Management of Oil Pollution

• What are strategies to reduce oil spills?

  • MARPOL agreement
  • double hulled oil tankers as both hulls need to be damaged for spill to occur
  • use defined shipping routes which reduces risk of collision
  • use oil pipelines rather than ships
• MARPOL (Reducing oil spills in marine environments) - international convention for the prevention of pollution from ships (1)

  • sets our regulations covering pollution by oil, sewage, rubbish and toxic liquids
  • before this convention, it was common for ships to dispose of waste or clean their storage tanks in the middle of the ocean
• MARPOL (Reducing oil spills in marine environments) - international convention for the prevention of pollution from ships (2)

  • rules introduced to cover the process of transferring crude oil from one vessel to another while at sea - common cause of oil spills
  • tankers must be certificated to show they have appropiate systems in place and records to show that they are being used - failure to comply can result in heavy fines or ships not given permission to leave port until suitable systems are in place and verified as working
• Tanker design (Reducing oil spills in marine environments) (1)

  • most likely reason for oil spills from a tanker is damage to the hull
  • an increase in the number of compartments contained within the hull of the ship will help reduce oil spills - if there is damage in one section the contents of the whole hull are not lost
• Tanker design (Reducing oil spills in marine environments) (2)

  • double-hulled tankers has reduced oil spills - a ship that has been built with two bulls so that if damage is done to the outer layer, the contents are still held securely by the inner plate
  • building double-hulled tankers cost significantly more than single-hulled ships
  • cost of buying new oil tankers meant phasing out single-hulled tankers
• Tanker design

  A) single hull

  B) double hull

  C) inner plate

  D) outer plate

  
• Minimising the impact of oil spills

  • technique used depends on local weather conditions, proximity to land and clamness of sea
• Use of floating booms (Minimising the impact of oil spills) - a boom is a floating barrier that can be used to surround the oil slick and prevent it from spreading to other areas

  • works well when the spill covers a relatively small areas and the sea is calm
  • can be used as a barrier to protect environmentally sensitive areas while a spill is dealt with
  • don’t work well when the sea is rough and stormy which are conditions that mainly cause the damage to the ship
• Detergent sprays (Minimising the impact of oil spills) - detergents help break down the oil slick into smaller droplets and disperse it

  • smaller droplets of oil will float away and degrade over time
  • most effective on smaller spils
  • can cause environmental damage greater than the crude oil itself - coral reefs have low tolerance to detergents
• Skimmers (Minimising the impact of oil spills) - uses a material that oil easily attaches to and drags oil off the seawater surface and then mechanically scraped off into a container

  • cleans the water without changing the chemical or physical properties of the oil
  • used once an oil slick has been contained within a boom
  • very useful technique but skimmers will not work effectively in rough or stormy sea conditions
• When oil reaches beaches, the only effective way is to physically remove the oil by hand

  • difficult and time consuming operation