Short CommunicationHigh resolution 3D confocal microscope imaging of volcanic ash particles

- 3D surface structure of volcanic ash particles was investigated using high resolution confocal microscopy.
- A range of discrete particle types was observed including appearances characterised by sharp or concave edges.
- The imaging enabled calculation of initial particle surface area/volume ratios.
- This approach may help in modelling volcanic particle damage to aircraft engines and human tissue following inhalation.

We present initial results from a novel high resolution confocal microscopy study of the 3D surface structure of volcanic ash particles from two recent explosive basaltic eruptions, Eyjafjallajökull (2010) and Grimsvötn (2011), in Iceland. The majority of particles imaged are less than 100 μm in size and include PM10s, known to be harmful to humans if inhaled. Previous studies have mainly used 2D microscopy to examine volcanic particles. The aim of this study was to test the potential of 3D laser scanning confocal microscopy as a reliable analysis tool for these materials and if so to what degree high resolution surface and volume data could be obtained that would further aid in their classification. First results obtained using an Olympus LEXT scanning confocal microscope with a × 50 and × 100 objective lens are highly encouraging. They reveal a range of discrete particle types characterised by sharp or concave edges consistent with explosive formation and sudden rupture of magma. Initial surface area/volume ratios are given that may prove useful in subsequent modelling of damage to aircraft engines and human tissue where inhalation has occurred.

Volcanic ash clouds can cause massive disruption to aircraft travel as well as being associated with a number of health conditions. In both cases it thought that the nature of the volcanic particles might be the underlying cause of the deleterious effects. Previous studies have mainly used 2D microscope imaging techniques to examine volcanic particles. The aim of this study was to apply 3D confocal microscopy to image volcanic ash particles. Strew type slides were prepared with particles from one of two Icelandic volcanic eruptions. The slides were successfully imaged using an Olympus LEXT confocal microscope with a × 50 or × 100 objective lens. The images obtained demonstrate what appear to be sharp edges to the particles and in some cases concave surfaces presumably resulting from the breakup of volcanic gas bubble inclusions. The sharp knife like appearance of volcanic ash particles may help in explaining some of the harmful effects of inhalation as well as damage to aircraft engines and airframes.118