Unexploded ordnances still litter the seafloor worldwide. Northeastern engineers are trying to sniff them out. - Northeastern University College of Science

The two world wars that took place during — and in many ways defined — the 20th century left a legacy of trauma and devastation that’s echoed throughout the years. But the threat of those old weapons persists in the form of unexploded ordnances, which litter many of the world’s oceans.

In the North and Baltic seas, the problem is so complex that German officials have deployed remote-controlled seabed crawlers and robots to remove old weapons that release toxic chemicals in the water. In recent weeks, Swiss officials began soliciting researchers for ideas to help them clean up munitions in deep lakes, offering a cash prize of $58,000 to the top three entries in a competition.

That’s where Loretta Fernandez, an associate professor of civil and environmental engineering at Northeastern University, comes in. Fernandez and her colleagues have been working on creating passive samplers that would allow them to locate these munitions by detecting degraded compounds in the water.