Lecture Marine environmental studies Topic: Major marine pollutants. In this topic, the following content will be discussed: Oil, sewage, pesticides and other persistent organic chemicals, metals, radioactivity.
MAJOR MARINE POLLUTANTS GOOD MORNING CLASS! 上午好学生们！ Shang wu hao xue sheng men! The major marine pollutants are: • • • • • Oil Sewage Pesticides and other Persistent Organic Chemicals Metals Radioactivity OIL Oil is not a single homogeneous compound but consists of many different compounds Some physical properties of oil include; • • • Toxicity Solubility Viscosity OIL – cont’d FACTS: • about billion tonnes of crude oil is produced annually, and half of this is carried by sea • Averagely, 8.25 million tonnes of oil is floating on the sea daily MOVEMENT OF OIL MAJOR CONSUMERS MAJOR PRODUCERS • Arabian gulf • Gulf of México • North sea • • America Western Europe • China The risk of accidents by tankers is highest during maneuvers in port OIL SOURCES INTO THE OCEAN • • • • • • Offshore oil production Routine ship operation Ship accidents Ocean dumping Natural sources Land-based sources Contd Oil pollution Sources 15% 2% 3% 7% 10% 1% 62% Industrial waste Refineries/Terminals Natural sources Tanker operations Tanker accidents Other shipping Offshore Source: UNEP EFFECTS OF OIL POLLUTION EFFECTS OF OIL POLLUTION • • • Gross fouling of beaches Effects on fish, birds, mammals & plants Economic effects EFFECTS ON FISH • Fish become tainted and unpalatable • Young fish can die • Fish eggs may not be hatched as a result of pollution • Breeding patterns may be affected if the spawning grounds are polluted or if migratory routes are blocked EFFECTS ON MAMMALS • Mammals which use their fur for insulation loose their thermal insulation (coated fur is a poor insulator) E.g Northern Seal • The oil affects their eyes and nostrils • Mammals may die as a result of ingestion of oil EFFECTS ON PLANTS • Plants like mangroves, Kelp, Marsh grass and sea grasses are destroyed by oil pollution • These plants serve as a habitat for other organisms within an ecosystem As a result of pollution, there can be loss of cover and this may lead to serious environmental impacts ECONOMIC EFFECTS OF OIL POLLUTION • Harbours, marinas, tourist beaches may be closed due to oil pollution • Hunting and fishing may be suspended and this may affect the traditional lifestyle of native people • Tourist guides, fishermen and outfitters may loose their sources of income Some Major Oil Spill Catastrophies Cleaning-up oil spills: • Dispersants: Oil can be broken down more quickly by spraying dispersants (chemicals) on the oil slick from boats or planes This method only works on fresh, small oil spills • Booms: A boom has a floating skirt suspended down in the water and a sail holding it above the water line The floating skirt stops the oil from passing These are used to prevent oil from entering delicate and protected areas • Slick-lickers: This method uses a belt of oil absorbing material that sucks up the oil from the ocean water The oil is then squeezed out of the absorbing material into a collecting bin SEWAGE From an environmental point of view, the problem with sewage disposal has to with: BIOLOGICAL OXYGEN DEMAND (BOD) Biological Oxygen Demand (BOD) • It is the amount of oxygen required by bacteria to consume and degrade the waste • If the amount of oxygen present is equal to or less than the BOD, then anoxic conditions are created, which is very toxic to aquatic life • Most sewage treatment systems are designed to reduce the BOD SEWAGE – cont’d • Sewage is usually separated into waste water and sewage sludge • The waste water is not always harmless; it sometimes contains nutrients like phosphates and nitrates which if discharged incorrectly, can stimulate excessive algae growth with very high oxygen demand • This is referred to as EUTROPHICATION SEWAGE – cont’d • Another problem with sewage disposal has to with contaminated sea food • Fish and shell fish can accumulate pathogens from sewage and when these are eaten by humans it can result in illnesses like simple stomach ache, typhoid, paratyphoid, diarrhea, salmonelisis, septicemia, gastroenteritis, infectious hepatitis, and skin infections Pesticides & Other Persistent Organic Chemicals • These are chemicals that cause great harm to the marine environment • They are usually in the form of Chlorinated Hydrocarbons (e.g DDT) – dichlorodiphenyltrichloroethane • and Polychlorinated Biphenyls (PCB’s) General Properties Of These Chemicals • They are generally fairly toxic • Persistent in the marine environment • Bioaccumulated Effects of Pesticides • DDT has been cited as the cause of the decline in the population of predatory birds like Peregrine Falcon, Osprey, Brown Pelican and the American Bald eagle in the 1960’s • DDT is said to interfere with the metabolism of calcium therefore causing the birds to lay eggs with abnormally thin shells Therefore eggs were prone to breakages Effects of Pesticides - cont’d • PCB’s have been cited as the cause of infertility in Northern Seals • The PCB’s are thought to interfere with ovulation akpe na mi! ...GOOD MORNING CLASS! 上午好学生们！ Shang wu hao xue sheng men! The major marine pollutants are: • • • • • Oil Sewage Pesticides and other Persistent Organic Chemicals Metals... sea • Averagely, 8.25 million tonnes of oil is floating on the sea daily MOVEMENT OF OIL MAJOR CONSUMERS MAJOR PRODUCERS • Arabian gulf • Gulf of México • North sea • • America Western Europe •... Tourist guides, fishermen and outfitters may loose their sources of income Some Major Oil Spill Catastrophies Cleaning-up oil spills: • Dispersants: Oil can be broken down more quickly by spraying