Micro plastics

These results confer with the findings of Jambeck (discussed in the earlier blog post 'How much of our trash ends up in the oceans), who found that only 2% of the worlds annually produced plastic waste ended up in the oceans.

Given a quadrupling of plastic production in recent years we would expect to see that oceanic plastic pollution has as such increased. Given the laxities of pollution legislation it seems unlikely that pollution levels have dropped. This conundrum leads me to ask the question: where has all the pollution gone?

Given the properties of plastic scientists have begun to consider that the relative abundance and mass of plastics within the oceans isn't as high as models predicted due to:

• Biodegradation of 'macro' sized plastic to smaller particles 'microplastics' (Law et al, 2010)
• Sinks of pollution

One potential sink of plastic pollution is proposed by Thompson et al (2004). Thompson identifies th presence of micro plastic accumulation on shorelines and in the water column, whereas comparatively large plastic pieces accumulate in near surface waters. Thompson continues in later work to identify the presence of plastic on the deep sea floor and in other remote regions of the globe, after exploring sites in the Mediterranean Sea and the Indian and Atlantic Oceans.  Thompson concludes that every square kilometre of deep ocean contains 4 billion plastic fibres, compared with a billion fibres found in surface and coastal waters. Thomson results show a large prevalence of microfibres within the ocean system, stating that its presence is ubiquitous in the deep sea.

Since the work of Law and Thompson the NOAA in the USA has defined microplastics as plastic fragments less than 5mm in diameter (Arthur et al, 2009).

Work by Goldstein et al (2012) confers with the work of Thompson in agreeing that micro plastic abundance is increasing in the oceans.