PCBs: Pollutants in Arctic Atmosphere
A Scientist-Mountaineer’s adventure in the Arctic
During the second leg of the expedition, Svalbard’s circumnavigation, Polarquest2018 will drop scientific coordinator Frédéric Gillet at the end of the Wijdefjorden, where he will climb the Nordenskiöld glacier, the highest on the Spitzbergen island, and join Pyramiden, an old Russian mining city and currently an intriguing ghost town worth visiting. During his mission, he will install special sensors that have to be in place for a sufficiently long time in the environment to obtain significant results in measuring the quantity of PCBs in the air. They will be recovered in one or two years’ time.
What are PCBs?
PCBs, or polychlorinated biphenyls, are a group of man-made organic chemicals containing carbon, hydrogen and differing amounts of chlorine. They have no known taste or smell, and range in consistency from thin, light-coloured liquids to yellow or black waxy solids. Due to their non-flammability, chemical stability, their resistance to acids and bases as well as to heat, PCBs have been used in hundreds of industrial and commercial applications such as plastics, paints, adhesives, surface coatings, inks, electric equipment, heat transfer fluids and lubricants. Their commercial production started in 1929 but their use has subsequently been banned or severely restricted in many countries since the 1970s and 80s because of the possible risks to human health and the environment: PCBs are toxic, carcinogenic, neurotoxic, and known to be endocrine disruptors.
They do not really break down once in the environment. PCBs are ubiquitous and persistent pollutants: half-life goes from 94 days to 2,700 years depending on the molecules. The atmosphere serves as the primary route for global transport of PCBs. They can remain for long periods cycling between air, water and soil. In rivers and lakes, they stick to sediments, where they can remain buried for a long time before being eventually released into water and air. PCBs in the air can reach the ground with falling rain and snow, or simply when suspended particles settle with gravity. They can be carried long distances and have been found in snow and sea water in areas far from where they were released into the environment. As a consequence, they are found all over the world.
Generally, PCBs are not very soluble in water, but readily soluble in fats. This solubility in fat explains why, like many lipiphilic toxins, PCBs bio-magnify up into the food chain: they accumulate in animals’ fatty tissues and along the food-chain. Humans can also accumulate PCBs by ingesting contaminated food and water or inhaling contaminated air. They can also be measured in many biological samples, such as human blood, milk, as well as in some foods such as animal tissues, fish and dairy products, or in several environmental samples, such as in air, drinking water, soil, sediment, and solid waste.
Why the Arctic?
Measuring PCBs in Arctic water and air is interesting to quantify their presence in areas distant from urbanised regions and, by doing so, to better understand transfer and accumulation mechanisms of this pollutant in the oceans and in the atmosphere.