The simultaneous influence of pH and Acid Volatile Sulphide on the speciation of heavy metals in calcareous sediments
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Series / Report no.
Open Access
Type
Report
Language
en
Date
1996-09-30
Research Projects
Organizational Units
Journal Issue
Title
The simultaneous influence of pH and Acid Volatile
Sulphide on the speciation of heavy metals in calcareous
sediments
Translated Title
De simultane invloed van de pH en zuur
extraheerbaar sulfide op de speciatie van zware metalen in kalkrijke
sedimenten
Published in
Abstract
In een aantal kalkrijke zoetwater sedimenten is de
invloed van de pH en het zuur extraheerbaar sulfidegehalte (AVS) op de
speciatie van zware metalen experimen-teel bestudeerd. Zowel de som van de
simultaan ge-extraheerde metalen (SEM: Cd, Cu, Ni, Pb en Zn), als het zuur
extraheerbare sulfidegehalte en de bijbehorende SEM-AVS verhouding, hetgeen
een maat is voor de beschikbaarheid van zware metalen, namen af met
toenemende pH. De steilheid van de bijbehorende helling was afhankelijk van
het carbonaatgehalte van het sediment. Het oplosgedrag van de metalen in de
sedimenten is beschreven met een vereenvoudigd uitwisselingsmodel. Dit
model kon alleen toegepast worden voor zink, omdat door analytische
beperkingen niet voldoende gegevens voor de andere metalen voorhanden waren.
Dit model was in staat om de verdeling van zink over de vrije en vaste fase
in het sediment goed te beschrijven. De bijbehorende
protonuitwisselcoefficient was in overeenstemming met literatuurwaarden. De
resultaten van dit onderzoek zijn van belang voor een juiste interpretatie
van ecotoxiciteitsexperimenten in sedimentsystemen en leveren derhalve een
bijdrage aan projecten als integrale normstelling (INS).
The simultaneous influence of pH and Acid Volatile Sulphide (AVS) on the speciation of heavy metals has been studied in a number of calcareous sediments. Both the sum of the simultaneously extracted metals (SEM: Cd, Cu, Ni, Pb and Zn) and the AVS content and the resulting SEM:AVS ratio, which is a measure of the availability of heavy metals, decreased with increasing values of pH. The corresponding slopes were dependent on the carbonate content of the sediment. In the sediment suspensions, the dissolution of metal due to acid conditions has been described by a simplified exchange model. For the present set of samples, the model could be applied for the metal zinc only due to limitations in the determination of the other metal concentrations. The model was able to predict the speciation of zinc in the sediments quite well. From this model a proton exchange coefficient was obtained, which appeared to be in line with literature data. The results are of practical importance for a correct interpretation of toxicity studies in sediments and, hence, are useful for projects like the setting of environmen-tal quality objectives.
The simultaneous influence of pH and Acid Volatile Sulphide (AVS) on the speciation of heavy metals has been studied in a number of calcareous sediments. Both the sum of the simultaneously extracted metals (SEM: Cd, Cu, Ni, Pb and Zn) and the AVS content and the resulting SEM:AVS ratio, which is a measure of the availability of heavy metals, decreased with increasing values of pH. The corresponding slopes were dependent on the carbonate content of the sediment. In the sediment suspensions, the dissolution of metal due to acid conditions has been described by a simplified exchange model. For the present set of samples, the model could be applied for the metal zinc only due to limitations in the determination of the other metal concentrations. The model was able to predict the speciation of zinc in the sediments quite well. From this model a proton exchange coefficient was obtained, which appeared to be in line with literature data. The results are of practical importance for a correct interpretation of toxicity studies in sediments and, hence, are useful for projects like the setting of environmen-tal quality objectives.
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