Chemical ban benefiting world's northernmost harbour seals

Svalbard's harbour seals are much less contaminated than they were just a decade ago (Photo: Wikipedia)

Since the Stockholm Convention came into effect in 2004, banning persistent organic pollutants, the concentration of these pollutants has declined by up to 90 percent.


“The PCBs and pesticides have declined quite a lot in the last decade,” says Heli Routti of the Norwegian Polar Institute to BarentsObserver

A decade-old ban on a class of toxic chemicals is paying off in the Arctic, according to Routti’s research conducted on the world’s northernmost population of harbour seals.

“They are declining because of the ban.”

In the late 90s, the United Nations Environmental Programme sounded the alarm over Persistent Organic Pollutants, or POPs. These are harmful compounds that persist in the environment and accumulate in plants and animals. Until 2004, when the Stockholm Convention came into effect, they were produced all over the world in industrial processes, and ended up concentrated in the fat cells of marine mammals among many other species.

A new paper in the journal Marine Pollution Bulletin has shown that since the ban, the concentration of some chemicals has decreased by up to 90 percent in just ten years in the population of harbour seals off the Svalbard Archipelago.

Harbour seals are a useful animal to study for contaminants because as a top marine predator they concentrate pollutants from animals lower in the food chain. Routti’s team caught 12 seals on the High Arctic island of Prins Karls Forland, and took samples their blubber, blood and teeth.

They found that not all contaminants are decreasing, however, and some are at concentrations closer to what should be expected in southern, industrialized areas rather than the relatively pristine protected area in Svalbard. Hexachlorobenzene (HCB), Hydroxy-PCBs, and perfluoroalkyl carboxylates (PFCAs) were all found at high concentrations in the seals. Some of those numbers surprised the researchers.

“HCB is quite equally distributed in the world because it’s a very light molecule,” explains Routti. “Others… that’s something that we don’t know. Hydroxy-PCBs are quite high compared to what can be toxic. It might affect hormone balance.”

While there is little industrial activity in the Arctic that might release pollutants there, some lighter pollutants like HCB are transported north in what is known as the “grasshopper effect”. Since they evaporate at low temperatures, they make their way to colder climates where they might eventually come to rest in snow, sea ice, or glaciers.

This accumulation in ice means that right now the Arctic is acting as a sink for many pollutants, some of which are now banned for the danger they present to the environment. They might not stay there in the future, however.

“They will be remobilized,” says Routti.