(IMAGE) Helmholtz Centre for Environmental Research - UFZ Caption The size of the circles corresponds to the number of substances detected per sampling point. The colours quantify the number of chemicals detected simultaneously at a sampling site (e.g. 51 to 100 substances were detected in 41% of the sites). Credit UFZ Usage Restrictions None License Original 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.