Low carbon dioxide concentrations can reverse stomatal closure during water stress

2007 ◽  
Vol 130 (4) ◽  
pp. 552-559 ◽  
Author(s):  
James A. Bunce
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Stomatal Closure ◽  
Low Carbon ◽  
Carbon Dioxide Concentrations

scholarly journals Using New Gas Exchange Methods to Estimate Mesophyll Conductance and Non-stomatal Inhibition of Photosynthesis Caused by Water Deficits

HortScience ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. 687-690 ◽  
Author(s):  
James Bunce
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Soil Water ◽  
Atmospheric Carbon Dioxide ◽  
Global Climate ◽  
Stomatal Closure ◽  
Carbon Dioxide Concentration ◽  
Mesophyll Conductance ◽  
Water Deficits ◽  
Air Space

Soil water deficits remain one of the most important factors reducing the yield of crop plants and may become even more limiting with changes in the global climate and competition for fresh water resources. Soil water deficits reduce plant growth partly by reducing photosynthesis. However, it remains unclear how important non-stomatal factors are in limiting photosynthesis under moderate water stress and whether rising atmospheric carbon dioxide may alter which processes limit photosynthesis under water stress. The conductance to CO2 from the substomatal air space to the site of carboxylation inside chloroplasts in C3 plants is now termed mesophyll conductance. Because of the competition between CO2 and O2 for RuBisco, the carbon dioxide concentration at the chloroplast can be estimated from the O2 sensitivity of photosynthesis, providing a new method of estimating mesophyll conductance. It has also recently been realized that partial stomatal closure resulting from water stress can often be reversed by exposing leaves to low CO2. This provides a new means of assessing the non-stomatal component of the inhibition of photosynthesis by water stress. These methods were applied to four C3 species and revealed that mesophyll conductance decreased substantially with water stress in two of the four species and that reopening of stomata did not eliminate the reduction in photosynthesis caused by moderate water stress at either the current ambient or elevated CO2 concentrations.

Photosynthesis in Leaves at Very Low Carbon Dioxide Concentrations

Nature ◽  
1949 ◽  
Vol 163 (4140) ◽  
pp. 359-360 ◽  
Author(s):  
E. K. GABRIELSEN
Keyword(s):  
Carbon Dioxide ◽  
Low Carbon ◽  
Carbon Dioxide Concentrations

Host location by Aedes aegypti (Diptera: Culicidae): a wind tunnel study of chemical cues

1991 ◽  
Vol 81 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Alvaro E. Eiras ◽  
Paul C. Jepson
Keyword(s):  
Carbon Dioxide ◽  
Lactic Acid ◽  
Wind Tunnel ◽  
Aedes Aegypti ◽  
Carbon Dioxide Concentration ◽  
Elevated Carbon Dioxide ◽  
Low Carbon ◽  
Human Sweat ◽  
Carbon Dioxide Concentrations ◽  
Tunnel System

AbstractLactic acid, carbon dioxide and human sweat stimuli were presented singly and in combination to female Aedes aegypti (Linnaeus) within a wind-tunnel system. The take-off, flight, landing and probing responses of the mosquitoes were recorded using direct observation and video techniques. The analyses determined the nature of the response to different stimuli and the concentration ranges within which specific behaviours occurred. A threshold carbon dioxide concentration for taking-off of approximately 0.03% above ambient was detected. Lactic acid and human sweat samples did not elicit take-off when presented alone, however, when they were combined with elevated carbon dioxide, take-off rate was enhanced in most of the combinations tested. Flight activity was positively correlated with carbon dioxide level and some evidence for synergism with lactic acid was found within a narrow window of blend concentrations. The factors eliciting landing were more subtle. There was a positive correlation between landing rate and carbon dioxide concentration. At the lowest carbon dioxide concentration tested, landing occurred only in the presence of lactic acid. Within a window of low to intermediate concentrations, landing rate was enhanced by this combination. At the highest carbon dioxide concentration, landing was however inhibited by the presence of lactic acid. The sweat extract elicited landings in the absence of elevated carbon dioxide. This indicated the presence of chemical stimuli, other than lactic acid, active in the short range. Probing occurred only at low carbon dioxide concentrations and there was no probing when lactic acid alone was tested. There was however probing in the presence of combined stimuli, the level of response seemed to be positively correlated with the ratio of carbon dioxide and lactic acid concentrations.

scholarly journals The Well-Being of Children in Nurseries Does Not Have to Be Expensive: The Real Costs of Maintaining Low Carbon Dioxide Concentrations in Nurseries

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2035
Author(s):  
Katarzyna Ratajczak ◽  
Małgorzata Basińska
Keyword(s):  
Carbon Dioxide ◽  
Mechanical Ventilation ◽  
Air Quality ◽  
Carbon Dioxide Concentration ◽  
Well Being ◽  
Low Carbon ◽  
Number Of Children ◽  
Air Stream ◽  
Carbon Dioxide Concentrations ◽  
Carbon Dioxide Levels

There are different standards and regulations outlining the requirements regarding building air quality as well as in nurseries. These requirements specify air stream supplies and carbon dioxide concentration levels, both of which ensure proper indoor air quality. Mechanical ventilation should be used to maintain acceptable carbon dioxide levels. This article analyses the use of ventilation equipped with decentralized units, which helps secure the well-being of children. This paper proposes and evaluates economically affordable ventilation units. An algorithm for selecting the size of the devices is described by the supplied air stream depending on the number of children present at the nursery. A method of transferring the investment costs related to the assembly of the given units to the parents is proposed. Air quality in terms of CO2 concentrations was based on the following levels: 750 ppm, 1000 ppm, 1500 ppm. This assessment also includes the investment costs resulting from device usage and the costs of electricity consumed by the fans. These results showed the additional costs that assure the air quality improvement do not have to be high (45 PLN/month, ~10 EUR/month) per child attending the nursery. A 3% tuition increase returns the investment costs on mechanical ventilation within four years.

The Scenario Analysis of Carbon Emissions Based on Improved IPAT Model in China

2012 ◽  
Vol 616-618 ◽  
pp. 1484-1489 ◽  
Author(s):  
Xu Shan ◽  
Hua Wang Shao
Keyword(s):  
Carbon Dioxide ◽  
Economic Development ◽  
Carbon Dioxide Emissions ◽  
Industrial Structure ◽  
Energy Structure ◽  
Low Carbon ◽  
Policy Scenario ◽  
Social And Economic Development ◽  
Energy Environment ◽  
Development Goals

The coordination development of economy-energy-environment was discussed with traditional environmental loads model, combined with "decoupling" theory. Considering the possibilities of social and economic development, this paper set out three scenarios, and analyzed quantitatively the indexes, which affected carbon dioxide emissions, including population, per capita GDP, industrial structure and energy structure. Based on this, it forecasted carbon dioxide emissions in China in future. By comparing the prediction results, it held that policy scenario was the more realistic scenario, what’s more it can achieve emission reduction targets with the premise of meeting the social and economic development goals. At last, it put forward suggestions to implement successfully policy scenario, from energy structure, industrial structure, low-carbon technology and so on.

scholarly journals Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Jeremy Caves Rugenstein ◽  
Jason Goodman ◽  
Victor Brovkin
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Hydrological Cycle ◽  
High Surface ◽  
Dust Deposition ◽  
Carbon Dioxide Concentrations ◽  
Maximum Temperatures ◽  
Carbon Dioxide Levels ◽  
Earth’S Climate

AbstractSimple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.

scholarly journals Life Cycle Energy Consumption and Carbon Dioxide Emissions of Agricultural Residue Feedstock for Bioenergy

2021 ◽  
Vol 11 (5) ◽  
pp. 2009
Author(s):  
Valerii Havrysh ◽  
Antonina Kalinichenko ◽  
Anna Brzozowska ◽  
Jan Stebila
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Life Cycle ◽  
Carbon Dioxide Emissions ◽  
Crop Production ◽  
Agricultural Residues ◽  
Environmental Indicators ◽  
Low Carbon ◽  
Low Carbon Economy ◽  
Energy Inputs

The depletion of fossil fuels and climate change concerns are drivers for the development and expansion of bioenergy. Promoting biomass is vital to move civilization toward a low-carbon economy. To meet European Union targets, it is required to increase the use of agricultural residues (including straw) for power generation. Using agricultural residues without accounting for their energy consumed and carbon dioxide emissions distorts the energy and environmental balance, and their analysis is the purpose of this study. In this paper, a life cycle analysis method is applied. The allocation of carbon dioxide emissions and energy inputs in the crop production by allocating between a product (grain) and a byproduct (straw) is modeled. Selected crop yield and the residue-to-crop ratio impact on the above indicators are investigated. We reveal that straw formation can consume between 30% and 70% of the total energy inputs and, therefore, emits relative carbon dioxide emissions. For cereal crops, this energy can be up to 40% of the lower heating value of straw. Energy and environmental indicators of a straw return-to-field technology and straw power generation systems are examined.

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