Figure 4
From: Contribution of sewage to occurrence of phosphodiesterase-5 inhibitors in natural water
Contour map explaining (a) population density (colored green) and (b) nightlife spots (colored red) of areas served by STP#1 and STP#2. Geographic data obtained from the National Geographic Information Institute of Korea (http://map.ngii.go.kr) and processed using ArcGIS Pro (version 2.5; http://esri.com).
