Comparing single-particle analysis data of volcanic ash of the 2010 Eyjafjallajökull eruption obtained from scanning electron and light microscope images

This study examines the influence of different analysis techniques on the results concerning the particle size distribution and mineralogical composition of airborne particles. Volcanic ash from the Eyjafjalla volcano was examined with a transmitted light microscope (TLM), a scanning electron microscope (SEM), SEM equipped with an automatic single-particle analysis program, and an electron microprobe (EMP) and the results differ considerably. Main error source is the specific particle size determination for each method. Here, a sample containing airborne particles of volcanic material was analyzed for sizedifferentiated particle number (n) on the evaluation area per unit time (number settling rate). The results of the TLM reveal a higher abundance of particles ≥ 8 μm than those obtained by manual SEM and EMP analysis, whereas the opposite is observed for particles