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Activities of Cu2+ and Cd2+ in Soil Solutions as Affected by pH
Author(s) -
Cavallaro N.,
McBride M. B.
Publication year - 1980
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1980.03615995004400040013x
Subject(s) - organic matter , copper , chemistry , precipitation , cadmium , salt (chemistry) , soil water , environmental chemistry , saturation (graph theory) , metal , ion , soil organic matter , inorganic chemistry , soil science , environmental science , physics , mathematics , organic chemistry , combinatorics , meteorology
The concentrations of free copper and cadmium ions in soil suspensions were measured by an ion‐selective electrode as a function of pH after equilibrating metal salt solutions with the soils. Similar experiments were done with water‐extractable organic matter. Free (uncomplexed) Cu 2+ concentrations were strongly pH‐dependent in the soil systems, but well below the level where precipitation could have occurred. Free Cd 2+ concentrations were much less affected by pH adjustment, and the nonacid soil systems approached saturation or oversaturation with respect to CdCO 3 precipitation at high pH. Similiar dependence of the free metal ion concentration on pH was found in water extracted organic matter solutions. Precipitation of CdCO 3 in oversaturated solutions containing the extracted organic matter was slow, while none of the copper‐organic matter solutions attained oversaturation with respect to Cu(OH) 2 or Cu 2 (OH) 2 CO 3 .