Arsenic (As) and manganese (Mn) biogeochemistry is intimately linked with dissolved organic matter (DOM) in subsurface aqueous environments. In this study, we explore the role of contrasting DOM quality on the distributions of Mn and As in groundwater. Tubewell and subsurface sediment samples were collected from Murshidabad, West Bengal (WB), India, as well as the Claromecó basin of Argentina. A parallel factor (PARAFAC) model is presented for WB samples that delineate key DOM components in sites characterized by high concentrations of both Mn and As (HMHA), and high Mn concentrations but low As (HMLA). An association between humic-like DOM and elevated As is clear, whereas Mn concentrations are high in the presence of both humic and protein-like DOM. In Claromecó basin groundwaters, an inverse relation between As and Mn is presented and future efforts are planned to incorporate the role of DOM.