Microplastics are affecting melt rates of snow and ice

Microplastics have reached the farthest corners of the Earth, including remote fjords and even the Mariana Trench, one of the deepest parts of the ocean.

Recently, these pollutants have been found in another distant region of our planet: glaciers and ice sheets. An EOS article published in March examines how microplastics transform these icy ecosystems, and underscores the importance of properly separating them from another form of pollution in ice, black carbon.

In addition to large plastic waste, such as water bottles and milk jugs that end up on distant beaches, many pieces of plastic are broken into smaller and smaller pieces by sea water and air. These are small particle microplastics, small pieces of plastic that have either broken over time or were initially small, such as fibers from clothing or beads in face washes.

How do microplastics initially find their way into and out of the ice? Peter Dennen, an author of Watershed Progressive, who is not affiliated with the article, explained, “Often microplastics end up in the ice through accumulation in the air.

Microplastics … are lighter than dust particles and more Easily formed in the air … Their size, can remain airborne and can achieve sufficient height to be transmitted with the weather on a large scale and can be transported to distant locations. ” One of the article’s authors, Jing Ming, stressed that air travel is one of the reasons why microplastics are so prevalent.

The article sheds light on the difference between microplastics and black carbon, another form of pollution that also collects on ice. Black carbon particles come from the combustion of fossil fuels by humans as well as natural sources such as wildfires.

Due to their dark color, black carbon particles absorb sunlight and heat the surfaces on which they land. When they accumulate on ice and snow, they increase the melting rate. As a result of this melting, the bright, reflective surfaces of the planet decrease in area. And as a result of that reduction, even more sunlight is absorbed by the surface, resulting in greater warming.

Currently, almost all studies of black carbon ignore the co-presence of microplastics in ice, which also has an effect on melting rate. Ming explained, “Microplastics deposited in ice will last hundreds of years or even longer. They can absorb solar radiation and reduce surface albedo because they are not completely transparent but with color.”

The authors emphasize that it is not only colored microplastics that absorb and heat sunlight, but also more translucent plastics. Translucent plastic, which usually will not absorb light, may wear, break, or scratch; All these processes increase their absorption level.

Since current measurements and equipment are not responsible for the presence of microplastics, their effect on melt rates may be erroneously attributed to black carbon. Ming explained that, as a result, “the tightness of black carbon in ice may need to be reevaluated due to the coexistence of microplastics.”

In other words, the measured effect of black carbon on ice melting may be significantly different from the actual effect, due to the neglected presence of microplastics.

To begin sorting out the various effects of microplastic and black carbon, the article suggests three simple changes. The first thing to do to avoid plastic contamination is to use glass bottles to collect field samples. The second is to filter molten ice samples to separate microplastic particles.

And third are samples of centrifuges (spin at high speed) to separate microplastic particles, as they typically have lower densities than black carbon particles. Ming emphasized that “we should quickly establish a protocol to measure microplastics in ice, separate microplastics from black carbon, and their individual roles in influencing ice.”

Deneen highlighted another important idea of ​​microplastics in ice. “The thing about microplastics on ice / ice is that ice / ice is not what we call a ‘microplastics sink’,” explained Deneen, former editor of GlacierHub. “Ice and snow melt and as it happens, those particles are transported through various ecosystems, contaminating riparian habitats, estuaries and eventually the marine.”

As they reach these ecosystems, whether through melting ice or otherwise, microplastics pick up chemical contaminants and can disturb many forms of life: animals can swallow them, not only themselves, but eat them Can also harm humans. The small invertebrates will consume the microplastic, then be consumed by the fish, and the plastic makes its way up the food chain until it arrives on a plate.

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