Are existing pollution matrices sufficient in characterizing coastal environment quality in Macajalar bay, Southern Philippines?

Macajalar Bay, a catchment basin adjacent to economic, industrial, urban and agricultural center, is known to be the gateway of Northern Mindanao in the Philippines. Lush pristine forests beside large commercial banana, cassava, corn, sugar cane, and pineapple plantations earmarked its watershed as one of the breadbaskets of the Philippines. Two large rivers drain the watershed surrounding Macajalar Bay, which are proudly categorized as Class A waters since water quality monitoring started in the 1990s. This is especially favorable for the sardine industry that the bay is known for. Recent increase in population, land-use change, and deforestation may exert environmental stress to the bay. This study reviews the condition of the bay against existing pollution indices: water quality distribution-multi-statistical assessment, coastal water risk quotient (RQ), water quality index (WQI), fish-metal health risk assessment (EDI and THQ), microplastics (fragments and fibers), and clean coast index (CCI). Our socio-demographic survey revealed unregulated disposal of solid wastes by coastal communities that resulted to deposition of microplastics and beach litters. This is corroborated by the CCI, which characterized beach sands in urban coasts extremely dirty with microplastic fibers compared to municipal coasts still classified as clean but with microplastic fragments. Based on WQI, the bay waters are classified excellent despite RQ>1 for COD, TSS, oil and grease, and phosphate concentration. This discrepancy is due to the limited parameters factored in WQI. Likewise, the strong riverine flux especially during rainy season actively flushes the coastal waters out of the bay. The Pb and Cd in flesh of 23 fishes revealed acceptable EDI and THQ within the WHO/FAO guideline. Further analyses of microplastics, persistent (i.e. polyaromatic hydrocarbons) and emerging (i.e. pharmaceutical and personal care products) organic pollutants in aqueous, particulate and biogenic forms, will be included for a more encompassing environmental quality evaluation and will be reported during the conference.