Ocean scientists already know that persistent organic pollutants—potentially harmful chemicals that stick around for a long time—accumulate in marine environments and wildlife. But they’re murkier on what’s happening in the deep ocean. Now, a new paper suggests that ecologists studying the spread of these chemicals through the world’s seas might get some help from blubbery elephant seals. Scientists took blubber samples from elephant seals (pictured, with pup) before and after a 7-month foraging trip, and satellite-tracked some of them as they hunted across the northern Pacific at great depths. (The researchers sedated the seals and applied a local anesthetic before taking a sample from the animals’ hind flank with a small biopsy punch.) Not surprisingly, seals that stayed closer to populated areas showed higher levels of DDT compounds and PBDEs (the types of chemicals used in flame retardants), as well as PCBs, industrial chemicals banned by the United States in 1979. Seals that hunted farther from shore had lower levels of most chemicals—but they still absorbed high concentrations of PCBs, the team will report in an upcoming issue of Science of The Total Environment. That shows PCBs spread farther through the ocean than other chemicals. Although researchers had already supposed elephant seals were ingesting contaminants from their environment, the study, they say, is the first empirical evidence quantifying it, and one of the first to use satellite tracking to show exactly how and where marine predators pick up specific contaminants.