(HAO) Ocean Pollution Lesson

Ocean Pollution

The oceans are huge, interconnected ecosystems. In the United States, we have laws that prevent much oceanic contamination, but other countries do not necessarily have the same environmental protection laws and because the oceans are interconnected and worldwide, even if we aren't doing the contaminating, our oceans can still become contaminated.

Sewage

When we clean our sewage, we release it back into the environment. Our sewage treatment plants have very strict regulations regarding the levels to which our water must be cleaned before it is released back into the environment.  

Sometimes, however, even with regulations in place, things do not always go as planned. For example, this picture was taken in 2009 in Roswell, Georgia. This is an overflowing sewer on Riverside road. In older sections of Atlanta there are combined sewer systems that are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. These overflows, called combined sewer overflows (CSOs) contain not only stormwater but also untreated human and industrial waste, toxic materials, and debris. They are a major water pollution concern for the cities in the U.S. that have combined sewer systems. The City of Atlanta is spending about $3 billion dollars to put in separate storm and waste systems in the metro Atlanta area.

Other countries, however, do not have the same regulations regarding the release of sewage.   In developing countries, sewage is often released straight back into the environment without being cleaned.   These waterways can eventually run into the oceans, releasing sewage into the ocean.

Chemicals

Inorganic chemicals, such as acids, salts, and heavy metals are sometimes dumped into the ocean.   This doesn't happen much in the United States because we have laws regarding toxic waste, but developing countries may not have these same regulations and laws. Lead from pre-1986 gasoline, incinerators, and paints is a heavy metal that can contaminate waterways, which can run into the ocean. Lead is very toxic to humans in small quantities, so it is highly regulated and no longer allowed in gasoline or paint.  

Mercury from burning coal and compact fluorescent lightbulbs (CFLs) can also deposit in waterways, which flow into oceans.

Bioaccumulation is problem where small, seemingly harmless amounts of something received over long periods of time eventually reach toxic levels because the body has no way to metabolize these compounds.  

When bioaccumulation becomes compounded through a food chain, it is called biomagnification.   For example, if mercury is released into a waterway, even in low doses, the plankton will absorb the low dose and will be unable to process the mercury. When the plankton are eaten by a larger fish that requires many plankton to survive, the larger fish will have the mercury from all of the plankton in its body. Then, an even larger fish may eat the smaller fish. This larger fish will need many smaller fish to survive, so it will have all of the mercury that was in the smaller fish, resulting in even higher levels of contamination. This process repeats up the food chain until apex predators have very high levels of contaminants in their bodies.  

These phenomena most often occur with heavy metal pollution, such as mercury or lead. Heavy metals are especially toxic because they are easily absorbed in the body, but cannot be metabolized, so they bioaccumulate in our cells and can biomagnify up the food chain, making large predators that have been exposed to heavy metals hazardous to eat because they have such high levels of pollutants in their bodies.  

 

A famous case study of mercury poisoning was the town of Minamata in Japan. Chisso, a fertilizer manufacturing company, released mercury into the waterways near the fishing village of Minamata, causing many of the residents to suffer neurological problems and die. Acid mine drainage from coal and other mines can also pollute waterways, making them too acidic for organisms to survive and making the water supply unfit for humans to drink. Inorganic chemicals are persistent in the environment, which means they do not degrade easily and can pollute the environment for a very long time.

Picture: Water pollution causes serious risks to people's health. However, as the pollution of Minamata Bay in Japan showed, it can be the pollutants that cannot be seen which cause most harm.

Trash

Litter from humans also gets into the ocean. Plastic pollution is especially prevalent in the ocean because plastic takes a very long time to degrade. These plastic pieces and bottles can wash up on remote beaches and are eaten by a variety of oceanic organisms and seabirds.  

Because these pieces of plastic do not degrade and aren't digested, they can fill up the stomachs of seabirds and fish, making them unable to eat and causing them to starve. Single use plastic bags can also make their way into the oceans. When they are underwater, they look very similar to jellyfish, the food of choice for green sea turtles. These turtles inadvertently eat plastic bags, filling up their stomachs with plastic instead of food, and they can starve. There is also a place in the Pacific Ocean where plastic has been accumulating known as the Great Pacific Garbage Patch.  

This garbage patch stretches from Hawaii to Japan and contains more than 100 million tons of plastic and gets larger every year. This plastic is made up of tiny, tiny pieces of plastic that can be ingested by many different oceanic animals.

Oil

Drilling and mining for oil can also pollute the oceans. The act of drilling and mining aren't too terrible, pollution-wise, even though they do destroy benthic, bottom, habitats. When something goes wrong with one of these operations, however, is when we can run into serious issues with pollution.  

Left - Photograph of the after effects of an oil spill; Right - Aerial od a maxi-bargw with water tanks and spill workers hosing a beach on Prince William Sound.

On March 24, 1989, the Exxon Valdez ship ran aground, spilling approximately 11 million gallons of oil in a very pristine area of Alaska's coast. Exxon spent $2.1 billion dollars over 4 summers to clean up the spilled oil. Some of the beaches remain oily, even today. Because this location was so remote and teeming with wildlife, it is considered one of the worst oil spills in history, even though it was not the largest.

On April 20, 2010, an explosion on the Deepwater Horizon drilling platform released millions of barrels of oil into the Gulf of Mexico and it took many days to stop the oil leak. BP settled the case against it for $8.8 billion in natural resource damage and restoration. This oil spill is now known as the worst oil spill in United States' history.

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