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Increased atmospheric carbon dioxide has been found to reduce plant water use, and consequently, the uptake of nitrogen, so particularly benefiting crop yields in arid regions. [10] The carbohydrate content of crops is increased from photosynthesis, but protein content is reduced due to lower nitrogen uptake.
Through photosynthesis, plants use CO 2 from the atmosphere, water from the ground, and energy from the sun to create sugars used for growth and fuel. [22] While using these sugars as fuel releases carbon back into the atmosphere (photorespiration), growth stores carbon in the physical structures of the plant (i.e. leaves, wood, or non-woody stems). [23]
The CO 2 compensation point (Γ) is the CO 2 concentration at which the rate of photosynthesis exactly matches the rate of respiration. There is a significant difference in Γ between C 3 plants and C 4 plants: on land, the typical value for Γ in a C 3 plant ranges from 40–100 μmol/mol, while in C 4 plants the values are lower at 3–10 μmol/mol. Plants with a weaker CCM, such as C2 ...
Carbon on Earth naturally occurs in two stable isotopes, with 98.9% in the form of 12 C and 1.1% in 13 C. [1] [8] The ratio between these isotopes varies in biological organisms due to metabolic processes that selectively use one carbon isotope over the other, or "fractionate" carbon through kinetic or thermodynamic effects. [1]
The concentrations of carbon dioxide in the atmosphere are expressed as parts per million by volume (abbreviated as ppmv, or ppm(v), or just ppm). To convert from the usual ppmv units to ppm mass (abbreviated as ppmm, or ppm(m)), multiply by the ratio of the molar mass of CO 2 to that of air, i.e. times 1.52 (44.01 divided by 28.96).
Carbon dioxide liquid/vapor equilibrium thermodynamic data: Temp. °C P vap Vapor pressure kPa H liq Heat content liquid J/g H vap Heat content vapor J/g
In free-air carbon dioxide enrichment (FACE) experiments plants are grown in field plots and the CO 2 concentration of the surrounding air is artificially elevated. These experiments generally use lower CO 2 levels than the greenhouse studies. They show lower gains in growth than greenhouse studies, with the gains depending heavily on the ...
The spores of lycopods are highly flammable and so have been used in fireworks. [30] Lycopodium powder, the dried spores of the common clubmoss, was used in Victorian theater to produce flame-effects. A blown cloud of spores burned rapidly and brightly, but with little heat. (It was considered safe by the standards of the time.) [citation needed]