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elevated carbon dioxide

Vitaly L Sushkevich, Jeroen A van Bokhoven
At least two distinct processes occur during heating of the copper-exchanged mordenite in oxygen-free environment depending on the sample synthesis procedure. The first process corresponds to the reaction of Cu(ii) sites with the residual traces of carbonaceous impurities left in the sample after the synthesis without calcination in an oxidant-containing environment, yielding Cu(i) and carbon dioxide. The second relates to autoreduction of Cu(ii) into Cu(i) species accompanied with the release of molecular oxygen...
June 18, 2018: Chemical Communications: Chem Comm
Rose M Martin, Cathleen Wigand, Elizabeth Elmstrom, Javier Lloret, Ivan Valiela
Salt marshes may act either as greenhouse gas (GHG) sources or sinks depending on hydrological conditions, vegetation communities, and nutrient availability. In recent decades, eutrophication has emerged as a major driver of change in salt marsh ecosystems. An ongoing fertilization experiment at the Great Sippewissett Marsh (Cape Cod, USA) allows for observation of the results of over four decades of nutrient addition. Here, nutrient enrichment stimulated changes to vegetation communities that, over time, have resulted in increased elevation of the marsh platform...
May 2018: Ecology and Evolution
Rupali Sharma, Hukum Singh, Monica Kaushik, Raman Nautiyal, Ombir Singh
Winter cherry or Ashwagandha ( Withania somnifera ) is an important medicinal plant used in traditional and herbal medicine system. Yet, there is no information available on response of this plant to changing climatic conditions particularly elevated atmospheric CO2 concentrations. Therefore, we conducted an experiment to examine the effect of elevated CO2 concentrations (ECs) on Withania somnifera . The variations in traits of physiological adaptation, net primary productivity, carbon partitioning, morphology, and biomass in response to elevated CO2 concentrations (ambient, 600 and 800 µmol mol-1 ) during one growth cycle were investigated within the open top chamber (OTC) facility in the foothill of the Himalayas, Dehardun, India...
June 2018: 3 Biotech
Kristen A Bishop, Pauline Lemonnier, Jennifer C Quebedeaux, Christopher M Montes, Andrew D B Leakey, Elizabeth A Ainsworth
Species have different strategies for loading sugars into the phloem, which vary in the route that sugars take to enter the phloem and the energetics of sugar accumulation. Species with passive phloem loading are hypothesized to have less flexibility in response to changes in some environmental conditions because sucrose export from mesophyll cells is dependent on fixed anatomical plasmodesmatal connections. Passive phloem loaders also have high mesophyll sugar content, and may be less likely to exhibit sugar-mediated down-regulation of photosynthetic capacity at elevated CO2 concentrations...
June 2, 2018: Photosynthesis Research
Yang Dai, Meng-Fei Wang, Shou-Lin Jiang, Yi-Fei Zhang, Megha N Parajulee, Fa-Jun Chen
Rising atmospheric carbon dioxide (CO2 ) levels can markedly affect the growth, development, reproduction and behavior of herbivorous insects, mainly by changing the primary and secondary metabolites of their host plants. However, little is known about the host-selection behavior and the respective intrinsic mechanism of sap-sucking insects in response to elevated CO2 . In this experiment, the host-selection behavior, as well as the physiological mechanism based on the analysis of growth, development and energy substances, and the expression of the olfactory-related genes of the cotton aphid, Aphis gossypii, were studied under ambient (407...
May 31, 2018: Journal of Insect Physiology
M H Stiasny, F H Mittermayer, G Göttler, C R Bridges, I-B Falk-Petersen, V Puvanendran, A Mortensen, T B H Reusch, C Clemmesen
Ocean acidification (OA), the dissolution of excess anthropogenic carbon dioxide in ocean waters, is a potential stressor to many marine fish species. Whether species have the potential to acclimate and adapt to changes in the seawater carbonate chemistry is still largely unanswered. Simulation experiments across several generations are challenging for large commercially exploited species because of their long generation times. For Atlantic cod (Gadus morhua), we present first data on the effects of parental acclimation to elevated aquatic CO2 on larval survival, a fundamental parameter determining population recruitment...
May 29, 2018: Scientific Reports
Chunwu Zhu, Kazuhiko Kobayashi, Irakli Loladze, Jianguo Zhu, Qian Jiang, Xi Xu, Gang Liu, Saman Seneweera, Kristie L Ebi, Adam Drewnowski, Naomi K Fukagawa, Lewis H Ziska
Declines of protein and minerals essential for humans, including iron and zinc, have been reported for crops in response to rising atmospheric carbon dioxide concentration, [CO2 ]. For the current century, estimates of the potential human health impact of these declines range from 138 million to 1.4 billion, depending on the nutrient. However, changes in plant-based vitamin content in response to [CO2 ] have not been elucidated. Inclusion of vitamin information would substantially improve estimates of health risks...
May 2018: Science Advances
Aanindeeta Banerjee, Matthew W Kanan
CO2 hydrogenation is a potential alternative to conventional petrochemical methods for making commodity chemicals and fuels. Research in this area has focused mostly on transition-metal-based catalysts. Here we show that hydrated alkali carbonates promote CO2 hydrogenation to formate, oxalate, and other C2+ carboxylates at elevated temperature and pressure in the absence of transition-metal catalysts or solvent. The reactions proceed rapidly, reaching up to 56% yield (with respect to CO3 2- ) within minutes...
May 23, 2018: ACS Central Science
Rima Habre, Hui Zhou, Sandrah P Eckel, Temuulen Enebish, Scott Fruin, Theresa Bastain, Edward Rappaport, Frank Gilliland
BACKGROUND: Exposure to ultrafine particles (UFP, particles with aerodynamic diameter < 100 nm) is associated with reduced lung function and airway inflammation in individuals with asthma. Recently, elevated UFP number concentrations (PN) from aircraft landing and takeoff activity were identified downwind of the Los Angeles International Airport (LAX) but little is known about the health impacts of airport-related UFP exposure. METHODS: We conducted a randomized crossover study of 22 non-smoking adults with mild to moderate asthma in Nov-Dec 2014 and May-Jul 2015 to investigate short-term effects of exposure to LAX airport-related UFPs...
May 22, 2018: Environment International
Philip J Williams, Matthew Reeder, Natalie J Pekney, David Risk, John Osborne, Michael McCawley
The Marcellus Shale Energy and Environment Laboratory (MSEEL) in West Virginia provides a unique opportunity in the field of unconventional energy research. By studying near-surface atmospheric chemistry over several phases of a hydraulic fracturing event, the project will help evaluate the impact of current practices, as well as new techniques and mitigation technologies. A total of 10 mobile surveys covering a distance of approximately 1500 km were conducted through Morgantown. Our surveying technique involved using a vehicle-mounted Los Gatos Research gas analyzer to provide geo-located measurements of methane (CH4 ) and carbon dioxide (CO2 )...
May 21, 2018: Science of the Total Environment
Sue-Ann Watson, Bridie J M Allan, David E McQueen, Simon Nicol, Darren M Parsons, Stephen M J Pether, Stephen Pope, Alvin N Setiawan, Neville Smith, Carly Wilson, Philip L Munday
Ocean warming and acidification are serious threats to marine life; however, their individual and combined effects on large pelagic and predatory fishes are poorly understood. We determined the effects of projected future temperature and carbon dioxide (CO2 ) levels on survival, growth, morphological development and swimming performance on the early life stages of a large circumglobal pelagic fish, the yellowtail kingfish Seriola lalandi. Eggs, larvae and juveniles were reared in cross-factored treatments of temperature (21 and 25°C) and pCO2 (500 and 985 μatm) from fertilisation to 25 days post hatching (dph)...
May 22, 2018: Global Change Biology
Christopher D Rodeheffer, Sarah Chabal, John M Clarke, David M Fothergill
BACKGROUND: Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 - 5000 ppm) than what is typically considered normal (i.e., 400 - 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2...
June 1, 2018: Aerospace Medicine and Human Performance
Daniela Römer, Martin Bollazzi, Flavio Roces
Social insects show temperature and humidity preferences inside their nests to successfully rear brood. In underground nests, ants also encounter rising CO2 concentrations with increasing depth. It is an open question whether they use CO2 as a cue to decide where to place and tend the brood. Leaf-cutting ants do show CO2 preferences for the culturing of their symbiotic fungus. We evaluated their CO2 choices for brood placement in laboratory experiments. Workers of Acromyrmex lundii in the process of relocating brood were offered a binary choice consisting of two interconnected chambers with different CO2 concentrations...
May 17, 2018: Journal of Insect Physiology
Paul Edwards, Patricia-Ann Therriault, Ira Katz
Introduction: Medical air (MA) is widely used in hospitals, often manufactured onsite by compressing external ambient air and supplied through a local network piping system. Onsite production gives rise to a risk of impurities that are governed by the same pharmacopoeia purity standards applicable to commercially produced MA. The question to be addressed in this paper is how to assess if a lack of purity poses a medical problem? Methods: The MA produced onsite at a major Canadian hospital was monitored for carbon dioxide (CO2 ) and other impurity gases at high frequency (one per minute) over a two-month period...
2018: Multidisciplinary Respiratory Medicine
Katarina Jennifer Ruscic, Janne Bøgh Stokholm, Johann Patlak, Hao Deng, Jeroen Cedric Peter Simons, Timothy Houle, Jürgen Peters, Matthias Eikermann
BACKGROUND: Propofol impairs upper airway dilator muscle tone and increases upper airway collapsibility. Preclinical studies show that carbon dioxide decreases propofol-mediated respiratory depression. We studied whether elevation of end-tidal carbon dioxide (PETCO2) via carbon dioxide insufflation reverses the airway collapsibility (primary hypothesis) and impaired genioglossus muscle electromyogram that accompany propofol anesthesia. METHODS: We present a prespecified, secondary analysis of previously published experiments in 12 volunteers breathing via a high-flow respiratory circuit used to control upper airway pressure under propofol anesthesia at two levels, with the deep level titrated to suppression of motor response...
May 10, 2018: Anesthesiology
Michael J Aspinwall, Chris J Blackman, Víctor Resco de Dios, Florian A Busch, Paul D Rymer, Michael E Loik, John E Drake, Sebastian Pfautsch, Renee A Smith, Mark G Tjoelker, David T Tissue
Intraspecific variation in biomass production responses to elevated atmospheric carbon dioxide (eCO2) could influence tree species' ecological and evolutionary responses to climate change. However, the physiological mechanisms underlying genotypic variation in responsiveness to eCO2 remain poorly understood. In this study, we grew 17 Eucalyptus camaldulensis Dehnh. subsp. camaldulensis genotypes (representing provenances from four different climates) under ambient atmospheric CO2 and eCO2. We tested whether genotype leaf-scale photosynthetic and whole-tree carbon (C) allocation responses to eCO2 were predictive of genotype biomass production responses to eCO2...
May 8, 2018: Tree Physiology
Jungho Jang, Byoung Wook Jeon, Yong Hwan Kim
The conversion of carbon dioxide to formate is a fundamental step for building C1 chemical platforms. Methylobacterium extorquens AM1 was reported to show remarkable activity converting carbon dioxide into formate. Formate dehydrogenase 1 from M. extorquens AM1 (MeFDH1) was verified as the key responsible enzyme for the conversion of carbon dioxide to formate in this study. Using a 2% methanol concentration for induction, microbial harboring the recombinant MeFDH1 expressing plasmid produced the highest concentration of formate (26...
May 8, 2018: Scientific Reports
Shuwei Liu, Cheng Ji, Cong Wang, Jie Chen, Yaguo Jin, Ziheng Zou, Shuqing Li, Shuli Niu, Jianwen Zou
The net balance of greenhouse gas (GHG) exchanges between terrestrial ecosystems and the atmosphere under elevated atmospheric carbon dioxide (CO2 ) remains poorly understood. Here, we synthesise 1655 measurements from 169 published studies to assess GHGs budget of terrestrial ecosystems under elevated CO2 . We show that elevated CO2 significantly stimulates plant C pool (NPP) by 20%, soil CO2 fluxes by 24%, and methane (CH4 ) fluxes by 34% from rice paddies and by 12% from natural wetlands, while it slightly decreases CH4 uptake of upland soils by 3...
May 7, 2018: Ecology Letters
Yang Yang, Robert Tang, Hong Qiu, Poh-Chin Lai, Paulina Wong, Thuan-Quoc Thach, Ryan Allen, Michael Brauer, Linwei Tian, Benjamin Barratt
BACKGROUND: Several studies have reported associations between long term exposure to air pollutants and cause-specific mortality. However, since the concentrations of air pollutants in Asia are much higher compared to those reported in North American and European cohort studies, cohort studies on long term effects of air pollutants in Asia are needed for disease burden assessment and to inform policy. OBJECTIVES: To assess the effects of long-term exposure to particulate matter with aerodynamic diameter < 2...
May 3, 2018: Environment International
Ryan P McClure, Kathleen D Hamre, B R Niederlehner, Zackary W Munger, Shengyang Chen, Mary E Lofton, Madeline E Schreiber, Cayelan C Carey
Metalimnetic oxygen minimum zones (MOMs) commonly develop during the summer stratified period in freshwater reservoirs because of both natural processes and water quality management. While several previous studies have examined the causes of MOMs, much less is known about their effects, especially on reservoir biogeochemistry. MOMs create distinct redox gradients in the water column which may alter the magnitude and vertical distribution of dissolved methane (CH4 ) and carbon dioxide (CO2 ). The vertical distribution and diffusive efflux of CH4 and CO2 was monitored for two consecutive open-water seasons in a eutrophic reservoir that develops MOMs as a result of the operation of water quality engineering systems...
April 30, 2018: Science of the Total Environment
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