Spatial and temporal variations of coastal microplastic pollution in Hong Kong.

Further to our 2015-16 investigation, this study revealed the repeated presence of microplastics (MPs) in the coastal environment (Deep Bay, Tolo Harbour, Tsing Yi and Victoria Harbour) of Hong Kong from July 2016 to March 2017. The highest level of MPs in coastal surface water (17,182 particles/100 m3) was detected in Tsing Yi. Microplastic abundance in sediments of different sites (59 to 225 plastic particles/kg), however, did not vary significantly. MPs in the size of ≤1 mm were predominated in surface waters (53.3% to 98.6%) and sediments (79.1% to 96.8%). MPs in the shape of pellets and fragments were prevalent in surface waters and sediments respectively. Seasonal pattern of microplastic pollution was consistently observed in Victoria Harbour and Tsing Yi, where the number of MPs was always higher in dry season than in wet season for two consecutive years.

Microplastic pollution in the marine waters and sediments of Hong Kong.

The presence of plastic waste with a diameter of less than 5mm ("microplastics") in marine environments has prompted increasing concern in recent years, both locally and globally. We conducted seasonal surveys of microplastic pollution in the surface waters and sediments from Deep Bay, Tolo Harbor, Tsing Yi, and Victoria Harbor in Hong Kong between June 2015 and March 2016. The average concentrations of microplastics in local coastal waters and sediments respectively ranged from 51 to 27,909particles per 100m3 and 49 to 279particles per kilogram. Microplastics of different shapes (mainly fragments, lines, fibers, and pellets) were identified as polypropylene, low-density polyethylene, high-density polyethylene, a blend of polypropylene and ethylene propylene, and styrene acrylonitrile by means of Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy. This is the first comprehensive study to assess the spatial and temporal variations of microplastic pollution in Hong Kong coastal regions.