Marine Pollution:What are the main sources of marine pollution?

Marine Pollution is caused when harmful or even potentially harmful chemicals, particles, industrial, agricultural and residential waste, noise or may be even invasive species of plants or animals enter the ocean and disrupt the whole system. The maximum amount of substances that result into marine pollution originate in land and then flow into the ocean due to the rivers carrying the waste substances and then depositing them on the ocean bed itself which constitute of almost 80% of the total ocean pollution taking place. Air pollution is also responsible for degrading the ocean water quality by carrying the dirt and pesticides off the coast. Both land and air pollution have jointly hampered the sanctity of the marine environment and also disrupted the habitat of its entire species.

The pollution that is drained to the ocean is mainly from non-point sources which include agricultural runoff, debris and dust blown off by the wind. Nutrient pollution is the excessive input of nutrients which contaminate the water and degrade its quality. This causes eutrophication of surface waters in which mainly nutrients like nitrogen and phosphorus stimulate algae growth to an extreme level causing algal bloom.

As and when pesticides are introduced into the marine ecosystem these chemicals are immediately absorbed into the marine food webs. These pesticides have the potential to cause mutation in the genes of the species and cause deformities or even diseases within the species which is fatal for all. It is deadly not only for the human beings but the whole food webs and marine ecosystem consequently.

There are numerous potentially toxic chemicals which attach themselves to tiny particles. These particles are the consumed by planktons & benthos animals who mainly feed on either the deposit or filter foods. This makes the toxic substances being concentrated primarily in the lower order food chains. Many particles have the capability of chemically reacting and combining in such a manner that depletes the oxygen to a huge extent and make the water body anoxic.

Numerous toxic metals are also introduced into the marine food webs. These metals can totally degenerate the tissue matter, biochemistry, behavior, reproduction & might also suppress the growth and prosperity of marine life. Animal feed contains high amount of fish meals or fish hydro lysate content. These toxics in turn are carried forward to land animals when the fish is consumed by other animals and humans further up in the food chain.

Sources of Marine Pollution

Generally there are three types of inputs of pollution into the ocean which includes direct discharge of waste into the ocean, runoff due to rain & pollutants that are air borne.
  • Direct Discharge
    There are pollutants that are directly discharged from urban sewerage and industrial waste discharges which might be toxic and hazardous into the seas. Inland mining of gold and copper also causes marine pollution. It also interferes with the life and development of coral polyps.Much of the materials carried by the rivers are soil which ends up in the ocean floor. According to the USEnvironmental Protection Agency (USEPA), the contamination of head water portions up to 40% in the western continental US is because of mining. Also, most of these pollutants are taken to the sea.
  • Ship Pollution
    Ships pollute oceans in devastating ways. Polycyclic aromatic hydrocarbons (PAHs) in crude oil which is not only toxic but also don’t degenerate easily as they stay as sediments in the marine ecosystem. Oil spills are the worst marine pollutants. Oil spills from tankers that contains untreated water on return ships and leaking pipes and engine oil disposed into sewers can cause a great deal of damage as well.
  • Deep Sea Mining
    Deep sea mining is the mineral extraction process that is carried out on the ocean floor. These mining sites are mainly found in areas of polymetallic nodules or active &extinct hydrothermal vents below the ocean’s surface. Because of this, now there are sulphide deposits which contain cobalt, copper,silver, gold,zinc and manganese. Deep sea mining has raised concerns about the damage it causes to its surroundings. There are several unanswered questions about the exact consequences which need to be answered and discovered. The toxicity of water and sediment plumes from tailings also increases because of removal of sea floor parts. This also harms the benthic layer. The tailings from mining when dumped back into the ocean forms clouds of particles floating in the water.
  • Land Runoff
    there is a huge amount of surface runoff taking place from farming, urban areas, construction of roads, building, ports and harbors which carry soil and particles full of carbon, nitrogen, phosphorus and other minerals. This water rich with nutrients is great for algae and phytoplankton to live in coasts causing algal bloom which is using up all the available oxygen.
  • Atmospheric Pollution
    Dust and debris that are windblown has plastics. Sahara dust is taken to southern periphery of subtropical ridge into Caribbean & Florida. There is global transport of dust from Gobi & Taklamakan deserts to Hawaiian Islands. Due to climate change the ocean temperatures and levels of CO2 is rising with increase in the acidifying effect of oceans.

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