Shipping is a huge industry as it’s hugely important for trade between countries – over 90% of global trade is done by cargo ships. With around 50,000 merchant ships it’s no surprise there is an issue with them causing marine pollution issues. If you think that one massive container ship is equal to 50 million cars then you should be able to imagine the huge amount of fumes and other pollutants it must be emitting to the atmosphere and our oceans!
How the ships release pollution:
- Release of oil and chemicals – ships obviously need oil/petrol to run and many ships also carry oil around as their cargo; this can then be released into the ocean by accidental spills and operational discharges.
- Release of biocides – antifouling paints (which are used on ship hulls to prevent the build-up of barnacles, algae, sponges, molluscs etc.) generally contain toxic substances; a big concern is tributyltin (TBT) which has been shown to have a damaging effect on the endocrine system – being most problematic in molluscs.
- Air pollution – the fuel used for ships is basically waste oil, it is very thick and contains a lot of sulfur. Shipping is by far the largest transport polluter of sulfur oxides in world, releasing 20 million tons annually.
- Waste disposal – garbage and sewage from the ships is often just dumped in the sea; this contributes to the plastic pollution of the oceans as well as eutrophication.
- Transfer of invasive species – as ships are travelling all over the world they can unintentionally pick up species from one place and carry them to another (generally on their hull or in their ballast water). When new species are introduced to a new environment they can sometimes have a detriment effect and become a pest.
- Physical damage – from dropping of anchors, dredging, noise and wave disturbance and even the hitting of whales and other marine mammals
The distribution of shipping pollution is due to the shipping routes – more damage is detectable in shipping lanes and ports as more ship congestion is found in these places.
Map of the worlds shipping lanes showing the traffic density:
Image: Fred Pierce
So what can be done to reduce the pollution caused by shipping?
Because the shipping industry is so huge and so important for the economy it’s not really something that can be stopped, however measures can be taken to make sure that it is more environmentally friendly. However, as members of the general public all we can really do is make more people aware of the damage that is currently being caused and thus help to persuade large organisations to make a change to the legislation.
The UN Convention on the Law of the Sea (UNCLOS) is basically the rules that all ships on the sea have to apply to:
The International Marine Organisation (IMO) is the organisation responsible for the safety and security of shipping and the prevention of marine pollution by ships. You can check out their website for more details on what they do: www.imo.org
Gizmag.com, (2016). Big polluters: one massive container ship equals 50 million cars. [online] Available at: http://www.gizmag.com/shipping-pollution/11526/ [Accessed 19 Feb. 2016].
MNN – Mother Nature Network, (2016). Eniram outsmarts waves to reduce cargo emissions. [online] Available at: http://www.mnn.com/green-tech/research-innovations/blogs/eniram-outsmarts-waves-to-reduce-cargo-emissions [Accessed 19 Feb. 2016].
Network, M. (2011). 8 Ways in which Cruise Ships Can Cause Marine Pollution. [online] Marine Insight. Available at: http://www.marineinsight.com/environment/8-ways-in-which-cruise-ships-can-cause-marine-pollution/ [Accessed 19 Feb. 2016].
Omae, I. (2003). Organotin Antifouling Paints and Their Alternatives. ChemInform, 34(14).
OSPAR Commission, (2010). Releases of anti-fouling chemicals. Assessment of the impact of shipping on the marine environement. [online] Available at: http://qsr2010.ospar.org/media/assessments/p00440_supplements/p00440_suppl_5_release_of_anti-fouling_chemicals.pdf [Accessed 19 Feb. 2016].
Wwf.panda.org, (2016). Marine problems: Shipping. [online] Available at: http://wwf.panda.org/about_our_earth/blue_planet/problems/shipping/ [Accessed 19 Feb. 2016].