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

There are many observable attributes in which we can classify the various types of marine pollution. Marine Pollution is a major setback and not only hampers the marine species but also is passed on to the land animals as well. Sea water covers around 2/3rd of the planet, which plays an important role in maintaining the essential biological and ecological balance. There has been increasing amount and the various kinds of waste products which originates from expanding technology but with not much knowledge about how these might react with the ecosystem and disrupt our well being.

Types of Pollution Observed in Marine Life

• Acidification – Oceans act as natural Carbon Sinks. They absorb carbon dioxide from the atmosphere. As the level of carbon dioxide is increasing, oceans are turning more acidic. Structures made of Calcium Carbonate (CaCO₃) will be endangered due to dissolution killing coral & shellfishes. With carbon dioxide levels increasing and decreasing ability of the ocean to absorb it, is resulting in rising temperatures around the globe.In the journal of Science in May 2008 from NOAA scientists declared an up-welling of acidic waters within 4 miles of Pacific Continental Shelf a critical zone with thriving marine lives being born or living there.
• Plastic Debris –Discarded plastic waste in the form of bags and other solids that end up in the sea endanger sea life. Aquatic animals run the risk of dying from entanglement, suffocation and ingestion of plastic. Ghost nets left or lost by fishermen in the ocean entangle fishes, dolphins, sea turtles, crocodiles, crabs, sea birds, dugongs and sharks. They restrict movement and causes starvation, lacerations and infections and suffocate them.
• Eutrophication – the increase in chemicals containing mainly nitrogen and phosphorus. Eutrophication increases the ecosystem’s ability of primary productivity, effects lack of oxygen and reduction in the water quality harming fishes and other marine populations.
• Underwater Noise – marine ecosystem is susceptible to noise pollution from passing ships, oil explorations, seismic surveys and naval low frequency sonar. Marine animals with weak eyesight like crustaceans and others living in the dark depend on acoustic information.
• Toxins – toxins don’t degenerate in marine environment like Dichloro diphenyl trichloroethane(DDT), pesticides, Tributyltin(TBT), dioxins and radioactive wastes do. Heavy metals like mercury, nickel, lead, arsenic and cadmium have both high density and are toxic. They harm all the species through Bio-accumulation and settle in the benthic zone.

Causes of Marine Pollution

• Large Scale Oil Spills – Oil spills from ships have a devastating impact as well. Crude is extremely toxic and suffocates the marine life to death by forming a layer on the sea water. Ships spill huge amount of oil due to accidents, emergencies and storms every year. Extracting oil causes noise pollution, ballast water and europhication through algal bloom. Other invading species harm the life cycles of other organisms. This gives rise to clashes within the ecosystem which is already damaged due to pollution.
• Land Runoff –Excessive water from rain, flooding or melted ice penetrates deep into the soil and flows into the ocean along with those impurities dissolved in them. It results in man-made, harmful contaminants polluting the ocean. This is predominantly due to the fertilizers, petroleum, pesticides and other soil contaminating chemicals. Dead zones are created by the inflow of fertilizers and wastes from land animals and also humans too which is a huge detriment to the oceans.
• Littering – objects far inland are transported back into oceans by polluted rivers and other sewage released into the oceans. These objects range from natural to man-made substances like dust, sand and debris to trash. Plastic debris doesn’t decompose remaining suspended for years. Animals can even choke to death if they consume it. Turtles, fishes, sharks, dolphins and sea birds lose their lives due to plastics. Increasing CO₂ is affecting the ecosystem and fish communities.
• Ocean Mining – Due to mining activities in ocean for copper, gold, silver, etc. sulphide deposits are created. Deep sea mining damages the lowest levels of the ocean and increases toxicity. Leaking, oil spills and corrosion aggravates the whole scenario.
• Sewage – Sewage flows through rivers, drains and sewers connected to the ocean. Minerals and mining waste also ends up in oceans. Release of toxins depletes the oxygen content, decays plant life and leads to severe decline in ocean water quality. Sewage or polluting substances flow through sewage, rivers, or drainages directly into the ocean.
• Industry’s Toxin Chemicals – Dumping of toxic chemicals hampers marine life as they are hazardous in nature and are let out to the oceans untreated. It increases the temperatures causing thermal pollution. At this temperature animals and plants can’t exist and eventually perish.

Read More:
Oceanic Pollution: What are the effects of marine pollution?
Marine Pollution:What are the main sources of marine pollution?
GIS and Marine Resource Management
Ways of controlling Air pollution
What are the harmful Effects of Air Pollution?

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