Insight on Hydrogen peroxide concentration in selected rivers across Japan, potential toxicity and underlying factors

Abstract

Hydrogen peroxide (H₂O₂) is the most stable reactive oxygen species formed in river water. At high concentration, it can be toxic to aquatic organisms. It is therefore important to monitor its concentration in order to establish potential toxicity concerns in the water body. In this study, H₂O₂ concentration in selected rivers across Japan was investigated. In addition, the factors responsible for its formation were considered. Twelve rivers were sampled over different seasons of the year and their H₂O₂ concentration was determined by the Fenton method using benzene as a probe. The DOM optical properties were investigated via UV absorption properties and fluorescence measurement with parallel factor (PARAFAC) analysis. The results showed that the H₂O₂ concentration ranged from 21 – 2929 nM. Kokubu river had the highest concentration which was consistently higher than the PNEC value regardless of the sampling season. This suggests potential H₂O₂-mediated toxicity in the river. PARAFAC analysis showed Kokubu river had some fluorescence whitening agents, which have a high H₂O₂ photoformation rate.