An investigation on floatable marine microplastic pollution in Hong Kong

Microplastics refer to small plastic marine debris that is not readily visible to the naked eye. This pollutant has recently been identified by UNEP as one of the most-pressing environmental concern at the global level due to its ubiquitous occurrence in the environment. Ingestion of microplastics would potentially cause physical damage to the organism and that would serve as a potential pathway through which hydrophobic pollutants adsorbed on the particles are transferred into the food chain. There are two main sources of microplastics, first is from transportation accidents such as spillage of plastic pellets into local waters from a ship during typhoon Vicente in the summer of 2012; the other source is through the process of physical and photodegradation of large plastic debris. Despite the potential environmental impacts of this pollutant, there had been few surveys on the abundance of microplastics in the marine environment of Hong Kong, which is located downstream of the largest plastic production province in China: Guangdong. This study represents a pilot survey of microplastic abundance in the local waters. The study involved sampling of microplastics on two selected beach in Hong Kong. microplastic particles which float on the sea can be brought to shore by ocean waves, thus the abundance of microplastics on beach represents an indirect survey of its abundance the sea. Two beaches were chosen to compare the amount of microplastics on west and east coast in Hong Kong: Fan Lau Tung Wan on Lantau Island in the west and Sai Wan in Sai Kung in the east. Following a random sampling approach, sediment samples were collected from the high tide line on the beaches and density separation were performed to extract the microplastics in the matrix. The collected plastic particles were weighted and identified by Fourier transform infrared spectroscopy. It was observed that the average counts per m2 were 316 and 3,489 respectively, for the west and east sample sites, and the most abundant type of microplastic debris was foamed polystyrene. Moreover, microplastics pollution in Hong Kong is found to be relatively more severe comparing with that observed overseas. The findings indicated the severity of microplastics pollution in Hong Kong waters and public attention should be drawn onto this issue.