It's sedimentary, my dear Watson

Chris Sommerfield of the University of Delaware and colleagues are tracking radioactive iodine, used in medical treatments, through waterways to learn how substances travel along rivers to the ocean. The essentially harmless trace amounts of radioisotopes, specifically the synthetic radionuclide iodine-131 used in treating thyroid cancer, entering waterways from waste water treatment systems are providing scientists with a unique way to go with the flow and to trace how substances travel through rivers to the ocean. "There are only a few recent research papers documenting the behavior I-131 in rivers and estuaries worldwide, and nothing for Delaware," Sommerfield says.