Assessment of plastic content and microbial transformation of plastics in estuary of Can Gio

Abstract

In recent years, we are seeing more and more clearly the dangers posed by microplastics. This is a serious problem that the whole world is very concerned about today. In this study, I show the physical characteristics, chemical composition and abundance of microplastics according to environmental characteristics in Can Gio, Ho Chi Minh City, Vietnam. Four sampling sites along the coast with different ecological characteristics and human activities were selected. Sediment samples were collected to evaluate the spatial distribution of microplastics. The density separation method using a 1.5g/cm3 solution of zinc chloride (ZnCl2) applied during microplastic extraction was examined by Fourier transform infrared spectroscopy for total attenuation (FTIR-) ATR). Microplastics were found at all sites with a total quantity of 321 particles/kg d.w in Can Thanh; 258 particles/kg d.w in Ky Nam; 222 particles/kg d.w at Long Hoa; 327 particles/kg d.w in Ly Nhon. Microplastic sizes range from 0.01 to 5 mm. Microfiber accounted for the highest percentage (89%). The colors of microplastics are also very rich including black, white, blue and red. Polypropylene and polyethylene are the two most common polymers. Due to their properties, microplastics can come from a variety of sources, including plastics, tourism and aquaculture. In addition, this study also assessed the ability of microorganisms to metabolize plastic in the region of Can Gio estuary. Two experiments were conducted for microbial transformation of 4 types of plastics, including: HDPE, LDPE, PE, Biodegradable. One experiment, mesocosm, was designed by placing 4 types of plastics at the two estuary sites. One experiment was done in laboratory with similar type of plastics and inoculated with the microorganism taken mesocosm. Mass lost was highest for HDPE which up to 8.06% after 40 days of culture. Mass loss was lower for other plastics. The study also classified plastic groups of microorganisms that can live in the estuaries of mangroves in Can Gio and their ability to consume plastic over time.