By most metrics, the Pyrenees mountains can be considered pristine wilderness. Many parts of the range between France and Spain are remote, hard to access, and sparsely populated. But there’s one thing that can reliably reach them: Man-made pollution.
Thanks to wind patterns, the Pyrenees have been a sentinel of pollution for centuries, according to a report published in Nature Geoscience this week. Samples from lake bottoms and peat in the Pyrenees contain lead and “remarkable” levels of arsenic from industrial activity that stretches as far back as 685 AD. Metal pollution from the Bronze Age, more than 3,000 years ago, has also been found in boggy land in the mountains.
And what will be our century’s contribution to the great Pyreneean pollution portfolio? Microplastics, apparently.
A team of researchers from France and Scotland spent five months over the 2017-2018 winter season regularly sampling a remote patch of land high in the mountains on the French side, far from any human settlement. They concluded that each square meter of land accumulated around 365 pieces of microplastic per day.
The pieces were carried on the wind to their wilderness resting place, though the researchers couldn’t prove exactly where they came from. Based on the lack of nearby population centers, they wrote that the plastic must have come from cities up to 100 kilometers (62 miles) away—places like Barcelona. They noted also that fine orange dust from the Saharan Desert also regularly falls on the Pyrenees, so the microplastics could conceivably come from even farther away than that.
Microplastics are popping up everywhere, from the waters of Antarctica to our table salt, but for now the main mode of microplastic transport has been water. The potential for the tiny pieces of forever-material to blow around on the wind has been understudied.
“Longer-distance transport modeling may be possible,” the researchers wrote. But how far microplastics can sail with air currents—or perhaps fall down to Earth with the rain—remains a mystery. “It is highly recommended that further monitoring and analysis be undertaken,” they concluded.