Mina in Pool (image) Penn State Share Print E-Mail Caption Lead researcher Odette Mina in one of the vernal pools. Conditions in the pools are very different from streams. They hold standing water with scant dissolved oxygen in which duckweed is growing, and the physical and chemical parameters affect the persistence, transformation and degradation of the estrogens. Credit Heather Gall Research Group, Penn State Usage Restrictions Non commercial use only 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.