IN-SITU WEIGHT-GAIN RATES ON COPPER DURING OUTDOOR EXPOSURES - DEPENDENCE ON AIRBORNE POLLUTANTS AND CLIMATIC PARAMETERS

An outdoor adapted quartz crystal microbalance probe for atmospheric c orrosivity studies was used to monitor in. situ mass changes during ex posure of copper in one rural and two urban sites. Weight gain rates, calculated over consecutive 12 h intervals of the exposures, were comp ared to 12 h averages in the concentration of aerosol particles, SO2, relative humidity, and temperature. The comparison exhibited coincidin g time variations which demonstrated causal relationships. In descendi ng order, the most important factors to influence copper weight gain r ates seem to be relative humidity, concentration of aerosol particles, a temperature above -5 degrees C, and possibly the concentration of s ulfur dioxide. The weight gain rates show a clear seasonal dependence with the lowest rates (2 ng cm(-2) h(-1)) in June and the highest (10 ng cm(-2) h(-1)) in December. The seasonal dependence found dominates the difference between the investigated rural and urban sites.