ABSTRACT
Recent studies have deduced that both recalcitrant and labile organic matters were implicated in As mobility in the Hetao Basin, China. We therefore monitored optical characteristics using fluorescence spectroscopy and molecular signatures of DOM by FT-ICR MS analysis in the As-prone aquifers. The results revealed that high-As groundwater was associated with more DOM with humic-like fluorescence, and with a large number of polycyclic aromatics and polyphenols compounds. The possible reason was that DOM with high bioreactivity was preferential consumed in high-As groundwater. Surface water contained much more abundant labile DOM formulas, which could act as electron donors for the reductive dissolution of Fe(III) oxides once introduced into groundwater. The humic-like substances showed remarkably association with polycyclic aromatics and polyphenols, while tryptophan-like substances were similar to phenolic and aliphatic compounds.
