Highly polluted shipping lane near Sri Lanka
An Indian Ocean shipping lane near Sri Lanka is one of the most polluted shipping lanes in the world, according to latest NASA satellite imagery.
For more than a decade, scientists have observed “ship tracks” in natural-color satellite imagery of the ocean. These bright, linear trails are a visible manifestation of pollution from ship exhaust, and scientists can now see that ships have a more subtle, almost invisible, signature as well.
Data from the Dutch and Finnish-built Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite show long tracks of elevated nitrogen dioxide (NO2) levels along certain shipping routes.
The NO2 signal is most prominent in an Indian Ocean shipping lane between Sri Lanka and Singapore, appearing as a distinct orange line against (lighter) background levels of NO2.
Nitrogen dioxide is a nasty gas produced largely by internal-combustion engines. A small whiff of NO2 is enough to anesthetize the nose, and its chemical byproducts can harm the cardiovascular system and trash a good pair of lungs.
The map is based on OMI measurements acquired between 2005 and 2012.
It’s easy to see the pollution signature above major shipping lanes – the long orange track in the Indian Ocean between Signapore and Sri Lanka, the smudges from Singapore to various ports in China, the L-shaped path through the Red Sea into the Gulf of Aden.
Other shipping lanes that run through the Gulf of Aden, the Red Sea, and the Mediterranean Sea also show elevated NO2 levels, as do routes from Singapore to points in China. These aren’t the only busy shipping lanes in the world, but they are the most apparent because ship traffic is concentrated along narrow, well-established lanes.
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