CORRELATIONS BETWEEN GRAVIMETRY AND LIGHT-SCATTERING PHOTOMETRY FOR ATMOSPHERIC AEROSOLS

Light scattering photometers are useful for in situ measurements of mass concentrations of environmental aerosols if certain requirements are fulfilled. For the determination of relative concentrations, the composition of the aerosol (particle size distribution, refractive index) has to be constant during the experiments. Absolute measurements of mass concentrations additionally require a calibration of the photometer in terms of gravimetric units. In the case of atmospheric aerosols special attention has to be paid to the relative humidity which has a strong effect on particle size. Preliminary measurements indicate that for atmospheric background aerosols with a dominating accumulation mode a fairly linear relationship between photometer response and mass (volume) concentration exists, a result, which is in agreement with theoretical predictions.