Fragmentation and biodegradation rates of weathered plastics in the marine environment - The new challenges

Summarization: Plastic debris represents a significant problem among the various problems facing the marine environment. In this work we focus on the determination of fragmentation rates, which represent the rate of microplastics generation in the marine environment (plastics weathered on beach sand as well as plastics weathered while floating in seawater) and we shall also present biodegradation data for weathered plastic films. The HOBO Pendant Temperature & Light Data Logger was used to measure temperature in the range -20 to 70 oC and light radiation (illuminance) in the range 0 to 320,000 lux. Integration over time of the latter gives the cumulative luminance exposure of the monitored area. A novel technique to determine experimentally the onset of fragmentation was employed which was linked to the degree of weathering by exposure to natural sunlight. On the other hand, the indigenous pelagic microbiome was incubated with polyethelene (PE) weathered films and showed promising results. In particular, the acclimated consortia reduced more efficiently the weight of PE films in comparison to non-Acclimated bacteria. The SEM images revealed a dense and compact biofilm layer while the rheological results suggest that the polymer had wider molecular mass distribution and a marginally smaller average molar mass after microbial treatment. Concerning the microbial communities attached on the plastic pieces as biofilm, a shift in the PE-Associated microbial assemblages was observed towards efficient degrading microbial network. Taking into account the above results, we can suggest that the tailored indigenous marine community represents an efficient consortium for degrading weathered PE plastics prior to their fragmentation to microplastics.Παρουσιάστηκε στο: 40th Arctic and Marine Oilspill Program - Technical Seminar on Environmental Contamination and Respons