ABSTRACT
Globally, microplastic has been acknowledged as a newly discovered pollutants that have a negative impact on man and the natural ecosystem. These microplastic have found their way into our waters where aquatic organisms now ingest these particles which poses health hazards to aquatic inhabitants and man generally. Microplastic consist of minutes particles of 5mm in size. They arise from degradation of plastic products over the years. Due to its small size, microplastic can enter human food and aquatic food chain.
In this study, the occurrence of microplastic in freshwater apple snail P. ovata, was carried out with the samples purchased from selected markets in Benin City, Edo State, Nigeria and they include; Oliha market, Ekiuwa market and Ekiosa market for 3 months of October, November and December. The snail samples were cleaned, the morphometric measurements were taken and duly recorded. Digestion of the sample was carried out and then purification of the digested sample. The sample was sieved using the Nitrate Cellulose Filter paper and subjected to a temperature of 1000C for 12 hours. Further study of the collected microplastic was carried out by visual identification with the use of an electrical microscope. Further verification of the microplastic was carried out to avoid error.
Based on physical characteristics, the microplastic type found in P. ovata included; Fragments, Fiber and Filaments of which Filaments is of most occurrence and mostly found in Ekiuwa market. Based on chemical characteristics, type of microplastic found included; Polyester, Polyethylene and Polypropylene of which Polyester is the most occurring. Samples gotten from Ekiuwa market has been found to contain microplastic of Polyester, Polypropylene and Polyethylene of which Polyester is dominant during sampled month.
The mean level, cutting across sampled markets and months, ranges from 0.001particles/snail to 6.00 particles/snail. It was observed that there is no significant differences in Ekiuwa and Ekiosa market but there is a significant difference in Oliha market based on vertical comparison only. The estimated daily intake for each market in MP/person/day includes; Oliha market: 0.001, Ekiuwa market: 0.0003 and Ekiosa market: 0.00004 in which samples from Ekiosa market has the least estimated daily intake. This findings establishes the fact that Freshwater snails purchased from Ekiosa market has less microplastic level compared to the other markets sampled.
