Hydrodynamic Trajectory Model of Macro- and Microplastic Surfaces in the Deep Sea of the Haruku Strait Indonesia

Marine plastic debris is a primary problem in most countries. The study aims to analyze the abundance and spatial trajectory of marine plastic debris using a new horizontal and vertical trajectory approach in the deep seawater column of the Haruku Strait, Central Moluccas, Indonesia. The methodology integrates macro- and microplastic field sample abundance, photomicroscope analysis, and 2D hydrodynamic trajectory modeling. The study revealed that the composition of macroplastics was 69% plastic bag or plastic item (17%), bottle and cup fragments, nylon fishing gear 8%, polystyrene blocs 3%, clothes and footwear 2%, and rubber 1%. The components of microplastics are plastic fragments (64%), fibers (33%), pallets (1%), and plastic films (2%). The essential finding is that the size range of microplastic is 100-500 µm out of the five size classes potentially swallowed by marine organisms. Macro and micro-plastics spread by a current speed of 0.1-1.3 m.s -1 with the north and southward trajectory pattern. Plastic debris mainly spreads in the shallow coastal high biodiversity area depth of 0-15m out of ten depth-class trajectories up to 204 m in the deep sea of 2,100 m at the Haruku Strait. The dominant microplastic color is bright blue (75%). This scientific problem-solving contribution can be used for public and government awareness regarding communal plastic waste disposal behavior and as a basis for planning, mitigation strategies, and policies. Keywords: hydrodynamics, microplastics, trajectory, Haruku Strait. https://doi.org/10.55463/issn.1674-2974.51.6.15