See water, structural.
See water, structural.
H2O adsorbed by soil that is equilibrated with the atmosphere to which it is exposed at a given temperature and relative humidity, usually 25oC at 98 % relative humidity.
Water (or more precisely, H2O molecules) adsorbed between the (1:1 or 2:1) layers of a phyllosilicate. The use of “water” is a misnomer because the interlayer H2O is not equivalent to bulk water (i.e., a phase, a liquid), which involves randomly oriented H2O. Instead, the interlayer H2O is affected structurally by the adjacent 1:1 or 2:1 layers and by the cations present in the interlayer.
Cf., water, adsorbed
See water, structural.
See water, structural.
Water (more precisely, H2O or OH molecules) that is directly bound to cations at crystallographic sites in a crystal structure. This H2O or OH is capable of being driven off at elevated temperature, generally by heating to 1000oC. For phyllosilicates, structurally bound “water” is in the form of hydroxyl (OH) groups coordinated to cations, and the high temperature is required to promote dehydroxylation. Fluorine and certain other anions may be driven off at these temperatures also. However, hydrates, such as gypsum (CaSO4 .2H2O), have structural water coordinated to cations as H2O (e.g., water of hydration) that is liberated by heating to relatively low values, 65 – 95oC.
Syn. combined water, molecular water, structurally bound water, water of crystallization, water of hydration. “Lattice water” is also used, but is not recommended because a “lattice” refers to a collection of identipoints, see “lattice”.
Cf., water, adsorbed
See water, structural.
Water molecules adsorbed within the cavities/tunnels of the zeolite framework structure, commonly removed by heating at 350 to 400oC for about 12 hours. “Zeolitic water” was a term used by early workers to describe interlayer water of phyllosilicates. However, the analogy is imperfect (and not in use anymore) because the number of interlayer water molecules affects the layer-to-layer spacing of a phyllosilicate, whereas the shape and size of zeolitic tunnels are not significantly affected by the number of H2O molecules present.
Cf., water, structural; water, adsorbed
The physical (mechanical) and/or chemical breakdown of rock, sediment, and soil in place under the influence of the hydrosphere and/or atmosphere. Biota may influence or control physical or chemical weathering.
See physical weathering, chemical weathering.
Cf., erosion