Hazardous and Noxious Substances Spill Incidents

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On this database it is collected information on the fate and weathering of hazardous and noxious substances (HNS) accidentally spilt at the sea around the world. It gathers and systematizes existing information to assist stakeholders involved in spill preparedness and response, and builds return of experience datasheets for the chemicals involved. It will facilitate the incorporation of lessons from past incidents on the decision process to improve preparedness.

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HNS Spilt



Amount Spilt (T)600

CAS Number-


Physical Behaviour (SEBC code)


Pollution Category (MARPOL Annex 2)


Class according to IMDG code


Subsidiary Risk Class according to IMDG code

Classification as Marine Pollutant


HNS Classification (2010 HNS Convention)

Fate and weathering facts observed/reported

The sea grass bed, Posidonia sp. (a protected species since 1988) and the sessile animals were covered by a thick layer of wheat, ranging from dozens of centimetres to several metres. Wheat had been sprayed with 15 kg of biodegradable pesticide with a half life in seawater of no more than a few days. The pesticide had been diluted in 250 L of vegetable oil to mitigate dust and prevent infestation by weevils. The pumping operation commenced on 4th December and the wheat was allowed to drip dry via a sieve system situated in a hosepipe used for disposing of the polluted water far from the creek. Emissions of hydrogen sulphide, in addition to significant quantities of methanol and ethanol affecting men and equipment led the Préfecture Maritime to suspend the operation on 20th December for health reasons. After appropriate protection of workers, cleaning proceeded. CEDRE had already closely examined the fermentation process and the hydrogen sulphide emissions caused by microbial proliferation of sulphate-reducing bacteria. Wheat degradation processes was monitored in addition to bacteriological developments in the polluted area. The work in question is currently underway and will allow our scientists to gain more knowledge about wheat degradation kinetics, bacteriological pollution developments, how long it takes fauna and flora, and in particular the Posidonia beds, to recolonize in addition to ascertaining whether or not to reinstate the Posidonia beds in a bid to speed up recolonisation. According to the information currently available, eight hectares of Posidonia have been affected one way or another. A serious impact has been noted in 3.9 hectares and complete destruction of the grass beds has been reported on 2 500 m2 of Posidonia. The effect is therefore evident but is thankfully limited to a small portion of the park that covers 10,000 hectares. Fermentation also caused local acidity.

Material Safety Data Sheets (MSDS)