Algal blooms and consequential dead zones are a problem plaguing the globe. In order to understand what algal blooms and dead zones are, and the impact they have on the environment, you have to understand the nitrogen and phosphorus cycles.
Algal blooms are caused because of human disruptions in the nitrogen or phosphorus cycle. Nitrogen and phosphorus are two of the main chemical elements of earth. The nitrogen and phosphorus cycles are biochemical cycles; biochemical cycles are simply cycles in which matter moves through out the earth. An algal bloom is a rapid increase in the amount of algae in an aquatic environment. These blooms often occur because excess amounts of nitrogen and phosphorus enter the aquatic environment, and stimulate the increased growth of algae. (Science Daily)
Nitrogen and phosphorus are naturally occurring elements but they become overabundant from nutrient pollution. An example of nutrient pollution is runoff from farms using fertilizer containing a large amount of fixed nitrogen or phosphorus. Nitrogen fixation is the first step in the nitrogen cycle; it is the process by which nitrogen oxide from the atmosphere is converted into nitrate or ammonia. In the form of ammonia or nitrate nitrogen can be used in fertilizer to stimulate the growth of producers. Phosphorus is more readily dissolved by soil than by water, so even a small amount of phosphorus within fertilizer runoff can stimulate growth of producers. Nitrogen and phosphorus may be helpful as fertilizers, but they can deadly when entering an aquatic environment. Nutrient pollution can occur in different ways, but the end result is always the sane, an abundant amount of nitrogen or phosphorus stimulating the growth of algae, creating an algal bloom. The abundance of algae in the aquatic environment turns the water green or red, (Figure 1 illustrates this). (National Geographic)
What is a dead zone and how does an algal bloom create it? Well, once the algae produced in the algae bloom dies, it sinks to the bottom, and bacterium decomposes the algae through cellular respiration. The bacteria takes in dissolved oxygen and produces carbon dioxide and chemical energy. The excess amount of decomposition decreases the amount of dissolved oxygen, creating hypoxic zones, areas with low amounts of oxygen. This lack of oxygen causes mass amounts of organisms requiring oxygen to die, or find new habitats, leaving an aquatic wasteland: also known as a dead zone.Now that you have an understanding of what algal blooms and dead zones are, and why they occur, it’s important to understand their significant impact on the environment. In 2007, an algal bloom in China’s Lake Taihu, the third largest lake in the country left 2 million people without water. “Overnight the city had no drinking water… what happened is folks woke up in the morning to make tea and found green Jello-like stuff coming out of the faucet. “ said Hans Pearl, a professor of the University of North Carolina-Chapel Hill. (Circle of Blue) Figure two shows an image of Lake Taihu:
Depriving an entire population of drinking water is a clear indication that something needs to be done in order to combat the nutrient pollution entering aquatic environments. Nonetheless, if you need something closer to home, in August, “a toxic bloom shut down the water supply system in Toledo Ohio. Since 2004 blooms of toxic algae shut down water supplies for more than 3 million people on three continents and have closed hundreds of inland lakes to recreation.” (Circle of Blue)
So, what should be done?
State legislation needs to be passed in order to allow government to regulate the amount of waste entering aquatic environments. But, because of the lack of political urgency in which this issue is viewed, nothing is being done. Teresa Fedor, a Democrat from Toledo articulates my view on the issue perfectly when she says, “We need regulations on seatbelts for cars to save lives, and on air pollution to shut down acid rain. So why would we not do this for the most fundamental, basic need of water?” ( Circle of Blue)
The only way to combat this issue is through limiting the use of fertilizers rich with nitrogen and phosphorus. Legislation passing laws limiting the use of such materials must enforce this. I think right now attention needs to be called to this issue; the people need to be informed of the environmental impact of algal blooms. If the people rally for it, politicians have no choice but to legislate. In this situation, knowledge is power!