All unnatural material that finds its way to the world’s seas is classified as ocean pollution, however these materials built up over time. This process is known as bioaccumulation.
There are many contributing pollutants to bioaccumulation in oceans such as toxins, marine debris, oil, sewage, eroded soil, and heavy metals. In the past, dumping small amounts of pollutants into the oceans, known as dilution, was not thought of to be a threat to the environment because all of the oceans combined cover 75% of the earths surface. There used to be a saying which was common, “The solution to pollution is dilution.” Eventually it was found that dilution was really not the solution. Not only does bioaccumulation affect marine life, it also has a huge impact on how land mammals survive. Namely, birds, seals; even humans. Sewage released into marine systems due to inadequate sanitation will cause disease. Fertilizers used in agriculture cause eutrophication. Oil spills from tankers smother animals. Pesticides used in agriculture and by health services also causes problems in reproductive organs of animals.
There are two types of ways pollutants enter the ocean, non-point sources and point sources. Non-point sources are caused by agriculture, construction, and urbanization. When it rains the water runoff collects the pollutants from the surface and carries them into the streams. This, in turn, leads to the oceans making it hard to tell where the problem is. Point sources, however, are sewage over flows, out-pipes from factories and oil spills. We can determine where these pollutants come from. The major convenience of a point source is that it is easier to regulate since it is coming from one spot. It is also easier to determine an approximate an amount of how much of a pollutant is entering the ocean.
However ocean pollution does not effect just the area where the source is, it effects much of the ocean due to the ocean conveyer belt, which is ocean circulation that involves wind and thermohaline currents. The ocean conveyor belt starts in Europe, settles to the bottom, circles around on the bottom making its way through the Indian ocean and comes out by Alaska after traveling through the Pacific ocean. After it comes out in Alaska it travels down the west coast of North and South America where it cycles over.
What happens when the water gets polluted? Once sewage and fertilizers get into the water there becomes a high level of nutrients which encourages the growth of algae and plants blocking light that is needed in deep water, known as eutrophication. However, this results in a discouragement in the process known as photosynthesis, where green plants take in carbon dioxide to produce oxygen. Concordantly, an accumulation of organic materials, which are dumped in the ocean, causes oxygen levels to decrease because an extensive amount is being used up to decompose them. Bioamplification also occurs, the process in which sewage and toxins, such as mercury, get stored in the fatty tissues of fish. This, in turn, results by disrupting the marine food chain, as well as what humans intake from seafood. “The ACC-HUMAN, which is a model of organic chemical bioaccumulation of trophic levels and food chains, was very similar model of chemical fate in the physical environment and parameterized for conditions in southern Sweden” (Czub and McLachlan). This is a serious problem because in the oceans, as well as in rivers and lakes, there are trophic levels, which are roughly an organism’s feeding status in an ecosystem. Naturally, the top trophic level is impacted the most by such pollutants. An example of this would be seagulls becoming bioamplified with PCB and DDT. Such birds which have had an intake of these pesticides produce eggs which have an exceptionally soft shell, if it’s even considered one, and are unable to become living embryos. The use of DDT and output of PCBs into bodies of water have been, since,...
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