Every year, farmers in countries including India, China, Russia, the U.S., and some developing countries protect their crops using tens of thousands of tons of pesticides such as endosulfan. Researchers know that these compounds can travel long distances by air and water and reach the Arctic.

On a four-month research cruise from the East China Sea northward to the Chukchi Sea in the High Arctic, researchers led by Zhiyong Xie of the Helmholtz Center in Geesthacht, Germany, measured levels in air and water of the pesticides chlorothalonil, chlorpyrifos, dacthal, dicofol, endosulfan, and trifluralin. The team developed new air sampling methods to detect some of these pesticides.

The Arctic Monitoring and Assessment Program, a transnational scientific working group that monitors pollutants, previously had tracked the insecticide endosulfan and the herbicide trifluralin. While some Arctic data previously existed on chlorothalonil, chlorpyrifos, dacthal, and dicofol, the team collected the first measurements of the compounds in air and water levels along an ocean path from East Asia to the Arctic. This information should help researchers understand if the pollutants travel more readily by air or by sea, as well as how they degrade along the way.

The study suggests that these pesticides could cause environmental problems far from farms, says Xie. While the compounds degrade as they travel to the Arctic, he points out that once they are in the Arctic’s cold temperatures, the pesticides could become more stable and last longer. He thinks researchers next need to focus on the pollutants’ effects in Arctic ecosystems.