The spatial distribution of microplastic in the sands of a coral reef island in the South China Sea: Comparisons of the fringing reef and atoll

Microplastic pollution of coral reef ecosystems has received increasing attention since the discovery that several typical coral types have the ability to ingest (micro-) plastics. However, data on the distribution of microplastics in coral reef ecosystems are still very limited. The study reported here selected sands/sediments from coral reef islands located in the South China Sea as a representative study site. The abundance of microplastics was found to reach 90 ± 5 items/kg and 530 ± 7 items/kg at the Weizhou Island and Sanya Lu Hui Tou (LHT) sites (fringing reef), respectively. Each of these qualities are lower than the quantity of microplastics collected from the Xisha Islands (atoll) (60 ± 3 to 610 ± 11 items/kg), which experiences less human activity and pollution. Moreover, further investigation demonstrated that the differences in the microplastics in the sands of these atolls and fringing reefs were determined not only by their sources, but were also dependent on their water exchange rates. The primary type and color of the microplastics found in these four sampling zones was red polypropylene and there was a greater proportion of smaller size particles (<1 mm) in the remote atolls of the Nansha and Xisha islands than in the other fringing reef sites. Additionally, there were no obvious differences found in the abundance of microplastics and the compositions/structures of coral sand in the Weizhou Island and Sanya LHT sites.