Characterization of dissolved organic matter in deep groundwater by convenient analytical methods

Mochizuki, Akihito  ; Sasamoto, Hiroshi   ; Ikigaki, Kayoko*

Convenient characterization methods available to small volume of samples were applied to groundwater and surface water in the Horonobe area, Hokkaido, to characterize dissolved organic matter (DOM) including humic substances. 3D-fluorescense spectrum obtained from small volume of groundwater was similar to those from isolated humic substances, and showed little variation with depth. However, the peak position of spectrum for surface water was different from those for groundwater. Gel permeation chromatography showed that DOM in groundwater mainly consists of humic substances with molecule weight of approximately 1,2002,000 Da, and that the molecule weight decreases with depth. These results were consistent with the characteristics of isolated humic substances. Ion chromatography revealed that low molecule weight organic matter was minor component of DOM in the groundwater, which was consistent with the result of gel permeation chromatography.