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Carbon: freshwater plants
Author(s) -
KEELEY J. E.,
SANDQUIST D. R.
Publication year - 1992
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1992.tb01653.x
Subject(s) - photosynthesis , aquatic plant , terrestrial plant , carbon fibers , aquatic ecosystem , environmental chemistry , dissolved organic carbon , organic matter , total inorganic carbon , botany , respiration , environmental science , total organic carbon , chemistry , biology , ecology , carbon dioxide , materials science , macrophyte , composite number , composite material
δ 13 C values for freshwater aquatic plant matter varies from −11 to −50‰ and is not a clear indicator of photosynthetic pathway as in terrestrial plants. Several factors affect δ 13 C of aquatic plant matter. These include: (1) The δ 13 C signature of the source carbon has been observed to range from +1‰ for HCO 3 − derived from limestone to −30‰ for CO 2 derived from respiration. (2) Some plants assimilate HCO 3 − , which is –7 to –11‰ less negative than CO 2 . (3) C 3 , C 4 , and CAM photosynthetic pathways are present in aquatic plants. (4) Diffusional resistances are orders of magnitude greater in the aquatic environment than in the aerial environment. The greater viscosity of water acts to reduce mixing of the carbon pool in the boundary layer with that of the bulk solution. In effect, many aquatic plants draw from a finite carbon pool, and as in terrestrial plants growing in a closed system, biochemical discrimination is reduced. In standing water, this factor results in most aquatic plants having a δ 13 C value similar to the source carbon. Using Farquhar's equation and other physiological data, it is possible to use δ 13 C values to evaluate various parameters affecting photosynthesis, such as limitations imposed by CO 2 diffusion and carbon source.