Plastics at sea (microplastics) : a potential risk for Hong Kong

Plastics are cheap and convenient materials that are widely adopted in our daily applications. High production and consumption of plastics, however, are resulting in the issue of marine plastic pollution. Plastic debris is often divided into two categories: macroplastics and microplastics. Macroplastic is a well-known international problem to the world’s oceans, while microplastics often receive less attention. Many coastal areas and remote islands are suffering from plastic pollution. Marine plastic debris is responsible for negative impacts on organisms and the environment, including entanglement, ingestion, absorption of toxic chemicals, and transportation of invasive species. Human society and the economy may also be threatened. It is noticed that impacts caused by microplastics are comparatively more critical than those caused by macroplastics. Microscopic size and large surface area to volume ratio increase the potential for microplastics being ingested or used as vectors to absorb chemicals. Micro particles may enter the circulatory system, cause damage to cells and tissues, and release contaminated chemicals to the body, and hence result in health and safety issues. Ingested plastics may undergo bioaccumulation and pass up the food web, which may influence the entire ecosystem as well as human populations. Guangdong province is the largest plastic production centre in Mainland China. Any discharge from Guangdong province will enter the Pearl River and move downstream to the mouth of the estuary where Hong Kong is located. Hong Kong, especially it’s western waters, is directly susceptible to discharge from Mainland China. Data of plastics collected from beaches illustrated that higher quantities of plastic pellets have been collected from the western part of Hong Kong. This implies Hong Kong is suffering from plastic pollution generated from the Pearl River. Hong Kong may also receive overseas plastics carried by ocean currents and monsoon winds, which may have a stronger effect on the southern and eastern waters. There are many valuable marine biota and environments in Hong Kong. The presence of microplastics may pose a significant threat to the entire marine ecosystem and food chain. It is necessary to take action on the prevention and mitigation of the impacts of microplastics. Efforts should be made at national and international levels, and all sectors are responsible to take appropriate actions.