Lead and Calcium Binding to Fulvic Acids:  Salt Effect and Competition

Knowledge of the speciation of Pb in natural aquatic systems is important if we want to understand the bioavailability and mobility of Pb in polluted and natural environments. The results given in this paper were obtained under conditions as close as possible to natural conditions. These new data sh...

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Bibliographic Details
Published in:Environmental science & technology 1999-10, Vol.33 (19), p.3398-3404
Main Authors: Pinheiro, J. P, Mota, A. M, Benedetti, M. F
Format: Article
Language:English
Subjects:
Analytical chemistry
Applied sciences
Biological and physicochemical phenomena
Biological and physicochemical properties of pollutants. Interaction in the soil
BIOLOGICAL AVAILABILITY
CALCIUM
Chemical Sciences
Earth Sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
ENVIRONMENTAL SCIENCES
ENVIRONMENTAL TRANSPORT
Exact sciences and technology
FULVIC ACIDS
Geochemistry
Global Changes
LAND POLLUTION
LEAD
MATHEMATICAL MODELS
Natural water pollution
or physical chemistry
Pollution
Pollution, environment geology
Sciences of the Universe
Soil and sediments pollution
SOIL CHEMISTRY
Theoretical and
Water
WATER CHEMISTRY
WATER POLLUTION
Water treatment and pollution
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Summary:Knowledge of the speciation of Pb in natural aquatic systems is important if we want to understand the bioavailability and mobility of Pb in polluted and natural environments. The results given in this paper were obtained under conditions as close as possible to natural conditions. These new data show that Pb strongly binds to fulvic acids. We also show that the competitive effect of Pb on Ca binding to the same fulvic acid is smaller than the salt effect on Ca binding to fulvic acids as pH varies from 4 to 8. All the data were analyzed with the NICCA−Donnan model developed to describe metal ion binding to natural organic matter. The model predictions of competitive and salt effects are excellent. Comparison of our results with previously published data suggests that metal ion binding strength is similar for fulvics acids from different origins. Thus, all data sets could be interpreted within the framework of a unified modeling approach.
ISSN:0013-936X
1520-5851
DOI:10.1021/es990210f