Use of different physical separation techniques for trace element speciation studies in natural waters (original) (raw)

Hydrochemical balance studies require knowledge on the speciation of the elements concerned, i.e. the distribution between soluble and suspended forms and among different soluble species. The present paper is focused on the separation of truly soluble forms of trace elements from the fraction associated with the particulate phase in natural fresh waters. The commonly used filtration through a 0.45 pm membrane is not satisfactory in this respect. Improvements can be achieved by introducing alternative separation techniques such as ultrafiltration, centrifugation, dialysis in slta or in the laboratory, electrodialysis, free-liquid electrophoresis, or a combination of separation steps based on these techniques. In general separations that can be carried out at the sampling site are preferable. In this paper each of the above mentioned separation techniques will be critically discussed regarding their feasibility for speciation studies in natural waters, and examples from applications to groundwaters, lakes and rivers will be given, mainly from work carried out by the authors.