Measurements, sources and sinks of photoformed reactive oxygen species in Japanese rivers

Reactive oxygen species (ROS) are photochemically generated in sunlit natural water and involved degradation of organic matter, redox reactions, biological processes. Hydroxyl radicals (·OH), nitric oxide (NO·), singlet (1O2) some the dominant ROS water. In this study, these three were measured samples collected from nine rivers across 65 stations along west to east axis Japan. Quantification ·OH, NO·, 1O2 was performed by High-Performance Liquid Chromatography using benzene, 4, 5-diaminofluorescein-2, furfuryl alcohol as chemical probes, respectively. The absorption coefficient at 300 nm (a300, m-1), which ranged 2.44 36.2 m-1, used investigate chromophoric dissolved matter (CDOM) properties rivers. photoformation rate ranges (13.9-944) × 10-12 M s-1 for (2.76-2610) (9.48-133) 10-9 1O2. steady-state concentration (1.53-16) 10-16 (10.2-1520) (3.79-53.4) 10-14 results showed that nitrite a major source both ·OH CDOM all According significant relationships with sources, models predict formation rates (in s-1) known concentrations compounds equations R·OH (10-12) = 19.2 [NO2-1]-μM + 36.9, RNO· 41.4 44, R1O2)(10-9) 3.52 (a300)-m-1 1.61. Dissolved escape atmosphere, molecules sinks river 1O2, A general scavenging constant function carbon obtained [kC,OH [(7.5 ± 6.8) 108 L (mol C)-1 s-1]. These will allow easy prediction on large-scale.