High CO2 Partial Pressure Research Articles

Novel Strategy to Produce Ultrapure Hydrogen from Coal with Pre-combustion Carbon Capture

Abstract Integrated Gasification Combined Cycles (IGCCs) are one of the emerging clean coal technologies which paves the way for producing power from coal with a higher net power efficiency than conventional PC-fired boiler power plants. It is also advantageous that in an IGCC power plant a carbon capture unit can be applied to a stream having a very high CO2 partial pressure upstream of gas combustion that would not be available in case of a PC-fired boiler power plant, leading to less energy penalty involved in the carbon capture. In this study it is aimed to design a cogeneration process where a Hydrogen Pressure Swing Adsorption (H2 PSA) unit is retrofitted to an IGCC power plant with pre-combustion capture for producing ultrapure hydrogen (99.99+ vol%). The ultrapure hydrogen is commonly utilised as feedstock for deep desulphurisation and hydrocracking units at refineries as well as H2 fuel cells. It is found that, at the same H2 purity of 99.99 + %, the hydrogen recovery could be improved up to 93% with the increasing number of columns. Improving the H2 recovery at the H2 PSA to its maximum can contribute to reducing the power consumption for compressing the H2 PSA tail gas by minimizing the yield of the H2 PSA tail gas by-product. Furthermore, it is demonstrated that the H2 PSA can also be designed to achieve 90% H2 recovery even when a portion of the tail gas is recycled to the shift reactors in order to improve the overall advanced IGCC performance by increasing the H2 yield and by reducing the auxiliary power consumption at carbon capture unit.

Observed CO2-induced reactivity in Werkendam gas field, the Dutch storage analogue

Natural CO2 fields provide important insights in the long-term geochemical behaviour of CO2 in a reservoir and the potential of permanent trapping in carbonate minerals. The Werkendam gas field in The Netherlands, discovered during gas exploration activities in 1991, contains >70% CO2. Core samples were selected from the Werkendam natural analogue (WED) as well as from the nearby Barendrecht-Ziedewij (BRTZ) and Waalwijk-Noord (WWN) CH4-bearing reservoirs. The three gas reservoirs are all Triassic Bunter sandstones, with BRTZ and WWN containing respectively 0.8% and 1.4% CO2. Mineralogical and petrographic analyses were performed to unravel the diagenetic evolution of each field for comparison. Early diagenetic mineral reactions were similar for the three field. Minor differences are attributed to variation in primary mineralogy and the K+/H+ ratio of the formation water. The late stage mineral reactions that are observed in WED which are absent in BRTZ and WWN were interpreted to be induced by the influx of CO2. These include the (additional) dissolution of K-feldspar and anhydrite, and the precipitation of Mg-rich siderite, quartz and barite. Even though carbon isotope analysis could not confirm (but also not exclude) this, petrographic analysis gave strong indications for the precipitation of siderite in WED as a result of the high CO2 partial pressure. The estimated amount of carbon trapping in siderite is 20% to 58% of the total CO2. Barite precipitation was probably the result of K-feldspar and anhydrite dissolution, since barium is a common impurity in K-feldspar. In the overall reaction between the sandstone and carbonized brine, several unknowns remain. A sink for calcium, potassium and aluminium from anhydrite and K-feldspar dissolution was not observed in the samples from WED. In addition, potential sources of magnesium and iron for Mg-rich siderite could not be deduced from the comparison of the fields. Possibly, these sinks and sources can be found in the clay-rich intervals within the sandstone reservoir. Future research should investigate the effect of heterogeneity within storage complexes on mineral trapping.

Controls on CO2 fate and behavior in the Gullfaks oil field (Norway): How hydrogeochemical modeling can help decipher organic-inorganic interactions

Oil degradation in the Gullfaks field led to hydrogeochemical processes that caused high CO2 partial pressure and a massive release of sodium into the formation water. Hydrogeochemical modeling of the inorganic equilibrium reactions of water-rock-gas interactions allows us to quantitatively analyze the pathways and consequences of these complex interconnected reactions. This approach considers interactions among mineral assemblages (anorthite, albite, K-feldspar, quartz, kaolinite, goethite, calcite, dolomite, siderite, dawsonite, and nahcolite), various aqueous solutions, and a multicomponent fixed-pressure gas phase (CO2, CH4, and H2) at 4496-psi (31-mPa) reservoir pressure. The modeling concept is based on the anoxic degradation of crude oil (irreversible conversion of n-alkanes to CO2, CH4, H2, and acetic acid) at oil-water contacts. These water-soluble degradation products are the driving forces for inorganic reactions among mineral assemblages, components dissolved in the formation water, and a coexisting gas at equilibrium conditions. The modeling results quantitatively reproduce the proven alteration of mineral assemblages in the reservoir triggered by oil degradation, showing (1) nearly complete dissolution of plagioclase; (2) stability of K-feldspar; (3) massive precipitation of kaolinite and, to a lesser degree, of Ca-Mg-Fe carbonate; and (4) observed uncommonly high CO2 partial pressure (61 psi [0.42 mPa] at maximum). The evolving composition of coexisting formation water is strongly influenced by the uptake of carbonate carbon from oil degradation and sodium released from dissolving albitic plagioclase. This causes supersaturation with regard to thermodynamically stable dawsonite. The modeling results also indicate that nahcolite may form as a CO2-sequestering sodium carbonate instead of dawsonite, likely controlling CO2 partial pressure.

Unusual Small Subunit That Is Not Expressed in Photosynthetic Cells Alters the Catalytic Properties of Rubisco in Rice

Rubisco small subunits (RbcSs) are encoded by a nuclear multigene family in plants. Five RbcS genes, OsRbcS1, OsRbcS2, OsRbcS3, OsRbcS4, and OsRbcS5, have been identified in rice (Oryza sativa). Among them, the amino acid sequence of OsRbcS1 differs notably from those of other rice RbcSs. Phylogenetic analysis showed that OsRbcS1 is genetically distant from other rice RbcS genes and more closely related to RbcS from a fern and two woody plants. Reverse transcription-PCR and promoter β-glucuronidase analyses revealed that OsRbcS1 was not expressed in leaf blade, a major photosynthetic organ in rice, but was expressed in leaf sheath, culm, anther, and root central cylinder. In leaf blade of transgenic rice overexpressing OsRbcS1 and leaf sheath of nontransgenic rice, OsRbcS1 was incorporated into the Rubisco holoenzyme. Incorporation of OsRbcS1 into Rubisco increased the catalytic turnover rate and Km for CO2 of the enzyme and slightly decreased the specificity for CO2, indicating that the catalytic properties were shifted to those of a high-activity type Rubisco. The CO2 assimilation rate at low CO2 partial pressure was decreased in overexpression lines but was not changed under ambient and high CO2 partial pressure compared with nontransgenic rice. Although the Rubisco content was increased, Rubisco activation state was decreased in overexpression lines. These results indicate that the catalytic properties of Rubisco can be altered by ectopic expression of OsRbcS1, with substantial effects on photosynthetic performance in rice. We believe this is the first demonstration of organ-specific expression of individual members of the RbcS gene family resulting in marked effects on Rubisco catalytic activity.

Metal release from limestones at high partial-pressures of CO2

CO2 leakage from underground CO2 sequestration and storage poses potential risks to degradation of water quality in shallow aquifers. Increased CO2 concentrations can result in decreased pH and lead to subsequent metal release from mineral dissolution or desorption from mineral surfaces. Dissolution of carbonate minerals present in aquifer sediments or rocks will buffer pH and is generally thought to reduce the potential risk of metal release in the event of a CO2 leak. As a result, much of the research on geochemical impacts of CO2 leakage has focused on siliciclastic aquifers with little to no carbonate minerals present. However, carbonate minerals contain trace amounts of metals in their crystal structure that will be released into solution with dissolution and may pose a risk to drinking water quality. Here, we perform laboratory water–rock experiments to analyze the potential for metal release due to carbonate mineral dissolution in limestone aquifers. Rock samples from three limestone aquifers were dissolved in batch reactors with varying partial-pressures of CO2 (from 0.01 to 1bar) in the headspace. As CO2 dissolved into the fluid and decreased the pH, the carbonate minerals dissolved and released metals into solution. The concentrations of calcium, magnesium, strontium, barium, thallium, uranium, and cobalt increased but remained below any regulatory limits. The concentrations of arsenic and nickel increased and exceeded primary drinking water standards set by the USEPA and the State of California, respectively. Potential sources of metals in the rocks were determined through detailed sample characterization using sequential extractions, laser ablation inductively coupled mass spectrometry, and high resolution mineralogical mapping with QEMSCAN. We found that calcite dissolution released more metals to solution than pyrite dissolution or metal desorption from mineral surfaces in these experiments. Geochemical models based on the experimental data were used to evaluate the relative importance of calcite dissolution versus pyrite dissolution over a 30-year time frame. Under both oxic and sub-oxic conditions, calcite dissolution is the dominant source of metals to solution immediately after exposure to CO2. Pyrite dissolution becomes the dominant source at later times as the fluid reaches equilibrium with respect to calcite. For all model scenarios, the cumulative contribution of metals to solution was dominated by calcite dissolution. Results from this study suggest that the pH-buffering benefit of carbonate mineral dissolution in the event of a CO2 leak may be offset by the potentially negative effect of trace metal release from the crystal structure. This study highlights the need for detailed sample characterization at individual sites to identify sources of metals when assessing the potential risk of CO2 leakage into shallow aquifers.

Space–time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay and adjacent part of the Laptev Sea

Abstract. This study aims to improve understanding of carbon cycling in the Buor-Khaya Bay (BKB) and adjacent part of the Laptev Sea by studying the inter-annual, seasonal, and meso-scale variability of carbon and related hydrological and biogeochemical parameters in the water, as well as factors controlling carbon dioxide (CO2) emission. Here we present data sets obtained on summer cruises and winter expeditions during 12 yr of investigation. Based on data analysis, we suggest that in the heterotrophic BKB area, input of terrestrially borne organic carbon (OC) varies seasonally and inter-annually and is largely determined by rates of coastal erosion and river discharge. Two different BKB sedimentation regimes were revealed: Type 1 (erosion accumulation) and Type 2 (accumulation). A Type 1 sedimentation regime occurs more often and is believed to be the quantitatively most important mechanism for suspended particular matter (SPM) and particulate organic carbon (POC) delivery to the BKB. The mean SPM concentration observed in the BKB under a Type 1 regime was one order of magnitude greater than the mean concentration of SPM (~ 20 mg L−1) observed along the Lena River stream in summer 2003. Loadings of the BKB water column with particulate material vary by more than a factor of two between the two regimes. Higher partial pressure of CO2 (pCO2), higher concentrations of nutrients, and lower levels of oxygen saturation were observed in the bottom water near the eroded coasts, implying that coastal erosion and subsequent oxidation of eroded organic matter (OM) rather than the Lena River serves as the predominant source of nutrients to the BKB. Atmospheric CO2 fluxes from the sea surface in the BKB vary from 1 to 95 mmol m−2 day−1 and are determined by specific features of hydrology and wind conditions, which change spatially, seasonally, and inter-annually. Mean values of CO2 emission from the shallow Laptev Sea were similar in September 1999 and 2005 (7.2 and 7.8 mmol m−2 day−1, respectively), while the CO2 efflux can be one order lower after a strong storm such as in September 2011. Atmospheric CO2 emissions from a thawed coastal ice complex in the BKB area varied from 9 to 439 mmol m−2 day−1, with the mean value ranged from 75.7 to 101 mmol m−2 day−1 in two years (September 2006 and 2009), suggesting that at the time of observations the eroded coastal area served as a more significant source of CO2 to the atmosphere than the tundra (mean value: 22.7 mmol m−2 day−1) on the neighboring Primorsky coastal plain (September 2006). The observed increase in the Lena River discharge since the 1990s suggests that increased levels of "satellite-derived" annual primary production could be explained by an increasing load of humic acids delivered to shelf water; in this water the color resulting from the presence of CDOM (colored dissolved organic matter) mimics the color resulting from the presence of Chl a when seen from space. Because the BKB area can be employed as an integrator of ongoing changes in the surrounding environment, we suggest that under ongoing changes, more nutrients, products of eroded OC transformation and river transport, will be delivered to the Arctic Ocean with its shrinking ice cover, potentially increasing primary production outside of the shallow East Siberian Arctic Shelf (ESAS). At the same time, because the ESAS is characterized by very low transparency which limits euphotic layer thickness, excessive pCO2 will not be utilized by photosynthesis but will rather be emitted to the atmosphere at increasing rates, affecting regional CO2 balance.

CO2-induced shift in microbial activity affects carbon trapping and water quality in anoxic bioreactors

Microbial activity is a potentially important yet poorly understood control on the fate and environmental impact of CO2 that leaks into aquifers from deep storage reservoirs. In this study we examine how variation in CO2 abundance affected competition between Fe(III) and SO42--reducers in anoxic bioreactors inoculated with a mixed-microbial community from a freshwater aquifer. We performed two sets of experiments: one with low CO2 partial pressure (∼0.02atm) in the headspace of the reactors and one with high CO2 partial pressure (∼1atm). A fluid residence time of 35days was maintained in the reactors by replacing one-fifth of the aqueous volume with fresh medium every seven days. The aqueous medium was composed of groundwater amended with small amounts of acetate (250μM), phosphate (1μM), and ammonium (50μM) to stimulate microbial activity. Synthetic goethite (1mmol) and SO42- (500μM influent concentration) were also available in each reactor to serve as electron acceptors. Results of this study show that higher CO2 abundance increased the ability of Fe(III) reducers to compete with SO42- reducers, leading to significant shifts in CO2 trapping and water quality. Mass-balance calculations and pyrosequencing results demonstrate that SO42- reducers were dominant in reactors with low CO2 content. They consumed 85% of the acetate after acetate consumption reached steady state while Fe(III) reducers consumed only 15% on average. In contrast, Fe(III) reducers were dominant during that same interval in reactors with high CO2 content, consuming at least 90% of the acetate while SO42- reducers consumed a negligible amount (<1%). The higher rate of Fe(III) reduction in the high-CO2 bioreactors enhanced CO2 solubility trapping relative to the low-CO2 bioreactors by increasing alkalinity generation (6X). Hence, the shift in microbial activity we observed was a positive feedback on CO2 trapping. More rapid Fe(III) reduction degraded water quality, however, by leading to high Fe(II) concentration.

Metal release from dolomites at high partial-pressures of CO2

The potential for metal release associated with CO2 leakage from underground storage formations into shallow aquifers is an important consideration in assessment of risk associated with CO2 sequestration. Metal release can be driven by acidification of groundwaters caused by dissolution of CO2 and subsequent dissociation of carbonic acid. Thus, acidity is considered one of the main drivers for water quality degradation when evaluating potential impacts of CO2 leakage. Dissolution of carbonate minerals buffers the increased acidity. Thus, it is generally thought that carbonate aquifers will be less impacted by CO2 leakage than non-carbonate aquifers due to their high buffering potential. However, dissolution of carbonate minerals can also release trace metals, often present as impurities in the carbonate crystal structure, into solution. The impact of the release of trace metals through this mechanism on water quality remains relatively unknown. In a previous study we demonstrated that calcite dissolution contributed more metal release into solution than sulfide dissolution or desorption when limestone samples were dissolved in elevated CO2 conditions. The study presented in this paper expanded our work to dolomite formations and details a thorough investigation on the role of mineral composition and mechanisms on trace element release in the presence of CO2. Detailed characterization of samples from dolomite formations demonstrated stronger associations of metal releases with dissolution of carbonate mineral phases relative to sulfide minerals or surface sorption sites. Aqueous concentrations of Sr2+, CO2+, Mn2+, Ni2+, Tl+, and Zn2+ increased when these dolomite rocks were exposed to elevated concentrations of CO2. The aqueous concentrations of these metals correlate to aqueous concentrations of Ca2+ throughout the experiments. All of the experimental evidence points to carbonate minerals as the dominant source of metals from these dolomite rocks to solution under experimental CO2 leakage conditions. Aqueous concentrations of Ca2+ and Mg2+ predicted from numerical simulation of kinetic dolomite dissolution match those observed in the experiments when the surface area is three to five orders of magnitude lower than the surface area of the samples measured by gas adsorption.

Changes in reservoir heterogeneity and quality as a response to high partial pressures of CO2 in a gas reservoir, New Zealand

The Kapuni Field is the largest onshore petroleum field in New Zealand and produces CO2-rich, gas (c. 40–45 mol% CO2). Diagenesis within the reservoir is dominated by CO2-related reactions that have resulted in localised precipitation of kaolin (abundant), quartz, calcite, dolomite, and siderite, along with localised generation of secondary porosity.Most of the CO2 in the reservoir is thought to have been sourced from intraformational coals, with subsequent up-dip migration to the crest of the Kapuni structure. During migration, CO2 will have dissolved into undersaturated pore fluids and the resulting acidic pore fluids catalysed feldspar (and minor carbonate) dissolution, thereby providing ions for precipitation of authigenic minerals. Timing of the diagenetic reactions, as determined by paragenetic observations and fluid inclusion analysis, suggests that both quartz and carbonate formed at a very late stage (>100 °C, corresponding to 0–4 Ma), which is consistent with modelled maturation and expulsion of CO2 from intraformational source rocks (5 Ma to present). The carbon isotope composition of carbonate cements (median δ13CPDB −12.4‰) is similar to that of the reservoired CO2 (δ13CPDB −14.5‰), and this is supportive of late-stage cement formation with carbon sourced primarily from thermal maturation reactions.The degree of CO2-related reactions observed within the Kapuni Field appears dependent upon grain size, lithofacies and stratigraphic position in the reservoir. Coarse-grained, high-energy facies have undergone the most feldspar dissolution, coupled with formation and local preservation of secondary porosity. This is interpreted to be due to preferential migration of large volumes of CO2-rich fluids through permeable beds, thereby further enhancing reservoir quality. By comparison, much less feldspar reaction but locally significant authigenic mineral precipitation occurs within finer-grained, lower-energy sandstone facies. This is considered to be due to relatively low permeability (prior to CO2 circulation), restricting the degree of fluid circulation, and resulting in net mineral precipitation. Authigenic kaolin has precipitated close to the mineral source, whilst ions required to precipitate calcite/dolomite cements are likely to have migrated further, resulting in a complex distribution of carbonate cements, with pervasive cements observed at gas/water contacts.Results from this study demonstrate how CO2-related reactions are dependent on grain size and mineralogy. We show that these reactions can affect vertical heterogeneity of a reservoir by increasing the degree of compartmentalisation through development of ‘sweet spots’ (due to mineral dissolution) and tight beds (due to mineral cementation).

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 (PCO2) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high PCO2 (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between PCO2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of PCO2 (0.05, 1.52 and 3.01kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated PCO2 resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated PCO2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated PCO2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd2+ concentration remained the same, while intracellular levels of free Zn2+ increased suggesting that Cd2+ substitutes bound Zn2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn2+ but led to a profound increase in the intracellular levels of labile Cu2+ and Fe2+. An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05kPa PCO2); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and PCO2 in clams and indicate that variations in environmental PCO2 may modulate the biological effects of trace metals in marine organisms.

Interactive effects of elevated temperature and CO2 levels on energy metabolism and biomineralization of marine bivalves Crassostrea virginica and Mercenaria mercenaria

The continuing increase of carbon dioxide (CO2) levels in the atmosphere leads to increases in global temperatures and partial pressure of CO2 (PCO2) in surface waters, causing ocean acidification. These changes are especially pronounced in shallow coastal and estuarine waters and are expected to significantly affect marine calcifiers including bivalves that are ecosystem engineers in estuarine and coastal communities. To elucidate potential effects of higher temperatures and PCO2 on physiology and biomineralization of marine bivalves, we exposed two bivalve species, the eastern oysters Crassostrea virginica and the hard clams Mercenaria mercenaria to different combinations of PCO2 (~400 and 800μatm) and temperatures (22 and 27°C) for 15weeks. Survival, bioenergetic traits (tissue levels of lipids, glycogen, glucose and high energy phosphates) and biomineralization parameters (mechanical properties of the shells and activity of carbonic anhydrase, CA) were determined in clams and oysters under different temperature and PCO2 regimes. Our analysis showed major inter-species differences in shell mechanical traits and bioenergetics parameters. Elevated temperature led to the depletion of tissue energy reserves indicating energy deficiency in both species and resulted in higher mortality in oysters. Interestingly, while elevated PCO2 had a small effect on the physiology and metabolism of both species, it improved survival in oysters. At the same time, a combination of high temperature and elevated PCO2 lead to a significant decrease in shell hardness in both species, suggesting major changes in their biomineralization processes. Overall, these studies show that global climate change and ocean acidification might have complex interactive effects on physiology, metabolism and biomineralization in coastal and estuarine marine bivalves.

Fruit maturity, controlled atmosphere delays and storage temperature affect fruit quality and incidence of storage disorders of ‘Fuji’ apples

The effects of storage temperature, harvest maturity, controlled atmosphere (CA) storage regime, and CA strategies on fruit quality and the incidence of storage disorders during storage of ‘Fuji’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] were investigated. Flesh browning incidence was lower in fruit stored at 2°C than at 0°C, but fruit were also softer and had lower titratable acidity (TA) at the higher storage temperature. All subsequent studies were carried out at 0°C. High partial pressures of CO2 (pCO2) of 2.5kPa compared with <1kPa did not consistently affect flesh firmness, soluble solids concentration (SSC), and TA. The incidence of flesh browning was higher in more mature fruit and it was further aggravated by higher pCO2 in the storage atmosphere, irrespective of pO2, while watercore disappearance was more rapid at <1kPa CO2 than at 2.5kPa CO2. Flesh browning was also higher at 1.5kPa CO2 than at <1kPa CO2, although ethylene production was lowest at 1.5kPa pCO2. Stepwise delay of high CO2 or low O2 CA storage did not affect flesh firmness, TA, internal ethylene concentration, respiration rate, and ethylene production, but watercore disappearance was more rapid, compared with standard CA storage at 2 months. Flesh browning was not detected in the stepwise CO2 delayed CA treatment and low CO2 CA storage (<0.2kPa CO2), but a low (<4%) incidence of flesh browning was found in a delayed CA treatment and standard CA storage. These results indicate that ‘Fuji’ apples could be stored at 0°C in 1–2kPa O2/<1kPa CO2 if harvested at less than 190 days after full bloom. Stepwise CO2 delay CA or low CO2 CA storage regimes are recommended to retard the loss of fruit quality factors and reduce development of CA-related storage disorders.

Estimation of epikarst air [formula omitted] using measurements of water δ13CTDIC, cave air [formula omitted] and [formula omitted

When present, an epikarst represents the starting point (the first karst compartment) of water flow through a karst system. The air characteristics in a karst, and especially in an epikarst, determine the initial water characteristics, e.g., water aggressiveness, which depends on the partial pressure of CO2 (PCO2) in equilibrium with water. This paper proposes a method to estimate PCO2 in epikarst air using spring water measures as HCO3-, temperature, pH and δ13C of Total Dissolved Inorganic Carbon (TDIC) and cave air measures as PCO2 and δ13C of CO2. This method accounts for the TDIC variations of δ13C that are caused by CO2 degassing and calcite precipitation from water. The calculations are based on the influence of pH variations and carbon loss on δ13C of TDIC. Measurements are taken at two sites: Lascaux cave and the Cussac cave sites located in Perigord, southwest of France. Four water springs are presented in this case study: two springs from an epikarst compartment, one spring from an unsaturated zone and one spring from a saturated zone. The PCO2 in epikarst air is estimated to be from 4.4% (44,000ppm) in winter to 10% in summer. These values are higher than the values of air PCO2 measured in the soil (0.27–1.60%) or in the caves (0.30–3.1%, up to 7.50% in some parts of Lascaux). We show that in epikarst air, PCO2 and δ13CCO2 are not constant values but vary annually with high PCO2 and depleted values (−22.31‰ VPDB) in the winter and higher PCO2 and more depleted values in the summer (−24.20‰ VPDB).

Investigation on water vapor effect on direct sulfation during wet-recycle oxy-coal combustion

During oxy-coal combustion process, limestone desulfurization may change from indirect into direct sulfation due to the high partial pressure of CO2. When the wet flue gas is recycled, the water vapor will also be enriched in the furnace and affect the desulfurization reactions. In the paper, two limestone sorbents were used to study the effect of water vapor on direct sulfation. Parameters including water vapor concentration, temperature and SO2 concentration were analyzed. Results show that the presence of water vapor has a negligible effect on the direct sulfation during the kinetically-controlled regime, while enhances the calcium conversion during the diffusion-controlled stage. The presence of water vapor promotes the solid-state diffusion of the sulfated product, and sintering of the product layer is intensified. The vacancies in the particles migrate along crystal grain boundaries and through the crystal lattice, resulting in a reverse flow of mass into the pores. The pore structure character of the products sulfated in the presence of water vapor is improved.

Interactive effects of photoperiod and light intensity on blood physiological and biochemical reactions of broilers grown to heavy weights

The effects of photoperiod, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. A 3 × 3 factorial experiment in a randomized complete block design was used in this study. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d, and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8 to 56, regular/intermittent (2L:2D), and short/nonintermittent (8L:16D) from d 8 to 48 and 23L:1D from d 49 to 56, respectively] and exposure to 3 light intensities (10, 5.0, and 0.5 lx) from d 8 through d 56 at 50% RH. Feed and water were provided ad libitum. Venous blood samples were collected on d 7, 14, 28, 42, and 56. Main effects indicated that short/nonintermittent photoperiod significantly (P < 0.05) reduced BW, pH, partial pressure of O2, saturated O2, Na(+), K(+), Ca(2+), Cl(-), osmolality, triiodothyronine (T3), and total protein along with significantly (P < 0.05) elevated partial pressure of CO2, hematocrit, hemoglobin, and lactate concentrations. In addition, there were no effects of photoperiod on HCO3(-), glucose, anion gap, and thyroxine (T4). Plasma corticosterone was not affected by photoperiod, light intensity, or their interaction. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during photoperiod and light intensity exposure did not deteriorate despite a lower pH and higher partial pressure of CO2 with normal HCO3(-). These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on blood physiological variables, whereas the short photoperiod markedly affected most blood physiological variables without inducing physiological stress in broilers.

Temperature affects the early life history stages of corals more than near future ocean acidification

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 475:85-92 (2013) - DOI: https://doi.org/10.3354/meps10077 Temperature affects the early life history stages of corals more than near future ocean acidification Chia Miin Chua1,*, William Leggat1,2, Aurelie Moya1,3,4, Andrew H. Baird1 1ARC Centre of Excellence for Coral Reef Studies and 2School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland, 4811, Australia 3INSU-CNRS, Laboratoire d’Océanographie de Villefranche, B.P. 28, 06234 Villefranche-sur-mer Cedex, France 4UPMC University of Paris 06, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-mer, France *Email: chiamiin.chua@my.jcu.edu.au ABSTRACT: Climate change is projected to increase ocean temperatures by at least 2°C, and levels of pH by ~0.2 units (ocean acidification, OA) by the end of this century. While the effects of these stressors on marine organisms have been relatively well explored in isolation, possible interactions between temperature and OA have yet to be thoroughly investigated. OA at levels projected to occur within this century has few direct ecological effects on the early life history stages of corals. In contrast, temperature has pronounced effects on many stages in the early life history of corals. Here, we test whether temperature might act in combination with OA to produce a measurable ecological effect on fertilization, development, larval survivorship or metamorphosis of 2 broadcast spawning species, Acropora millepora and A. tenuis, from the Great Barrier Reef. We used 4 treatments: control, high temperature (+2°C), high partial pressure of CO2 (pCO2) (700 µatm) and a combination of high temperature and high pCO2, corresponding to the current levels of these variables and the projected values for the end of this century under the IPCC A2 scenario. We found no consistent effect of elevated pCO2 on fertilization, development, survivorship or metamorphosis, neither alone nor in combination with temperature. In contrast, a 2°C rise in temperature increased rates of development, but otherwise had no consistent effect on fertilization, survivorship or metamorphosis. We conclude that OA is unlikely to be a direct threat to the early life history stages of corals, at least in the near future. In contrast, rising sea temperatures are likely to affect coral population dynamics by increasing the rate of larval development with resulting changes in patterns of connectivity. KEY WORDS: Coral reefs · Climate change · Connectivity · Development · Larval ecology · Survivorship · Settlement Full text in pdf format PreviousNextCite this article as: Chua CM, Leggat W, Moya A, Baird AH (2013) Temperature affects the early life history stages of corals more than near future ocean acidification. Mar Ecol Prog Ser 475:85-92. https://doi.org/10.3354/meps10077 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 475. Online publication date: February 14, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Solubility of Carbon Dioxide in Aqueous 2-(2-Aminoethylamine)ethanol (AEEA) Solution and Its Mixtures with N-Methyldiethanolamine/2-Amino-2-methyl-1-propanol

Solubility measurements of carbon dioxide (CO2) in aqueous 2-(2-aminoethylamino)ethanol (AEEA, 15 wt %), AEEA + N-methyldiethanolamine (MDEA, 5, 10 wt %), and AEEA + 2-amino-2-methyl-1-propanol (AMP, 5, 10 wt %) solutions as CO2 absorbents were performed at CO2 partial pressure from (0.8 to 800) kPa and temperatures of (303, 313, and 323) K. With increasing the MDEA/AMP amount to AEEA, CO2 loading of the absorbents decreased, while the absorption rate increased. At low CO2 partial pressure (< 30 kPa), the loading of AEEA + AMP was higher than that of AEEA + MDEA, while at high CO2 partial pressure (> 100 kPa), the loading of AEEA + AMP was lower than that of AEEA + MDEA at the same concentration. Furthermore, the absorption rate was in the order AEEA + AMP > AEEA + MDEA > AEEA.

Calcium Looping Process: Experimental investigation of limestone performance regenerated under high CO2 partial pressure and validation of a carbonator model

A key aspect of the Calcium Looping process is the implementation of the oxy-fuel combustion for the endothermic sorbent regeneration, which imposes high partial pressure of CO2 (75vol.-% dry). These conditions enhance lime sintering and thus, the decrease of the sorbent's maximum CO2 carbonation conversion (Xmax), which is an important parameter that influences the CO2 capture. This paper presents results from tests performed in presence of high CO2 volumetric concentration in a 10kWth Dual Fluidized Bed system. High regeneration extents and CO2 capture efficiencies of more than 80% is attained with sorbent residual activity of 8,5%. A carbonator model is validated and active space time is proposed to be the main parameter to be used for up scaling design purposes.

Why the Geochemical Diversity of CO2-Bearing Groundwaters in Crystalline Massifs Occurs

The diversity of geochemical types of CO2-bearing waters in crystalline massifs of similar mineralogical and petrogra- phic composition in water–rock systems is due to the influence of the following physicochemical parameters: chloride type - mainly high Rock/Water mass ratio (R/W); carbonate type - joint action of low Rock/Water mass ratio (R/W) and high CO2 partial pressure (PCO2); sulfate type - joint action of high Rock/Water mass ratio (R/W), CO2 partial pressure (PCO2), and temperature.

Development of Chemical CO2 Solvent for High-Pressure CO2 Capture

To develop high performance chemical CO2 solvents for high-pressure CO2 capture, we have evaluated several tertiary amine solutions on CO2 absorption and desorption rates and CO2 loading-differences under high-pressure conditions, and also their CO2 absorption heats have been measured. High performance CO2 solvents, RH-1, RH-2 series, and RH-3 series, that are regenerable under high CO2 partial pressure conditions have been developed. These developed CO2 solvents are able to recover CO2 under higher pressure than that of supplied CO2. RH-3c is estimated to reduce the total energy for CO2 capture process, including compression process, to 1.2 GJ/t-CO2.