Highly read on pubs.acs.org in November

Waste water from oil and gas production is contaminating surface waters and sediments in western Pennsylvania — even after it has been treated.

In the United States, such waste is sometimes sent to treatment facilities and then discharged into streams and rivers. Nathaniel Warner, Avner Vengosh and their colleagues at Duke University in Durham, North Carolina, analysed the effluent in 2010–12 at a facility that treated water from gas wells in the Marcellus Shale. They looked at samples taken upstream and downstream of the facility, and found increased contaminants such as chloride and bromide downstream.

Although treatment lowered the levels of barium and radium in the waste water, radioactivity levels from radium in river sediments near the facility were 200 times greater than background levels, and were above regulatory limits.

The authors say that the elevated radium levels suggest a risk of radioactivity accumulating in wastewater disposal areas, and that better treatment technologies are needed to reduce contamination.

Environ. Sci. Technol. 47, 11849–11857 (2013)