Muddy Waters? (IMAGE) Arizona State University Caption Postdoctoral research associate Benny Pycke holds a sediment sample from a Minnesota lake. The samples were collected from the upper 10 cm of the bed surface and stored in a freezer prior to analysis. Credit Biodesign Institute at Arizona State University 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.