The accumulation of microplastics and their associated heavy metals on the surfaces of microplastics in various tissues of the pelagic fish Rastrelliger kanagurta, from the northern coast of Central Java, Indonesia

Microplastics (MP) and heavy metals present considerable risks to aquatic ecosystems and human health, therefore requiring attention to their accumulation in the pelagic zone of the North coast of Central Java, Indonesia. This study examines the physical and chemical properties of MP and the presence of heavy metals bind to the surface of microplastics in various tissues of pelagic mackerel Rastrelliger kanagurta from the northern coast of Central Java. Samples were obtained from four distinct locations along the coastline. The study's findings indicated that microplastics in the gills, stomach, intestines, and liver of R. kanagurta, as well as in seawater, were predominantly fragment-shaped, black in color, and measured less than 500 µm. The concentration of microplastics in seawater ranges from 10 to 42 particles/L, while in the tissues of R. kanagurta, it ranges from 9 to 13 particles/ind. The Tegal site showed a significant correlation between microplastic concentration and R. kanagurta length or weight, but other sites did not. Seven types of MPs polymers were identified in the tissues of R. kanagurta collected from the north coast of Central Java: polyamide, polypropylene, polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride, and nylon. Four categories of plastic additives were detected in the tissues of R. kanagurta: plasticizers, emulsifiers, antioxidants, and thermal stabilizers. Metal elements detected on the surface of MP include Mn, Cr, Al, Ni, Cu, Zn, As, Cd, Co, Sn, Hg, Fe, and Pb. Additionally, non-metallic elements including O, Na, Ca, Mg, C, Si, and K were identified on the surface of MPs.