A recent study of the River Thames in London, UK, found ” that a large unseen volume of submerged plastic is flowing into the marine environment”. Over a three month period, nets attached to the river bed caught 8,490 submerged items, most of which were of some type of plastic. The most contaminated sites were in the vicinity of sewage treatment works. More than 20% of the items were components of sanitary products. While floating litter is visible, the authors claim that this study demonstrates that a large unseen volume of submerged plastic is flowing into the marine environment.

The frequency of articles of this kind is increasing and the study undertaken by the Royal Holloway college researchers is easily replicated by groups all over the world. GallonDaily has little doubt that the research will be replicated and that similar results will be found in many rivers that flow through urban areas.

The challenge is what to do to mitigate or eliminate the problem. Another recent review paper by a scientist in the Department of Public Health, University of Otago, New Zealand, claims to discuss some of the ways to mitigate the problem but its proposals are somewhat limited:

• more research to assess the actual threat posed by plastic debris to marine species;
• more international legislation such as the 1978 Protocol to the International Convention for the Prevention of Pollution from Ships, but the existing Protocol is widely ignored;
• more national legislation, but this comes with the big challenge of enforcing it in an area as vast as the world’s oceans;
• education is also a very powerful tool to address the issue. Since land-based sources provide major inputs of plastic debris into the oceans, if a community becomes aware of the problem, and obviously willing to act upon it, it can actually make a significant difference.
• biodegradable and photodegradable plastics, but the effects of the final degradation products of those materials are not yet known, and there is the danger of substituting one problem for another.

Though we have some doubts about the effectiveness of the initiatives presented in the review paper, GallonDaily concurs that the environmental hazards that threaten the oceans’ biodiversity, such as the pollution by plastic debris, must be urgently addressed. Almost all industry is engaged with plastics in one form or another. A major Canadian initiative to identify and implement ways to reduce, and eventually eliminate, the problem of marine pollution by plastics could play a valuable role.

The River Thames study is available at http://pure.rhul.ac.uk/portal/en/publications/plastic-in-the-thames-a-river-runs-through-it(4fa9f702-c47f-4479-9f21-90f6f6d9a6fb)/export.html The abstract is free, a subscription or a fee is required for the full paper.

The paper The pollution of the marine environment by plastic debris: a review is available at no cost at http://www.sciencedirect.com/science/article/pii/S0025326X02002205