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Yang Z, Zhang J, Haruka N, Murat C, Arakawa H. Spectral analysis of environmental microplastic polyethylene (PE) using average spectra. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:171871. [PMID: 38531446 DOI: 10.1016/j.scitotenv.2024.171871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 03/19/2024] [Accepted: 03/20/2024] [Indexed: 03/28/2024]
Abstract
In this study, microplastic samples from surface seawater of Tokyo Bay were collected, polyethylene (PE) microplastics were used to calculate carbonyl index (CI), and average spectra of PE were analyzed and compared with a previous study applying agitation during chemical treatment. It was found that PE and polypropylene (PP) were the predominant polymer type in the samples. Among PE samples, fragments were the most commonly observed shape, with white being the dominant color. Deviations were found in the average spectra among different shapes and colors when compared to the standard PE spectrum. A comparison of the average spectra between the two datasets suggests that pronounced peaks related to oxidation are most likely resulted from agitation during the chemical treatment. Additionally, it was found a closer spectral resemblance between the sample spectra and the spectrum of standard sample of oxidized PE (PEOx) than with the standard PE spectrum, suggesting that using the oxidized PE as a reference spectrum might be more effective for identification. These findings highlight the complex factors affecting the spectral properties of microplastics and highlight the importance of understanding these variations to enhance the accuracy of microplastic identification workflows and understanding of environmental fate of microplastics.
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Affiliation(s)
- Zijiang Yang
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
| | - Jiaqi Zhang
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
| | - Nakano Haruka
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan.
| | - Celik Murat
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan
| | - Hisayuki Arakawa
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
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S Gomes R, Fernandes AN, Waldman WR. How to Measure Polymer Degradation? An Analysis of Authors' Choices When Calculating the Carbonyl Index. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:7609-7616. [PMID: 38624261 DOI: 10.1021/acs.est.3c10855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
The carbonyl index aims to measure the degradation level and is used in plastic degradation research as a proxy for the general degradation level of collected plastic pieces. According to the choices for carbonyl index calculation, comparison using this index is prevented and must be unveiled by the authors, which does not always happen. In order to study the proper usage of the carbonyl index, regarding the choice of the reference band and the usage of the band intensity or the absorption area, we systematically reviewed the methodologies used for polypropylene as a case study. Based on 95 studies gathered from 2000 to 2024, two main methods were used to determine the carbonyl index: the ratio between the carbonyl band area and the reference band area (33.68%) and the ratio between the highest intensity of the carbonyl band and the reference band (66.31%). The reference band of choice and the type of calculation method produce different carbonyl index values for the same spectra and mean different information, preventing comparison among works with different calculations.
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Affiliation(s)
- Raimara S Gomes
- Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Porto Alegre, RS 91501-970, Brasil
| | - Andreia N Fernandes
- Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Porto Alegre, RS 91501-970, Brasil
| | - Walter R Waldman
- Centro de Ciências e Tecnologia para Sustentabilidade, Universidade Federal de São Carlos (UFSCar), Rodovia SP-264, km 110, Sorocaba, SP 18052-780, Brasil
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Sunil M, N M, Charles M, Chidangil S, Kumar S, Lukose J. Visualization and characterisation of microplastics in aquatic environment using a home-built micro-Raman spectroscopic set up. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 354:120351. [PMID: 38382433 DOI: 10.1016/j.jenvman.2024.120351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/22/2023] [Accepted: 02/08/2024] [Indexed: 02/23/2024]
Abstract
Microplastics (MP) which are tiny plastic particles of sizes range from 1 μm (μm) to 5 mm (mm), have become a growing cause of concern due to their widespread presence in the environment and their potential impacts on ecosystems and human health. Marine organisms have the potential to consume microplastics, which could lead to physical injuries, blockages, or the transfer of harmful substances up the food chain. Humans may indirectly consume microplastics through contaminated seafood and water, although the complete scope of health risks is currently under investigation. An essential step in gaining a comprehensive understanding of microplastic pollution in waterbodies is the identification of microplastics, which is also crucial for further development of effective environmental regulations to address its adverse impacts. Majority of the researchers are accomplishing it globally using commercial platforms based on Raman spectroscopy. However, the development of indigenous Raman systems, which can enable microplastic identification, particularly in developing nations, is the need of the hour due to the outrageous cost of commercial platforms. In the current study, a custom-designed micro-Raman spectroscopy system was developed to detect and characterize microplastics from waterbodies. The developed system enabled visualization, size measurement and characterization of microplastics. Experimental parameters were fine-tuned, and a standardized Raman database was established for each type of plastic. This system exhibited high resolution which was capable of analysing microparticles of size up to 5 μm. Principal component analysis was carried out on the experimental Raman data, demonstrating good classification amongst different kinds of plastics. The performance of the developed system in analysing real samples was evaluated through experiments conducted on water samples obtained from the shore of Malpe Beach in Udupi district. The results revealed the presence of polyethylene and polyethylene terephthalate in the samples, along with the detection of pigments like copper phthalocyanine and indigo blue.
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Affiliation(s)
- Megha Sunil
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Mithun N
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Meril Charles
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Santhosh Chidangil
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Satheesh Kumar
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Jijo Lukose
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
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Yang Z, Murat Ç, Nakano H, Arakawa H. Accessing the intrinsic factors of carbonyl index of microplastics: Physical and spectral properties, baseline correction, calculation methods, and their interdependence. MARINE POLLUTION BULLETIN 2023; 197:115700. [PMID: 37897964 DOI: 10.1016/j.marpolbul.2023.115700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/25/2023] [Accepted: 10/19/2023] [Indexed: 10/30/2023]
Abstract
Carbonyl index (CI) is a measure of the degradation status of microplastics. While many studies address environmental factors of microplastic degradation, intrinsic factors like physical properties, spectral properties, baseline correction, and CI calculation methods are less explored. This research focused on these aspects using surface seawater samples. We found that color and shape have limited dependence on particle size or signal-to-noise ratio (SNR). Baseline correction can significantly alter CI values, with the direction of the shift depending on the methods used. Additionally, most CI values before and after baseline correction and those calculated using different methods tend to be strongly correlated. Using the selected CI calculation methods, we found that CI values varied significantly by shape and color. CI's relation to the similarity between the sample and its pristine form suggests an alternative degradation measure. Our findings emphasize the need for standardized CI calculation methods.
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Affiliation(s)
- Zijiang Yang
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
| | - Çelik Murat
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan
| | - Haruka Nakano
- Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan.
| | - Hisayuki Arakawa
- Faculty of Marine Resources and Environment, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
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