Researchers found high levels of radioactivity, metals, and salts in sediments and water downstream from a Pennsylvania facility that treats fracking wastewater. Radioactivity levels downstream of the treatment plant were about 200 times higher than in surrounding areas, and concentrations of some salts and metals were also higher than background levels, the scientists reported in Environmental Science and Technology. The Duke University team traced the radioactivity’s source to the Marcellus Shale formation, which is naturally high in salts and radioactivity. Although the treatment plant removes more than 90 percent of the radioactive metals radium and barium, the effluent still exceeds federal limits for radioactive waste disposal, the researchers said. Plants, fish, and other organisms near the facility are potentially at risk for radium bioaccumulation. Downstream, carcinogenic byproducts can form when water with excess levels of the salt bromide mixes with disinfection chemicals at municipal drinking water plants, the study said. A mile downstream from the treatment facility, bromide levels were 40 times higher than background levels, the researchers reported.