Microplastic pollution is serious environmental problem of marine debris due to its difficulty to decompose which can be up to hundreds of years. Currently, airborne microplastic has been observed in atmosphere which includes indoor and outdoor environments. The microplastics can be through wind from the ocean and surrounding land areas. In 2017, the production of plastic reached 348 million metric tons. The production of plastic worldwide has continued to increase at approximately 3% each year. From the amount, only 3% of plastic used were recycled. Based on the trends, it is estimated that on 2050 approximately 67.8 million metric ton of plastics will be at the environment or landfill (Ebere et al., 2019). Microplastic can be recognized with size less than 5 mm in diameter (Dowarah et al., 2020; Wagner et al., 2014; Waite et al., 2018; Wu, 2020). Besides, this marine debris can be categorized based on its various sizes either nano, micro, meso, macro and megaplastics.
The smaller size of microplastic might be ingested by aquatic life which includes plankton, fish, mussel, seashell, crab and other animal that life on land. Plastic that is difficult to decompose cause harm to animal and human health as the food chain contained of the aquatic life (Han, 2020). It has been classified onto primary microplastic (personal care and cosmetic products) and secondary microplastic (fragmentation from chemical and biological interaction) (Defu et al., 2018). Some of the primary microplastic is microbead which originated from personal care. Microbeads usually have white and opaque colors (Hu et al., 2019). In the ocean and rivers, the microplastic fragment from the synthetic fiber usually come from fabric washing (Firdaus et al., 2020). Plastic which made up of polymer consisted of several types. The types of polymer microplastic are polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), nylon (all polyamide), acrylonitrile butadiene styrene (ABS), cellulose acetate (CA), polycarbonate (PC), polyurethane (PU), polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) (Cai et al., 2019; Defu et al., 2018; Jung et al., 2018). Previous study has focused on characterizing microplastic pollution in freshwater, ocean, terrestrial environment and wastewater treatment plant (WWTP) (Wang et al., 2020). However, there is lack of information on microplastic pollution at the estuarine ecosystem in Malaysia (Athey, 2020).
The estuary is an enclosed body of water that mixes freshwater and saltwater from the sea (Wu, 2020). It is also connected between land and sea. The classification of estuary consisted of harbors, inlets, bays, lagoons, wetlands and swamps. Estuarine play an important role as the nursery of the ocean. Besides, it provides rich feeding ground for fish and birds. The animals located at estuaries ecosystem includes fish, crab, sea birds, marine worms, skunks and shellfish (mussel). From the previous research, polypropylene (PP) and polyethylene (PE) bring an impact to ragworm and fish (Revel et al., 2020). However, there is lack of information on microplastic trends in shellfish or mussel. Mussel which known as bivalves is a valuable organism to determine the different levels of pollutants in the environment. In addition, mussel can be used as global bioindicator of microplastics (Dowarah et al., 2020). The mussel can act as a filter feeder which traps and accumulate the microplastic pollutant due to their low excretion rates (Su et al., 2018). Rather than aquatic life, sediment sample has been used to determine the microplastic pollutant due to its different density. Previous study show that from collected sediments, type of film microplastic found abundance at rivers strait of Johor (Shazani et al., 2018). However, the type of plastic ingested by marine might be different.
In this study, microplastic pollution in estuarine ecosystem was investigate at Sungai Laloh, Pasir Putih. The objective of this study are to (1) identify the trends of microplastic present in the mussel and sediment sample at estuarine of Sungai Laloh; (2) determine the characteristic of microplastic present based on color and size; (3) identify the functional group of polymer microplastic present; (4) compare abundance of microplastic pollution from similar total weight between wild mussel and cultured mussel. The scope of this study is covered on the mussels and sediments located within the research area from October to November 2020. In situ parameters were analysis for DO, pH, temperature, salinity, conductivity and turbidity. Lab analysis includes digestion, separation and identification using microscope and ATR FT-IR.