Nitrogen Chemistry in Earth's Atmosphere (IMAGE) University of California - Los Angeles Caption Scientists have discovered a planetary-scale tug-of-war between life, deep Earth and the upper atmosphere that is expressed in atmospheric nitrogen. Credit Courtesy of ISS Expedition 7 Crew, EOL, NASA Usage Restrictions None License Licensed 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.