The causes of marine pollution take place when harmful effects or substances enter the ocean or sea. These harmful substances have a great impact on aquatic animals. Therefore, this day’s marine population has become an alarming concern.
Not many years ago the oceans were considered infinite sinks, the immensity of the seas and oceans seemed impervious to assault. This is no longer the case. But now, the Sea and oceans have become fragile. There are two major areas in the ocean – the continental shelf and the deep oceans. The former is more productive in terms of the food supply. They also receive a great pollution load.
In the 1970s, the oil spill was synonymous with marine pollution. The World production of oil, per year, is around 600 billion gallons. About sixty percent of this is ferry by sea, around 360 billion gallons. Assuming a 0.1% spillage, the actual Influx could be even more. When there is oil leakage, it kills thousands of marine birds. Thus, it affects the surface-dwelling birds when they dive for food. Besides, it also affects a variety of marine organisms.
Sewage, not oil, is now, the main problem of the seas along with the dumping of industrial wastes and the destruction of coastal ecosystems. The country of India is no exception. Sewage could destroy corals.
Major Causes of Marine Population are:
Oil Spills are a threat to marine organisms with visible effects like the presence of oil film on surface water, soiling of beaches with tarballs, etc. Through the sources like natural seepage from the seabed, tanker accidents, sewage wastes, disposal of spent lubricants, motorboat activity, and petroleum-based industry, etc., the petroleum, hydrocarbons are introduced into the marine environment which causes a lethal effect to the organism. Thus, it causes the formation of thick, chocolate brown color water-in-oil emulsions famous as “chocolate mouses”. This can last for many years in the ocean and cause serious environmental problems. Floating over long distances they can lead to distress and death of organisms such as endangered turtles, some carnivorous fish, etc.
To reduce the tarballs, hand cleaning is favor because it minimizes the removal of unoiled sediment and causes less harm to sand-dwelling organisms. Besides, the beemer beach cleaner can also clean the tarballs.
Oil-spill results in the disturbance of oceanic ecology. Oil spills inhibit plankton growth and photosynthetic activity too. Sometimes oil spilled over the surface may catch fire and damage aquatic life. The oil may also eventually reach the shore, where the feathers of shorebirds become coated with oil, causing the birds to drown. Oil spill till recently was cleared using detergents but then detergents themselves are harmful to the aquatic life.
Toxic contamination is another factor that causes marine pollution
Chlorinated organic compounds (including pesticides and industrial chemicals), heavy metals and radioactive substances contaminate ocean waters. In the 1950s, the fishing village of Minamata, Japan, suffered a tragedy that indicated the enormous human costs of pollution. A chemical plant in the village routinely dumped mercury-laden liquid wastes into the adjacent bay.
Local people depended on the waters of the bay or fish, their staple diet. In 1953, many of the villagers began showing symptoms of neurological disorders, such as blurred vision and speech and numbness in the lips and limbs. Children were born with serious congenital defects.
As a result, people began to die. By 1959, it was evident that the villagers were suffering from mercury poisoning produced by the wastes from the chemical plant. Inorganic mercury and phenyl mercury are actually harmless and tend to accumulate in bottom sediments. However, bacteria converted these forms of mercury into toxic methyl mercury. Thus, it enters the food chain and becomes highly present in the fatty tissues of fish. In fact, the villagers eat these fishes. As a result, it causes the Minamata disease.
These days, detergent has become one of the main causes of marine pollution. Due to detergent, water pollution occurs by “foaming” in rivers due to “hard” detergents. These are poorly biodegradable, both naturally and in sewage treatment works. Foaming in air photosynthesis and oxygenation in rivers as well as reducing the operating efficiency of sewage treatment plants.
PCBs (Polychlorinated biphenyls)
These are a group of stable chlorinated compounds that are used in a variety of industrial processes such as electrical fittings and pants. Although these compounds do not affect the BOD of water but they are extremely toxic. Although the compounds are no longer in production. But they are extremely persistent. They remain in large quantities in the atmosphere and in landfill sites. They are not water-soluble and float on the surface of the water. Thus, the aquatic animals eat the PCBs and so enter the food chain. PCBs are fat-soluble and are therefore easy to take into the system, but difficult to excrete. As a result, it causes marine pollution and it also harms the aquatic animals.
A number of the seal populations, most notably in the Dutch Wadden Sea and the Baltic sea, have exhibited reproductive abnormalities attributed to PCBs which have had a significant impact on populations. The main symptoms of PCB poisoning are changes that occur in the uterus of mammals, implantation or abortion and premature pupping. Amongst the top predator birds, the main effect has been the thinning of eggs shells and interference with the reproductive system. There have also been suggestions that the PCBs may cause carcinogenic, teratogenic and immunological effects.
A striking correlation between a clean environment and the presence of birds is well familiar. The great London smog of 1952 killed more than 400 people and a large number of birds. Following the enactment of the Clean Air Act in 1956, there were improvements. By 1978, at least 200 species of birds could be spots in the vicinity of St. Paul’s Cathedral.
The Department of Environment Government of India, as well as the Andhra Pradesh Pollution Control Board, laid down strict emission standards on the Nagarjuna Fertilizers and Chemicals Ltd. in Kakinada in Andhra Pradesh. As a result, the 695-acre site of the factory has been planted with quarter-million trees constituting a green belt or a green leaf-wall around it, separating the Kakinada town. Several mini-bird sanctuaries have been planned to monitor the quality of air and water in this area.
Similarly, the treated effluents of SPIC are able to attract Flamingos, presumably because of the growth of algal blooms and plankton on which the birds feed.
It is well-established that high concentrations of chlorinated hydrocarbons (like the DDT) residues accumulate in flesh-eaters like hawks and pelicans. Among the results are upset in normal breeding behavior and eggs too fragile to survive. The chemical interferes with the calcium metabolism of the birds, resulting in the thinning of eggshells and affecting their reproduction.
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