Low CO2 Levels Research Articles

Isolating substituent effects in Re(I)-phenanthroline electrocatalysts for CO2 reduction

The development of highly-active molecular electrocatalysts for reducing CO2 to value-added products requires an intimate knowledge of the structural and electronic features surrounding the active site. We previously illustrated how electronic modifications to fac-[ReI(R2phen)(CO)3Cl] electrocatalysts (R2phen = 2,9-disubstituted-1,10-phenanthrolines) strongly dictate CO2 reduction; more specifically, introducing methoxy substituents at both the ortho/para positions of a phenyl ring attached to phenanthroline generated high catalytic activity. In the current work, we have prepared four structurally-related Re(I) electrocatalysts to isolate the electronic effects associated with each methoxy group’s positioning around the phenyl ring (i.e. none, ortho, meta, or para). The diimine ligands 2,9-diphenyl-1,10-phenanthroline (Ph2phen), 2,9-bis(2,6-dimethoxyphenyl)-1,10-phenanthroline ((2,6-dmp)2phen), 2,9-bis(3,5-dimethoxyphenyl)-1,10-phenanthroline ((3,5-dmp)2phen), and 2,9-bis(4-methoxyphenyl)-1,10-phenanthroline ((4-mp)2phen) were prepared, and the subsequent fac-[ReI(R2phen)(CO)3Cl] complexes were synthesized, characterized, and studied for electrocatalytic CO2 reduction. Following 90 min electrolysis at Eapp = −2.55 V vs. Fc+/0 in DMF solvent, the ortho methoxy-substituted analogue (labeled Re((2,6-dmp)2phen)) produced 35 μmol CO, corresponding to a turnover number = 14 (TON = mol CO per mol Re catalyst) and a Faradaic efficiency = 84% (F.E. = mol CO per mol electrons). The remaining Re electrocatalysts produced significantly lower levels of CO (Re(Ph2phen): 1.8 μmol CO; Re((3,5-dmp)2phen): 2.4 μmol; Re((4-mp)2phen): 4.2 μmol CO), emphasizing the important electronic contribution that ortho substituted methoxy groups provide towards enhancing electron density at the Re active site to rapidly, and selectively, convert CO2 substrate to CO product.

Sublethal Cobalt Toxicity Effects on Rainbow Trout (Oncorhynchus mykiss)

Abstract The purpose of this study was to investigate the sublethal Co toxicity on rainbow trout (Oncorhynchus mykiss). Trout were exposed to Co and selected parameters were evaluated at intervals of 1, 15 and 30 days. Fish exposed to higher levels of Co grew slower than fish exposed to lower levels of Co. Weight gain, specific growth rate (SGR) decreased linearly with the increase of cobalt in the water. The body condition factor (CF) of fish reared in water with low cobalt concentration decreased substantially but this decrease was not significant for fish exposed to higher cobalt concentration. The values of the feed conversion ratio (FCR) increased in fish exposed to higher levels of Co. Co significantly changed the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and decreased at day 30, and in both cases this decrease was more remarkable at day 15 so that the level of AST and ALT reached the control value at day 30. The alkaline phosphatase (ALP) level also showed a remarkable 15-day decline. There was a significant increase in glucose (G) concentration in both Co-exposed groups on day 15. However, serum cholesterol (Chl) was significantly reduced on day 15 and increased on day 30; there were no significant differences in both exposed Co-groups. The triglyceride (TG) level also decreased substantially. There was no regular pattern of total protein (TP) in the serum, so that no significant differences were found in the level of TP between low and high-exposed fish. In summary, this study suggests that exposure of essential trace elements such as cobalt may change growth and biochemical parameters, and that measurement of these parameters may be used in toxicological studies to determine the general health status of fish.

A dynamic botanical air purifier (DBAP) with activated carbon root-bed for reducing indoor carbon dioxide levels

Indoor Air Quality (IAQ), is important in buildings because it can affect an occupant’s health and productivity. Carbon Dioxide (CO2) is a main indicator of IAQ. 4 decades ago, researchers discovered the potential for indoor plants to remediate indoor air pollutants via photosynthesis. This study investigates the CO2 removal rate when a Maranta Leuconeura is paired with activated carbon (AC), as well as a mechanical ventilation system that draws air into its root-bed making it an active system (DBAP). The results were compared to passive systems i.e plant with AC, potting soil etc. The study was conducted in a 0.7 m3 Plexiglas chamber with initial CO2 concentrations of 1500±100 ppm while initial temperatures ranged between 24 ± 2°C for a duration of 6 hours continuously. Results showed, the DBAP reduced CO2 levels by 40.90% while a passive plant with AC only, was able to lower CO2 levels by 15.20%. The other passive systems did not reduce CO2 levels. All systems were able to raise humidity and reduce temperature in the chamber, with the exception of the DBAP, which slightly increased the temperature in the chamber.

Head Down Tilt Bed Rest Plus Elevated CO2 as a Spaceflight Analog: Effects on Cognitive and Sensorimotor Performance.

Long duration head down tilt bed rest (HDBR) has been widely used as a spaceflight analog environment to understand the effects of microgravity on human physiology and performance. Reports have indicated that crewmembers onboard the International Space Station (ISS) experience symptoms of elevated CO2 such as headaches at lower levels of CO2 than levels at which symptoms begin to appear on Earth. This suggests there may be combinatorial effects of elevated CO2 and the other physiological effects of microgravity including headward fluid shifts and body unloading. The purpose of the current study was to investigate these effects by evaluating the impact of 30 days of 6° HDBR and 0.5% CO2 (HDBR + CO2) on mission relevant cognitive and sensorimotor performance. We found a facilitation of processing speed and a decrement in functional mobility for subjects undergoing HDBR + CO2 relative to our previous study of HDBR in ambient air. In addition, nearly half of the participants in this study developed signs of Spaceflight Associated Neuro-ocular Syndrome (SANS), a constellation of ocular structural and functional changes seen in approximately one third of long duration astronauts. This allowed us the unique opportunity to compare the two subgroups. We found that participants who exhibited signs of SANS became more visually dependent and shifted their speed-accuracy tradeoff, such that they were slower but more accurate than those that did not incur ocular changes. These small subgroup findings suggest that SANS may have an impact on mission relevant performance inflight via sensory reweighting.New And NoteworthyWe examined the effects of long duration head down tilt bed rest coupled with elevated CO2 as a spaceflight analog environment on human cognitive and sensorimotor performance. We found enhancements in processing speed and declines in functional mobility. A subset of participants exhibited signs of Spaceflight Associated Neuro-ocular Syndrome (SANS), which affects approximately one in three astronauts. These individuals increased their visual reliance throughout the intervention in comparison to participants who did not show signs of SANS.

Effect of core-alloy composition and particle size of stabilized Pt Skin/PtCo alloy nanocatalysts on the CO-Tolerant hydrogen oxidation electrocatalysis

We have, for the first time, examined the effects of core-alloy composition and particle-size of Pt100−xCox alloy nanocatalysts with a stabilized Pt-skin (one to two atomic layers) supported on carbon black (PtxAL‒Pt100-xCox/C) on the activities for the hydrogen oxidation reaction (HOR) and its tolerance of low levels of CO. The optimum composition for the HOR was found in the range x = 30 to 50 atom%. Such a dependency was correlated with an optimal adsorption strength for atomic hydrogen on (111) terraces according to DFT calculations. The CO tolerance trend was explained based on weakened adsorption of CO on step and terrace sites. It was found that the smallest particles retained high CO-tolerant HOR activity during the accelerated durability test, enabling the alloy nanoparticles as small as 2.2 nm to be very promising for increased mass activity in polymer electrolyte fuel cells with reformate fuel as well as pure H2.

Economic, technical, and environmental viability of biodiesel blends derived from coffee waste

In this study we investigated the potential use of coffee waste feedstock in biodiesel production, considering economic viability, technical feasibility, and environmental compatibility. The investment potential for a small-scale biodiesel production facility (8000 t/y) was gauged by estimating relevant economic performance indicators. Biodiesel was then extracted from spent coffee grounds and blended with fossil diesel to develop four blends: B5, B10, B15, and B20. The conformity of this fuel with relevant standards (ASTM D6751 and ISO EN14214) was determined by characterizing and adjusting the fuel’s properties during the production process. The technical and environmental performance of these blends was then tested in a single-cylinder compression ignition engine with an extended range of engine speeds under three engine loading conditions (100%, 75%, and 50%), using pure diesel fuel for benchmark comparisons. The evaluated economic metrics paint an optimistic picture of investment in this project. Waste coffee could result in improved economic performance over other feedstocks. Diesel fuel outperformed the biodiesel blends in terms of engine power, thermal efficiency, and fuel economy, whereas the blends were superior in terms of exhaust gas temperature; average exhaust gas temperature drops of 11 °C and 35.2 °C were measured under full load conditions for B5 and B20, respectively. All blends emitted lower levels of CO2, CO, and HC than did diesel, but higher NOx emissions were present, all proportional to the blend used. Our results clearly show that SCG has great potential as a feedstock for biodiesel production, given its derivation from existing waste materials, cleaner but comparable performance, and economically viable production.

New insight into light-enhanced calcification in mytilid mussels, Mytilus sp., infected with photosynthetic algae Coccomyxa sp.: δ13C value and metabolic carbon record in shells

The posterior shell edge (PSE) of wild mytilid mussels that are highly infected with unicellular photosynthetic green algae Coccomyxa sp. exhibits an extra shell material (ESM). A recently proposed mechanism of ESM formation shows similarity with light-enhanced calcification (LEC), i.e., algae photosynthesis mediates low respiratory CO2 level in shell calcification site (PSE) to promote ESM precipitation. The present study evaluates if infection with algae may affect the δ13C content and metabolic carbon (CM) contribution to shells (PSE) in mussels from the Lower St. Lawrence Estuary, Québec, Canada. Environmental conditions may influence shell δ13C records. To underline possible algae photosynthesis effects, mantle, adductor muscle and shell δ13C are analyzed in infected and non-infected mussels collected from two sites with different salinities, seawater dissolved inorganic carbon (DIC) content, and hydrodynamic regimes. Shell δ13C and tissue δ13C correlate with seawater DIC and salinity. Shell δ13C values are lowest in non-infected mussels, whereas tissues δ13C values show the opposite relationship; in both cases, differences between δ13C values in non-infected and infected mussels are about 0.5‰. The percentage of CM incorporated into shell is higher (ca. 18%) for non-infected mussels than infected mussels (ca. 15%). Literature on the subject suggests that increased δ13C content and decreased %CM in shells of infected mussels must be related to algal photosynthetic activity. Our findings show that shell δ13C records permit the interpretation of ESM formation via LEC.

A global perspective on national climate mitigation priorities in the context of air pollution and sustainable development

Air pollution and climate change are key global challenges for cities and both have large impacts on human health and economic development. Although there are many long term opportunities to address these issues with integrated policies, the immediate needs of addressing air pollution and climate change mitigation are not the same for all countries in the short run. We examined the relationships between greenhouse gases (GHG) emissions, outdoor air pollution, and levels of socioeconomic development to identify specific near-term mitigation policy responses to climate change and air pollution for countries with different levels of human development. Human development index, as defined by The United Nations Development Programme (UNDP) is a measure of achievement in the basic dimensions of human development across countries, which combines the gross national income index, an education index and a life expectancy index (http://hdr.undp.org/en/humandev). Country-level data were collected on indicators of socioeconomic development, emissions of GHG, and outdoor levels of fine particulate matter (PM2.5) from the World Bank, the UNDP, and the Task Force on Hemispheric Transport of Air Pollution. Differences in GHG emissions and air pollution concentrations, as well as socioeconomic development indicators, were assessed at national, sub-national, and global scales. Countries were divided into four categories based on CO2 emissions per capita and an estimation of outdoor PM2.5: Group A was characterized by high CO2 emissions per capita and low PM2.5 concentrations, Group B by high CO2 emissions per capita and high PM2.5 concentrations, Group C by low CO2 emissions per capita and low PM2.5 concentrations, and Group D by low CO2 emissions per capita and high PM2.5 concentration. Per-capita emissions of CO2 were strongly correlated with the level of socioeconomic development, while differences in non-CO2 greenhouse gas emissions per capita across the groups were not correlated. Atmospheric PM2.5 concentrations were not correlated with either CO2 emissions per capita or levels of socioeconomic development. Energy and environmental policies focused on CO2 emission reductions may not inherently lead to development pathways that sufficiently reduce population exposure to air pollution. Countries with low CO2 and high air pollution levels should pursue short-term policies to reduce air pollution and increase human development, beginning to address GHG emissions after critical human health and development needs are met.

Desert Palm Date Seeds as a Biodiesel Feedstock: Extraction, Characterization, and Engine Testing

The development of alternative fuels is increasingly important in order to maintain ongoing global economic and technological progress in the face of fossil fuel depletion and increasing environmental damage. Desert palm date seeds have clear potential as feedstock for biodiesel production given their high oil content and availability as food waste that requires no further cultivation. In this study we investigated the optimum production processes and conditions for date seed oil biodiesel, including characterizing the intermediate product and correcting its composition to meet international fuel standards. Four biodiesel blends were prepared (B5, B10, B15, and B20) and tested in a compression ignition engine at engine speeds from 1600 to 3600 rpm (200 rpm increments) and three engine loads (50%, 75%, and 100%). The highest oil yield and biodiesel conversion achieved were 10.74 wt.% and 92%, respectively. The biodiesel properties conformed well with the standards; the values for brake power, brake thermal efficiency, and brake specific fuel consumption were comparable with petrol diesel, though the latter was slightly superior. All blends produced lower levels of CO2, CO, and HC but higher levels of NOx emissions. These results demonstrate the fundamental suitability of date seeds as biodiesel feedstock, deserving of further research.

Reduction of smoke and NOx from the combined effect of thermal barrier coatings and Raphanus sativus biodiesel in a diesel engine for transport sectors

ABSTRACTThe present research work is to analyze the effect of the ceramic coating materials like Partially Stabilized Zirconia (PSZ), Titanium di-oxide (TiO2), and Radish biodiesel on its performance, combustion, and emission characteristics of single cylinder 4-s, DI diesel engine fueled with diesel and Radish biodiesel blends. In the first phase, Radish seed oil is converted into biodiesel by transesterification process. The properties of biodiesel blends (B0, B25, B50, B75, and B100) are evaluated and presented; tests were conducted at 1500 rpm constant speed with 220 bar of nozzle opening pressure and 23°bTDC of static injection timing as engine setup under steady state condition. The cylinder head, valves, and piston crown of the engine components were coated with 450 µm of PSZ and TiO2 by atmospheric plasma spray coating techniques (APS) for test purpose. From the test results, it could be observed that PSZ-coated mode of operation gives better specific fuel consumption (SFC) than the conventional diesel engine, slight hike in brake thermal efficiency, reduction in hydrocarbon by 16–30% and low level of CO in emissions were observed. However, the NOx increases by 17–23% when compared to conventional engine operation. In case of TiO2-coated mode of operation, slight increase in the SFC is recorded, whereas, Oxides of Nitrogen, Smoke, Hydro Carbon, and Carbon monoxide emissions are decreased for all test fuels (B0, B25, B50, B75, and B100) when compared with that of the conventional engine.

Triggered Gate Opening and Breathing Effects during Selective CO2 Adsorption by Merlinoite Zeolite.

Zeolites with flexible structures that adapt to coordinate extraframework cations when dehydrated show a rich variety of gas adsorption behavior and can be tuned to optimize kinetics and selectivity. Merlinoite zeolite (topology type MER) with Si/Al = 3.8 has been prepared in Na, K, and Cs forms and its structural response to dehydration measured: the unit cell volumes decrease by 9.8%, 7.7%, and 7.1% for Na-, K-, and Cs-MER, respectively. Na-MER adopts Immm symmetry, while K- and Cs-MER display P42/nmc symmetry, the difference attributed to the preferred locations of the smaller and larger cations. Their performance in CO2 adsorption has been measured by single-component isotherms and by mixed gas (CO2/CH4/He) breakthrough experiments. The differing behavior of the cation forms can be related to structural changes during CO2 uptake measured by variable-pressure PXRD. All show a "breathing" transition from narrow to wide pore forms. Na- and Cs-MER show non-Type I isotherms and kinetically-limited CO2 adsorption and delivery of pure CH4 in CO2/CH4 separation. However, K-MER shows good uptake of CO2 (3.5 mmol g-1 at 1 bar and 298 K), rapid adsorption and desorption kinetics, and promising CO2/CH4 separation. Furthermore, the narrow-to-wide pore transition occurs rapidly and at very low pCO2 via a "triggered" opening. This has the consequence that whereas no CH4 is adsorbed from a pure stream, addition of low levels of CO2 can result in pore opening and uptake of both CO2 and CH4, although in a continuous stream the CH4 is replaced selectively by CO2. This observed cation size-dependent adsorption behavior derives from a fine energetic balance between different framework configurations in these cation-controlled molecular sieves.

Effects of Hot Exhaust Gas Recirculation (EGR) on the Emission and Performance of a Single-Cylinder Diesel Engine

With the increment in global demand for energy, there is a need to reduce vehicle emission, which is among the major causes of air pollution around the world. In order to reduce the emissions levels, this study focuses on the effects of hot exhaust gas recirculation (EGR) system on the performance and emissions of a direct injection (DI) diesel engine. The performance studied includes engine power, torque, brake mean effective pressure, fuel consumption and the exhaust emission. The engine used in this study was a single-cylinder, four-stroke engine with an air-cooled system at a rated speed of 3600 rpm with displacement of 0.219 litres. The engine was operated at varying speeds of 1600 to 3600 rpm with different percentages of EGR (5%, 7%, 10% and 15%). Based on the results, it was shown that EGR had decreased the engine brake power and torque while increasing fuel consumption at the same time. The engine with EGR has reduced the emission level of NOx from 800 to 240 ppm and CO2, from 9% to 4%, while increasing the CO from 2% to 4% and UHC from 10 to 100 ppm. Hence, it was concluded that low emission level of NOx and CO2 could be obtained using EGR as it can be used to improve the emission level of a homogeneous charge compression ignition (HCCI) even further in the extension of this study.

Are patients with mild to moderate renal impairment on metformin or other oral anti-hyperglycaemic agents at increased risk of contrast-induced nephropathy and metabolic acidosis after radiocontrast exposure?

To investigate whether the use of metformin during computed tomography (CT) with radiocontrast agents increases the risk of contrast-induced nephropathy (CIN) and metabolic acidosis after CT in type 2 diabetes patients with mild to moderate renal failure. Patient records from January 2015 to December 2017 were reviewed retrospectively. A total of 374 patients were included in the final analysis. Of them, 157 patients received metformin, and 217 patients were taking other oral hypoglycaemic agents (OHAs) during radiocontrast administration. No significant difference in CIN incidence was observed between the metformin use group and the other OHAs group (p=0.085). Metabolic acidosis after CT was seen in 91 (58%) patients who used metformin and 141 (65%) patients who were taking other OHAs. There was no relationship between metabolic acidosis after CT and the use of metformin (p=0.195). Metabolic acidosis after radiocontrast agent exposure was associated with malignant disease, low serum albumin level, and low serum total CO2 level at baseline. These data show that other factors, but not metformin use, are associated with metabolic acidosis after radiocontrast agent exposure in patients with reduced renal function. These data support current recommendations that there is no need to discontinue metformin before CT using radiocontrast agents in patients with mild to moderate renal failure.

Environmental impacts of biodiesel production from waste spent coffee grounds and its implementation in a compression ignition engine

This study explores the environmental, economic, and technical feasibility of using spent coffee grounds as parent feedstock for biodiesel production. Biodiesel is produced from the spent coffee grounds, and four blends are prepared—B5, B10, B15, and B20. The effects of two extraction solvents (hexane and petroleum ether) on oil yields of the spent coffee grounds are investigated, employing the Soxhlet extraction technique. The properties of any intermediate yield throughout the production process are characterised and adjusted by post processes to ensure the conformity of the final biodiesel product with the standards (ASTM D6751 and ISO EN14214). The major part of the study investigates the effects of blends on tailpipe emissions and performance of a naturally aspirated single-cylinder compression ignition engine. A wide range of engine speeds (1600–3600rpm at 200-rpm increments) has been considered at three engine loads (100, 75, and 50%). The standard diesel fuel is set as a basis for comparison. Results show that the post processes on the extracted oil yielded water content of 0.038%, free fatty acid fraction of 0.41%, and acid number of <2mg KOH/g. The highest oil extraction (14.12%) was obtained over a 45-min extraction time using a hexane solvent. Biodiesel blends produced lower levels of CO2, CO, and HC. Blend B5 showed average reductions of 0.34, 12.5, and 4.23% at full load for the three aforementioned emissions, respectively; B10 reductions were 3.12, 29.85, and 19.14%, respectively. Higher levels of NOx emissions were detected from all blends. At full load, the average NOx increments of B5, B10, B15, and B20 were 0.35, 1.28, 1.8, and 2.3%, respectively. The outstanding environmental and ecological benefits of using the spent coffee grounds as a potential feedstock for biodiesel production are apparent.

Responses of carbonic anhydrases and Rubisco to abrupt CO2 changes of seawater in two marine diatoms.

Diatoms are experiencing striking fluctuations in seawater carbonate chemistry in the natural marine environment, especially in coastal seawaters. Here, we show that the diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, which utilize different carbon acquisition mechanisms, respond differently to short-term changes in seawater carbonate chemistry. Our results showed that T. weissflogii showed significantly higher photosynthetic oxygen evolution rates than that of P. tricornutum at low levels of CO2 or HCO3-. This suggests that T. weissflogii had higher affinities for CO2 or HCO3- when their concentrations were not sufficient to support saturated growth and photosynthesis. While the activity of Rubisco in P. tricornutum positively correlated with carbonic anhydrases (CA), we observed negative relationship between Rubisco and CA activity in the diatom T. weissflogii. These contrasting physiological responses of diatoms with varied carbon acquisition mechanisms indicate different abilities to cope up with abrupt changes in seawater carbonate chemistry. We propose that the ability to respond to varying carbonate chemistry may act as one determinant of the diatom distributions and phytoplankton community structures.

Energy optimization associated with thermal comfort and indoor air control via a deep reinforcement learning algorithm

The aim of this work is to propose an artificial intelligence algorithm that maintains thermal comfort and air quality within optimal levels while consuming the least amount of energy from air-conditioning units and ventilation fans. The proposed algorithm is first trained with 10 years of simulated past experiences in a subtropical environment in Taiwan. The simulations are carried out in a laboratory room having around 2–10 occupants and a classroom with up to 60 occupants. The proposed agent was first selected among different configurations of itself, with the 10th-year of training data set, then it was tested in real environments. Finally, a comparison between the current control methods and this new strategy is performed. It was found that the proposed AI agent can satisfactorily control and balance the needs of thermal comfort, indoor air quality (in terms of CO2 levels) and energy consumption caused by air-conditioning units and ventilation fans. For both environments, the AI agent can successfully manipulate the indoor environment within the accepted PMV values, ranging from about −0.1 to +0.07 during all the operating time. In regards to the indoor air quality, in terms of the CO2 levels, the results are also satisfactory. By utilizing the agent, the average CO2 levels fall below 800 ppm all the time. The results show that the proposed agent has a superior PMV and 10% lower CO2 levels than the current control system while consuming about 4–5% less energy.

Analysis of heat-affected zone microstructures of steel P92 after welding and after post-weld heat treatment

Modern thermal power plant operating on fossil fuels has to be highly efficient and should emit low levels of CO2. One of possible ways to fulfil these requirements is to increase thermal power plant peak service temperature. P92 steel enables service temperature of up to 650 °C. It is stronger, more resistant to creep and enables higher service temperature than P91. During welding of steam boiler components made of P92, it is important to consider proper preheating, welding and post-weld heat treatment parameters in order to avoid cracks and diminish sensitivity to creep in service. The research focused on analysis of simulated heat-affected zone (HAZ) microstructures and distribution of carbides. The FG HAZ (fine-grain heat-affected zone) (Tmax is 950 °C) is the most problematic when it comes to occurrence of type IV cracks, as in this zone, the average representation of carbides on PAGB is 72%, while the average representation of carbides on PAGB in the P21 steel is 58%. After the heat treatment, maximum hardness is recorded in the CG HAZ (coarse-grain heat-affected Zone) (Tmax is 1300 °C), where the values reached 248 HV, which was below the maximum allowable value of 250 HV. Other areas of HAZ expressed the values from 218 to 227 HV. Charpy impact test at service temperatures of 650 °C showed that the CG HAZ was the most critical immediately after welding as the energy for crack initiation was 30 J. However, after obligatory post-weld heat treatment, FG HAZ appeared to be more problematic than CG HAZ, so this research showed that the crack initiation energy value increased due to the fine-grain microstructure, yet the crack propagation energy reduced.

Elevated CO2 alters behavior, growth, and lipid composition of Pacific cod larvae

High-latitude seas, which support a number of commercially important fisheries, are predicted to be most immediately impacted by ongoing ocean acidification (OA). Elevated CO2 levels have been shown to induce a range of impacts on the physiology and behavior of marine fish larvae. However, these responses have yet to be characterized for most fishery species, including Pacific cod (Gadus macrocephalus). Based on laboratory experiments, we present a multi-faceted analysis of the sensitivity of Pacific cod larvae to elevated CO2. Fish behavior in a horizontal light gradient was used to evaluate the sensitivity of behavioral phototaxis in 4–5 week old cod larvae. Fish at elevated CO2 levels (∼1500 and 2250 μatm) exhibited a stronger phototaxis (moved more quickly to regions of higher light levels) than fish at ambient CO2 levels (∼600 μatm). In an independent experiment, we examined the effects of elevated CO2 levels on growth of larval Pacific cod over the first 5 weeks of life under two different feeding treatments. Fish exposed to elevated CO2 levels (∼1700 μatm) were smaller and had lower lipid levels at 2 weeks of age than fish at low (ambient) CO2 levels (∼500 μatm). However, by 5 weeks of age, this effect had reversed: fish reared at elevated CO2 levels were slightly (but not significantly) larger and had higher total lipid levels and storage lipids than fish reared at low CO2. Fatty acid composition differed significantly between fish reared at high and low CO2 levels (p < 0.01) after 2 weeks of feeding, but this effect diminished by week 5. Effects of CO2 on FA composition of the larvae differed between the two diets, an effect possibly related more to dietary equilibrium and differential lipid class storage than a fundamental effect of CO2 on fatty acid metabolism. These experiments point to a stage-specific sensitivity of Pacific cod to the effects of OA. Further understanding of these effects will be required to predict the impacts on production of Pacific cod fisheries.

Physiological and biochemical responses of &amp;lt;i&amp;gt;Emiliania huxleyi&amp;lt;/i&amp;gt; to ocean acidification and warming are modulated by UV radiation

Abstract. Marine phytoplankton such as bloom-forming, calcite-producing coccolithophores, are naturally exposed to solar ultraviolet radiation (UVR, 280–400 nm) in the ocean's upper mixed layers. Nevertheless, the effects of increasing carbon dioxide (CO2)-induced ocean acidification and warming have rarely been investigated in the presence of UVR. We examined calcification and photosynthetic carbon fixation performance in the most cosmopolitan coccolithophorid, Emiliania huxleyi, grown under high (1000 µatm, HC; pHT: 7.70) and low (400 µatm, LC; pHT: 8.02) CO2 levels, at 15 ∘C, 20 ∘C and 24 ∘C with or without UVR. The HC treatment did not affect photosynthetic carbon fixation at 15 ∘C, but significantly enhanced it with increasing temperature. Exposure to UVR inhibited photosynthesis, with higher inhibition by UVA (320–395 nm) than UVB (295–320 nm), except in the HC and 24 ∘C-grown cells, in which UVB caused more inhibition than UVA. A reduced thickness of the coccolith layer in the HC-grown cells appeared to be responsible for the UV-induced inhibition, and an increased repair rate of UVA-derived damage in the HC–high-temperature grown cells could be responsible for lowered UVA-induced inhibition. While calcification was reduced with elevated CO2 concentration, exposure to UVB or UVA affected the process differentially, with the former inhibiting it and the latter enhancing it. UVA-induced stimulation of calcification was higher in the HC-grown cells at 15 and 20 ∘C, whereas at 24 ∘C observed enhancement was not significant. The calcification to photosynthesis ratio (Cal ∕ Pho ratio) was lower in the HC treatment, and increasing temperature also lowered the value. However, at 20 and 24 ∘C, exposure to UVR significantly increased the Cal ∕ Pho ratio, especially in HC-grown cells, by up to 100 %. This implies that UVR can counteract the negative effects of the “greenhouse” treatment on the Cal ∕ Pho ratio; hence, UVR may be a key stressor when considering the impacts of future greenhouse conditions on E. huxleyi.

Indoor climate and energy performance in nearly zero energy day care centers and school buildings

This study presents the assessment of actual indoor climate condition and energy performance in eight NZEB school and daycare centers of NERO H2020 project. Physical parameters such as indoor temperature, relative humidity, CO2, airflow rate and temperature were measured during heating and cooling seasons, in parallel with an occupants’ questionnaires survey. Besides, calculated and measured energy data was collected from energy performance certificates and energy bills. Thermal comfort and IAQ were assessed based on categories in EN15251 standard with color footprints. Results showed that all the buildings had good or excellent indoor climate during the heating season. However, a large percentage of occupied hours were categorized as category IV during the cooling season, which mainly occurred due to too low indoor temperature caused by the low outdoor temperature during the measurement period. Also, all buildings achieved low CO2 levels. Moreover, the conducted questionaries’ survey showed good correlation with measured results for all buildings except in one building, which had odor and noise problems. In contrast, the measured energy use in 5 buildings out of 7 was increased by factor 2.1-3.0 compared to calculated annual energy use due to a full-time operation of the ventilation system and presence of hot kitchens.