Microplastics update, the news is not good

[GordMay]

“Microplastic discovered in ‘pristine’ Pyrenees mountain air” ~ The French National Centre for Scientific Research [CNRS]

Previously detected in rivers, oceans, and snow, microplastic has now been found in the high-altitude air surrounding the Pic du Midi (2,877 m)—by an international research team including scientists from the CNRS, Université Grenoble Alpes,2 and the University of Strathclyde (Scotland). [1]

After analysing the composition of 10,000 m3 of air captured weekly by a pump installed at the Pic du Midi Observatory,3 the researchers report a microplastic concentration of approximately one particle per 4 m3. This plastic (e.g., polystyrene or polyethylene polymers) comes predominantly from packaging. While posing no direct threat, its presence far from sources of pollution is nonetheless surprising. Mathematical models of air mass trajectories used by the scientists indicate that the particles originated in Africa, North America, or the Atlantic Ocean, which indicates intercontinental atmospheric transport of microplastic.

The team’s findings [1], published in Nature Communications (21 December 2021), describe a new stage in the microplastic life cycle and offer an explanation for their presence at the poles, on Mount Everest, or in other remote regions of our planet.
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More about ➥ https://www.cnrs.fr/en/microplastic-...s-mountain-air

[1] “Evidence of free tropospheric and long-range transport of microplastic at Pic du Midi Observatory” ~ by S. Allen et al
➥ https://www.nature.com/articles/s41467-021-27454-7#Sec5

[GordMay]

Microplastics accumulating in rivers and in the air

Microplastic pollution is usually associated with the oceans, where it's been widely studied. Two new studies [1 & 2] have examined the accumulation of these tiny particles, often barely visible to the human eye, in rivers, and in our air.

One study [1], from researchers in the U.S. and the U.K., estimated that microplastics can linger for up to seven years in rivers, before eventually being washed downstream.

The tiny plastic particles can enter rivers, from waste treatment plants, and other sources, and it had been assumed that since the particles are so small and light, and as plastic often floats, it would wash downstream quickly. But the researchers found that the particles can become integrated into sediments, on river bottoms, through something called hyporheic exchange.

This is a process by which water on the surface of the river, mixes with water at the bottom, transporting the particles downwards, where they become part of sediments, then later are excavated, and moved downstream. They can persist in the sediment for long periods, where the river flows slowly, or be washed out more quickly, in fast currents. The study showed that the headwaters of rivers, is where particles can linger the longest, taking up to seven years just to move one kilometre.

Once embedded in the river bottom, the microplastic particles may not biodegrade as quickly, because they are not as exposed to ultraviolet radiation from the sun.

Another significant source of microplastic pollution, in water, is laundry. Tiny fibres from synthetic clothing [essentially lint] flow out of the rinse-water, from your washing machine, into municipal wastewater, and on into the wider environment, in large numbers.

But another study [2] found that household tumble-dryers can also release a large volume of cotton and polyester microfibres, into the air. The study found that just one dryer can release 120 million microfibres, in a year. These are tiny fragments, that are rubbed off clothing, as it tumbles around in the drum. The particles are small enough to make it through the dryer's standard filters, and are blown out the vent, into the air, and there is concern that they can persist in the atmosphere, and travel long distances.

The obvious solution to this problem, is improving the [air & water] filtration on our washers, and dryers, to capture these particles, before they escape.



[1] "Microplastic accumulation in riverbed sediment via hyporheic exchange from headwaters to mainstems” ~ by Jennifer D. Drummond et al
➥ https://www.science.org/doi/10.1126/sciadv.abi9305

[2] “Microfibers Released into the Air from a Household Tumble Dryer” ~ by Danyang Tao et al
➥ https://pubs.acs.org/doi/full/10.102...stlett.1c00911