Spatial and temporal variations and factors controlling the concentrations of hydrogen peroxide and organic peroxides in rivers
EnvironChem_6_524.pdf 910 KB
Mostofa, Khan M. G.
dissolved organic carbon
fluorescent dissolved organic matter
upstream and downstream
Earth sciences. Geology
Hydrogen peroxide (H2O2) and organic peroxides (ROOH) were examined in water samples collected from the upstream and downstream sites of two Japanese rivers (the Kurose and the Ohta). H2O2 concentrations during monthly measurements varied between 6 and 213nM in the Kurose River and 33 and 188nM in the Ohta River. ROOH varied between 0 and 73nM in the Kurose River and 1 and 80nM in the Ohta. Concentrations of peroxides were higher during the summer months than in winter. H2O2 concentrations correlated well with the measured content of dissolved organic carbon and/or the fluorescence intensity of the fluorescent dissolved organic matter (FDOM) in the water from these rivers, which suggested that the dissolved organic matter and FDOM are the major sources of H2O2. Further characterisation of FDOM components by excitation emission matrix spectroscopy and parallel factor (PARAFAC) analysis indicated that fulvic acid is a dominant source of H2O2 in river waters, which accounted for 23-70% of H2O2 production in the Ohta River, 25-61% in the upstream and 28-63% in the downstream waters of the Kurose River, respectively. A fluorescent whitening agent and its photoproduct (4-biphenyl carboxaldehyde) together contributed 3-7% of H2O2 production in the downstream waters of the Kurose River. Tryptophan-like substances were a minor source of H2O2 (< 1%) in both rivers. An increase in the H2O2 concentration was observed in the diurnal samples collected at noon compared with the samples collected during the period before sunrise and after sunset, thus indicating that H2O2 was produced photochemically. This study demonstrates that H2O2 and ROOH are produced mainly from the photodegradation of FDOMs, such as fulvic acid.
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Commonwealth Scientific and Industrial Research Organisation Publishing
Graduate School of Biosphere Science