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

Sulphuric acidLiquid


Amount Spilt (T)8000

CAS Number7664-93-9


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

ii, iii

HNS Classification (2010 HNS Convention)

Fate and weathering facts observed/reported

Sulphuric acid is denser than water (d = 1.84). We can therefore safely assume it immediately followed the vessel to the bottom of the sea, gradually dissolving as it went. When mixed with water, the acid releases great quantity of heat. In shallow waters, the water can heat up to the point of boiling. In very deep waters, the pressure would likely prevent boiling. In the absence of a sudden exothermic reaction when the acid sank, the risk incurred by marine flora and fauna was a risk of mortality due to strong acidification of their habitat, situated near the shipwreck. The acid would have dissolved in the seawater, which has a strong neutralizing capacity and represents a huge volume. The pH would therefore return rapidly to its original level in the area affected. At the depth in question (4600-4700m), the sea bed populations have a low biomass per surface unit, are low in diversity and are not the subject to any exploitation. There is therefore no risk in terms of fishing, and the environmental impact is too temporary and localized to be quantified.

Material Safety Data Sheets (MSDS)