ISSN:
1365-2389
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
A discrete-site/electrostatic model of ion binding by humic substances has been applied to proton-and copper-binding data for a soil humic acid. The proton data cover the pH range 3–9 and the ionic strength range 0.001 m-0.1 m, while those for copper refer to the pH range 4–5, ionic strengths between 0.005 m and 0.1 m, and p[Cu] values between 3 and 8. The model is able to explain the major observed trends, including the dependence of proton and copper binding on ionic strength and the binding of copper as a function of pH. However, the calculated ionic strength dependence of copper binding is slightly less than that observed. In addition, the model has been used to predict ratios of protons released to copper bound under different conditions, on the basis of the separately estimated parameters for proton and copper binding. The model correctly predicts the ratios to be between 1 and 2, and to decrease with increasing bound copper and with pH.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2389.1995.tb01815.x
Permalink