Abstract
Microplastics are polymer-based materials that require a variety of organic and inorganic chemical additives during the manufacturing process. These chemicals have an impact on aquatic organisms. This study aimed to quantify the impact of microplastics on the growth and quality of microalgae Spirulina sp. We studied the interaction between Spirulina sp. and 500 mg of polyethylene (PE) and polypropylene (PP) microplastics. Three glass bioreactors containing 2 L of Spirulina sp. were observed for 30 days. The first bioreactor was untreated and acted as a control. The second was treated with PE microplastic of 1 mm in size, and the third was treated with similarly sized PP microplastics. Each day, the optical density (OD) was measured to determine the rate of growth of the Spirulina sp. After harvesting, the Spirulina sp. biomass was dried in an oven at 30-35oC for 24 hrs and subsequently analyzed using Fourier transform infrared spectroscopy (FTIR). With PE treatment, the results showed a change in the organic structure on Spirulina sp., as well as a decline of polysaccharides and the loss of one peak at wave number 875.45 cm-1 . Meanwhile, in Spirulina sp. with PP treatment, two peaks that showed polysaccharides at wavelengths of 875.45 cm-1 and 1,245.67 cm-1 were lost. The results also indicated that microplastics had a significant impact on the growth and the quality of Spirulina sp., especially in decreased polysaccharide content.
Highlights
Microplastics are small (< 5 mm) particles formed from organic polymers
The optical density (OD) in variable 2, remained lower and reached 0.912 on the last day, followed by variable 3 which reached an OD of 0.886. This is in line with research conducted by Cunha et al (2019), who demonstrated that microalgae contaminated with microplastic showed a decrease of up to 42% in the number of cells
The results of this study indicate that the presence of microplastics has a significant impact on the growth and quality of Spirulina sp. produced, especially in polysaccharide content
Summary
Microplastics are small (< 5 mm) particles formed from organic polymers. They have a profound influence on freshwater and marine ecosystems as they get ingested and do not get caught in planktonic nets (Setälä et al, 2014). Microplastics influence higher trophic levels (Farrell and Nelson, 2013; Van Cauwenberghe and Janssen, 2014; Besseling et al, 2015) and show toxicity and increased mortality in marine plankton (Bergami et al, 2017). Several studies on the toxicity of microplastics of various sizes and characteristics show how aquatic ecosystems, including algae, ciliate, invertebrates, crustaceans, and fish (Bergami et al, 2017). Polyolefins, have a broad range of applications, packaging being one of them. Several broad classes of plastics that are used in packaging are PE, PP, polystyrene, Polyethylene terephthalate, and Polyvinyl chloride (Andrady, 2011)
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