How bad could the ship collision be for the environment?

How bad could the collision in the North Sea of an oil tanker and a cargo ship be for the environment?

Environmental organisations and the UK authorities are assessing the potential fallout for marine species and nearby wildlife populations from toxic chemicals.

While it's still too early to tell whether this will have a major impact, and weather conditions in coming days will be a major factor, a lot will depend on exactly which and how much of these substances were on the ships and how much has spilled.

Maritime operations company, Crowley, which was managing the oil tanker the MV Stena Immaculate, has confirmed that it was carrying 220,000 barrels of jet fuel in 16 containers at the time of the incident.

It was not clear on the status of all the containers but Crowley said one had "ruptured" and was leaking fuel into the sea.

The contents of the cargo ship, the Solong, which crashed into the tanker have been less clear.

Lloyds List, a shipping data company, said on Monday that it was carrying sodium cyanide.

But on Tuesday Ernst Russ, owners of the cargo ship said: "We are able to confirm that there are no containers on board ladened with sodium cyanide.

"There are four empty containers that have previously contained the hazardous chemical and these containers will continue to be monitored."

It remains unclear if the ship was carrying other contents at the time of the crash.

Jet fuel is a toxic substance that can be lethal to marine organisms and other animals like seabirds if ingested.

The level of toxicity is dependent on the crude oil that it has been refined from.

Sodium cyanide, which is used in industry including for metal cleaning, is a also a toxic substance and poisonous for living organisms as it disrupts cell function and leads to oxygen starvation.

Sodium cyanide is also highly soluble in water and it can react vigorously to produce the gas hydrogen cyanide - which is also toxic.

The confirmation that it was only empty containers on board will allay some concerns about environmental damage and make the clean-up operation easier.

The third consideration for authorities will be whether the fuel used to run both ships - the bunker fuel - has also leaked out.

Marine fuel is a lot heavier than jet fuel and can remain in the environment for longer.

Alex Lukyanov at the University of Reading, UK, said. "Marine diesel can smother habitats and wildlife, affecting their ability to regulate body temperature, potentially resulting in death."

"The environmental toll could be severe," he said.

The collision happened within an environmentally rich area - both for marine species but also onshore populations of birds who feed on fish and other aquatic organisms.

The Humber Estuary is a site of special scientific interest and along with Bempton Cliffs Nature Reserve supports more than half a million birds annually including pink footed geese, puffins, avocets and bar-tailed godwits.

Within the wider marine environment at this time of year there are breeding seals and harbour porpoises.

Martin Slater, Director of Operations at Yorkshire Wildlife Trust said the time of the year that this spill has occurred is particularly worrying.

"Many birds are gathering offshore on the sea ahead of the nesting season and we still have wintering waders – plus migrant birds stopping here – so we're very worried indeed about the threat to these birds," he said.

There is also concern for wildlife further south of the incident to which the jet fuel may spread depending on the wind and sea conditions.

The area off Lincolnshire's coast is "a unique habitat for fish where seabirds and cetaceans feed" explained Mr Slater.

Ecology experts have pointed out that animals do have reactionary mechanisms that mean the noise and smell of the crash will have alerted them to dangers and they could have already vacated the area.