Биотехнологии Biological processing of industrial wastes of various manufactures просмотров - 166
Petroleum oil is formed over millions of years deep under the ground from the remnants of forests and from a mixture of comparatively volatile liquid hydrocarbons (compounds composed mainly of hydrogen and carbon with some nitrogen, sulphur, and oxygen) that occurs in the Earth's crust. While it is a naturally occurring substance, it can be highly toxic and it burns fiercely.
Oil is petroleum in any form including crude oil, fuel oil, sludge and refined products such as diesel and kerosene.
Oil is used as fuel to run many types of engines for cars, planes, ships, tractors and trucks, and is also used to generate a large portion of the world's electrical-power supply. Petrochemicals derived from petroleum are the base for solvents, paints, plastics, synthetic rubber and fibres, soaps and cleansing agents, waxes and jellies, explosives, and fertilisers. Asphalt from petroleum is used to surface roads and highways. Petroleum is also used as a lubricant in a great variety of machines.
Large oil tankers (some of which can carry upwards of 100,000 tonnes of oil) bring crude oil from overseas to New Zealand’s only oil refinery at Marsden Point near the entrance to Whangarei Harbour. The oil is discharged from the tankers to the refinery where it is then refined and transformed into various petroleum-based products. These products are either then transported to Auckland via a big pipeline or transported by coastal tankers to other ports around the country, where they are then distributed to the consumers.
In addition to tankers coming into the refinery, there are also a significant number of general cargo, container and log and woodchip ships that travel to and from the main ports of Marsden Point, Auckland and Tauranga right here on our eastern doorstep. Given the expansion of these ports in the near future, significant increases in shipping movements are expected.
The majority of Northland’s commercial shipping activities are based at Port Whāngārei, Marsden Point and the refinery facilities at Marsden Point. On average there are 100 oil tanker visits and 100 non oil tanker ship visits to these two facilities each year. There are a further 110 visits per year made to the Portland cement out-loading facility and a largely transient fishing fleet where numbers vary between 20 - 40 vessels operating from facilities in the upper Whāngārei Harbour and in other Northland harbours. There are also on average 30 commercial cruise ships that visit the Bay of Islands each year.
Both the Poor Knights Islands and the Hen & Chicken Islands are very close to the navigation routes of ships travelling to and from these ports, and up until recently a large proportion of these ships travelled between the Poor Knights Islands and the Tutukaka coast.
A couple of reasonably significant oil spills in this area in the late 1990’s resulted in a ban being imposed on vessels over 45 metres in length prohibiting them from travelling through the area between the Poor Knights Islands and the mainland. This is called a Mandatory Area to be Avoided.
The majority of oil spills reported are investigated and evaluated and in most cases the source cannot be identified.
However, these are examples where the source has been identified:
vessels sinking, listing or grounding account for about 10% of marine oil spills
discharges of contaminated bilge water from vessels account for about 15% of all marine oil spills
accidents occurring the refuelling of vessels account for 15% of marine oil spills
intentional spills into the storm water drains, spills from motor vehicle accidents and road runoff during heavy rain events can all lead to small oil slicks on the water. While these account for 15% of the oil spills reported, they are not classified as a marine oil spill because the source of the spill did not originate from vessel or refuelling facility. Costs in responding to these incidents are met by the Council unless the spiller can be identified.
Northland has one of the most beautiful and pristine coastlines in New Zealand. Some parts of it like the Whāngārei Harbour and the Bay of Islands are enjoyed by thousands of people, particularly during the summer months, occupied in fishing, swimming, diving, sailing, surfing and shellfish gathering activities. And so it is very important that the coastline and the marine environment are protected from pollution, especially oil spills.
Marine oil spills, even very small spills are likely to cause environmental damage, have impacts on social, cultural and amenity values and may interfere with the commercial and recreational use of the coastal environment.
While an oil spill on exposed sandy beaches and rocky shores would be unsightly, these would most likely recover more quickly then say the estuarine areas of our upper harbours. This is because the wave action would help agitate, disperse and break down the oil. This would assist with clean up operations.
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 are very sensitive to oil pollution and do not recover that well. This vegetation plays an important part in the environment by oxygenating estuary waters, trapping sediment and offering a safe shelter for many varieties of fish, invertebrates and birds to live and to breed. Estuaries are usually dense with vegetation and access is always tricky, so any clean-up operation would be extremely difficult if an oil slick floated in to coat the mangroves and their breathing roots.
The effect of oil on sea birds can be devastating. The oil clogs to 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.
Marine mammals such as seals coming into contact with oil after surfacing may be killed outright. Oiled wildlife not killed outright can be successfully cleaned and rehabilitated but it is a long process which can take up to six weeks. The animals and birds must be cleaned thoroughly, putting them under a lot of stress which could kill them.
The Poor Knights Islands marine reserve is another area that is highly sensitive to oil pollution. While it is characterised by exposed rocky shores which would recover reasonably quickly from an oil spill, the marine and bird life living in and around the islands are special and internationally important, and are therefore particularly vulnerable to oil pollution.
The effect on people and amenity values are just as important as those on the natural environment. The greatest hazard to human health from oil spills is the risk of explosion or fire at the spill site and also the inhalation of oil vapours. Oil fumes can cause headaches, dizziness, nausea, vomiting and abdominal pains. Oil on skin can lead to rashes and irritation.
Now just imagine this. Two ships have a head-on collision out in the middle of Bream Bay. One of the ships is an oil tanker, fully laden with heavy crude oil on its way in to Marsden Point to discharge its cargo at the oil refinery. It is badly damaged and spews hundred of tonnes of ghastly, smelly black toxic oil into the sea.
Within several hours, the white sandy beaches at Ruakaka and Ocean Beach are covered in oil. Hundreds of sea-birds, some of them endangered species, are smothered in oil and many become fatalities. Residents living in the nearby coastal communities are forced to leave their homes due to the toxic fumes coming from the oil. All the beaches in the vicinity are closed in the interests of public safety. There are restrictions placed on shipping, port operations and recreational boating activities in the area. And fishing and the taking of shellfish are banned for health reasons.
Not a pretty thought is it? But this could very well happen one day and when it does we need to ensure that we will be ready to clean it up! A major shipping disaster would quickly become a national scale emergency.
- What is oil?
- What resources and activities are most at risk?
- Types of oil pollution
- How can you help?