EGU2020-21376
https://doi.org/10.5194/egusphere-egu2020-21376
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The influence of biofilms and mineral loading on marine plastic fate

Nicole Rita Posth1, Joan Antoni Carreres Calabuig1, Sascha Mueller1, Kelsey Rogers1, and Nynke Keulen2
Nicole Rita Posth et al.
  • 1Department of Geosciences and Natural Resource Management (IGN), Geology Section, University of Copenhagen, Copenhagen K, Denmark
  • 2Geological Survey of Denmark & Greenland (GEUS), Copenhagen K, Denmark

Plastic pollution is a global concern and potential marker of the Anthropocene, yet controls on the environmental fate of this contaminant remain underexplored. Synthetic polymers emitted to aquatic systems undergo chemical, physical and biological forces that affect their weathering, aggregation, degradation, leaching, transport and burial. In the aquatic environment, plastic surfaces attract both biological and mineralogical loading. The presence of biofilm on marine plastics suggests a significant microbial role in the fate of plastic in this new ecological niche, called the Plastisphere. Microorganisms may influence degradation, transport and burial of plastic in the sediment, but also plastic´s incorporation into biogeochemical cycles. Likewise, mineral crystallization on plastic surfaces (i.e., phosphate, iron – rich) induced by microbial processes or formed abiotically may play an important role in plastic aggregation, transport, degradation and burial of meso- to nanoscale size plastics. 

Here, we present our current field and laboratory investigations of biological and mineralogical loading of plastics in various geochemical settings. We combine bioimaging (He-ion microscopy (HIM), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), microbial community and eco-physiology studies, as well as elemental analysis to test mechanisms of loading on plastics, aggregation, transport, and potential impact on element cycling. Results of an on-going in situ study of polystyrene (PS), polyethylene (PE), marine paint, and wood exposed in Svanemøllen Harbor, Copenhagen and laboratory experiments are described. We explore whether surface characteristics and biogeochemical setting are important drivers for the development of mineral-rich biofilm and the role of these mineral-microbe associations in the fate of plastics.

How to cite: Posth, N. R., Carreres Calabuig, J. A., Mueller, S., Rogers, K., and Keulen, N.: The influence of biofilms and mineral loading on marine plastic fate , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21376, https://doi.org/10.5194/egusphere-egu2020-21376, 2020

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Presentation version 1 – uploaded on 06 May 2020
  • CC1: PE and biofouling on sediment-water interface, Gholamreza Shiravani, 06 May 2020

    Hi dear author(s),

    you mentioned "PE exposed to the sediment water interface", but PE because of its lighter density compared to water is buoyant.

    - Did you run your experiments on a floating PE and allowed to sink by means of biofouling or you forced PE to stay at bed?

    -by "Sediment water interface", do you mean seabed?

    Regards!

    • AC1: Reply to CC1, Nicole R. Posth, 06 May 2020

      Yes, we have been looking in biofilm formationa and potential degradation in situ at Svanemøllen Harbor using three ways to "anchor" the plastic. 

      1. We have some plastic (PE and PS) floating at the surface and attached as flags to a float
      2. We have placed some of the plastics into cages and hung at 1 m depth and also at bottom waters (near sediment). Note: water depth here is ~3 m throughout the year.
      3. And in order to investigate potential sediment degradation processes across any redox gradients, we have also fixed these plastics into windowed frames (so that the pre-UV degraded plastic sheet is directly exposed to sediment & porewater but also easy to harvest for study). In this way, we could insert the plastic and study plastic buried at known depth (and defined biogeochemical conditions) over time. 

      The overall aim is test the potential processes the plastic will undergo at different phases of transport and deposition over time. 

      • CC2: Reply to AC1, Gholamreza Shiravani, 06 May 2020

        Thanks for your answer. You did the experiments for one year. Could you propose a growth rate (N/m2/month) for the attached micro-organisms on MPs? Is the polymer-type important for micro-organisms?Could you provide : temperature, salinity and percentage of sonny days over the measurments period?