Identifying the processes controlling the distribution of H2O2 in surface waters along a meridional transect in the eastern Atlantic

Hydrogen peroxide (H2O2) is an important oxidant for many bio?relevant trace metals and organic compounds and has potential as a tracer for mixing in near surface waters. In this study we combine H2O2 and bio?optical measurements with satellite data for a meridional transect from 46°N to 26°S in the eastern Atlantic in order to determine the key processes affecting its distribution. Surface H2O2 ranged from 21–123 nmol L?1, with maximum inventories (0–200 m) of 5.5–5.9 mmol m?2 found at 30°N and 25°S. Analyses showed a strong positive correlation of surface H2O2 with daily irradiances and recent precipitation, though poor correlations with CDOM suggest sunlight is the limiting reactant for H2O2 formation. Vertical distributions of H2O2 were controlled by a combination of mixing processes and phytoplankton activity. The present study highlights processes controlling global H2O2 distributions and points towards the development of parameterization schemes for prediction via satellite data