found stem lengths of combined cultivars to be longer (p < .05) in the CO2 enriched houses. Mean stem lengths were 68.8 cm and 63.9 cm for flower stems in CO2 enriched and ambient houses, respectively. Dry weight data from the Christmas crop, and results from the 1993 Valentine's crop will be presented.

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Rastrick, Samuel S. P., Helen Graham, Kumiko Azetsu-Scott, Piero Calosi, Melissa Chierici, Agneta Fransson, Haakon Hop et al. « Using natural analogues to investigate the effects of climate change and ocean acidification on Northern ecosystems ». ICES Journal of Marine Science 75, n^o 7 (16 octobre 2018) : 2299–311. http://dx.doi.org/10.1093/icesjms/fsy128.

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Abstract Northern oceans are in a state of rapid transition. Still, our knowledge of the likely effects of climate change and ocean acidification on key species in the food web, functionally important habitats and the structure of Arctic and sub-Arctic ecosystems is limited and based mainly on short-term laboratory studies on single species. This review discusses how tropical and temperate natural analogues of carbonate chemistry drivers, such as CO2 vents, have been used to further our knowledge of the sensitivity of biological systems to predicted climate change, and thus assess the capacity of different species to show long-term acclimation and adaptation to elevated levels of pCO2. Natural analogues have also provided the means to scale-up from single-species responses to community and ecosystem level responses. However, to date the application of such approaches is limited in high latitude systems. A range of Arctic and sub-Arctic sites, including CO2 vents, methane cold seeps, estuaries, up-welling areas, and polar fronts, that encompass gradients of pH, carbonate saturation state, and alkalinity, are suggested for future high latitude, in-situ ocean acidification research. It is recommended that combinations of monitoring of the chemical oceanography, observational, and experimental (in situ and laboratory) studies of organisms around these natural analogues be used to attain better predictions of the impacts of ocean acidification and climate change on high latitude species and ecosystems.

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Howes, Neil, Fabrizio Innocenti, Andrew Finlayson, Chris Dimopoulos, Rod Robinson et Tom Gardiner. « Remote Measurements of Industrial CO2 Emissions Using a Ground-Based Differential Absorption Lidar in the 2 µm Wavelength Region ». Remote Sensing 15, n^o 22 (17 novembre 2023) : 5403. http://dx.doi.org/10.3390/rs15225403.

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Carbon dioxide (CO2) is a known greenhouse gas and one of the largest contributors to global warming in the Earth’s atmosphere. The remote detection and measurement of CO2 from industrial emissions are not routinely carried out and are typically calculated from the fuel combusted or measured directly within ducted vents. However, these methods are not applicable for the quantification of fugitive emissions of CO2. This work presents the results of remote measurement of CO2 emissions using the differential absorption lidar (DIAL) technique at a wavelength of ~2 µm. The results from the DIAL measurements compare well with simultaneous in-stack measurements, these datasets were plotted against each other and can be described by a linear regression of y (t/h) = 1.04 x − 0.02, suggesting any bias in the DIAL data is likely small. Moreover, using the definition outlined in EN 15267-3 a lower detection limit of 0.12 t/h was estimated for the 2 µm wavelength DIAL data, this is three orders of magnitude lower than the corresponding CO2 detection limit measured by NPL in the 1.5 µm wavelength region. Thus, this paper demonstrates the feasibility of high-resolution, ground-based DIAL measurements for quantifying industrial CO2 emissions.

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Mirasole, Alice, Fabio Badalamenti, Antonio Di Franco, Maria Cristina Gambi et Nuria Teixidó. « Boosted fish abundance associated with Posidonia oceanica meadows in temperate shallow CO2 vents ». Science of The Total Environment 771 (juin 2021) : 145438. http://dx.doi.org/10.1016/j.scitotenv.2021.145438.

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Robidoux, Philippe, Daniela Pastén, Gilles Levresse, Gloria Diaz et Dante Paredes. « Volatile Content Implications of Increasing Explosivity of the Strombolian Eruptive Style along the Fracture Opening on the NE Villarrica Flank : Minor Eruptive Centers in the Los Nevados Group 2 ». Geosciences 11, n^o 8 (25 juillet 2021) : 309. http://dx.doi.org/10.3390/geosciences11080309.

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Potential flank eruptions at the presently active Villarrica, Southern Andes Volcanic Zone (33.3–46 °S) require the drawing of a comprehensive scenario of eruptive style dynamics, which partially depends on the degassing process. The case we consider in this study is from the Los Nevados Subgroup 2 (LNG2) and constitutes post-glacial minor eruptive centers (MECs) of basaltic–andesitic and basaltic composition, associated with the northeastern Villarrica flank. Petrological studies of the melt inclusions volatile content in olivine determined the pre-eruptive conditions of the shallow magma feeding system (<249 Mpa saturation pressure, 927–1201 °C). The volatile saturation model on “pressure-dependent” volatile species, measured by Fourier Transform Infrared Microspectrometry (FTIR) (H2O of 0.4–3.0 wt.% and CO2 of 114–1586 ppm) and electron microprobe (EMP), revealed that fast cooling pyroclasts like vesicular scoria preserve a ~1.5 times larger amount of CO2, S, Cl, and volatile species contained in melt inclusions from primitive olivine (Fo76–86). Evidence from geological mapping and drone surveys demonstrated the eruption chronology and spatial changes in eruption style from all the local vents along a N45° corridor. The mechanism by which LNG2 is degassed plays a critical role in increasing the explosivity uphill on the Villarrica flank from volcanic vents in the NE sector (<9 km minimum saturation depth) to the SW sector (<8.1 km), where many crystalline ballistic bombs were expulsed, rather than vesicular and spatter scoria.

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Story, Virginia S., Douglas A. Hopper et Troy T. Meinke. « FLOWERING COMPARISONS OF THREE POPULAR ROSE (ROSA HYBRIDA L.) CULTIVARS ». HortScience 28, n^o 5 (mai 1993) : 574c—574. http://dx.doi.org/10.21273/hortsci.28.5.574c.

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Two-year-old Rosa hybrida L. `Royalty', `Emblem', and `Samantha' plants were pinched 20 Oct. and 28 Dec. 1992 for Christmas and Valentine's Day crops. Two greenhouses received ambient CO2 and two were enriched to 1200 ppm CO2 when vents were closed. All temperature set points were 22C/17C day/night. At 10 and 25 days after pinch, and at flowering, 5 shoots from each bench location were destructively sampled for leaf (node) number, stem diameter, stem length, and fresh weights of stem, leaves, and flower bud. Time to visible bud and to flowering from pinch also were recorded.Analysis of variance for the 1992 Christmas crop did not find significant differences for flowering times, but trends in response were evident. The 3 cultivars had mean flowering times of: `Royalty', 51.3 days; `Emblem', 52.3 days; and `Samantha', 54.0 days. Enrichment with CO2 showed a trend for decreased average flowering times for all 3 cultivars. Results from the 1993 Valentine's Day crop will also be presented.

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AIB, Ekejiuba. « Universal “Plug and Play” Real-Time Entire Automotive Exhaust Effluents, Industry Vents and Flue Gas Emissions Liquefiers : The Game Changer Approach-Phase Two Category ». Petroleum & ; Petrochemical Engineering Journal 7, n^o 2 (4 avril 2023) : 1–56. http://dx.doi.org/10.23880/ppej-16000349.

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The first in the series of Azuberths Game Changer publications “Synergy of the Conventional Crude Oil and the FT-GTL Processes for Sustainable Synfuels Production: The Game Changer Approach-Phase One Category” a.k.a. (DOI: 10.23880/ppej16000330) is targeted at reducing 80 per cent CO2 emissions from the internal combustion engines by upgrading from the conventional crude oil refinery products to the synthetic fuels products (ultra-low-carbon fuels). This paper will focus on the complete elimination of the remaining 20 per cent CO2 emissions (i.e. to achieve zero- CO2 emissions) in transportation and power generating internal combustion engines as well as in the other centralized emissions/emitters such as petroleum industry flare lines, industrial process and big technology industries scrubber flue gas, et cetera. This invention stems from similar biblical quote {Isaiah 6:8-New International Version (NIV)} which states, and then I heard the voice of the Lord saying, “Whom shall I send? And who will go for us?” And I (Isaiah) said, “Here am I. Send me!” Laterally, in this case I (Azunna) said, “Here am I. Please use me”. Hence the aftermath, IJN-Universal Emissions Liquefiers is a plug and play units for all categories of pollutants discharge into the atmosphere. The work is motivated by the scientific facts that (i) The release of CO2 from automotive exhaust effluents, industry vents and flue gas emissions into the atmosphere contributes to greenhouse gas (GHG) accumulation causing global warming hence climate changes issues such as flooding of coastlines/sea-rising, melting of the glaciers, disrupted weather patterns, bushburning/wildfire, depletion of Ozone layer, smog and air pollution, acidification of water bodies, runaway greenhouse effect, etc. (ii) Every gas stream (e.g., flue gas) can be made liquid by e.g. a series of compression, cooling and expansion steps and once in liquid form, the components of the gas can be separated in a distillation column. (iii) Captured liquefied gases can be put to various uses, especially carbon dioxide (CO2 ), which can be used for the production of renewable energy via Synfuels such as the e-fuel/solar fuel. The natural atmosphere is composed of 78% nitrogen, 21% oxygen, 0.9% argon, and only about 0.1% natural greenhouse gases, which include carbon dioxide, organic chemicals called chlorofluorocarbons (CFCs), methane, nitrous oxide, ozone, and many others. Although a small amount, these greenhouse gases make a big difference - they are the gases that allow the greenhouse effect to exist by trapping in some heat that would otherwise escape to space. Carbon dioxide, although not the most potent of the greenhouse gases, is the most important because of the huge volumes emitted into the air by combustion of fossil fuels (e.g., gasoline, diesel, fuel oil, coal, natural gas). In general, the major contributors to the greenhouse effect are: Burning of fossil fuels in automobiles, deforestation, farming processing and manufacturing factories, industrial waste and landfills, increasing animal and human respiration, etc. The increased number of factories, automobiles, and population increases the amount of these gases in the atmosphere. The greenhouse gases never let the radiations to escape from the earth atmosphere and increase the surface temperature of the earth. This then leads to global warming. The petroleum industry well sites vent/flare gases (methane, ethane, propane, butanes, H2 O (g), O2 , N2 , etc.). Internal combustion engines (automobiles-cars, vehicles, ships, trains, planes, etc.) release exhaust effluents (containing H2 O (g), CO2 , O2 , and N2 ); steam generators in large power plants and the process furnaces in large refineries, petrochemical and chemical plants, and incinerators burn considerable amounts of fossil fuels and therefore emit large amounts of flue gas to the ambient atmosphere. In general, Flue gas is the gas exiting to the atmosphere via a “flue”, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. The emitted flue gas contains carbon dioxide CO2 , carbon monoxide CO, sulphur oxide SO2 , nitrous oxide NO and particulates. Furthermore, GTL plants produce CO2 , H2 O and waste heat, while both pyrolysis and gasification plant generate gaseous products consisting of (a mixture of non-condensable gases such as H2 , CO2 , and CO and light hydrocarbons “e.g. CH4 ” at room temperature, as well as H2 O (g), O2 and complex hydrocarbons e.g. C2 H2 , C2 H4 , etc.). In general, all combustion is as a result of air-fuel mixture burning (i.e. air or oxygen mixing directly with biomass/ coal or with liquid/gaseous hydrocarbon inside internal combustion engines), releases carbon dioxide and steam (H2 O) back into the atmosphere as well as producing energy for work. Specifically, during combustion, carbon combines with oxygen to produce carbon dioxide (CO2 ). The principal emission from transportation and power generating internal combustion engines is carbon dioxide (CO2 ). The level of CO2 emission is linked to the amount of fuel consumed and the type of fuel used as well as the individual engine’s operating characteristics. For instance, diesel-powered engines have higher emission than petrol/gasoline-powered engines. Although emphasis is places more on CO2 , this investigation is ultimately concerned with the real-time liquefaction of all the components of gaseous release/emissions -related to air pollution/health problem. It is believed that the mortality rate from air pollution is eight times larger than the mortality caused by car accidents each year. Pollutants with the strongest evidence for public health concern include particulate matter (PM), ozone (O3 ), nitrogen dioxide (NO2 ) and sulphur dioxide (SO2 ). All the exhaust effluents gases/flue gas and vent/flare gases are captured by liquefying them and then put to various uses, to achieve “Net zero” emissions. Fundamentally, the objective of the present invention is to develop a compact device (Universal Emissions Liquefiers) that can be retro-fitted onto the exhaust tailpipe-end of the internal combustion engines (diesel-powered, gasoline-powered, and hybrid automobiles-cars, vehicles, SUV’s, trucks, motor cycles, tri-cycles, portable electric generators, sea and cargo ships/ boats, trains, planes, rockets, etc.) and outlet of industrial machines that release flue gases through exhaust/scrubber channels, as well as crude oil, refined products storage tanks that vent greenhouse gases into the atmosphere, coal processing units/ plants and turn them into liquid { CO2 (l), N2 (l), O2 (l), etc.} or powdered components or chemically transform them in realtime with selective catalysts to any other specific compound, e.g. treating CO2 with hydrogen gas (H2) can produce methanol (CH3 OH), methane (CH4 ), or formic acid (HCOOH), while reaction of CO2 with alkali (e.g. NaOH) can give carbonates (NaHCO3 ) and bicarbonates (Na2 CO3 ). Nitrogen (N2 ) to ammonia (NH3 ) or Hydrazine (N2 H4 ), and molecular oxygen (O2 ) to hydrogen peroxide (H2 O2 ), et cetera. Alternatively, in new automobiles designs, the universal emissions liquefiers’ device can be directly net-worked on the floor alongside the catalytic converters and may eliminate the need for muffler/silencer/resonator. This is achieved by the application of any of the five main gas capture/separation technologies: Liquid absorption, Solid adsorption, Membrane separation (with and without solvent- organic or inorganic), Cryogenic refrigeration/distillation, and Electrochemical pH-swing separation or their combination to selectively trap and liquefy the individual pollutants. According to the fact from CarBuster, almost 0.009 metric tons of carbon dioxide is produced from every gallon of gasoline burned, which means that the average car user makes about 11.7 tons of carbon dioxide each year from their cars alone

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Goffredi, S. K., J. J. Childress, N. T. Desaulniers et F. J. Lallier. « Sulfide acquisition by the vent worm Riftia pachyptila appears to be via uptake of HS-, rather than H2S. » Journal of Experimental Biology 200, n^o 20 (1 octobre 1997) : 2609–16. http://dx.doi.org/10.1242/jeb.200.20.2609.

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Deep-sea hydrothermal vents are home to a variety of invertebrate species, many of which host chemosynthetic bacteria in unusual symbiotic arrangements. The vent tubeworm Riftia pachyptila (Vestimentifera) relies upon internal chemolithoautotrophic bacterial symbionts to support its large size and high growth rates. Because of this, R. pachyptila must supply sulfide to the bacteria, which are far removed from the external medium. Internal H2S ([H2S+HS-+S2-]) can reach very high levels in R. pachyptila (2-12mmoll-1 in the vascular blood), most of which is bound to extracellular hemoglobins. The animal can potentially take up sulfide from the environment via H2S diffusion or via mediated uptake of HS-, or both. It was expected that H2S diffusion would be the primary sulfide acquisition mechanism, paralleling the previously demonstrated preferential uptake of CO2. Our data show, however, that the uptake of HS- is the primary mechanism used by R. pachyptila to obtain sulfide and that H2S diffusion into the worm apparently proceeds at a much slower rate than expected. This unusual mechanism may have evolved because HS- is less toxic than H2S and because HS- uptake decouples sulfide and inorganic carbon acquisition. The latter occurs via the diffusion of CO2 at very high rates due to the maintenance of an alkaline extracellular fluid pH. H2S accumulation is limited, however, to sulfide that can be bound by the hemoglobins, protecting the animal from sulfide toxicity and the symbionts from sulfide inhibition of carbon fixation.

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Madonia, Paolo, Marianna Cangemi, Marcello Colajanni et Aldo Winkler. « Atmospheric Concentration of CO2 and PM2.5 at Salina, Stromboli, and Vulcano Islands (Italy) : How Anthropogenic Sources, Ordinary Volcanic Activity and Unrests Affect Air Quality ». International Journal of Environmental Research and Public Health 19, n^o 8 (15 avril 2022) : 4833. http://dx.doi.org/10.3390/ijerph19084833.

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Geogenic and anthropogenic sources of atmospheric particulate and CO2 can lead to threats to human health in volcanic areas. Although the volcanic CO2 hazard is a topic frequently debated in the related scientific literature, space and time distribution of PM2.5 are poorly known. The results of combined CO2/PM2.5 surveys, carried out at Salina, Stromboli, and Vulcano islands (Aeolian archipelago, Italy) in the years 2020–2021, and integrated with investigations on bioaccumulation of metallic particulate matter by the mean of data on the magnetic properties of oleander leaves, are presented in this work. The retrieved results indicate that no significant anthropogenic sources for both CO2 and PM2.5 are active in these islands, at the net of a minor contribution due to vehicular traffic. Conversely, increments in volcanic activity, as the unrest experienced by Vulcano island since the second half of 2021, pose serious threats to human health, due to the near-ground accumulation of CO2, and the presence of suspended micro-droplets of condensed hydrothermal vapor, fostering the diffusion of atmophile viruses, such as the COVID-19. Gas hazard conditions can be generated, not only by volcanic vents or fumarolic fields, but also by unconventional sources, such as the outgassing from shallow hydrothermal aquifers through drilled or hand-carved wells.

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Marchi, Susanna, Roberto Tognetti, Francesco Primo Vaccari, Mario Lanini, Mitja Kaligarič, Francesco Miglietta et Antonio Raschi. « Physiological and morphological responses of grassland species toelevated atmospheric CO2 concentrations in FACE-systems andnatural CO2 springs ». Functional Plant Biology 31, n^o 2 (2004) : 181. http://dx.doi.org/10.1071/fp03140.

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Stomatal density, leaf conductance and water relations can be affected by an increase in the concentration of atmospheric CO2, and thus affect plant productivity. However, there is uncertainty about the effects of elevated CO2 on stomatal behaviour, water relations and plant productivity, owing to the lack of long-term experiments in representative natural ecosystems. In this work, variations in stomatal density and index, leaf water relations and plant biomass of semi-natural grassland communities were analysed under field conditions by comparing plants in three different experimental set-ups (natural CO2 springs, plastic tunnels and mini-FACE systems). Natural degassing vents continuously expose the surrounding vegetation to truly long-term elevated CO2 and can complement short-term manipulative experiments. Elevated CO2 concentration effects on stomata persist in the long term, though different species growing in the same environment show species-specific responses. The general decrease in stomatal conductance after exposure to elevated CO2 was not associated with clear changes in stomatal number on leaf surfaces. The hypothesis of long-term adaptive modifications to stomatal number and distribution of plants exposed to elevated CO2 was not supported by these experiments on grassland communities. Elastic cell wall properties were affected to some extent by elevated CO2. Above-ground biomass did not vary between CO2 treatments, leaf area index did not compensate for reduced stomatal conductance, and the root system had potentially greater soil exploration capacity. Considerable between-species variation in response to elevated CO2 may provide a mechanism for changing competitive interactions among plant species.

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Takahashi, M., S. H. C. Noonan, K. E. Fabricius et C. J. Collier. « The effects of long-term in situ CO2 enrichment on tropical seagrass communities at volcanic vents ». ICES Journal of Marine Science 73, n^o 3 (7 septembre 2015) : 876–86. http://dx.doi.org/10.1093/icesjms/fsv157.

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Abstract The effects of long-term exposure to elevated levels of carbon dioxide (CO2) on seagrass communities are still poorly understood. This study investigates the tropical subtidal seagrass communities at three shallow volcanic CO2 vents in Papua New Guinea. Seagrass cover and biomass increased threefold and fivefold, respectively, from control to medium and high pCO2 sites (average pH = 7.9, 7.7, and 7.5, respectively). The seagrass community composition differed significantly between the pCO2 sites: Cymodocea serrulata, Cymodocea rotundata, and Halodule uninervis were more abundant at high pCO2 sites, whereas Halophila ovalis, Thalassia hemprichii, and Syringodium isoetifolium occurred only at low and mid pCO2 sites. Cymodocea rotundata was the only species common among all pCO2 sites and locations. The δ13C in its leaves significantly declined with increasing pCO2, indicating that additional CO2 influenced seagrass carbon uptake, and specifically, that there was discrimination against the heavier isotope (13C) when carbon was more abundant. Size-specific leaf growth rates (i.e. leaf turnover) also significantly declined with increasing pCO2; however, leaf growth rates showed no consistent difference in response to elevated pCO2 in two of four surveys. Our study suggests that progressive ocean acidification may lead to higher cover and above- and below-ground biomass, but lower size-specific growth and altered species composition in tropical seagrass communities. The effects of co-limiting factors, such as light and nutrient availability, on early-responding parameters, such as growth rates, require further attention to improve projections.

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Porzio, L., S. L. Garrard et M. C. Buia. « The effect of ocean acidification on early algal colonization stages at natural CO2 vents ». Marine Biology 160, n^o 8 (14 mai 2013) : 2247–59. http://dx.doi.org/10.1007/s00227-013-2251-3.

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Cocozza di Montanara, A., E. Baldrighi, M. López Correa, E. Chianese, L. Appolloni, N. Simoncini, R. Sandulli et al. « Meiobenthos and ocean acidification : Effects on meiobenthic communities inhabiting Mediterranean cold shallow CO2-vents ». Estuarine, Coastal and Shelf Science 300 (mai 2024) : 108730. http://dx.doi.org/10.1016/j.ecss.2024.108730.

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McClintock, J. B., C. D. Amsler, M. O. Amsler, A. Duquette, R. A. Angus, J. M. Hall-Spencer et M. Milazzo. « Trace elements in shells of common gastropods in the near vicinity of a natural CO2 ; vent : no evidence of pH-dependent contamination ». Biogeosciences Discussions 11, n^o 4 (3 avril 2014) : 5215–37. http://dx.doi.org/10.5194/bgd-11-5215-2014.

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Abstract. There is concern that the use of natural volcanic CO2 vents as analogs for studies of the impacts of ocean acidification on marine organisms are biased due to physiochemical influences other than seawater pH alone. One issue that has been raised is whether potentially harmful trace elements in sediments that are rendered more soluble and labile in low pH environments are made more bioavailable, and sequestered in the local flora and fauna at harmful levels. In order to evaluate this hypothesis, we analyzed the concentrations of trace elements in shells (an established proxy for tissues) of four species of gastropods (two limpets, a topshell and a whelk) collected from three sites in Levante Bay, Vulcano Island. Each sampling site increased in distance from the primary CO2 vent and thus represented low, moderate, and ambient seawater pH conditions. Concentrations of As, Cd, Co, Cr, Hg, Mo, Ni, Pb, and V measured in shells using ICP-OES were below detection thresholds for all four gastropod species at all three sites. However, there were measurable concentrations of Sr, Mn, and U in the shells of the limpets Patella caerulea, P. rustica, and the snail Osilinus turbinatus, and similarly, Sr, Mn, U, and also Zn in the shells of the whelk Hexaplex trunculus. Levels of these elements were within the ranges measured in gastropod shells in non-polluted environments, and with the exception of U in the shells of P. caerulea, where the concentration was significantly lower at the collecting site closest to the vent (low pH site), there were no site-specific spatial differences in concentrations for any of the trace elements in shells. Thus trace element enhancement in sediments in low-pH environments was not reflected in greater bioaccumulations of potentially harmful elements in the shells of common gastropods.

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Chauhan, Bhavin V., Daleniece Higgins Jones, Goutam Banerjee, Saumya Agrawal, Irshad M. Sulaiman, Chunrong Jia et Pratik Banerjee. « Indoor Bacterial and Fungal Burden in “Moldy” versus “Non-Moldy” Homes : A Case Study Employing Advanced Sequencing Techniques in a US Metropolitan Area ». Pathogens 12, n^o 8 (1 août 2023) : 1006. http://dx.doi.org/10.3390/pathogens12081006.

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The presence of fungi in the indoor environment is associated with allergies and other respiratory symptoms. The aim of this study was to use sequencing and molecular methods, including next-generation sequencing (NGS) approaches, to explore the bacterial and fungal communities and their abundance in the indoor environment of houses (n = 20) with visible “moldy” (HVM) and nonvisible “non-moldy” (HNM) in Memphis, TN, USA. Dust samples were collected from air vents and ground surfaces, and the total DNA was analyzed for bacteria and fungi by amplifying 16S rRNA and ITS genes on the Illumina Miseq. Results indicated that Leptosphaerulina was the most abundant fungal genus present in the air vent and ground samples from HNM and HVM. At the same time, the most abundant bacterial genera in the air vent and ground samples were Propionibacterium and Streptococcus. The fungi community diversity was significantly different in the air vent samples. The abundance of fungal species known to be associated with respiratory diseases in indoor dust samples was similar, regardless of the visibility of fungi in the houses. The existence of fungi associated with respiratory symptoms was compared with several parameters like dust particulate matter (PM), CO2 level, temperature, and humidity. Most of these parameters are either positively or negatively correlated with the existence of fungi associated with respiratory diseases; however, none of these correlations were significant at p = 0.05. Our results indicate that implementing molecular methods for detecting indoor fungi may strengthen common exposure and risk assessment practices.

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