Aquatic Pollution and Coastal Management

Unit 6 : Oil pollution

6.2.2.Non Tanker Accidents
When a ship is in accident, its fuel oil may be lost to the sea. So this source of oil contamination is not negligible (0.02 milion tonnes).

Marine Terminals
Accidents through human error and pipeline failure are an inevitable accompaniment to loading oil on to tankers and discharging it at oil terminals (0.03 million tonnes).

Offshore Oil Production
The oil extracted from the seabed invariably contain some water (production water), which must be extracted before the oil is transported to the refinery. This is done by oil separators on the platform and the oil concentration in the water that is discharged is usually 40 ppm, but in total this amounts to a substantial quantity.

When an oil well is being drilled, ‘drilling muds’ are pumped down the well. These maintain a head of pressure and prevent a blow out when oil is struck, cool and lubricate the drill bit, and carry the cuttings back to the surface. The drill mud contains water and oil and the oil contaminates the water.

Blow-Outs
Uncontrolled release of oil from the well (0.05 million tonnes).

Coastal Oil Refineries
The waste water discharged from oil refineries should contain only 5 ppm or less of oil (0.10 million tons).

Municipal and Industrial Wastes
Domestic wastes and sewage contain a quantity of oils and greases and depending on the nature of the industry, industrial wastes may also contain a considerable quantity of petroleum hydrocarbons (lubricating oils).

Municipal Waste
Oil from cleanings, automobile washings, sewage treatment plants and the degraded asphalt from roads.

Industries
Metal industries, core plants, woolen textiles, paint industries, meat and fish processing plants.

Urban and River Runoff
Every time it rains, the oil and petrol, as the roads is washed down drains and into water causes and eventually reaches the sea.

Dumping at Sea
Shipping channels in estuaries and ports commonly need regular dredging. The dredging oil, which is usually dumped at sea, is contaminated with oil.
Various industrial wastes and solid municipal wastes that are dumped at sea may also contain petroleum hydrocarbons.

Atmosphere
The incomplete combustion of petrol or diesel in motor vehicles results in petroleum hydrocarbons being released into the atmosphere. These hydrocarbons are washed out in rain into the sea.