Sustainable Ocean Resources Network

Abstract

Prevalence of microplastics in the marine environment has been a growing problem as they can impose deleterious impacts on marine biota. Though the issue has a global concern, this has not been taken up in Sri Lanka. The present study is the first attempt to study the occurrence of microplastics in beach sand of Sri Lanka from three study sites namely, Pitipana, Catamaran, and Duuwana, along the coastline of Negombo, collecting samples bimonthly intervals between March to November 2017. Microplastics were categorized into two size classes (1-5 mm and <1mm). Microplastics were separated using density separation with the aid of vacuum filtration. Identification of the 1-5 mm category microplastics type as fiber, foam, fragment, and pellet was done visually using a stereo microscope, and they were counted. Polymer types of the microplastics of <1mm were determined by analyzing the FTIR spectrum. In addition, the gut contents of Sardinella sp caught from Pitipana was analyzed for microplastic ingestion by visual observation as well as identification of the polymer using FTIR spectrum. Catamaran and Duuwana beaches were dominated by microplastic fragments (25 and 13 items / m3 respectively). Followed by fiber (2 and 1 items / m3 respectively). At Pitipana beach, there were only foam plastics but in significantly high numbers (36 items / m3). However, pellets that are used for plastic manufacturing were not recorded in any of the sites. From all the three beaches studied, microplastic polymers were also recognized. In Pitipana beach, only polyvinyl chloride was found, and in Duuwana and Catamaran beaches only polyester was found. Amongst the gut content of the Sardinella sp samples subject to FTIR analysis for polymer types, polyethylene and polypropylene were recorded in the gut content of Sardinella sp suggesting the presence of microplastics in sea water as well as the potential for accumulation in the food chain of marine biota. Almost all microplastics found were of secondary origin and that reveals the occurrence of microplastics in beach sand of Negombo is through the breakdown of larger plastics into smaller plastics.