Ion-binding properties of humic substance in deep sedimentary groundwater

Saito, Takumi*; Terashima, Motoki  

Humic substances (HSs) are ubiquitous in various environments and play an important role for the fate of pollutants. Deep underground environment is not an exception, although physicochemical and ion-binding properties of HSs there are largely unknown due to difficulties of their extraction. Based on limited studies on deep underground HSs, it has been recognized that they are distinctive from their counterparts in surface or shallow sub-surface environments. Thus, we have been studying humic and fulvic acids extracted from sedimentary groundwater at -250 m below ground surface at the Horonobe underground research laboratory, JAEA, including their chemical compositions, size distributions, spectroscopic properties, and ion bindings. The aim of this talk is to demonstrate similarities and differences between the Horonobe HSs and surface HSs.