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Einfluß von pH-Wert und Redoxpotential auf die Bindung und Mobilisierung von Schwermetallen in kontaminierten Sedimenten
Citation Link: https://doi.org/10.15480/882.447
Other Titles
Influence of pH value and redox potential on binding and mobilization of heavy metals in contaminated sediments
Publikationstyp
Journal Article
Date Issued
1992
Sprache
German
Author(s)
TORE-DOI
Generally, contaminated dredged sediments are deposited on spoiling areas on land or directly re-stored in water. As a result, anoxic sediments have contact with air oxygen or oxygenated water, and redox conditions change. The change in redox potential leads to changes in particulate heavy metal binding forms. In weakly buffered sediments this may lead to a distinct decrease in the pH value, which has consequences in increasing mobilities of most heavy metals.
In a contaminated sediment from Hamburg harbour, acid production, mobilization of Cu, Zn, Pb, and Cd at different redox- and pH-conditions, and the tranfer and change in particle bound metals were studied. During oxidation the pH value in the sediment suspension decreases from about 7 to 3.4 because of the low acid neutralization capacity (ANC). This leads to a mobilization of heavy metals, whereby Cd and Zn are strongly released, as compared to Cu and Pb. A change in particulate heavy metal compounds is also found. Generally, the easily and moderately reducible fractions increase during oxidation while the sulfidic fraction decreases.
The results show that at identical pH values significantly more metals are mobilized in the oxidized sediment than in the reduced state. But although the pH value is the key factor - in particular if it sinks below 4.5 - the redox conditions may also control the mobilization of certain metals. Consequently, even in well buffered sediments a mobilization of metals during oxidation cannot be excluded.
In a contaminated sediment from Hamburg harbour, acid production, mobilization of Cu, Zn, Pb, and Cd at different redox- and pH-conditions, and the tranfer and change in particle bound metals were studied. During oxidation the pH value in the sediment suspension decreases from about 7 to 3.4 because of the low acid neutralization capacity (ANC). This leads to a mobilization of heavy metals, whereby Cd and Zn are strongly released, as compared to Cu and Pb. A change in particulate heavy metal compounds is also found. Generally, the easily and moderately reducible fractions increase during oxidation while the sulfidic fraction decreases.
The results show that at identical pH values significantly more metals are mobilized in the oxidized sediment than in the reduced state. But although the pH value is the key factor - in particular if it sinks below 4.5 - the redox conditions may also control the mobilization of certain metals. Consequently, even in well buffered sediments a mobilization of metals during oxidation cannot be excluded.
Subjects
Metallbindungsformen
periodische Redoxprozesse
Säurebildungsvermögen
Pufferkapazität
Sedimentqualität
DDC Class
550: Geowissenschaften
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