What trace elements reveal about a changing ocean

September 17, 2026

When Jay Cullen drops a line 2,500 metres into the Arctic Ocean, he isn’t fishing. Instead, he’s collecting water samples that will tell him what else is in the deeps: Iron, manganese, cobalt and any of a dozen other trace elements. And beyond what’s there, the UVic ocean geochemist is looking at where those elements came from and where they’re going.

“Trace elements and isotopes provide information on ocean processes that are relevant to climate, water circulation, mixing, distribution of materials and the role they play in the partitioning of CO2 between the atmosphere and the ocean,” he says.

As climate change warms the Arctic four to five times faster than other regions of the globe, permafrost thaws and ice sheets melt. Freshwater flows off the land, changing the currents, salinity and content of the sea, and sometimes carrying legacy toxic chemicals from human activities like mining. At the same time, sea ice disintegrates, making travel unsafe and food supply insecure.

“Certain elements behave as nutrients for microbes,” Cullen explains. “They’re the base of the food web and therefore key to fisheries yields and, ultimately, wellbeing in Canada. Northern peoples rely on the sea for food.

“I’ve witnessed firsthand diminishing sea-ice cover and multi-year sea ice,” he says. “It’s very impactful on biological processes and it’s happening in real time, before our eyes.”