Air Quality Atmosphere And Health vol:5 issue:4 pages:425-431
A significant part of ambient dust consists of fine particles derived from natural soils. Because many toxic
constituents are concentrated in the smallest particle fractions, and because these small particulates are the most
easily inhaled, the fine-particle fraction of soil (PM10 and
smaller) is what presents the greatest health concern.
Assessing the potential risk of a soil requires examining
its chemical content, its biological and mineralogical
composition, its sedimentological characteristics, detailed
data on grain size distribution, and other information. This
analysis requires a relatively large mass of appropriate size fraction(s), obtained by dry extraction. Most methods for extracting fine particulates from soil collect only small amounts of sediment, or use wet extraction. This paper
describes the Soil Fine Particle Extractor, a setup for dry
extracting large volumes (dozens of grams and more) of fine particulate matter (PM10 and smaller) from bulk soil samples. Separation takes place in two steps. Primary separation in a cylindrical separator 70 cm high and 40 cm in diameter removes all coarse particles from the sample. The remaining sediment then flows through a 200 cm long and 7 cm diameter inclined elutriator connected to a three-engine vacuum cleaner. The setup allows extraction of different size fractions depending on the adjustment of the control parameters (suction rate, length, diameter and inclination of the elutriator, thickness of the sediment layer drawn in by the system). The article presents examples of extractions from soil collected in loess and desert environments, ranging from PM2.5 to PM10. It also evaluates
the efficiency of the technique by investigating the extraction efficiency for a large number of particle sizes, varying from 0.1 to 70 μm. Extraction occurs most efficiently for particles between 1 and 10 μm, with an optimum around 5 μm.