Wastewater Treatment Plant is a stock that refers to the primary treatment process in WWTPs. (Units are in millions of suspected microplastics). While WWTP are efficient and effective at retaining MPs, WWTPs are a significant source of MPs in aquatic environments because so much wastewater is filtered.
Biologically Active Filter, BAF is a stock that refers to the secondary treatment process in WWTPs (and acts as a simplification for all the other elaborate processes going on during this step). This traps further MPs.
Population of Island Communities is a stock that refers to the amount of people in island communities in the Pacific.
Coral Reefs is a stock that refers to the abundance of coral reefs in the Pacific Ocean.
Plastic in Coral Reef Islands refers to the amount of suspected microplastics/plastic units in coral reef habitats (regardless if the reef dies or not)