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Battulga, B.; Atarashi-Andoh, Mariko; Matsueda, Makoto; Koarashi, Jun
Environmental Science and Pollution Research, 30(31), p.77226 - 77237, 2023/05
Times Cited Count：0 Percentile：0(Environmental Sciences)The global survey for the presence of microplastics (MPs) in aquatic environments has attracted widespread scientific attention over the past decade. This study demonstrates a multidimensional analytical approach, including isotopic and thermogravimetric analyses to evaluate characteristics and behavior of MPs in the environment. The MP samples were collected in two contrasting coastal areas of Japan. The 
C values of field-collected polyethylene (PE), polypropylene (PP), and polystyrene (PS) MPs were ranged from -25.6 to -31.4, -23.4 to -30.9, and -27.3 to -28.6 per mil, respectively. The differences in C signature between MPs with the same polymer types (i.e., PE and PP) but different colors. Through thermal analysis, the single-step endothermic process was observed for environmental PE and PS-MPs. The results reveal that degradation may play a significant role in the behavior and characteristics of MP debris in the aquatic environment.
Battulga, B.; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
Plastic debris has been recognized as an emerging contaminant in the global ecosystem. Although microplastics (MPs) have received special attention from the scientific community owing to their widespread distribution, application of highly sensitive techniques to evaluate the characteristics of MPs is still under consideration. In this study, we demonstrate multiple analytical approaches including microscopic, spectroscopic, and isotopic analyses to track MP characterization obtained from coastal river environment. We selected two sampling sites from coastal areas in Japan and collected visible plastic samples. At the same time, surface water and coastal sand samples were collected to evaluate the seasonal variations in MP occurrence and composition. Seasonal differences in occurrence and morphotypes of MPs were detected in both sampling sites, suggesting variations in geographical patterns and consumption of plastic materials in the studied region. We also found differences in carbon isotopic composition between the MPs composed of the same polymer (i.e., polyethylene and polypropylene) but with different colors. Preliminary results of 
Cs activity concentrations revealed that plastics serve as carriers for radionuclides mediated by biofilms in the coastal river environment. Furthermore, occurrences and differences in the composition of the MPs in the study areas indicate that point and nonpoint sources of MPs strongly affect their concentration in the aquatic environment.
Battulga, B.; Nakayama, Masataka; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
Plastic debris in the aquatic environment has become a growing concern due to their long-term ecological consequences. The current study is focused on microbial community composition on microplastics (MPs; sizes 
5 mm) and characteristics of MP-associated biofilms in coastal river environments of Japan in order to understand the impact of MP-associated biofilms on aquatic organic matter cycling. The aims of the current study are i) extraction and characterization of microbial biofilms on MPs and ii) identification of diversity and composition of microbial communities on MP surfaces and in surrounding surface waters and sediments. The samples were collected from two coastal rivers during 2021-2022 on a seasonal basis. In this study, we proposed a new method to extract biofilms from MPs using ultrasound-assisted syringe treatment for isotopic analysis. Morphotypes of MPs and associated specific microbial taxa as well as seasonal differences were also observed.
Battulga, B.; Nakayama, Masataka; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
A growing attention has been addressed on microbial attachment and biofilm formation on plastic debris especially on microplastics (MPs; sizes: 5 mm) in the aquatic environment. The current study is focused on bacterial and fungal community composition, diversity, and structure in MP-associated biofilms to emphasize potential alteration of elemental cycling by the presence of MPs in the coastal aquatic environment. We collected MP, surface water, bottom sediment, and coastal sand samples from two contrasting coastal areas of Japan on a seasonal basis. Surface morphology and attached microorganisms on MPs were visually inspected by scanning electron microscopy (SEM). A high-throughput sequencing using Illumina MiSeq was performed in the collected samples to investigate the microbial community composition and diversity among different samples.
