Microplastics – An emerging threat not only for marine ecosystems
Since the middle of last century the global production of plastics was accompanied by an accumulation of plastic litter in the marine environment. Being dispersed by currents and wind, persistent plastic items are rarely degraded but become fragmented over time. Together with micro-sized primary plastic litter (pellets) these degraded secondary micro-fragments lead to an increasing amount of small plastic particles, so called “microplastics” (MP), in the aquatic environment. An increasing number of studies and publications have demonstrated the ubiquitous presence of MP in marine habitats, but freshwater environments (e.g. lakes, rivers, estuaries) have not been sufficiently explored until now. Furthermore, a comparison of studies is mostly hampered by the lack of standardized methods for sampling, extraction and analysis. Concerning the latter it was already shown, that the -still used- classification, identification and counting of MP by means of stereo-microscopy and “expert-knowledge” lead to drastic overestimations of the MP load. However, meanwhile this problem is recognized by the scientific community and more suitable techniques (FTIR, Raman, PyGCMS) are increasingly applied. In general MP harbour the risk of entering food webs and of being propagated up the food web thereby harbouring the risk of ending up in human food. The consequences can be severe as MP can release toxic additives upon degradation and accumulate persistent organic pollutants (POPs). In contrast to interactions of large marine organisms with microplastics, the interaction of microorganisms with plastics is of completely different nature. Plastic particles function as habitats and are rapidly colonized by marine microorganisms which form dense biofilms on the plastic surface. Still little is known about the qualitative and quantitative composition of biofilms on microplastics surfaces, but previous studies suggest that floating microplastic particles might function as vectors for the dispersal of microorganisms to new habitats. This is especially problematic as these studies report the presence of toxic and pathogenic alien species which potentially pose a risk of invasion when arriving in new habitats with favourable conditions. Furthermore, a few recent studies report evidences for the biodegradation of microplastics by marine bacteria but there is still a fundamental lack of information concerning this topic. Biofilm formation can also alter the buoyancy and stickiness of floating microplastic particles leading to an export to the deeper ocean and sediments. Meanwhile, scientists and authorities worldwide have recognized the massive accumulation of MP in the aquatic environment. On the part of the EU monitoring is mandatory within the framework of the Marine Strategy Framework Directive (MSFD – indicator 10.1.3). However, although the potential risks of MP have been acknowledged the various potential impacts of MP in the aquatic environment have not been investigated in detail and are far from being understood.
Recent results indicate that the recorded numbers of plastic particles strongly increase towards smaller sizes in the low micrometre range. Of particular interest are particles smaller than 1 µm, the so-called nanofraction. Their small size and high surface area allow them to penetrate more deeply into organisms as well as adsorb and transport organic contaminants. Studies regarding nanoplastics identification, formation and sampling are only at the beginning. With nano-FTIR a new technology was developed that allows to visualise and simultaneously identify nanoplastics, providing new means to address these topics.
PACES: Topic 2 WP2
- Microplastics in the North Sea (in-house project; PIs: Claudia Lorenz (DBU stipend), Sebastian Primpke and Gunnar Gerdts)
- Fram Pollution Observatory / Microplastics in the Arctic (in-house project; PIs: Melanie Bergmann, Ilka Peeken and Gunnar Gerdts)
- “Microplastics Reactor” and “Sediment Separator” (in-house technology transfer projects; PI: Gunnar Gerdts)
- Biofilms on Microplastics (in-house project; PIs: Inga Kirstein, Antje Wichels and Gunnar Gerdts)
- JPI-O/BMBF project BASEMAN - Defining the baselines and standards for microplastics analyses in European waters); http://www.jpi-oceans.eu/ecological-aspects-microplastics (PIs: Sebastian Primpke and Gunnar Gerdts)
- WT.SH project “Size is important” (PIs: Michaela Meyns and Gunnar Gerdts)
- BMBF/FONA project PLAWES - Mikroplastikkontamination im Modellsystem Weser – Nationalpark Wattenmeer: ein ökosystemübergreifender Ansatz (PI: Gunnar Gerdts, Antje Wichels)
- BMWi-ZIM project PLAMOWA „MP Reaktor“ (PI: Gunnar Gerdts)
- BIS Project TRAMIS - Translokation von Mikroplastik in Speisefischen (PI: Gunnar Gerdts, Matthew James Slater (ZAF))
- AWI Strategy funding project OMAP - Oysters and mussels under anthropogenic pressure: Does microplastic limit the tolerance to climate change of ecologically and economically important bivalves? (PI: Gunnar Gerdts, Christian Bock (Integrative Ecophysiology))
- UBA-UFOPLAN project - Folgebewertung und Etablierung einer Langzeitüberwachung der Belastung verschiedener Meeresbereiche und Biota durch marine Abfälle (Meeresmüll) (PI: Gunnar Gerdts)
- DFG project Deep-MiPoll - The role of hadal zones in the long-term fate of marine microplastics: Identification of microplastics in the deep sea of the Kuril-Kamchatka Trench, Northwest Pacific (PIs: Angelika Brandt (Senckenberg Gesellschaft für Naturforschung), Gunnar Gerdts)