The Gibbs diagram (boomerang plot) of total dissolved salts (TDS) versus Na+/(Na+ + Ca2+) weight ratio for world surface waters distinguishes three end-member controls on water chemistry: precipitation dominance, rock (weathering) dominance, and evaporation-crystallization dominance.
In the classic Gibbs plot, the lower-right limb (low TDS, high Na+/(Na++Ca2+) ratio, since rainwater carries proportionally more cyclic marine Na+ salts despite low total...
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