The binding nature of humic substances with arsenic in alluvial aquifers of Chianan Plain, southwestern Taiwan

Arsenite Binding to Natural Organic Matter: Spectroscopic Evidence for Ligand Exchange and Ternary Complex Formation

“…Many observations made in field or field-related studies can be explained by the two As(III) sorption mechanisms identified in this study. Examples include correlations between dissolved As and dissolved NOM released from ombrotrophic peatlands during flooding events, anticorrelations between solid-phase As and Fe (Mn) in water-saturated peat bogs, and the simultaneous mobilization of As with NOM from wetland soils in percolation and extraction experiments. , Ligand exchange and ternary complex formation of As(III) may also account for the strong correlation observed between dissolved As(III) and dissolved NOM in a blackwater system, a significant correlation between solid-phase NOM and As in moderately reducing sediments of the Chianan Plain, Taiwan, and the association of As(III) with organic colloids in groundwaters of the Hetao basin, Inner Mongolia . Furthermore, the observed ligand-exchange mechanism may clarify the binding of As(III) to S(-II)-reacted peat and HS where As(III) retained its first-shell oxygens and the As(III)-dependent fluorescence quenching of HS extracted from mangrove forest sediments …”

Association between arsenic and different-sized dissolved organic matter in the groundwater of black-foot disease area, Taiwan

“…In the BFD area on the coastal alluvial Chianan Plain in southwestern Taiwan, arsenic concentration commonly exceeded 10 mg L À1 in the groundwater (Nath et al, 2011;Selim Reza et al, 2012). An investigation of shallow groundwater quality on the Chianan Plain revealed that high As concentrations were found in both aquifers and aquitards in this area (Liu et al, 2006), and thus the origin of As for this study is geological, i.e., As release is due to the reduction dissolution of Fe-oxyhydroxide minerals in the aquifer (Nath et al, 2011).…”

“…These functional group characteristics, which were similar to purified HA, could offer the ability of metal binding for the DOM. Selim Reza et al (2012) illustrated that naturally occurring complexes of humic substances, Fe, and As in the groundwater of Chianan plain exhibited several distinct peaks with wavelengths of 2,916, 1584 and 856 cm À1 as compared with a standard using FTIR. These distinct peaks were corresponding to the spectra of groundwater in this study (Fig.…”

“…Recent studies suggest that the overall controlling factor driving the release of arsenic in groundwater is the reactivity of the dissolved organic matter (DOM), because the formation of As-DOM complexes is important in regulating the transport, transformation, and bioavailability of arsenic in the environment Selim Reza et al, 2012;Majumder et al, 2014a). In natural settings, the DOM parent material is primarily derived from terrestrial and aquatic macro-and micro-organisms.…”