การประเมินไมโครพลาสติกในตะกอนชายหาดบริเวณชายฝั่ง จังหวัดภูเก็ต

Abstract

Marine microplastics are a global problem as they can be harmful to living organisms. This study determined the distribution of microplastics at the six beaches, Phuket Province included Kalim beach, Patong beach, Tri Trang beach, Chalong beach, Rawai beach and Makham bay. The sediment samples were collected 4 times (April, July, October and December 2019), divided into summer and rainy season. Samples were collected using a 0.5x0.5 m2 quadrat at five cm depth at the intertidal zone. Plastic debris was divided into 3 sizes (macroplastics >25 millimetr, mesoplastics 5-25 millimetr and microplastics <5 millimetr). The microplastic was analyzed by 5M NaCl solution for density separation, 0.05 M Fe (II) and 30% H2O2 for organic decomposition. The microplastic shape (fibers, formless parts, films and pellets) and color (white, red, black, blue, green and yellow) were classified by 40x microscopy (Olympus CX 31). The Fourier Transform Irtron Infrared Spectrometer (µFT-IR) was used to determine the polymer types of microplastics. The results showed that one piece of macroplastics was found on the beach of Makham bay, three pieces of mesoplastic found at Kalim beach and Makham bay. There were totally 2,150 pieces of garbage that is expected to be microplastics that can be divided into 2 sizes: ≥300 µm. 1,134 pieces and 20-300 µm. 1,016 pieces. At all 6 beaches, black color of garbage that is expected to be microplastics was predominant (1,135 pieces, 52.8%), followed by red (466 pieces, 21.7%) and white (275 pieces, 12.8%), respectively. In this study, fiber was the most commonly found (2,013 pieces, 93.63%), followed by fragment shape (126 pieces, 5.86%) and pellet (14 pieces, 0.65%). According to the Fourier Transform Irtron Infrared Spectrometer for polymers classification, Polyethylene terephthalate microplastics (PET) (34.9%), This was followed by polystyrene (PS) (9.2%) and polypropylene (PP) (5.5%). Non-plastic contaminants were also found, namely fabric fibers. (Cloth Cotton) (48.5%) and regenerated cellulose (RC) (43.4%) were among the highest polymer types found in this study. According to the statistical analysis, it found that the amount or density of microplastics was not significantly different among the six beaches (one-way ANOVA); and there was no difference between the west coast and the east beach, the microplastic sizes, and seasons (t-test). The Principal Component Analysis (PCA) showed the cumulative variance of 94% and 46.03% for the principal component one (PC1) that consisted of polyethylene terephthalate, polypropylene polyurethane (PUR) and mixed plastic. Three relationship groups can be divided into 1) polyethylene terephthalate correlated with Rawai beach; 2) polypropylene polyurethane and mixed plastic was correlated with Patong beach, Chalong beach and Ao Makham beach, and 3) polystyrene and polyvinylchloride was correlated with Tritrang beach, respectively. Therefore, it can be concluded that different beach activities may affect and encounter in different types of microplastics in this study.