Marine oil pollution
Marine oil pollution happens through spills, accidents, and leaks of diesel, fuel and other petroleum-based products getting into the sea.
Organisations such as Northland Regional Council are constantly working with the community to minimise oil pollution and its impacts.
What is the risk of a marine oil spill in Northland?
Northland has one of New Zealand’s highest oil spill pollution risks. This is because it is home to the country’s only oil refinery at Marsden Point near the entrance to Whangārei Harbour, and one of New Zealand’s busiest shipping routes also passes the region’s east coast.
An oil tanker in Whangārei Harbour to discharge crude oil at Marsden Point oil refinery.
Large overseas oil tankers carry more than 100,000 tonnes of unprocessed crude oil to Marsden Point oil refinery and deep-water port, making more than 400 visits each year.
The oil is discharged from the tankers to the refinery where it is then refined or transformed into various petroleum-based products. These are taken to other parts of New Zealand on coastal tankers or through a giant pipeline running from Marsden Point to Auckland.
Lots of other ships carrying general cargo, containers, logs and woodchips constantly call in to Marsden Point or travel past on their way to other ports. More than 200 ship visits are made to Portland cement works each year.
A ship heads to the Portland cement works. (Photo: Edward Fitzgerald).
This shipping traffic is continually increasing because of port expansions, bigger ships and significant increases in the amount of ship’s fuel (bunker fuel) that is transported along Northland’s coastline.
The Queen Mary II is one of more than 60 cruise ships that visit the Bay of Islands every year.
More than 60 cruise ship visits are made to the Bay of Islands each year and the number is growing as Northland’s popularity as a tourist destination grows. Northland’s commercial fishing fleet, combined with all manner of recreational yachts, launches and runabouts, contributes to an extremely busy coastal maritime scene in our region, and increases the risk of marine oil pollution incidents.
Likely sources of Northland’s oil spills are:
- Ships or boats sinking, listing or grounding
- Contaminated bilge water discharging from ships or boats
- Accidents when refuelling ships or boats
- Small oil slicks resulting from spills from motor vehicle accidents and road runoff during heavy rain.
The source of half of Northland’s reported oil spills cannot be identified.
This fishing boat grounded on the beach at Waipapakauri Landing. Fuel and oil was removed by regional council staff before the vessel was demolished and taken away by contractors.
What are some of the effects of oil pollution?
Northland has one of the most beautiful and pristine coastlines in New Zealand. Thousands of people use the coast for activities including fishing, swimming, diving, sailing, surfing and shellfish gathering. Even very small marine oil spills cause environmental damage and impact on social and cultural values.
While an oil spill on exposed sandy beaches and rocky shores would be unsightly, these areas would be expected to recover more quickly than the estuarine areas of our upper harbours. This is because the wave action would help agitate, disperse and break down the oil.
The most sensitive parts of the coastal marine area are our estuaries and harbours. The vegetation growing in these areas - such as mangroves, eelgrass and salt-marsh – plays an important part in the environment. The plants oxygenate estuary waters, trap sediment, and provide safe shelter for many varieties of fish, invertebrates and birds to live and to breed. Estuary plants are very sensitive to oil pollution and do not recover well.
The effect of oil on sea birds can be devastating. The oil clogs their feathers causing the birds to lose their waterproofing. Thin oils are also highly toxic. The birds might swim through the film of oil without problems but then die once they go back to their nest and start preening. The effect on wildlife can continue for a long time after obvious signs of the spill have disappeared.
Scraping up oiled sand off a beach in the Whangārei Harbour after a spill from a ship at Northport.
Marine mammals such as seals may be killed outright if they contact oil after surfacing. Oiled wildlife survivors can be successfully cleaned and rehabilitated, but it is a long process that can take up to six weeks. Some of them die from the stress of being cleaned thoroughly. The Poor Knights Islands Marine Reserve is highly sensitive to oil pollution. While it is characterised by exposed rocky shores that would recover reasonably quickly from an oil spill, the marine and bird life living in and around the islands is special and internationally important. An oil spill would be devastating in this protected area.
An oiled Motiti Island penguin being treated by the Wildlife Response Unit after the "Rena" oil spill near Tauranga.
Oil spills are not good for people either. The greatest human health risk is from explosion or fire at a spill site. Breathing in toxic benzene vapours is dangerous and a few breaths can be fatal. Lesser side effects include headaches, dizziness, nausea, vomiting, abdominal pains, skin rashes and irritation.
What is Northland Regional Council’s role in an oil spill emergency?
Northland Regional Council is responsible for dealing with oil spills in the coastal marine area extending 12 miles out to sea from the land. Spills are dealt with at a local or regional level if the estimated clean-up cost is less than $250,000 and there are enough local resources to do the job. Oil spills beyond this scale escalate to national emergencies and become the responsibility of Maritime New Zealand. An incident command centre is activated at the council’s Whangārei head office when needed.
Council's oil spill response team work with other organisations to train for an oil spill emergency.
The council has a Marine Oil Spill Contingency Plan for the region, and a 24/7 team that is trained specifically to deal with oil spill emergencies. This team comprises council staff and trained personnel from organisations including Northport Ltd, North Tugz, and Refining New Zealand. The Department of Conservation and wildlife agencies like the Whangārei Native Bird Recovery Centre and the Ornithological Society of New Zealand can assist with a wildlife response.
Many of Northland’s responders are also members of the national response team which may be called upon to respond to a spill anywhere in New Zealand.
Booms are deployed to contain an oil spill and stop it spreading into estuaries, channels or bays.
Oil Spill Response Equipment
Specialised Maritime New Zealand oil spill response equipment worth more than $1million is stored in Northland ready for use in an emergency. It includes:
- The “Taranui”, a self-propelled oil skimming recovery vessel. The skimmed oil is sucked from the water and stored in temporary storage tanks
- An oil boom - a floating fence made of material that absorbs oil, such as sphagnum moss or wool. The boom is used to contain an oil spill and stop it spreading, or to block off an estuary, channel or bay so oil cannot pass through. The boom has floats on one side and chain at the bottom to hold it in place in the sea
- Absorbent pillows and pads
- Specialised wildlife equipment for capturing and cleaning birds.
More equipment can be brought in from around New Zealand and overseas if needed.
The self-propelled oil skimming recovery vessel "Taranui" in action during an oil spill exercise.
The oil spill response trailer packed with protective clothing and absorbent pads for soaking up oil.
Types of oil pollution
Spilled oil spreads quickly. Its movement will be determined by tides and sea current as well as wind speed and direction. Oil will move at the same speed as the water carrying it and about three per cent of wind speed.
Some oils evaporate or disperse naturally within hours of being spilled while others will persist in the environment for much longer.
Types of oil commonly transported or used in Northland and the likely time to disperse naturally are:
|Time to dissipate naturally
|A few hours to one day
|A few hours to one day
|Up to one day
|Light marine diesel
|One to two days
|Light fuel oil
|One to four days
|One to seven days
|Heavy fuel oil
|One to two weeks
|Bitumen and crude oils
|Months, but will probably sink out of sight if not cleaned up
There is a lot of difference in crude oils depending on where in the world they come from. They are unprocessed oils with complex chemical make-ups containing as many as 300 different compounds. An international crude oil database has been put together by oil companies showing the different physical and chemical properties of their products. Information from this database lets the emergency response team know what it is dealing with. The different mixtures affect how the oil behaves on water and can determine the way in which oil spills can be cleaned up.
Heavier fuels, most likely to be encountered at Marsden Pt, will not evaporate so easily. They must be treated with dispersants or collected in booms and skimmed into containers. Sometimes choppy water ‘whips’ spilt oil until it looks like a frothy chocolate mousse, which is very difficult to dispose of because it floats easily and forms large masses.
Oil on rocks is very difficult to clean and requires a lot of labour to clean by hand.
Keeping detailed records of all that happens in an emergency oil spill response is an important part of the job. Northland Regional Council tries to recover maximum clean-up costs from the person or organisation responsible for the spill. Fines of up to $200,000 can be imposed as part of prosecution.
Protection for the Poor Knights
In recognition of the importance of the Poor Knights Marine Reserve and the real potential for an oil spill in the area, large ships (more than 45 metres long) are banned from using the corridor between mid-Northland’s east coast (Bream Head to Cape Brett) and the internationally-famous reserve. This ‘mandatory area to be avoided’ is a world first. It bans ships from the red striped section of the map below. The regional council supported the establishment of the area which was set up by Maritime New Zealand and designated by the International Maritime Organisation.
Tutukaka Coast: The first coastal area in the world (red striped zone) where large ships are legally banned from passing through, has been established to help protect the Poor Knights Islands from being damaged by an oil spill. A spill in 1992 led to a world first ban on large ships passing between the islands and Tutukaka coast mainland.
What to do if you come across an oil spill
Do not touch the spill or any wildlife affected by the spill and be careful not to inhale fuel vapours.
Call Northland Regional Council’s environmental hotline: 0800 504 639 for advice and help. The hotline operates 24 hours a day, seven days a week.