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Solution Composition Effects on Cadmium Sorption by Forest Soil Profiles
Author(s) -
Homann Peter S.,
Zasoski Robert J.
Publication year - 1987
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1987.00472425001600040023x
Subject(s) - sorption , chemistry , sulfate , cadmium , calcium , environmental chemistry , soil water , calcium nitrate , cation exchange capacity , soil ph , sodium , inorganic chemistry , soil science , geology , adsorption , organic chemistry
Cadmium sorption can reduce Cd transport through sewage sludge‐amended forest soils. Three mineral soil horizons from each of six western Washington State soil series were evaluated for their potential to sorb Cd. Horizons varied in pH from 3.6 to 6.4, in clay content from 100 to 470 g kg −1 , in organic C from 3 to 87 g kg −1 , and in cation exchange capacity from 1.8 to 35.8 cmol c kg −1 . Batch equilibrium experiments were conducted in three background solutions (calcium nitrate, calcium sulfate, and sodium sulfate) that had ionic strengths of 0.016 and were maintained at pH values close to the natural soil pH. Between 4 and 97% of the initial 10 µM Cd was sorbed by 1 g soil in 0.1‐L background solution. Sorption varied among the horizons in each soil profile, but there was no consistent trend with depth among the six profiles. Sorption did not differ significantly between calcium nitrate and calcium sulfate solutions. However, it was significantly lower in calcium sulfate than sodium sulfate solution, supporting the hypothesis that calcium competition lowers Cd sorption. The amount of Cd sorbed when a solution concentration of 1 µM free Cd 2+ is maintained (Cd sorbed ) decreased 81% when free Ca 2+ increased from 0.09 m M Ca 2+ in sodium sulfate to 4.0 m M Ca 2+ in calcium sulfate solution. The Cd sorbed increased with increased natural soil pH. A horizons had higher Cd sorbed than B horizons of similar natural soil pH, possibly due to their higher organic matter contents.