Studies on humic acid labelling

It is well known that humic and fulvic acids are able to complex polyvalent metal ions, e.g. radionuclides, leading to soluble complexes of significant strength, thereby decreasing the sorption of these compounds to soils and sediments. Obviously, the interaction of metal ions with humic materials may significantly influence the availability and transport of the pollutants in the environment. Typically, studies along these lines have focused almost exclusively on the pollutants, whereas the actual role of the humic material has been elucidated only indirectly. In order directly to study the behaviour of the naturally occurring organic macro molecules in relation to the environmental fate of radionuclides, radio-labelled humic-and fulvic acids can advantageously be applied. Radio-labels such as carbon-14 and iodine-125 have successfully been covalently incorporated in humic- and fulvic acids. The paper discuss the labelling of humic substances as well as preliminary migration studies. 25 refs., 1 tab