Understanding the Fragmentation Pattern of Marine Plastic Debris

Abstract

The global estimation of microplastic afloat in the ocean is only approximately 1% of annual global plastic inputs. This reflects fundamental knowledge gaps in the transformation, fragmentation, and fates of microplastics in the ocean. In order to better understand microplastic fragmentation we proceeded to a thorough physicochemical characterization of samples collected from the North Artlantic subtropical gyre during the sea campaign Expedition seventh Continent in May 2014. The results were confronted with a mathematical approach. The introduction of mass distribution in opposition to the size distribution commonly proposed in this area clarify the fragmentation pattern. The mathematical analysis of the mass distribution points out a lack of debris with mass lighter than 1 mg. Characterization by means of microscopy, microtomography, and infrared microscopy gives a better understanding of the behavior of microplastic at sea. Flat pieces of debris (2 to 5 mm in length) typically have one face that is more photodegraded (due to exposure to the sun) and the other with more biofilm, suggesting that they float in a preferred orientation. Smaller debris, with a cubic shape (below 2 mm), seems to roll at sea. All faces are evenly photodegraded and they are less colonized. The breakpoint in the mathematical model and the experimental observation around 2 mm leads to the conclusion that there is a discontinuity in the rate of fragmentation: we hypothesized that the smaller microplastics, the cubic ones mostly, are fragmented much faster than the parallelepipeds.

Using Numerical Model Simulations to Improve the Understanding of Micro-plastic Distribution and Pathways in the Marine Environment

“…Quantitative estimates of losses (and budgets) would fundamentally be improved with a more complete understanding of how microplastics move in the environment. Researchers are working on mesocosm or other small-scale experiments in the laboratory to look at wave action, fouling, and other aspects that affect movement (Gerritse et al, 2015;Fazey and Ryan, 2016a,b;ter Halle et al, 2016), but such exercises are relatively new and have yet to be applied at larger scales. There is a clear niche for experimental work in improving our understanding of plastic movement and the use of local, regional, and global models can significantly also significantly contribute to improving our understanding of the issue (see Table 1 for some of the available ocean circulation models and oceanographic datasets used for marine debris modeling/tracking).…”

Microfiber Masses Recovered from Conventional Machine Washing of New or Aged Garments

“…9,10 To date, microplastic origins are incompletely understood, but they include primary and secondary sources, with the latter including breakdown of products upstream of, or within, the environment. 3 In situ environmental fragmentation 11 is a difficult-tocontrol microplastic source because it stems from larger plastic debris continuously entering the environment. 3 However, the release of microplastics upstream conceivably could be managed if sources are identified and controlled.…”

Microplastic Distribution at Different Sediment Depths in an Urban Estuary

“…Microplastics are commonly found in the environment in three forms; fragments which form from mechanical and biological fragmentation of larger plastic items (ter Halle et al, 2016), microbeads which are manufactured as abrasives in cosmetics and air-blasting (Fendall and Sewell, 2009;Mason et al, 2016), and microfibers from sources such as synthetic fabrics and ropes (Browne et al, 2011). Studies have shown multiple damaging effects of microplastics in the environment, including adsorption of toxic organic contaminants (Endo et al, 2005;Teuten et al, 2007;Rochman et al, 2013), ingestion by animals with implications for human consumption (Van Cauwenberghe and Janssen, 2014;Rochman et al, 2015) and changing the heat transfer and water movement of sediment (Carson et al, 2011).…”