Urban Watershed (image) Virginia Institute of Marine Science Caption Urban organics may persist downstream because their more photoreactive compounds have already been degraded due to greater light exposure in urban areas, farm fields, and pastures. Credit Photo by David Malmquist/VIMS. Usage Restrictions One-time use only. 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.