The Occurrence of Organic Peroxides in Seawater

Abstract

Organic peroxides (ROOH), as well as hydrogen peroxide (H₂O₂), dissolved in seawater were determined by fluorometry. Seawater samples were collected at Hiroshima Bay and the Iyo-Nada in the Seto Inland Sea, western Japan in May 1995. Using an enzymatic destruction method, ROOH and H₂O₂ were descriminated from each other. The concentration of ROOH measured was in the range of 38–389 nM in seawater samples, whereas the H₂O₂ concentration was in the range of 0–195 nM. The vertical distribution (0–45 m depth) of ROOH in seawater was found to be almost uniform or a little higher at the bottom layer waters, whereas the H₂O₂ concentration was highest at surface waters and decreased with depth. Linear regression analysis was conducted to examine the correlations between peroxide concentrations and other analytical items such as CTD data, nutrients, fluorescent organic matter and dissolved organic carbon. The results showed that the ROOH concentration has almost no correlation with other parameters, whereas the H₂O₂ concentration highly correlates with the salinity in the Hiroshima Bay samples but mostly correlates with water temperature in the Iyo-Nada samples. These results clearly indicate that the generation and decomposition mechanism of ROOH is different from that of H₂O₂.