All About Water

The world’s oceans are so vast that they might seem immune to the influence of human waste. Unfortunately, this is not the case. Marine pollutants are a problem, and despite regulation and laws like the Clean Water Act, marine pollutants continue to be a problem. Marine pollutants, like urban runoff, biostimulants, petroleum, plastics, other debris and thermal pollution, severely harm our waterways and the life they contain.

Major Marine Pollutants: Urban Runoff

Human activity concentrates naturally occurring compounds until they become hazardous. When rainwater or wastewater from homes runs into storm drains, it picks up these hazardous compounds and deposits them into waterways. Man-made compounds like DDT and cleaners are also introduced into the marine environment this way. Much of human runoff results from individuals’ day-to-day activities.

Major Marine Pollutants: Biostimulants and Sewage

Biostimulants do not stimulate life, as their name might mislead one to believe; instead, they do more harm than good. Sewage is organic and breaks down via bacterial decay. The decay process depletes available oxygen and suffocates local animal life. Additionally, the chemical breakdown produces ammonia and hydrogen sulfide. These chemicals are toxic to fish, even in low concentrations. Bacteria and other contaminants may be consumed by shellfish, which then become hazardous to humans or other animals if consumed. Some forms of algae thrive on the nutrients created by biostimulants and can overgrow into algae blooms or “red tides.”

Marine Pollutants: Oil

Oil is introduced into waterways through spills like the massive Deepwater Horizon spill in the Gulf of Mexico on April 20, 2010. Oil production also leads to the seepage of oil into the marine ecosystem, as does rainwater runoff. Oil floats on the surface of the water, coating and suffocating any marine life that touches the water’s surface. Oil also prevents oxygen from permeating from the air into water, and thereby suffocates life that may not even directly touch the oil.

Marine Pollutants: Plastics and Other Debris

As humans travel the earth’s waters, we leave our mark. Despite regulation, we toss debris over the sides of ships, and lose things like containers and fishing nets overboard. This debris is eaten by fish and water mammals and can eventually kill them.

Marine Pollutants: Thermal Pollution

Nuclear power plants and other industrial outlets use water as a coolant. The heated water is disposed of directly into waterways where it increases the temperature of the body of water. This, again, stimulates the dangerous growth of algae blooms.

What happens when a plastic bottle cap is swept into a storm drain? It goes out to the ocean, of course. This is not a rare occurrence; plastic is washed out to sea all the time. Unfortunately, so much plastic has been disposed of over the years that a giant garbage patch has formed in the Pacific Ocean. The Pacific Garbage Patch is very harmful to marine life, but scientists have had trouble monitoring its growth and generating feasible ideas for cleaning it up.

What is the Pacific Garbage Patch?

Discovered about in 1997 by Captain Charles Moore, the Pacific Garbage Patch is made up of plastic debris that has been dumped into the ocean and swept together by large swirling currents called gyres.  Some refer to it as an “island of plastic,” but in actuality the greatest bulk of the Pacific Garbage Patch is not very visible. The patch is actually made up of very small, almost microscopic, pieces of plastic that float just beneath the surface of the water. This is just one form of water pollution, but it concerns scientists very much.

How did it form?

Once the plastic is washed out to sea, ocean currents and gyres swirl it into a vortex and hold it in the center of a high pressure area. Gyres, or large scale swirls of ocean current, can collect large amounts of debris in one spot. There it slowly breaks down into almost invisible pieces.  After decades of plastic dumping, the garbage patch has grown to an enormous size and continues to grow.  While some claim that the garbage patch is approximately twice the size of Texas, these estimates have recently been disputed.

How does it affect marine life?

The environmental impact of marine debris is profound. It is a particular threat to marine mammals, such as the endangered Pacific Monk Seal and many species of whales. Seabirds and turtles can become entangled in the larger pieces, and many birds, turtles, and fish are dying from ingesting the bits of plastic. Much of it is smothering coral reefs as it falls to the ocean floor. It is even a threat to human health when it washes up on beaches or floats in swimming areas.

How fast is the Pacific Garbage Patch growing?

It is reasonable to believe that the Pacific Garbage Patch is growing. As the human population grows, we use more plastic that is washed into the ocean. However, it is difficult to measure its growth rate. The patch is hard to see, as explained above, and its shape changes as the waters around it swirl. Further, the garbage patch is not a continuous mass. Within the area of the Pacific Garbage Patch, there are large expanses of clear water. All of these factors make it difficult for scientists to estimate how fast it is growing.

Why don’t we just clean it all up?

It is not that easy. First of all, lack of visibility makes it difficult to find pieces of plastic to collect. It might be in one area today, then swirled hundreds of miles away the next. Secondly, it is difficult and costly to travel hundreds of miles into the Pacific to pick up microscopic pieces of plastic.

What about skimming?

A lot of marine life lives under the plastic, but plankton live among it. Since plankton and plastic pieces are about the same size, a skimming and filtering operation would pick up both. In addition to the prohibitive cost, skimming could destroy the plankton that is both the base of the ocean’s food chain and responsible for half of the photosynthesis on Earth.

Unfortunately, little has been done to solve this growing problem, as scientists have struggled to come up with efficient and cost-effective ways to rid the ocean of the debris. With no well-defined border, The Pacific Garbage Patch is even hard to monitor. For now, scientists at the National Oceanic and Atmospheric Administration are working on the problem, but a solution seems to be a long way off.

Bisphenol-A, commonly referred to as BPA, is a chemical that is used in the manufacturing of some types of plastics and epoxy resins. Concerns have arisen in recent years regarding the safety of BPA, although the chemical’s ability to mimic estrogen was noted as early as 1936. Additionally, a study in 1997 demonstrated that even low doses of BPA could have adverse effects. Although scientists continue to study plastics with BPA, this potentially toxic chemical is still found in many products. But the use of BPA is beginning to be regulated by government agencies in many countries. Bisphenol-A is most commonly found in specific types of plastic products, and may cause negative health consequences, particularly in susceptible groups of people.

Why is BPA in plastic?

BPA is commonly found in polycarbonate plastics and epoxy resins because it is used during the chemical synthesis of these products. Plastics with BPA are used to make water bottles, sports and medical equipment, and CD/DVDs, among other items because it is clear and shatter resistant.

Where is BPA most commonly found?

Plastics with BPA, specifically polycarbonate, are the most common sources of exposure. These are hard, clear plastic products and frequently carry the number 7 recycling code. However, not all products labeled with recycle code 7 are polycarbonate or contain BPA. Flexible PVC products but not PVC pipes sometimes contain BPA and are typically recycle code 3. The polymer coating inside most aluminum cans also contains BPA, and the chemical can also be found in carbonless copy paper and thermal paper, which is frequently used for printing receipts(iv). Concerns about BPA consumption are most frequently linked to food storage containers. According to the National Institutes of Health, food stored in plastics with BPA can allow for BPA contamination especially if the food is hot or the container is heated(v).

What are the negative health consequences of BPA?

The National Toxicology Program (NTP) has stated that there is insufficient evidence to conclusively determine if BPA causes adverse effects on development or reproduction in humans, although there is evidence in animal studies that even low doses of BPA can be detrimental(vi). The NTP has also stated that there is some concern regarding adverse effects on development in fetuses, infants and children. Other health effects of BPA, including obesity, thyroid dysfunction, cancer and sexual difficulties, have been suggested, although research is inconclusive, but ongoing.

Who should be most concerned about BPA?

The strongest evidence of BPA causing harm is in fetuses, infants and children. The Department of Health and Human Services provides recommendations to help limit the exposure of these groups to plastics with BPA (vii).