Vessels can legally discharge certain tank cleanings int the sea, even in sensitive areas. It needs to stop, say researchers.
A loophole in regulations that allows certain oils and chemicals to be legally pumped into the sea from tankers needs to be closed say scientists.
The problem comes from the process of chemical and product tankers having to thoroughly clean their cargo tanks between cargoes of different grades to prevent contamination.
The process of cleaning is often with water and while there are strict regulations about discharges from mineral oils, the problem is more with fats and bio-oils such as the increased volume of shipped vegetable oils and biofuels.
Researchers issued a paper late last year and were taking part in a briefing in Stockholm recently to discuss their proposals which they would like to see passed at a European or international level to cover the Baltic Sea and even the North Sea.
Their call for tougher regulations comes after Swedish authorities detected a 10km2 slick from 600 liters of palm oil believed to have been discharged during tank cleaning.
While the vessel was identified there was nothing the authorities could do to either tackle the spill or detain or fine the vessel, despite it being boarded.
“This is something we see more and more often in our waters,” said Jonatan Örn from the Swedish Coastguard at the time. “Transports of various substances used above new fuels are increasing, and thus this type of discharges. Unfortunately, there is a lack of effective legal tools to deal with it today.”
The coastgurd said that spills of this type of oil are difficult, often not even possible, to combat. In this case, it is crude palm oil, which is used both for food and biofuel, and while it does breakdown eventually it can contaminate wildlife such as seabirds just like any other oil.
There are other chemcials which can be legally discharged into the sea, but which researchers say subsequently breakdown into dangerous chemicals.
The researchers from Chalmers University want to see the rules that apply to fuels and certain known pollutants to be applied to these lower grade cargoes.
Under these stricter rules a vessel’s cargo tank will have a prewash while still alongside after cargo discharge, and this wash water then pumped ashore. Other chemicals and oils, such as palm oil, can be pumped over the side of the ship during tank cleaning, under certain onditions such as volumes, distance from the shore, ships speed and it being under the water surface.
Not only should the discharge loads be reduced but the Baltic and possibly the North Sea should be further designated with complete discharge bans.
