New research this week is the latest to show that microplastics have polluted just about everywhere on Earth. Scientists discovered plastic particles in cloud samples collected from atop a mountain in Eastern China. The team also found evidence from lab experiments that these microplastics could potentially affect cloud formation and the weather, though more data will be needed to understand exactly how.
The study was led by scientists from Shandong University. Among other things, they were inspired by a recent study published in September—one where scientists found microplastics in samples of mist collected at the peaks of Mount Fuji and Mount Oyama, both in Japan. The team decided to look for and analyze microplastics in the clouds surrounding the top of Mount Tai, a well-visited and culturally important mountain that’s close to densely populated areas of Eastern China. They studied 28 liquid samples collected in mid-2021.
The team found microplastics in all but four of the samples. These samples contained common plastics such as polyethylene terephthalate, polypropylene, and polyethylene. Samples collected from low-altitude and denser clouds also tended to have greater amounts of microplastics. The concentration of plastics found in the samples overall was substantially lower than those collected from the atmosphere of urban areas, the researchers noted, but much higher than those found in nearby rainfall, remote polar regions, and the cloud water previously collected from Mount Fuji and Mount Oyama in Japan.
“This finding provides significant evidence of the presence of abundant [microplastics] in clouds,” the researchers wrote in their paper, published Wednesday in Environmental Science & Technology Letters.
The team additionally conducted a deeper analysis of the microplastics they found, as well as modelling and lab experiments. The older plastic particles tended to be rougher and smaller, for instance, and contained more lead, mercury and oxygen on average than fresher plastics. In the lab, they found that exposing plastics to cloud-like conditions—namely, ultraviolet radiation and filtered water—could cause these same sorts of changes. In other words, they found evidence that clouds can change the makeup of microplastics once they get there, possibly in ways that could then affect cloud formation and subsequently the weather.
There’s still a lot that we don’t know about the specific effects of microplastics, both on the environment and our health, but what we have learned so far hasn’t been comforting. Studies have identified over a hundred chemicals in plastic that could potentially harm us or other animals, including those that disrupt the regulation of important hormones. Chemicals from plastic pollution can also leak into soil and freshwater causing long-term negative consequences for the surrounding ecosystem.
The study authors say that more research will be needed to figure out how microplastics interact with clouds and the potential impacts of these interactions on cloud formation and the presence of toxic metals in the atmosphere. Many scientists, environmental, and public health organisations have already begun to call for widespread reductions in plastic pollution based on the possible dangers we know about.