Transport of pollution from the megacity Jakarta into the ocean: Insights from organic pollutant mass fluxes along the Ciliwung River

As with other emerging economies, the rapid economic development of Indonesia has led to a migration towards the cities. The coastal megacity Jakarta is one of the largest urban agglomerations worldwide. The uncontrolled increase in urban population results in increased pressure on public infrastructure such as sewage treatment facilities leading to severe pollution of surface waters. In this study, a mass flux approach was used to assess the transport of organic pollutants by the largest city bound river of Jakarta, the Ciliwung, into the adjacent coastal ecosystem. Mass flux approaches are useful to track the origin and transport of wastewater-borne pollution, but are mostly neglected in favor of solely concentration-based evaluations. Constituents of municipal sewage made up around 70-80% of the fluxes of the 32 quantified water pollutants. Personal care product ingredients, especially the insect repellent N,N-diethyl-m-toluamide (DEET), exhibited the highest fluxes. Our first assessment revealed that the Ciliwung River transports around 5-17 tons year(-1) of the quantified pollutants into the Java Sea. Such huge pollutant fluxes from municipal sources -a problem that is also relevant in other coastal megacities-might severely affect vulnerable coastal habitats.