Exploring factors driving macroplastic emissions of Mahiga Creek, Cebu, Philippines to the estuary.

Rivers function as a pathway for plastic pollution to enter the marine environment. This study presents one of the first field estimates of macroplastic emissions from the Mahiga Creek into its estuary. Thirty-minute plastic counting surveys were conducted for 31 days with the use of videos and a collecting trawl. The captured plastics were classified according to the OSPAR marine litter manual. The three main categories were crisp packets (27.96 %), small bags (27.08 %), and plastic/polystyrene pieces (2.5-50 cm) (18.35 %). Intraday and daily changes in plastic flux values were compared. Plastic flux comparisons between holidays and regular days were also done. No relationship between plastic flux and discharge was found on days without rainfall (r = 0.0237). However, a significant increase in plastic flux was observed during rainfall events. The findings in this study present an insight into different factors that may affect macroplastic emissions in the Philippines.