Marine Pollution: Causes and Consequences
Pollution of the world's oceans is quickly becoming a major problem on Earth. We know very little about the effect that pollution has on the oceans, but we continue to dispose off chemicals, sewage and garbage into it at an unprecedented rate. Most people likely do not even know what types of pollutants reach the oceans. There may be billions of people unconcerned about ocean pollution and hence this problem. Truly, the fish catch from the sea will tend to bio concentrate the pollutants to finally reach the humans.
Toxic pollutants in the ocean ecosystem have massive impacts on the plants and animals. Heavy metal poisoning (such as lead and mercury) from industrial effluents accumulate in the tissues of top predators such as whales and sharks (so do not hesitate to support ban of hunting whales and sharks but to the dislike of many others). Many a times such poisoning causes birth defects and damages nervous system. Dioxins from the pulp and paper bleaching process can cause genetic chromosomal problems in marine animals and may even cause cancer in humans. PCBs (polychlorinated biphenyls) typically cause reproduction problems in most marine organisms. PCBs usually come from older electrical equipment.
Poly-aromatic hydrocarbons (PAHs) are another source of marine toxic pollution and
typically come from oil pollution and burning wood and coal. These PAHs are
responsible for causing genetic chromosomal aberrations in many marine animals. Lastly, low-level radiation poisoning is also
possible in the ocean environment.
Though scientists know very little about how radiation affects marine
organisms, it cannot be a good thing anyway.
Some marine species such as a population of Beluga whales living in the
The toxic pollution varies from PAHs heavy metal pollution from industrial effluent and fallout, PCB pollution and even possible low level radiation. No matter what we humans do, there is potential for serious pollution of the oceans.
Marine garbage disposal is another major form of ocean pollution. The world's oceans are a virtual dumping ground for trash. Sometimes the garbage includes junked out fishing nets, plastics, general household garbage and even like bulbs. In one case, an island 300 miles from the nearest inhabited island (and 3000+ miles from the nearest continent) had 950 pieces of garbage ranging from plastics to tin cans.
Garbage in the oceans is a serious issue as fish entangle themselves in fishing nets and animals sometimes eat trash products and die. There are numerous examples of dolphins, sharks and whales entangling themselves in fishing nets and dying from oxygen starvation. It is possible to clean garbage from the oceans if humanity quits using it as a garbage dump. Marine garbage can often enter into animal gut; plastic pop tab rings accidentally strangle animals and so forth. Controlling this form of pollution is important to maintain a healthy ocean ecosystem.
Even simple plastic bags can have large pollutive impacts within the ocean. In one case, a deceased sperm whale was found to have a party balloon blocking its digestive system. The whale died from inability to process its food and died of starvation. Plastics can also have negative impacts to boats if they accidentally plug water intake lines.
Sewage Disposal in Ocean
Sewage is yet another major source of marine pollution. Typically, the problem with sewage is that it causes massive nutrient loading in the ocean ecosystem. Nutrient loading triggers algal blooms in the water leading to the loss of dissolved oxygen. After the depletion of oxygen levels, many organisms in the ocean die from being unable to breathe properly. Other problems associated with sewage include parasites/bacteria that force closure of public coastal beaches and poisoning of shellfish fisheries. For the most part, cities in the developed world have sewage treatment facilities but many of the cities in poorer areas have little to no sewage treatment. As the world population continues to increase, sewage pollution will be on the rise.
What we often do not realize is that the waste water out of washing our clothes, faces, dishes and cattle, is ultimately headed to the sea. This includes everything from our homes (toilets, washing machines, bathtubs, dishwashers and so forth), industrial effluents and even chemicals such as paints and fertilizers that we dispose of down the drains. Eventually, all of this sewage pollution adds up and we land in serious problems due to lack of oxygen for organisms and poisoned water.
The last major source of ocean pollutant is non-point. Non-point pollution can come from amazingly varying sources, viz., runoff from farmland (fertilizers, manure), industrial runoff (heavy metals, phosphorous), urban runoff (oils, salts, various chemicals) and atmospheric fallout of airborne pollution. Obviously, it is the hardest to control. Point pollution, in contrast, is pollution from a direct source like a factory outfall pipe.
The enrichment of water by nutrients, especially compounds of nitrogen and phosphorus, causes an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms and the quality of the water (Eutrophication). Input of nutrients like nitrogen and phosphorus to the sea is a natural prerequisite for life, not an environmental problem. It becomes a problem only when the input increases to such levels that the original properties or functions of the ecosystem change. Then, it becomes too much of a good thing. When this manifests in marine waters or a lake, it is referred to as eutrophication - a concept covering a series of events in the aquatic environment. Input of too large amounts of nutrients, followed by other events and effects is ominous and results in higher levels of nutrients in the water. Physical, chemical and biological changes that follow tend to reflect in the fauna and flora, oxygen conditions change and other changes in the water mass, in the sediments and on the surface of the bottoms.
Pollution of coastal waters: Kerala under microscope
The coastal waters of the maritime states
are under the constant threat of pollution from a number of sources. The relatively long shoreline of
The agrarian nature of land use itself has become a bane to the coastal water bodies of the state in the midland as well as in the lagoons in coastal land. Fertilizer residue originating from the tea, cardamom, and rubber plantations of the highland and midland are finally headed to the coastal water of the ocean. But, the brunt is borne by the waters in the lagoons, ponds and other inland water bodies. The intracoastal water way is no exception either. Obviously, the fertilizer residue leads to the eutrophication of the coastal waters, and adds to the reservoir of the chemicals that already exists in the sea.
Luckily, the amphibious
plant species that characterize the fresh water bodies and lead to their eutrophication, do not survive in the marine environment. However, if not checked, we may reach a
situation like in the mouth of
Where do we go from here?
Industrial pollution is not as bad as it used to be in the developed world as new techniques and better waste and effluent treatment are put in place. New laws and regulations make it difficult for people to dump their trash into the oceans though inevitably some dumping will always occur. One idea is to promote community beach-cleaning events where in everybody volunteers in to pick trash off the beaches. By cleaning up the trash on beaches, we lessen the potential chances of accidental animal kills and afford better and cleaner looks for beaches.
Reduction of sewage is possible through
the installation of better sewage treatment facilities and by adoption of
volume reduction technologies for the world's cities. Developed countries like
(Source: Marine Ecosystem: EMCBTAP-ENVIS Newsletter, Department of Geology, University of Kerala, Kariavattom - 695 581 Vol. 1, No. 2, 2003)