Course: BIS 105 Environmental Biology

Unit 11 Learning Module

Pollution

Nutrient Pollution

Algal blooms can occur naturally when nutrient-rich cold water from the seafloor rises to the surface, stimulating rapid reproduction of microscopic algae (phytoplankton). Phytoplankton is essential to the health and productivity of the oceans, as it forms the base of the marine food web, providing sustenance for higher level consumers—namely fish.

Phytoplankton bloom off the coast of Brittany, France

Most phytoplankton are too small to be individually seen without a microscope. However, when there is a high enough concentration of phytoplankton, they may appear as a green discoloration of the water due to the presence of chlorophyll within their cells. This is called an algal bloom. Phytoplankton obtain energy through photosynthesis and therefore live in the well-lit surface layers of oceans, seas, and lakes. In addition to light, algae are also dependent on the availability of nutrients such as nitrate, phosphate or silicic acid for growth.

A limited amount of nutrients is available naturally, which generally keeps the growth of algal blooms from getting too large. However, effects of human civilization are trickling their way into the oceans. Runoff from fertilizers applied to agricultural fields, golf courses, and suburban lawns; deposition of nitrogen from the atmosphere; erosion of soil containing nutrients; and discharge from aquaculture facilities and sewage treatment plants, are increasing the nutrient content in coastal waters and consequently increasing the size and longevity of algal blooms. This process of nutrient loading is known as eutrophication. Algal blooms can disrupt normal functioning of marine ecosystems, causing a variety of problems such as depletion of the oxygen in the water that fish and shellfish need to survive. Certain species of marine algae produce harmful blooms, known as red or brown tides, which can be toxic to both marine animals and humans.

Harmful Algae Blooms (HABs)

In addition to their ability to suffocate the oceans, some species of algae produce dangerous toxins that can be deadly to both sea and land life, including humans. The term "red tide" is often used to describe these phenomena, however scientists now prefer the term harmful algal bloom (HAB), since:

- toxic blooms don't necessarily appear red,
- blooms are not tied to tides, and
- phytoplankton species within so-called "red tides" may or may not be toxic.

The EPA has a website dedicated to nutrient pollution - http://www.epa.gov/nutrientpollution.

Oil Spills

Large oil spills, like the Exxon Valdez in Alaska in 1989, get a lot of attention, as they should. Besides these large spills, though, much more oil typically enters the oceans from small leaks (

Data excludes the Macondo Well spill from the Deepwater Horizon rig. In 2010, this one disaster leaked 205,800,000 gallons of oil into the Gulf of Mexico. The large spike in 2005 is due to damage by Hurricane Katrina.

On the night of April 20, 2010, the Deepwater Horizon oil rig, one of hundreds operating in the Gulf of Mexico, exploded, killing eleven men, and placing one of the most rich and diverse coastal regions on earth in imminent danger of petroleum poisoning. BP had been drilling in waters a mile deep, and in the next two days, as the rig slowly sank, it tore a gash in the pipe leading to the oil well on the ocean floor. Over the next three months, more than two hundred million gallons of crude oil poured into the Gulf before the technological means could be found to seal the undersea well. It was not until July 15, nearly three months after the accident, that the well was successfully capped. It was the worst environmental disaster in American history, and the largest peacetime oil spill ever.

Estimating the flow of oil into the Gulf from the well was extremely difficult because the leak was so far below the surface. The U.S. government estimates that about 4.9 million barrels (205.8 million gallons) entered the Gulf at a rate of 35,000 to 60,000 barrels a day. The largest previous oil spill in the United States was of 260,000 barrels by the Exxon Valdez in 1989 in Prince William Sound, Alaska.

Once the oil is in the water, there are three types of methods for dealing with it:

1. Removal: Oil is corralled and then burned; natural gas is flared off. Machines that can separate oil from the water (skimmers) are placed aboard ships stationed in the area. These ships cleaned tens of thousands of barrels of contaminated seawater each day.

1. Containment: Floating containment booms are placed on the surface offshore of the most sensitive coastal areas in an attempt to attempt to trap the oil. But the seas must be calm for the booms to be effective, and so were not very useful in the Gulf. Sand berms were also constructed off of the Louisiana coast to keep the oil from reaching shore.

A containment boom holds back oil, but it is only effective in calm water.

1. Dispersal: Oil disperses naturally over time because it mixes with the water. However, such large amounts of oil will take decades to disperse. To speed the process up, BP sprayed 1.84 million gallons of Corexit, a dispersant, on the spill. That action did not receive support from the scientific community since no one knows the risks to people and the environment from such a large amount of these harmful chemicals. Some workers have become ill from exposure to the chemicals. Before the spill, Corexit had primarily been tested for its effectiveness on dispersing oil but had not been evaluated for human and environmental safety. Subsequent tests have found oil becomes 52 times more toxic when combined with Corexit. In humans, short-term health symptoms include acute respiratory problems, skin rashes, cardiovascular impacts, gastrointestinal impacts, and short-term loss of memory and long-term impacts include cancer, decreased lung function, liver damage, and kidney damage. Many cleanup workers were not provided with necessary safety equipment, and may have also been accidentally exposed by overflying planes spraying dispersants.

Plugging the Well

BP drilled two relief wells into the original well. When the relief wells entered the original borehole, specialized liquids were pumped into the original well to stop the flow. Operation of the relief wells began in August 2010. The original well was declared effectively dead on September 19, 2010.

Impact

The economic and environmental impact of this spill will be felt for many years. Many people rely on the Gulf for their livelihoods or for recreation. Commercial fishing, tourism, and oil-related jobs are the economic engines of the region. Fearing contamination, NOAA imposed a fishing ban on approximately one-third of the Gulf.

The BP oil disaster caused untold short- and long-term damage to the region. The initial impact on the Gulf—the oil washing up on beaches from Texas to Florida, and economic hardship caused by the closing down of Gulf fishing—was covered closely by the news media. The longer term impacts of the oil spill on wetlands erosion, and fish and wildlife populations, however, will not likely receive as much attention.

Much public debate over the spill has focused on the specific causes of the spill itself, and in apportioning responsibility. As with the example of bee colony collapse, however, the search for simple, definitive causes can be frustrating, because the breakdown is essentially systemic. Advanced industries such as crop pollination and oil extraction involve highly complex interactions among technological, governmental, economic, and natural resource systems. With that complexity comes vulnerability. The more complex a system, the more points at which its resiliency may be suddenly exposed. In the case of the Deepwater Horizon rig, multiple technological “safeguards” simply did not work, while poor and sometimes corrupt government oversight of the rig’s operation also amplified the vulnerability of the overall system—a case of governmental system failure making technological failure in industry more likely, with an environmental disaster as the result.

Plastic Pollution

Trash can enter the ocean through several routes. Some of that is from runoff, some is blown from nearshore landfills, and some is dumped directly into the sea. Ships at sea may thrown trash overboard. It also includes lines and nets from fishing vessels. Ghost nets, nets abandoned by fishermen intentionally or not, float the seas and entangle animals so that they cannot escape. Containers sometimes go overboard in storms. Some noteworthy events, like a container of rubber ducks that entered the sea in 1992, are used to better understand ocean currents. The ducks went everywhere!

There are estimates that as much as 80% of the trash that ends up in the oceans is plastic. This is because a large amount of the trash produced since World War II is plastic. Also many types of plastic do not biodegrade, so they simply accumulate. While many types of plastic photodegrade — that is, they break up in sunlight — this process only works when the plastics are dry. Plastic trash in the water does break down into smaller pieces, eventually becoming molecule-sized polymers. Other trash in the oceans includes chemical sludge and materials that do biodegrade, like wood.

Some plastics contain toxic chemicals, such as bisphenol A. Plastics can also absorb organic pollutants that may be floating in the water, such as the pesticide DDT (which is banned in the U.S. but not in other nations) and some endocrine disruptors.

Marine birds, such as albatross, or animals like sea turtles, live most of their lives at sea and just come ashore to mate. These organisms can’t break down the plastic and they may eventually die. Boats may be affected. Plastic waste is estimated to kill 100,000 sea turtles and marine mammals annually, but exact numbers are unknown.

This bird likely died from the plastic it had ingested.

Plastic shopping bags are extremely abundant in the oceans. In the water these bags often resemble jellyfish, causing predators of jellyfish to ingest them. If an organism ingests one, it may clog digestion and cause starvation by stopping food from moving through or making the animal not feel hungry.

Trash from the lands all around the North Pacific is caught up in currents. The currents bring the trash into the center of the North Pacific Gyre. The concentration of trash increases toward the center of the gyre.

Capt. Charles Moore on the Seas of Plastic

The size of the garbage patch is unknown, since it can’t be easily seen from above. Some people estimate that it is twice the size of continental U.S, with a mass of 100 million tons. In some areas, plastics have seven times the concentration of zooplankton. This means that filter feeders are ingesting a lot of plastics. This may kill the organisms or the plastics may remain in their bodies. They are then eaten by larger organisms that store the plastics and may eventually die. Fish may eat organisms that have eaten plastic and then be eaten by people. This also exposes humans to toxic chemicals that the fish may have ingested with the plastic.

There are similar patches of trash in the gyres of the North Atlantic and Indian oceans.