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APHA
SMWW 3500-Ca
Calcium
2023
2
Standard methods for the examination of water and wastewater (543.3 APHA 24th ed. Ref. Treatises&monographs FL2)
Calcium (Ca) is the third element in Group IIA of the periodic table. It has an atomic number of 20, an atomic weight of 40.08, and a valence of 2. The average abundance of Ca in the earth’s crust is 4.9%; in soils it is 0.07 to 1.7%; in streams it is about 15 mg/L; and in groundwaters it is from 1 to >500 mg/L. The most common forms of calcium are calcium carbonate (calcite) and calcium-magnesium carbonate (dolomite)...