Volume 447, Pages 1-526 (1 March 2013)

Scott Lambert, Chris J. Sinclair, Emma L. Bradley, Alistair B.A. Boxall, Effects of environmental conditions on latex degradation in aquatic systems, Science of The Total Environment, Volume 447, 1 March 2013, Pages 225-234, ISSN 0048-9697, 10.1016/j.scitotenv.2012.12.067.
(http://www.sciencedirect.com/science/article/pii/S0048969712016245)
Abstract: Following use polymer materials may be released to the natural environment distributed to various environmental compartments and may undergo a variety of mechanical and chemical weathering processes. This study characterised the degradation of a latex polymer of different thicknesses under a range of environmental conditions in outdoor microcosms. Samples were immersed in either demineralised water, artificial freshwater and marine water media and exposed for a period of 200–250 days with exposure starting at different times of the year. Effects of pH, agitation and the exclusion of light on degradation were also studied. At the end of the exposure period, recovery of polymer material ≥ 1.6 μm ranged from a low of 22.04% (± 16.35, for the freshwater treatment at pH 5.5) to a high of 97.73% (± 0.38, for the exclusion of light treatment). The disappearance of the bulk material corresponded to an increase in nanoparticles and dissolved organic material in the test media. Modelled degradation kinetics were characterised by multi-phasic degradation patterns and the results indicated degradation rate is affected by light intensity and polymer thickness. Mass balance analysis indicates that losses of volatile materials to the air compartment may also be occurring.
Keywords: Polymers; Latex; Degradation; Nanoparticles; Photoxidation

Volume 416, Pages 1-542 (1 February 2012)

Christin Müller, Kathy Townsend, Jörg Matschullat, Experimental degradation of polymer shopping bags (standard and degradable plastic, and biodegradable) in the gastrointestinal fluids of sea turtles, Science of The Total Environment, Volume 416, 1 February 2012, Pages 464-467, ISSN 0048-9697, 10.1016/j.scitotenv.2011.10.069.
(http://www.sciencedirect.com/science/article/pii/S0048969711012630)
Abstract: The persistence of marine debris such as discarded polymer bags has become globally an increasing hazard to marine life. To date, over 177 marine species have been recorded to ingest man-made polymers that cause life-threatening complications such as gut impaction and perforation. This study set out to test the decay characteristics of three common types of shopping bag polymers in sea turtle gastrointestinal fluids (GIF): standard and degradable plastic, and biodegradable. Fluids were obtained from the stomachs, small intestines and large intestines of a freshly dead Green turtle (Chelonia mydas) and a Loggerhead turtle (Caretta caretta). Controls were carried out with salt and freshwater. The degradation rate was measured over 49 days, based on mass loss. Degradation rates of the standard and the degradable plastic bags after 49 days across all treatments and controls were negligible. The biodegradable bags showed mass losses between 3 and 9%. This was a much slower rate than reported by the manufacturers in an industrial composting situation (100% in 49 days). The GIF of the herbivorous Green turtle showed an increased capacity to break down the biodegradable polymer relative to the carnivorous Loggerhead, but at a much lower rate than digestion of natural vegetative matter. While the breakdown rate of biodegradable polymers in the intestinal fluids of sea turtles is greater than standard and degradable plastics, it is proposed that this is not rapid enough to prevent morbidity. Further study is recommended to investigate the speed at which biodegradable polymers decompose outside of industrial composting situations, and their durability in marine and freshwater systems.
Keywords: Marine debris; Digestive system; Sea turtle; Chelonia mydas; Caretta caretta; Moreton Bay