Sustainable Ocean Resources Network

Abstract

Since the beginning of mass production of plastics in 1940's prevalence of microplastics in tha marine environment has been a growing problem as microplastics impose negative impacts on marine biota. Though this fact is being investigated worldwide, Sri Lanka does not possess knowledge on occurrence of microplastics in marine habitats. As the first step to fill the knowledge gup, this study was done as the first study on microplastics, to investigate microplastics in beach sand of Sri Lanka selecting Negombo coastline as the study site Three representative locations from Negombo coast line was selected for the study and presence of microplastics in beach sand in lwo size classes (1-5 imm and <Imm microplastics) was confirmed using samples taken in March 2017. Identification of potential sources of 1-5 mm microplastics was done using the samples collected once in two months from March to November 2017 by determining the most available region and most available type of microplastics in each representative location. Temporal variation of 1-5mm microplastics was determined to understand the behavior of microplastics in beach sand and temporal variation of <1mm microplastics was determined to understand the potential sources of <1mm microplastics in beach sand. FTIR spectroscopy was used in identification of microplastics of <1 mm that are not detected by visual examination. Potential for the ingestion of microplastics present in sea water was determined using extraction and identification of polymer types in the gut content of Sardinella sp This study revealed the presence of microplastics in beach sand of Negombo and it was identified that the sources of microplastics are either sea based or land based and sources depend on the key ecosystem features and land use patterns around the particular location. All most all microplastics found were of secondary origin and that reveals the occurrence of microplasties in beach sand of Negombo is through the breakdown of larger plastics in to smaller plastics. Temporal variation of micraplastics reveals that there can be an effect of external factors such as climatic features other than anthropocentric activity on the availability of microplastics in the environment and one source may be the source of microplastics to beach sand. Two types of polymers; polyethylene and polypropylene was found in the fish gut content suggesting the presence of microplastics in sea water and potential accumulation of microplastics in marine biota. This is the first evidence of prevalence of microplastins in beach sand in Sri Lanka and the findings will be important to understand the occurrence and behavior of microplastics in the marine environment and for possible management implications.