Detection of microplastics in Arctic deep-sea sediments by µFTIR spectroscopy
Plastic is one of the most widely used materials in the manufacturing of different products. The global plastic production increased between 2011 and 2015 from 280 Mio. t per year to 322 Mio. t per year. In the last years the social and scientific interest in microplastics (<5 mm) increased as it...
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| Format: | Thesis |
| Language: | unknown |
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2017
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| Online Access: | https://epic.awi.de/id/eprint/44307/ https://hdl.handle.net/10013/epic.50647 |
| Summary: | Plastic is one of the most widely used materials in the manufacturing of different products. The global plastic production increased between 2011 and 2015 from 280 Mio. t per year to 322 Mio. t per year. In the last years the social and scientific interest in microplastics (<5 mm) increased as it has been already detected in all aquatic realms from rivers to beaches, oceans, ice and sediments. Because of differences in density some polymers are sinking in the water and reach the sediments. In addition the density of polymers can also change due to degradation or biofouling and lead to a sinking of the polymers. In the analysis of microplastics in environmental samples different methods are used. During the present study, the samples have been processed with a density separation, a purification step and analysed via Fourier transform infrared (FTIR) spectroscopy. Nine stations of the Long-Term Ecological Research (LTER) observatory HAUSGARTEN west off Svalbard (Norway) at ca 79°N in the Fram Strait were sampled at depths between 2342 m and 5570 m. Sediment samples were taken by multiple corer during the expedition ARK 29.2 of the research ice breaker FS Polarstern in summer 2015. A density separation was achieved using a MicroPlastic Sediment Separator (MPSS) and a zinc chloride (ZnCl2) solution (density: >1.70 g cm-3). During the density separation the sediments (density approx.: 2.65 g cm-3) sink while the plastic particles (density: <1.70 g cm-3) rise. Afterwards, the samples were divided into two size fractions (one >500 µm and one <500 µm) via filtration. Further, the fraction >500 µm was investigated visually with a stereomicroscope and analyzed via Attenuated Total Reflection (ATR) FTIR spectroscopy. The fraction <500 µm was treated with Fenton’s reagent for the reduction of organic materials and parts of the samples (between 1.25 % and 67.7 %) were filtrated onto an aluminum oxide filter. Theses filters were analyzed via µFTIR spectroscopy and the microplastics content was determined with a newly invented automatic evaluation method. Microplastics were detected in all samples for fraction >500 µm as well as fraction <500 µm. Overall, the total number of microplastic particles detected in the fraction <500 µm ranged from 40 to 6594 particles kg-1 dry sediment. These numbers are markedly higher than the abundance of microplastics in sediments presented by different studies in other regions on Earth. To enable a better comparison within different studies a unification of the sampling, separation and analysis methods is needed. Concluding, this study shows that microplastics are already present in regions as remote as the Arctic deep-sea. |
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