Greg Brennecka, Arizona State University (image) Arizona State University Share Print E-Mail Caption ASU graduate student Greg Brennecka stands in the W.M. Keck Foundation Laboratory for Environmental Biogeochemistry at ASU in front of the powdered carbonate rock samples collected in Dawen, Southern China. These samples are prior to chemical processing to ready for measurement on the mass spectrometer. There were about 40 samples total for this study. Credit P.S. Noonan Usage Restrictions None Share Print E-Mail 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.