Selenium Coal Ash (IMAGE) Duke University Caption A nanoscale view of two different sources of coal ash shows major differences in how selenium is part of its makeup. On the left, selenium (red) is diffusely distributed around multiple large ash grains made of iron (green) and carbon (blue). On the right, selenium is bound to the surface of ash grains made of iron and carbon, making it more difficult for the selenium to escape. Credit Helen Hsu-Kim, Duke University Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.