The CaCO3-CO2-H20 system in soils'
Equations used to develop the CO2-Ca-pH relation-ships in calcareous soils are reviewed. The equation Pco, (Ca)--- (H) 2 Ke, is used to draw a three-dimensional surface and to derive three partial differential equations to illustrate the rela-tionships between CO 2 partial pressure, Ca activity and...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.466.957 http://eprints.nwisrl.ars.usda.gov/436/1/548.pdf |
| Summary: | Equations used to develop the CO2-Ca-pH relation-ships in calcareous soils are reviewed. The equation Pco, (Ca)--- (H) 2 Ke, is used to draw a three-dimensional surface and to derive three partial differential equations to illustrate the rela-tionships between CO 2 partial pressure, Ca activity and pH. lc is a combination of Henry's Law constant, the first and second dissociation constants for carbonic acid and the calcite solubility product. The three dimensional CO2-Ca-pH surface illustrates how the three parameters relate to each other under ideal conditions. The partial differential equations are presented to illustrate how changes in one parameter affect the other two. The CO,-Ca-pH surface provides a graphical method for in-troducing the idea of three component equilibria, while the partial differential equations provide a mathematical representation of these interactions for those with chem-ical thermodynamics or strong mathematic or modeling backgrounds. Deviations from this Ideal model in natural systems are discussed for those who wish to ex-tend the discussion to natural systems. |
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