Multidimensional spectrofluorometry characterization of dissolved organic matter in arsenic-contaminated shallow groundwater.

Multidimensional spectrofluorometry was employed to characterize dissolved organic matter (DOM) in arsenic-contaminated shallow aquifers at Jianghan Plain (JHP), central China, to better understand the effect of biogeochemical processes on arsenic mobilization. The microbial humic quinone and amino acid components identified indicate the importance of microbially mediated processes in the reduction of iron oxyhydroxides. The relationship of quinone and amino acid-like components with Fe2+ and S2− helps us understand the sequential redox transformation (SRT) in the high arsenic aquifer system and the origin of bicarbonate in groundwater. Correlation between DOM components and dissolved arsenic and Fe suggests that arsenic mobilization could be linked to the microbial reduction of iron oxyhydroxides with liable DOM as electron donors as well as to the electron shuttling function served by humic quinones.