The Influence of Changing Land Use in a Fen Area on the Isotopic (~(14)C) and Chemical Signature of Doc-Conclusions for the Initial ~(14)C Content of Doc for Groundwater Dating

摘要

One still unsolved problem of radiocarbon groundwater dating with the fulvic acid fraction (FA) of dissolved organic carbon (DOC) is the determination of the correct starting concentration of ~(14)C in the FA fraction. The FA fraction of seepage water and freshly formed groundwater is a mixture of hydrophobic organic macromolecules formed by recent decomposition of plant material, with an actual ~(14)C concentration of around 113 +- 4 pmC, and older organic macromolecules adsorbed to the soil matrix [1,2]. Common to all sampled organic molecules is the same hydrophobic chemical behaviour with regard to the extraction procedure with XAD-8 resin.