Microplastics in the 1700s?

I'm thinking that, like in a jar with different size balls, the smaller objects will drop down in the cracks between the larger ones, the smaller in this case being the microplastic grains.

I am thinking there must be agitation or vibration for the particles to segregate,and then by specific gravity of the particles.This is what happens in water treatment plant filters.The filters are back flushed at a low rate to start (25%),then flow is increased to (75%),then to full flow(100%), then decreased slowly by reversing the same sequence at the finish.The larger,heavier particles settle to the bottom;gravel,sand,etc,then the lighter particles,charcoal,etc. end up at the top.

Plastic is not heavier than clay or sand,so how does it get to the bottom of the sediment?There might have been some past turbulent flow in the area where the samples were taken,possibly from a flood event,that stirred the sediment or brought it from elsewhere upstream.This is an uncontrolled flow,and the sediment may be mixed as it settles,not allowing gravity separation as it would in a controlled flow situation.

"Plastic is not heavier than clay or sand,so how does it get to the bottom of the sediment?"

According to one graphic in the article, they were studying particles in the size range from 100 to 500µm, which is 0.1 to 0.5 mm. Depending on the size of the grains of the natural sediments, articles that small could easily be carried between grains by flowing water.

Also, Latvia is generally in the latitude range from 56 to 58°N. At that latitude, there must be rather frequent freeze-thaw cycles, and freezing water is well known for opening natural (and manmade) cavities.

The very tiny size and low concentrations of the contaminants makes me wonder if static charges on these particles could explain how unexpected contamination could occur.

...."The fractional distillation of organic substances played an important role in the 9th-century works attributed to the Islamic alchemist Jabir ibn Hayyan, as for example in the Kitāb al-Sabʿīn ('The Book of Seventy'), translated into Latin by Gerard of Cremona (c. 1114–1187) under the title Liber de septuaginta.^[1] The Jabirian experiments with fractional distillation of animal and vegetable substances, and to a lesser degree also of mineral substances, formed the main topic of the De anima in arte alkimiae, an originally Arabic work falsely attributed to Avicenna that was translated into Latin and would go on to form the most important alchemical source for Roger Bacon (c. 1220–1292).^[2] "...

https://en.wikipedia.org/wiki/Fractional_distillation

Crude petroleum has been around for a long time. Is it so incredible that there could be some naturally or man made process that produced these particles?

Maybe it is just the case where if you are looking for micro and nano plastics you will find them?

It's a lot like Russian disinformation.

Polymerization conditions are not really that complex and we know that something as common as milk can be turned into a polymer ("plastic"). What is the likelihood that naturally occurring monomers were not polymerized due to naturally occurring conditions with acid as catalyst? That could explain traces of plastic occurring long before humans discovered and optimized the process of polymerization.

"What is the likelihood that naturally occurring monomers were not polymerized due to naturally occurring conditions with acid as catalyst?"

Or maybe microbial production?

"Microbial biotechnology offers sustainable routes to plastic production and waste management. Bacteria and fungi can produce plastics, as well as their constituent monomers, from renewable biomass, such as crops, agricultural residues, wood and organic waste."

https://www.nature.com/articles/s41564-023-01529-1#:~:text=for%20plastic%20production.-,PHAs,putida94%2C95.

I am sticking with my agitation of sediment by floods or mechanical agitation by machinery, making the sediment homogenized to a certain level,not allowing a gravity and time separated layer formation.

Put various sized and weight particles in a clear jar and shake it.Do not rotate the jar,just random movement,like turbulent flow agitation.Then stop the agitation and watch how the particles settle,then you will see my point.

Filtration in potable water plants contain large(50,000 gallons or more) filters consisting of many size and weight media.The must be back-flushed periodically,in a flow controlled manner to allow the filter media to settle into layers..otherwise,they are mixed when the flow is stopped and layers do not form properly and the filters do not function effectively.

Anyone else who has installed water processing-filtration equipment may chime in anytime.