The GPA has been mandated to provide guidance and develop activities to address nine source categories of land-based sources of marine degradation. These are: wastewater/sewage; Nutrients; Persistent Organic Pollutants; Radioactive substances; Heavy metals; Sediment mobilization; Litter; Oils (Hydrocarbons); and Physical Alteration and Habitat destruction (PADH). Physical alteration and habitat destruction is considered as the strongest reflection of the increasing population and economic activities in the coastal zone. PADH is also referred as "Habitat and Community Modification" by the Global International Water Assessment (GIWA) Programme or "Destruction and Alteration of Habitats" in other processes.