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Southern Ocean, Antarctica, Ship paint, Microplastics, Surface water
Abstract
Microplastics (MP) have been found in nearly all oceans and seas around the world with highest densities mostly recorded in areas directly impacted by human activities or the ocean gyres. Yet, MP pollution has also reached remote regions including the Southern Ocean surrounding Antarctica, where studies are relatively scarce. Further research is needed to help determine possible sources and areas vulnerable to MP accumulations. Ship paints (SP) containing synthetic polymers as e.g. polyurethane, alkyd and epoxy resins have recently been recognized as a MP source and can be released, inter alia, during normal ship operation. However, there is insufficient knowledge about the qualitative and quantitative contributions of MP from this source. In this study, 34 surface water samples were taken in the Weddell Sea one of the most inaccessible places in the Southern Ocean. ATR-FTIR spectroscopy of visually sorted particles (> 300µm, n=771) revealed MP concentrations ranging between 0 and 0.04 MP m-3 (mean 0.01 MP m-3). Polyester accounted for 48% of all assigned particles followed by PE (16%), PP (10%), Acrylates/PUR/varnish (8%) and synthetic resins (7%). Half of the sorted fragments had similar visual characteristics as SP taken from the research vessel as reference. Most of these fragments (90%), however, could not be clearly assigned by ATR-FTIR (HQ < 60%). To further examine the composition and source of potential SP fragments Raman spectroscopy was applied as a complementary technique. Multivariate analyses will be performed to compare the obtained FTIR and Raman spectra of environmental SP with reference samples from the vessel and the same SP freshly applied in the laboratory. Currently, measurements with micro X-ray fluorescence spectroscopy are performed to investigate the elemental composition of the SP particles. Besides providing evidence of MP in one of the most remote areas in the Southern Ocean, this study will evaluate the potential vessel-induced contamination of water samples and enable an evaluation of three different forensic methods to analyze environmental SP fragments.
