MAJOR SOURCES OF MARINE POLLUTION

 World health organization as the introduction by man ,directly or indirectly of chemical substance or energy in to the marine enviroment,including estuaries, which causes harm to living resources and marine environment, hazards to human health, affecting to marine activities such as fishing and other important uses of the sea. Marine and costal degradation is caused by population growth, increasing urbanization, industrialization and tourism in costal areas are the root causes of this marine pollution.

                                                            

SEWAGE WASTES

The greatest ammount of domestic,municipal wastes and sewage are discharged to the marine environment.Sewage sludge contains industrial wastes, House hold wastes ,municipal wastes and animal wastes and many other wastes. These wastes are generated daily from highly populated cities and these sewage or contaminated substances are flow throw sewage,river and drainages in to the marine environment. The releases of chemical nutrients in to the ocean`s ecosystem causes to reduction oxygen levels, decrease in the sea water quality, that leads to affect all oceanic life, such as plants and animals are highly affected.

                                 

OIL POLLUTION

Oil pollution, which can destroy marine ecosystems. It's from oil tanker disasters,spills,operational discharge of fuel from boating traffic and urban based runoff. Boat discharges 24% of the total ammount of oil in to the ocean and 8% of overall oil ocean pollution a result of spills during transportation process.  Oil cannot dissolve in to water and from a thick sludge in water,which makes it unpleasant to look at and it makes an un-pleasant odor to the atmosphere. That leads to suffocates fish , block light to photosynthesis of aquatic plants, fouling of fishing gears and oil coverage of shellfish beds and causing some destruction of burrowing shellfish.

                                                

MICRO PLASTIC POLLUTION

All of the world`s oceans are contaminated with microplastic. It includes resin pellets,microbeads,polystyrene,cigarette buds,plastic debris,tiny threads,nets,synthetic clothing and ropes fibers.They are specific challenge to the marine ecosystem.

Neoplastic and microplastics are also generated through industrial abrasion processes (eg.airblasting) synthetic paints and car tires.Wind and surface water run-off transports of these particles to aquatic eco systems. Synthetic textiles , are release large amount's of micro plastic fibers in to waste water during washing.

                                       

Sea birds and fishes eat microplastic floating in the ocean because the resemble their natural food.The ingestion of plastic debris by fishes and seabirds, that causes to reduces food uptake ,causes internal injury and death due to blockage of intestinal tract. The other harmful effect of the ingestion of plastics include blockage of gastric enzyme secrection,discreased food stimulus, lowered steroid hormone levels, delayed ovulation and reproductive failure.

METALS

Metals are common contaminants in marine environments that are accumulate in high concentration in costal, estuarine water and sediment. Heavy metals occur naturally in the marine environment. In addition these heavy metals enter the marine environment through a variety of ways,such as riverin,atmospheric inputs,sewage sludge and industrial dumping,etc.

                                                    

Some metals are in moderate concentration,(eg)calcium,magnesium and other metals are in very low concentration (eg) gold and silver.Certain metals combine with organic substances to form highly toxic metallo-organic complex (eg) methyl mercuric chloride .Some metals such as mercury,silver and copper are very toxic to marine organisms. Other metals which include sodium,iron,calcium,zinc and magnesium are pocesses vital nutrients in marine ecosystems. However all the metals are toxic at elevated concentration.

The current alarm about metal pollution in the sea ,however started with the incident of Minimata disease caused by the consumption of mercury-contaminated shell fish and fin fish taken from Minimata Bay in Japan. Then there was "Itai itai" disease caused by the consumption of foods contaminated by cadmium from Niigata in Japan.