Differences in properties and Cm(III) complexation behavior of isolated humic and fulvic acid derived from Opalinus clay and Callovo-Oxfordian argillite

Fulvic acids from deep clay formations have been isolated by the International Humic Substances Society (IHSS) standard protocol and analyzed. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy reveals, that the basic structural features relating to the origin of the clay organic matter (i.e., terrestrial or marine) are preserved even after the around 150 Ma since deposition (Jurassic sediment). Analysis by asymmetrical flow field flow fractionation (AFFFF) shows the size distribution peak found for typical fulvic acids. In addition, a second larger size peak is found for the fulvic acids influenced by marine deposition. These fulvic acids also have a considerable content of organic material which does not absorb in the visible range. The Cm(III) complexation behavior has been studied by time-resolved laser fluorescence spectroscopy (TRLFS). Despite considerable fluorescence quenching, the complexation constant is shown to be in the same range as published values found for different typical fulvic acids.