Particle Source Identification, Part 2: Assemblages

THE MICROSCOPE
2025, Volume 72:4, pp. 147–160
DOI
https://doi.org/10.59082/WDWK6701
AUTHORS
Russ Crutcher and Heidie Crutcher
ABSTRACT
Separating the particles in a field of view under the microscope into a count of fibers, dander, minerals, tire wear, plant parts, and so on, is of relatively little value if the goal is to assess environmental quality and to suggest ways to improve that quality. Particle assemblages identify sources, the method of generation, and the transport mechanisms that brought those particles to the location in question. With a little training, assemblages can be quickly identified and quantified. This article deals with how assemblages are identified. The human visual system functions at a subconscious level far more efficiently and accurately than conscious processing of the field of view. We use these subconscious functions regularly, at least hundreds or more times a day, though we generally don’t appreciate their analytical value. In Part 1 of this series, we introduced the power of ensemble analysis (see “Particle Source Identification, Part 1: Thinking in Assemblages,” The Microscope, Vol. 72:3, pp. 124–131, 2025; https://doi.org/10.59082/UGIK4736). In this article, "Part 2: Assemblages," we introduce "chunk" and "chunking” and how that applies to the analysis of assemblages of particles viewed through the microscope. Recognizing assemblages is an important part of assessing environmental quality. It is also used to determine the origin of honey, characterize paleoenvironments, determine pond water quality, and to identify the source of particles. A number of assemblages are presented here together with how they are identified.
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