Field and mesocosm methods to test biodegradable plastic film under marine conditions

• Published in: PloS one 2020-07, Vol.15 (7), p.e0236579-e0236579
• Main Authors: Lott, Christian, Eich, Andreas, Unger, Boris, Makarow, Dorothée, Battagliarin, Glauco, Schlegel, Katharina, Lasut, Markus T, Weber, Miriam
• Format: Article
• Language: English
• Subjects: Aquatic ecosystems; Biodegradability; Biodegradable materials; Biodegradable plastics; Biodegradation; Biology and Life Sciences; Bioplastics; Chemical analysis; Closed experimental ecosystems; Coastal ecology; Copolymers; Disintegration; Earth Sciences; Ecology and Environmental Sciences; Ecosystems; Engineering and Technology; Environmental effects; Field study; Field tests; Habitats; Laboratories; Low density polyethylenes; Marine environment; Marine pollution; Mediterranean climate; Metabolism; Observations; Oceans; Physical Sciences; Plastic pollution; Plastics; Polyethylene; Polyhydroxyalkanoates; Polyhydroxyalkanoic acid; Polymer films; Polymeric films; Polymers; Research and Analysis Methods; Sand & gravel; Seawater; Test methods; Test systems; Testing; Water analysis
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0236579

The pollution of the natural environment, especially the world's oceans, with conventional plastic is of major concern. Biodegradable plastics are an emerging market bringing along potential chances and risks. The fate of these materials in the environment and their possible effects on organisms and ecosystems has rarely been studied systematically and is not well understood. For the marine environment, reliable field test methods and standards for assessing and certifying biodegradation to bridge laboratory respirometric data are lacking. In this work we present newly developed field tests to assess the performance of (biodegradable) plastics under natural marine conditions. These methods were successfully applied and validated in three coastal habitats (eulittoral, benthic and pelagic) and two climate zones (Mediterranean Sea and tropical Southeast Asia). Additionally, a stand-alone mesocosm test system which integrated all three habitats in one technical system at 400-L scale independent from running seawater is presented as a methodological bridge. Films of polyhydroxyalkanoate copolymer (PHA) and low density polyethylene (LD-PE) were used to validate the tests. While LD-PE remained intact, PHA disintegrated to a varying degree depending on the habitat and the climate zone. Together with the existing laboratory standard test methods, the field and mesocosm test systems presented in this work provide a 3-tier testing scheme for the reliable assessment of the biodegradation of (biodegradable) plastic in the marine environment. This toolset of tests can be adapted to other aquatic ecosystems.