10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
The Size Distribution and Physical Characteristics of Surface Material in Iceland
MARY K. BUTWIN, Melissa A. Pfeffer, Throstur Thorsteinsson, Sibylle von Löwis, University of Iceland
Abstract Number: 1230 Working Group: Aerosols in Earth System
Abstract Iceland’s Highlands and South Coast are mostly made up of loose material that was created from volcanic eruptions, glacial erosion as well as the breakdown of lava fields from past eruptions over time. With large dust source areas and frequent windy conditions in Iceland it has been found that particulate matter is observed suspended in the air on average 135 days per year.
Unlike other large dust source areas such as the Sahara and the deserts of Asia, Iceland’s dust sources are not as extensively studied. Past research on size distribution of potential sources for suspended material has mainly been done on volcanic ash from an ongoing eruption. Having a more comprehensive understanding of the size distribution of surface material is important when considering impacts from dust storms in Iceland. Course material can greatly decrease visibility and cause structural damage to infrastructure. Whereas, fine material can be a health risk as it is easily inhaled, this is especially true for those with preexisting respiratory conditions. The risk for respiratory distress can increase depending on the physical characteristics of the material inhaled. Fine elongated grains that can be found in volcanic ash, increase the respiratory risk as it can behave similarly to asbestos and create scar tissue in the lungs. Although this type of fibrous ash is not common in Iceland, it has been produced from multiple eruptions.
To better understand the risk dust storms, pose to Iceland’s population surface samples from around the country were taken and analyzed for size, and shape. The size distribution of the surface material shows that the majority of material that can potentially be suspended has a diameter greater than 20 μm which will easily be filtered by the respiratory system and pose little risk. Due to the brittleness of the tephra some of the surface material must be breaking up into smaller particles forming PM10 and PM2.5. Data from Optical Particle Counters that were at the surface supports this theory as peak concentrations occur with PM2.5. However, when compared to the overall size distribution of potentially suspended material these fine particles make up a small percentage. Physical analysis of surface samples in Iceland are mostly consists of irregular shaped pieces of tephra, rather than elongated grains that can be found in fresh volcanic ash from some eruptions from volcanoes such as Hekla, Eyjafjajökull, and Grímsvötn. The lack of ash like particles coincides with the finding that eruptions have no long-term effect on the frequency of suspended material as much of the fresh volcanic ash either buried beneath vegetation, ice on glaciers or blown away.