Atmospheric H2O2 measurement and modeling campaign during summer 2004 in Zagreb, Croatia

Hydrogen peroxide (H2O2) in the gas phase and a number of other atmospheric components and variables (O3, CO, SO2, NO, NO2, benzene, toluene, ethylbenzene and xylene (BTEX)) were simultaneously measured during a field study performed in Zagreb, Croatia, from May until July 2004 (for selected variables until October 2004). Meteorological data from the nearby stations were provided by the Geophysical Institute and by Meteorological and Hydrological Service of Croatia. The collected data adjusted to hourly averages were used for modeling diurnal concentration behavior and development over a couple of days using Master Mechanism model developed by S. Madronich (NCAR, Boulder, CO). The H2O2 mixing ratios were found to vary between <0.05 and 6.2 ppb and also exhibited a strong diurnal pattern very similar to that of ozone, with concentration maxima in the afternoon, between 15:00 and 16:00 h, CET. Linear regression analysis showed that, during daytime, H2O2 positively correlated with ozone (r=0.4) and solar radiation (r=0.52), but showed only very weak negative correlations with NO2, CO and BTEX. Our H2O2 data are the first such reported data for the region and their modeling, along with ozone data, gives a valuable insight into the interplay of pollutants that affect their concentrations.