As pollengrains are very, very small and are floating through the air, identifying them is a pretty difficult job. You’ll can use a microscope to identify the type of pollen. Pollengrains are not like fashionmodels who can stand still and wait for the phototgrapher to take shot. So often the pollengrains are collected by a machine, fixed on sticky tape, which is (after some preparation) put on a glass microscope slide. The pollengrains on this slide can be analysed and counted using a microscope.
There are also techniques which don’t use the “light part of the spectrum” using microscope and camera.
You can also make an image of pollen using an electron microscope. Preparation of the samples takes a lot of time, but results look very cool. Basically you shoot electrons at the sample and look at the way they bounce back.
There are more of these indirect strategie to identify pollen. It’s also possible to create a hologram or a spectral by using laser and UV. These devices are called flow cytometers. You don’t need sticky tape or glass to fix the pollen, as these techniques work directly in the airflow containing pollen.
The output is more like a unique graph, which also needs to be analysed to identify the type op pollengrain. Besides pollen there can be a lot of other particles in the air like dust.
The result is a huge amount of images, which need to be sorted ofcourse. First get rid of the images which have nothing to do with pollen, like dust. Also the images of pollen which are blurry, out of focus or otherwise not clear should be removed. Finally try to identify and count the species of pollen. Fortunately researchers can make use of automatic identification algorithms to make this job easier. More images result in better algorithms who are able to identify the species.
Pretty new is the technology of DNA-barcoding. It’s the process of identifying pollen species through the amplification and sequencing of specific, conserved regions of plant DNA.
These are some examples of different ways to identify pollen. As smart scientists are working on this topic, new technologies might pop up. Can you smell pollen?
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cartoons by Maarten Claassen