The simultaneous influence of pH and Acid Volatile Sulphide on the speciation of heavy metals in calcareous sediments
De simultane invloed van de pH en zuur extraheerbaar sulfide op de speciatie van zware metalen in kalkrijke sedimenten
26 May 2012, PDF |
43 pages |
Buykx SEJ , Hoop MAGT van den
RIVM Report 502501043
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.