ISSN:
1573-5117
Schlagwort(e):
metals
;
chelation
;
model
;
geochemistry
;
speciation
;
prediction
;
site-saturation
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Ultrafilterable material 〈 0.15 µm was collected from six Wyoming surface waters, for which the chemical limnology had also been determined. The material was separated into four nominal size-fractions and the binding capacity of each for copper was determined by a hyperbolic, site-saturation model. The conditional, overall, thermodynamic stability constants (K′) for binding of copper were determined by two discrete models: The one- and two-component Scatchard functions, and two continuous multiligand models; The one- and three-component Gaussian Scatchard functions. The accuracy of the stability constants to predict the speciation of Cu(II) in the titration of the isolated fractions and of whole waters was evaluated by comparing the predictions of the thermodynamic, geochemical simulation model, GEOCHEM to those measured by selective ion electrode. The Cu-binding capacity of material retained by ultrafilters was positively correlated with the hardness and alkalinity of the surface waters, from which they were isolated as well as the percent ash content of the ultrafilter-retained material. The magnitude of the conditional stability constant (K infi sup′ ) decreased as the ratio of the total Cu concentration to total concentration of Cu-binding sites increased. The cumulative frequency distribution of K infi sup′ was log-normally distributed. All four of the models used to estimate the conditional stability constants gave reasonable prediction of the speciation of Cu for both fractionated and whole waters but, depending on the situation, the one- or two-component Scatchard estimate generally gave the best predictions of the proportion of copper, which would be expected to be bound.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00027834
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