The variation of hydrogen peroxide in rainwater over the South and Central Atlantic Ocean

The concentration of hydrogen peroxide in rainwater over the South and Central Atlantic Ocean was determined. The rainwater samples were collected during an Intergovernmental Oceanographic Commission (IOC) sponsored baseline expedition in May and June 1996. The concentration of hydrogen peroxide was determined on diluted samples using a cobalt-catalyzed luminol chemiluminesence method. The concentration of hydrogen peroxide in rainwater varied from 3.5 to 71 μM with an average (n=25) and standard deviation of 26 and 22 μM, respectively. These are similar to previously reported average hydrogen peroxide concentrations in marine rainwater of the Gulf of Mexico (40 μM), the western Atlantic Ocean (13 μM), and Florida Keys (28 μM). The concentration of hydrogen peroxide in rainwater varied with time of the day, with lower concentrations in early morning and higher concentrations in the late afternoon. The rainwater concentration of hydrogen peroxide also decreased during a rainstorm that may be an indication of a washout effect. The general levels of hydrogen peroxide in rainwater reported here and elsewhere together with the satellite-measured global distribution of precipitation indicate that wet deposition could affect water column hydrogen peroxide significantly in certain parts of the world.