Influence of the ITCZ on H2O2 in near surface waters in the equatorial Atlantic Ocean -: art. no. L23S04

H2O2 was measured in the upper water column (0-200 m) along a west-east transect through the Equatorial Atlantic as part of the German SOLAS (Surface Ocean Lower Atmosphere) cruise Meteor 55 (M55). Vertical profiles of H2O2 showed characteristic exponential decay consistent with light profiles and rainwater inputs. Integrated (0-100 m) water column H2O2 inventories ranged from 1.1-8.9 mmol m(-2) with the highest values in the Amazon Plume. H2O2 inventories were also higher at the Equatorial Upwelling and after heavy rain showers in the region of the Inter Tropical Convergence Zone (ITCZ). Analysis of rain water samples collected during the cruise gave a volume weighted mean of 10.8 mumol L-1 (range 1.5-22.3 mmol L-1). This work highlights the importance of rainwater as a major source for H2O2 in the surface waters under the ITCZ.