Modeling Pharmaceutical Contaminant Transport in an Urban Coastal Estuarine System: The Case of Manila Bay, Philippines

The increasing global prevalence of pharmaceuticals and personal care products (PPCPs) poses emerging concerns due to their possible effects on ecosystems and human health, even at low concentrations. Despite Manila Bay’s ecological and economic importance, there is limited information about the concentration and hotspots of PPCPs in the bay. This study determined the PPCP levels in the bay and its major tributaries, the Pampanga and Pasig Rivers. Utilizing the open-source DELFT3D-FLOW software, the transport of PPCPs within the Manila Bay is modeled, considering key parameters such as winds, tides, salinity, and river discharge. Anhydroerythromycin and caffeine predominate the detected PPCPs. Land use influences PPCP concentrations, which are higher in areas dense in health facilities and built-up structures compared to those in predominantly agricultural regions. Seasonal wind patterns affect the surface transport of PPCPs. Integration of river discharge data significantly affects the resulting water circulation and pollutant transport patterns. The study recommends the use of modeling to determine areas at a high risk of pollutant exposure and targeted PPCP analysis in aquatic organisms in urban estuaries. Furthermore, it is necessary for a comprehensive, interdisciplinary approach to managing the increasing occurrence of pharmaceutical contaminants in aquatic ecosystems.