Processes affecting the major chemical components of groundwater

component origin*

sodium ion sodium chloride dissolution (some pollutive)

plagioclase weathering

rainwater addition

potassium ion biotite weathering

K-feldspar weathering

biomass decreases

dissolution of trapped aerosols

magnesium ion amphibole and pyroxene weathering

biotite (and chlorite) weathering

dolomite weathering

olivine weathering

rainwater addition

calcium ion calcite weathering

plagioclase weathering

dolomite weathering

dissolution of trapped aerosols

biomass decreases

bicarbonate ion calcite and dolomite weathering

silicate weathering

sulfate ion pyrite weathering (some pollutive)

rainwater addition

chloride ion sodium chloride dissolution (some pollutive)

rainwater addition

hydrogen silicate silicate weathering

*The sources for each constituent are given in approximate order of decreasing importance.

Source: Adapted from Elizabeth Kay Berner and Robert A. Berner, The Global Water Cycle: Geochemistry and Environment, copyright 1987, Table 4.6, p. 170. Reproduced by permission of Prentice Hall, Inc., Englewood Cliffs, N.J.