Increasing CO2 Levels Research Articles

Simulating future climate change impacts on seed cotton yield in the Texas High Plains using the CSM-CROPGRO-Cotton model

The Texas High Plains (THP) region contributes to about 25% of the US cotton production. Dwindling groundwater resources in the underlying Ogallala aquifer, future climate variability and frequent occurrences of droughts are major concerns for cotton production in this region. Assessing the impacts of climate change on cotton production enables development and evaluation of irrigation strategies for efficient utilization of groundwater resources in this region. In this study, the CROPGRO-Cotton module within the Cropping System Model (CSM) that is distributed with the Decision Support System for Agrotechnology Transfer (DSSAT) was evaluated for the THP region using measured data from cotton water use efficiency experiments at Halfway over a period of four years (2010–2013). Simulated seed cotton yield matched closely with observed yield during model calibration (average percent error of 0.1) and validation (average percent error of 6.5). The evaluated model was able to accurately simulate seed cotton yield under various irrigation strategies over the four growing seasons. The evaluated CROPGRO-Cotton model was later used to simulate the seed cotton yield under historic (1971–2000) and future (2041–2070) climate scenarios projected by three climate models. On an average, when compared to historic seed cotton yield, simulated future seed cotton yield across the THP decreased within a range of 4–17% when carbon dioxide (CO2) concentration was assumed to be constant at the current level (380ppm) under three climatic model scenarios. In contrast, when the CO2 concentration was assumed to increase from 493ppm (in year 2041) to 635ppm (in year 2070) according to the Intergovernmental Panel on Climate Change (IPCC) A2 emission scenario, the simulated future average seed cotton yield in the THP region increased within a range of 14–29% as compared to historic average yield. When the irrigation amount was reduced by 40% (from 100% to 60%), the average (2041–2070) seed cotton yield decreased by 37% and 39% under the constant and increasing CO2 concentration scenarios, respectively. These results imply that cotton is sensitive to atmospheric CO2 concentrations, and cotton production in the THP could potentially withstand the effects of future climate variability under moderate increases in CO2 levels if irrigation water availability remains at current levels.

Linking dissolved carbon dioxide to dissolved organic matter quality in streams

Streams are typically supersaturated with carbon dioxide (CO2) thus playing a pivotal role in the global carbon cycle. To further our knowledge on stream CO2 dynamics, we tested the linkages between dissolved CO2 and dissolved organic matter quality during two time periods (spring and summer). We sampled 48 streams in Ontario, Canada that represent a range of catchment cropland cover (2–80 %), nutrients, dissolved organic carbon concentration (DOC), and dissolved organic matter (DOM) quality. For both sampling periods, DOM composition (quality) was found to be an important predictor of CO2 concentration in streams, more so than DOC concentration. In general, the more complex terrestrially-derived DOM was associated with elevated CO2 levels whereas microbial-like DOM had a poor relationship with CO2. The DOM characteristics associated with increased CO2 levels were related to wetlands rather than croplands. Nutrients (nitrogen and phosphorus) were also important predictors of CO2, however this relationship was not linear. Since the streams in the sampled network were of mixed land use, it appears that CO2 levels were affected by both land use types in a composite non-linear way. Overall, our findings suggest that DOM quality is a better predictor of stream CO2, however the relationship between DOM and CO2 is complicated by the presence of breakpoints in the data associated with non-linearity.

Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, <i>Porolithon onkodes</i> in an experimental system

Abstract. There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesised that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes, the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement was affected by increasing CO2 levels (365, 444, 676 and 904 μatm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by CO2. Our results show that there was no significant effect of CO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with CO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.

Irreducible uncertainty in near-term climate projections

Model simulations of the next few decades are widely used in assessments of climate change impacts and as guidance for adaptation. Their non-linear nature reveals a level of irreducible uncertainty which it is important to understand and quantify, especially for projections of near-term regional climate. Here we use large idealised initial condition ensembles of the FAMOUS global climate model with a 1 %/ year compound increase in CO2 levels to quantify the range of future temperatures in model-based projections. These simulations explore the role of both atmospheric and oceanic initial conditions and are the largest such ensembles to date. Short-term simulated trends in global temperature are diverse, and cooling periods are more likely to be followed by larger warming rates. The spatial pattern of near-term temperature change varies considerably, but the proportion of the surface showing a warming is more consistent. In addition, ensemble spread in inter-annual temperature declines as the climate warms, especially in the North Atlantic. Over Europe, atmospheric initial condition uncertainty can, for certain ocean initial conditions, lead to 20 year trends in winter and summer in which every location can exhibit either strong cooling or rapid warming. However, the details of the distribution are highly sensitive to the ocean initial condition chosen and particularly the state of the Atlantic meridional overturning circulation. On longer timescales, the warming signal becomes more clear and consistent amongst different initial condition ensembles. An ensemble using a range of different oceanic initial conditions produces a larger spread in temperature trends than ensembles using a single ocean initial condition for all lead times. This highlights the potential benefits from initialising climate predictions from ocean states informed by observations. These results suggest that climate projections need to be performed with many more ensemble members than at present, using a range of ocean initial conditions, if the uncertainty in nearterm regional climate is to be adequately quantified.

Hidden impacts of ocean acidification to live and dead coral framework.

Cold-water corals, such as Lophelia pertusa, are key habitat-forming organisms found throughout the world's oceans to 3000 m deep. The complex three-dimensional framework made by these vulnerable marine ecosystems support high biodiversity and commercially important species. Given their importance, a key question is how both the living and the dead framework will fare under projected climate change. Here, we demonstrate that over 12 months L. pertusa can physiologically acclimate to increased CO2, showing sustained net calcification. However, their new skeletal structure changes and exhibits decreased crystallographic and molecular-scale bonding organization. Although physiological acclimatization was evident, we also demonstrate that there is a negative correlation between increasing CO2 levels and breaking strength of exposed framework (approx. 20–30% weaker after 12 months), meaning the exposed bases of reefs will be less effective ‘load-bearers’, and will become more susceptible to bioerosion and mechanical damage by 2100.

External quality and sensory attributes of papaya cv. Golden stored under different controlled atmospheres

This work evaluates the sensory attributes of papaya cv. Golden stored under refrigeration in controlled atmosphere (CA) with suppressed O2 and increased CO2 levels. Fruit was kept at 13°C in chambers containing 1% or 3% O2 plus 6% or 12% CO2, with ethylene scrubbing. Fruit of the control treatment was maintained for 26 d under refrigeration in normal atmosphere. After 20 d of storage the fruit was maintained for 6 d at 23°C in ambient atmosphere to assure total ripening. Consumer preference evaluation was performed by untrained panelists (87) based on a nine-point hedonic scale. Mass loss and changes in peel color were evaluated with 60 replicates per treatment. It was verified that atmospheres containing 1% or 3% O2 with higher level of CO2 (12%) minimized mass loss and fruit ripening, but promoted stressful conditions that affected the sensory attributes of the fruit after the storage. The best condition that preserved the fruit quality was achieved in an atmosphere with 3% O2 plus 6% CO2.

Advances in understanding CO2 responsive plant metabolomes in the era of climate change

Anthropogenic climate change due to increased CO2 emission poses a major threat to global crop productivity, food quality, and security. Numerous studies, mostly classical, have predicted the effects of increased CO2 levels on environmental temperature and water balance, and on the life cycle, biomass, photosynthesis, leaf carbon/nitrogen ratio, and stomatal distribution in various plant species. With the advent of high-throughput tools for studying plant-CO2 responsiveness, it is now possible to obtain a metabolome-level view of the effect of climate change on plants. In this review, we examine the plant CO2-responsive primary and secondary metabolism, isoprene emission, in the presence of other stressors, and the advancement in state-of the art research methods that will facilitate future metabolomic studies.

Neurovascular coupling during cortical spreading depolarization and -depression.

Cortical spreading depolarizations (CSDs) are self-propagating waves of transient loss of neuronal transmembrane ion gradients, followed by prolonged suppression of neuronal activity (spreading depression). CSDs emerge spontaneously in animal models of traumatic brain injury,1 subarachnoid hemorrhage,2 and in focal ischemia3 where they are associated with infarct growth.4 In humans, CSDs have been demonstrated in traumatic brain injury,5 subarachnoid hemorrhage,6,7 and malignant hemispheric stroke,8 and they are believed to be the brain mechanism underlying migraine aura.9 CSDs are associated with dramatic changes in cerebral blood flow (CBF). During the depolarization phase of CSDs induced in healthy and well-perfused brain tissue in animal models, an early hyperemic response is observed, typically followed by prolonged oligemia after the neuronal repolarization. Despite the initial CBF increase, tissue hypoxia may develop in more distant territories of capillary supply.10,11 Similar CBF changes have been observed in patients with migraine aura.12–14 In the injured brain, CSDs can be accompanied by severe initial CBF reduction instead of a CBF increase during the depolarization phase, termed spreading ischemia.15 When this inverse hemodynamic response is observed, the energy-dependent recovery from CSD is delayed in a characteristic fashion, indicating a severe mismatch between oxygen supply and demand2 and a high risk of tissue damage.16 In rat and cat models of focal ischemia, CSD-related CBF transients range from monophasic, positive CBF responses in peri-ischemic tissue, over biphasic transients in mildly ischemic tissue, to negative CBF transients in more severe ischemia.17–19 During CSD in animal models, capillary flow patterns become severely disturbed.10,20,21 The passage of a CSD causes erythrocytes in some capillaries to reduce their speed, whereas other capillaries reveal 4-fold increases in flow or higher. …

The effect of carbon dioxide on growth and metabolism in juvenile turbot Scophthalmus maximus L.

Land-based aquaculture is an increasingly important method of fish production, and fish grown in such systems may be exposed to substantially higher carbon dioxide concentrations than fish in the wild. Chronic exposure to elevated CO2 levels in recirculated aquaculture systems can correlate with lower growth and condition indices for many fish species, however, the physiological basis behind this loss of performance is largely unknown. The aim of this study was to investigate the growth, condition and protein catabolism rates of juvenile turbot (55-176 g) reared for 8 weeks at three different dissolved carbon dioxide concentrations: 5, 26, and 42 mg l(-1) (-3000, 15000, 25000 mu atm; pH 7.37, 6.66, 6.44). A commercial diet was administered once per day until satiation, and uneaten food was collected from a solids collector. Oxygen consumption and ammonia excretion were measured weekly using high precision automated methods in a recirculating aquaculture respirometer system. Increased CO2 levels were associated with reduced condition factor, feed intake and weight gain. Compared to the low CO2 treatment, the specific growth rates under the medium and high treatments were reduced by 21% and 58%, respectively. Feed conversion ratios were similar between treatments. The oxygen consumption rates broadly followed a dose-response pattern, where fish in the low CO2 treatment exhibited the highest respiration rates. Comparison of ammonia quotients over time and at comparable feed intake showed the rates of protein catabolism correlated with CO2 exposure levels. By the end of the 8 week trial fish from the high CO2 treatment exhibited up to 3 times the protein catabolism rates observed in the low treatment, and the medium treatment was approximately intermediate between the two. The conclusion from the study was that the loss of growth and condition of turbot reared at elevated CO2 concentrations (relevant to land-based aquaculture systems) can be traced to decreased feed intake and an increased reliance on protein as a fuel source. (C) 2015 Elsevier B.V. All rights reserved.

Strain‐Dependent Variations in Carotid Body O2 Sensing: Role of CO‐H2S Signaling

Systemic responses to hypoxia vary among human subjects and in different strains of rats. We examined whether these inherent variations in hypoxic response to carotid body (CB) O2 sensing and involve CO‐H2S signaling. Experiments were performed on age and gender matched Sprague‐Dawley (SD), Brown‐Norway (BN) and Spontaneous Hypertensive (SH) rats. Compared to SD, BN rats exhibited impaired carotid body response to hypoxia, and developed pulmonary edema as a consequence of poor ventilatory adaptation to hypobaric hypoxia. SH rat carotid bodies displayed inherent hypersensitivity to hypoxia and develop hypertension. BN CBs have higher CO and lower H2S levels than SD, while SH carotid bodies have reduced CO and greater H2S generation. Reducing CO levels in BN carotid body increased H2S generation, restoring CB hypoxic sensing and preventing high‐altitude pulmonary edema. Increasing CO levels in SH carotid bodies reduced H2S generation, preventing hypersensitivity to hypoxia and controlling hypertension. Supported by NIH‐HL‐90554.

EFFECT OF AMBIENT AND SIMULATED CO2 ON THE GROWTH INVASIVE WEED Potentilla recta L.

SUMMARY The invasive weed species have been found among the most important threats to the native vegetation during recent times. The recent climate changes, particularly the increasing atmospheric CO2 levels are supposed to enhance the growth of invasive weed species. We evaluated the effect of ambient (current normal level of CO2 in the atmosphere) and simulated (elevated to double of normal CO2 in the atmosphere) CO2 levels on the invasive weed species Potentilla recta L. The invasive weed species was grown under normal (~400 ppm) and elevated (~800-850 ppm) CO2 in a controlled glasshouse. The data on fresh weight, dry weight, number of leaves, plant height and chlorophyll index were recorded. The results of the studies indicated that the elevated CO2 levels increased the growth of P. recta. The high levels of CO2 increased the fresh weigh, dry weight, plant height and number of leaves of P. recta compared with ambient CO2 while chlorophyll index was not affected. In conclusion, the increasing CO2 levels in the atmosphere can increase the growth, and hence the invasiveness of the invasive weeds species. Further, the generation of such information is very important for devising management strategies of invasive weed species.

Plant Responses to Drought Stress in Future Climate CO2: A Multi-level Analysis

Future climate scenarios indicate increasing CO2 levels in combination with more frequent drought spells. Recent studies suggest that elevated CO2 reduces the effect of drought stress, but the mechanisms underlying the reduced stress effects remain unclear. Therefore we investigated the growth, physiological, biochemical and genome-wide transcriptional responses of Arabidopsis thaliana to mild (MD) and severe drought (SD) under ambient (aCO2) and elevated CO2 (eCO2), 360 and 620ppm respectively. Kinematic analysis showed that drought reduced leaf growth by inhibiting cell division and expansion. High CO2 and drought showed opposite and interactive effects on growth. Where, eCO2 reduced the impact of MD on growth by limiting the effect on both cell number and size, and the impact of SD by reducing the effect on cell size only. Genome-wide transcriptional analysis showed that growth, photosynthesis and defense processes are more strongly affected by SD as compared to MD. These results were mirrored at the growth, physiological and biochemical levels, where SD inhibited photosynthesis and stomatal conductance and induced defense related parameters. Accumulation of antioxidants and osmolytes were not sufficient to completely recover the SD damage impact. In contrast, in SD conditions in particular, eCO2 significantly mitigated the detrimental effects of drought stress. The transcriptome and metabolic analyses did not implicate the antioxidant defense metabolism in protective effect of eCO2, with down regulation or no significant impact on most of measured antioxidant parameters. On the other hand, we found that eCO2 alleviated photorespiration; a stress-induced H2O2 generation process thus, the relaxation in antioxidant system could be a consequence of less oxidative pressure. Further induction of osmolytes was also observed and that could be associated with improved leaf relative water content under the drought and eCO2. We therefore concluded that elevated CO2 mitigates the effects of drought by maintaining plant turgor and reduced hydrogen peroxide production.

Overnight Transcutaneous Carbon Dioxide Monitoring in Eucapnic Patients with Obstructive Sleep Apnea Syndrome.

We monitored increases in CO2 levels during sleep by measuring transcutaneous pCO2 (PtcCO2) to determine its relationship with polysomnographic data in normocapnic patients with obstructive sleep apnea syndrome (OSAS). Between October 2011 and December 2012, 139 patients underwent PtcCO2 monitoring with polysomnography. All patients were evaluated with arterial blood gas (ABG) measurements and pulmonary function tests (PFTs). We excluded 13 patients with COPD and/or daytime hypercapnia and 29 patients whose PtcCO2 records could not be evaluated. The patients' mean age was 46.8±10.3 years. Fifty-nine patients (60.8%) were male, and 38 (39.2%) patients were female. The mean overnight PtcCO2 was ≤45 mm Hg in 84 (86.6%) patients and >45 mm Hg in 13 (13.4%) patients. In the group with PtcCO2>45 mm Hg, 10 patients had an apnea-hypopnea index (AHI) >15, and 3 patients had an AHI<15, without a statistically significant difference (p=0.078). The mean apnea and apnea/interapnea periods were similar. The mean PtcCO2 values correlated with time spent when the SpO2 was <90% (r=0.220, p<0.031). When we grouped the patients by AHI, 60 (61.8%) patients had an AHI>15 (moderate to severe OSAS), and 37 (37.2%) had an AHI<15 (mild OSAS). Of the former group, 16.7% had a mean PtcCO2 >45 mm Hg, whereas this ratio was 8.1% in the latter group. The difference was not statistically significant (p=0.359). In the group with an AHI>15, the highest PtcCO2 levels were significantly higher (p<0.05). We conclude that seemingly eucapnic OSAS patients may experience hypercapnia when sleeping, and PtcCO2 monitoring may be useful in the early diagnosis of hypercapnia.

Carbon dioxide sensitivity and its role in multifunctional neurons in the mollusk Onchidium

Intrinsically photoresponsive neurons in the abdominal ganglion of the amphibious mollusk Onchidium named Ip-1 and Ip-2 (Ip-1/2) react to several different stimuli. These neurons respond to light with slow hyperpolarization and to CO2 stimulation with slow depolarization. In this study, increasing the concentration of CO2 in the air caused hyperventilation and enlargement of the pneumostome in the intact animal. In a semi-intact preparation, pouring artificial seawater (ASW) with dissolved CO2 onto the central ganglia caused the previously closed pneumostome to open. In an ASW environment, Ip-1/2 neurons depolarized even under conditions of constant pH (alkaline ASW) and after dissolution of CO2. This depolarization prolonged the firing of action potentials in Ip-1/2 neurons. Adding protons (H+) to ASW caused Ip-1/2 depolarization only when the neurons' membranes were depolarized to a potential above the resting potential. Furthermore, in the presence of the carbonic anhydrase inhibitor acetazolamide (AZ), CO2-induced excitation in Ip-1/2 neurons was increased in both normal and alkaline ASW. These results suggest that when dissolved in ASW, CO2 directly induced the depolarizing response in Ip-1/2 neurons. Since Ip-1/2 neurons participate in pneumostome opening, these results suggest that increased CO2 levels in ASW directly stimulate CO2-sensitive central neurons, promoting ventilation.

Optimisation of the process parameters of combined high hydrostatic pressure and dense phase carbon dioxide on enzyme inactivation in feijoa (Acca sellowiana) puree using response surface methodology

Abstract The effects of pressure (200–600 MPa), process time (1–13 min), pH (3.0–3.6), and CO2 levels (no CO2, CO2 saturation, and saturation with addition of 8.5 mL CO2/g sample) in a combined high hydrostatic pressure (HHP) and dense-phase carbon-dioxide process on 3 enzymes: peroxidase (POD), polyphenoloxidase (PPO) and pectinmethylesterase (PME), of feijoa (Acca sellowiana) puree were studied using response surface methodology (27 treatments). Increasing treatment time reduced all enzyme activities, while increasing CO2 levels decreased PME activity, and pressure influenced PPO activity. The lower pH values tended to increase enzyme inactivation. The optimal process conditions of 13 min, 600 MPa, pH = 3, CO2 saturation, resulted in 74.3 ± 3.3%, 70.9 ± 2.6% and 53.9 ± 0.9% residual activity for POD, PPO and PME respectively. Combination of CO2 with HHP induced synergistic enzyme inactivation, and reduction of pH did not prove to be the main factor. Industrial relevance High hydrostatic pressure (HHP) achieves the safety of beverages as a non-thermal method, but it may activate undesirable enzymes. Therefore, the product may have a short shelf life due to e.g. settling and colour change. Addition of carbon dioxide to HHP was shown to increase enzyme inactivation. Our study determined the optimal conditions to reduce enzyme activity in feijoa puree by this method. When industrial means become available to combine these processes, then in addition to safety and nutrient preservation, the shelf life of products will also increase.

A closed-loop model of the respiratory system: focus on hypercapnia and active expiration.

Breathing is a vital process providing the exchange of gases between the lungs and atmosphere. During quiet breathing, pumping air from the lungs is mostly performed by contraction of the diaphragm during inspiration, and muscle contraction during expiration does not play a significant role in ventilation. In contrast, during intense exercise or severe hypercapnia forced or active expiration occurs in which the abdominal “expiratory” muscles become actively involved in breathing. The mechanisms of this transition remain unknown. To study these mechanisms, we developed a computational model of the closed-loop respiratory system that describes the brainstem respiratory network controlling the pulmonary subsystem representing lung biomechanics and gas (O2 and CO2) exchange and transport. The lung subsystem provides two types of feedback to the neural subsystem: a mechanical one from pulmonary stretch receptors and a chemical one from central chemoreceptors. The neural component of the model simulates the respiratory network that includes several interacting respiratory neuron types within the Bötzinger and pre-Bötzinger complexes, as well as the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG) representing the central chemoreception module targeted by chemical feedback. The RTN/pFRG compartment contains an independent neural generator that is activated at an increased CO2 level and controls the abdominal motor output. The lung volume is controlled by two pumps, a major one driven by the diaphragm and an additional one activated by abdominal muscles and involved in active expiration. The model represents the first attempt to model the transition from quiet breathing to breathing with active expiration. The model suggests that the closed-loop respiratory control system switches to active expiration via a quantal acceleration of expiratory activity, when increases in breathing rate and phrenic amplitude no longer provide sufficient ventilation. The model can be used for simulation of closed-loop control of breathing under different conditions including respiratory disorders.

The effect of hypercapnia on the sensitivity to flicker defined stimuli

Background/AimsTo investigate the effect of increased CO2 levels on flicker defined stimuli.MethodsThe sensitivity of two flicker defined tasks was measured in nine healthy, trained observers using the Flicker Defined Form...

CO2-Induced Sahel Greening in Three CMIP5 Earth System Models

Abstract The existence and productivity of vegetation is the basis for food and energy supply in the Sahel. Past changes in climate and vegetation abundance have raised the question whether the region could become greener in the future as a result of higher CO2 levels. By analyzing three Earth system models (ESMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) with dynamic vegetation, the authors demonstrate why an answer to this question remains elusive in contrast to more robust projections of vegetation cover in the extratropics. First, it depends on the location and the time scale whether vegetation expands or retreats. Until the end of the twenty-first century, the three models agree on a substantial greening in the central and eastern Sahel due to increased CO2 levels. This trend is reversed thereafter, and vegetation retreats in particular in the western Sahel because the beneficial effect of CO2 fertilization is short lived compared to climate change. Second, the vegetation cover changes are driven by different processes in different models (most importantly, precipitation change and CO2 fertilization). As these processes tend to oppose each other, the greening and browning trends are not a reliable result despite the apparent model agreement. The authors also find that the effect of vegetation dynamics on the surface energy balance crucially depends on the location. In contrast to the results of many previous studies, the Sahel appears as a hotspot where the physiological effects of CO2 can exert a cooling because vegetation structure and distribution overcompensate for the decreased stomatal conductance.

Choosing amine-based absorbents for CO2 capture

CO2 capture from gaseous effluents is one of the great challenges faced by chemical and environmental engineers, as the increase in CO2 levels in the Earth atmosphere might be responsible for dramatic climate changes. From the existing capture technologies, the only proven and mature technology is chemical absorption using aqueous amine solutions. However, bearing in mind that this process is somewhat expensive, it is important to choose the most efficient and, at the same time, the least expensive solvents. For this purpose, a pilot test facility was assembled and includes an absorption column, as well as a stripping column, a heat exchanger between the two columns, a reboiler for the stripping column, pumping systems, surge tanks and all necessary instrumentation and control systems. Some different aquous amine solutions were tested on this facility and it was found that, from a set of six tested amines, diethanol amine is the one that turned out to be the most economical choice, as it showed a higher CO2 loading capacity (0.982 mol of CO2 per mol of amine) and the lowest price per litre (25.70 €/L), even when compared with monoethanolamine, the benchmark solvent, exhibiting a price per litre of 30.50 €/L.

Root and rhizosphere processes-high time to dig deeper.

Root and rhizosphere processes-high time to dig deeper.