An overview of microplastic and nanoplastic pollution in agroecosystems.

Synthetic polymers, commonly named plastics, are among the most widespread anthropogenic pollutants of marine, limnic and terrestrial ecosystems. Disruptive effects of plastics are known to threaten wildlife and exert effects on natural food webs, but signs for and knowledge on plastic biodegradation are limited. Microorganisms are the most promising candidates for an eventual bioremediation of environmental plastics. Laboratory studies have reported various effects of microorganisms on many types of polymers, usually by enzymatic hydrolysis or oxidation. However, most common plastics have proved to be highly recalcitrant even under conditions known to favour microbial degradation. Knowledge on environmental degradation is yet scarcer. With this review, we provide a comprehensive overview of the current knowledge on microbiological degradation of several of the most common plastic types. Furthermore, we illustrate the analytical challenges concerning the evaluation of plastic biodegradation as well as constraints likely standing against the evolution of effective biodegradation pathways.

Prospects for microbiological solutions to environmental pollution with plastics

https://www.fpl.fs.fed.us/documnts/pdf2004/fpl_2004_stark002.pdf

Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and FTIR spectroscopy ☆

In this work, we present for the first time undeniable evidence of nano-plastic occurrence due to solar light degradation of marine micro-plastics under controlled and environmentally representative conditions. As observed during our recent expedition (Expedition 7th Continent), plastic pollution will be one of the most challenging ecological threats for the next generation. Up to now, all studies have focused on the environmental and the economic impact of millimeter scale plastics. These plastics can be visualized, collected and studied. We are not aware of any studies reporting the possibilities of nano-plastics in marine water. Here, we developed for the first time a new solar reactor equipped with a nanoparticle detector to investigate the possibility of the formation of nano-plastics from millimeter scale plastics. With this system, correlated with electronic microscopy observations, we identified for the first time the presence of plastics at the nanoscale in water due to UV degradation. Based on our observations, large fractal nano-plastic particles (i.e., >100 nm) are produced by UV light after the initial formation of the smallest nano-plastic particles (i.e., <100 nm). These new results show the potential hazards of plastic waste at the nanoscale, which had not been taken into account previously.

Marine plastic litter: the unanalyzed nano-fraction

Plastic waste disposal is one of the serious environmental issues being tackled by our society today. Polyethylene, particularly in packaging films, has received criticism as it tends to accumulate over a period of time, leaving behind an undesirable visual footprint. Degradable polyethylene, which would enter the eco-cycle harmlessly through biodegradation would be a desirable solution to this problem. However, the "degradable polyethylene" which is presently being promoted as an environmentally friendly alternative to the nondegradable counterpart, does not seem to meet this criterion. This article reviews the state of the art on the aspect of degradability of polyethylene containing pro-oxidants, and more importantly the effect these polymers could have on the environment in the long run. On exposure to heat, light, and oxygen, these polymers disintegrate into small fragments, thereby reducing or increasing the visual presence. However, these fragments can remain in the environment for prolonged time periods. This article also outlines important questions, particularly in terms of time scale of complete degradation, environmental fate of the polymer residues, and possible accumulation of toxins, the answers to which need to be established prior to accepting these polymers as environmentally benign alternatives to their nondegradable equivalents. It appears from the existing literature that our search for biodegradable polyethylene has not yet been realized.

Willy Demarteau

Papers

Photodegradation of polyethylene: comparison of various photoinitiators in natural weathering conditions

Energy transfer in polymers—I. Triplet-triplet transfer in solid polyvinylbenzophenone-naphthalene system

Energy transfer in polymers—III Polyphenylvinylketone—naphthalene system

Photolysis of polyvinylbenzophenone

Energy transfer in polymers—II Solid polyvinylnaphthalene—benzophenone system and copolymers vinylnaphthalene—vinylbenzophenone