By Akshita Prakash
It all begins through the simple act of farming. The excess nitrogen and phosphorus in animal manure and chemical fertilizers are necessary to grow crops. However, when these nutrients are not fully utilized by plants they can be lost from the farm fields and negatively impact air and downstream water quality. This simple act can cause problems for all wildlife, including those in the ocean.
But that’s not all- nutrient pollution can be caused by rain. When rain falls on our cities and towns it runs across hard surfaces - like rooftops, sidewalks and roads - and carries pollutants, including nitrogen and phosphorus, into local waterways we are being affected severely, and we don’t even know it. Another cause is from our wastewater. Our sewer and septic systems are responsible for treating large quantities of waste, and these systems do not always operate properly or remove enough nitrogen and phosphorus before discharging into waterways. Electric power generation, industry, transportation and agriculture have also increased the amount of nitrogen in the air through use of fossil fuels. And lastly, in your own home, the nitrogen and phosphorus in fertilizers, yard and pet waste and certain soaps and detergents (which contain nitrogen and phosphorus), can contribute to nutrient pollution if not properly used or disposed of. The amount of hard surfaces and type of landscaping can also increase the runoff of nitrogen and phosphorus during wet weather.
With all these causes, nutrient pollution has become disastrous in some parts of the world. Though the simple act of fertilizing your plants may seem unlikely to cause any damage, when too much nitrogen and phosphorus enter the environment (usually from a wide range of human activities) the air and water can become polluted. Nutrient pollution has impacted many streams, rivers, lakes, bays and coastal waters for the past several decades, resulting in serious environmental and human health issues, and impacting the economy. Too much nitrogen and phosphorus in the water causes algae to grow faster than ecosystems can handle.
Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive. Large growths of algae are called algal blooms and they can severely reduce or eliminate oxygen in the water, leading to illnesses in fish and the death of large numbers of fish. Some algal blooms are harmful to humans because they produce elevated toxins and bacterial growth that can make people sick if they come into contact with polluted water, consume tainted fish or shellfish, or drink contaminated water.
For those who don’t think this impacts us, you are severely mistaken. Nutrient pollution in groundwater - which millions of people in the United States use as their drinking water source - can be harmful, even at low levels. Infants are vulnerable to a nitrogen-based compound called nitrates in drinking water. Excess nitrogen in the atmosphere can produce pollutants such as ammonia and ozone, which can impair our ability to breathe, limit visibility and alter plant growth. When excess nitrogen comes back to earth from the atmosphere, it can harm the health of forests, soils and waterways. Through such catastrophic causes which can threaten the life of animals and humans alike, the federal, state and local governments spend billions of dollars per year to minimize these effects.
Here are the impacts of nutrient pollution listed:
Direct exposure to algae
Harmful algal blooms sometimes create toxins that are detrimental to fish and other animals. After being consumed by small fish and shellfish, these toxins move up the food chain and can impact larger animals like sea lions, turtles, dolphins, birds and manatees.
Even if algal blooms are not toxic, they can negatively impact aquatic life by blocking out sunlight and clogging fish gills.
Dead zones and hypoxia
Nutrient pollution can create dead zones - areas in water with little or no oxygen - where aquatic life cannot survive. Also known as hypoxia, these areas are caused by algal blooms consuming oxygen as they die and decompose. Aquatic animals - particularly young fish and seafloor dwellers like crabs and clams - must leave the affected area to survive.
Over 166 dead zones have been documented nationwide, affecting water bodies like the Chesapeake Bay and the Gulf of Mexico. The Gulf of Mexico dead zone is the largest in the United States, measured to be 5,840 square miles in 2013. It occurs every summer because of nutrient pollution from the Mississippi River Basin, an area that drains 31 upstream states. The Mississippi River/Gulf of Mexico Hypoxia Task Force coordinates nutrient management in this area.
Acid rain
Acid rain, caused by nutrient pollution in the air, damages lakes, streams, estuaries, forests and grasslands across the country.
Air pollution
Airborne nitrogen compounds like nitrogen oxides contribute to the formation of other air pollutants such as ground-level ozone, a component of smog which can restrict visibility. Wind and weather can carry ozone many miles from urban to rural areas. Ozone pollution can damage trees and harm the appearance of vegetation and scenic areas.
More information on how you can make a difference to reduce nutrient pollution can be found on:
Works Cited
Zaneveld, Jesse R., et al. “Overfishing and Nutrient Pollution Interact with Temperature to Disrupt Coral Reefs down to Microbial Scales.” Nature News, Nature Publishing Group, 7 June 2016, www.nature.com/articles/ncomms11833.
“Sources and Solutions.” EPA, Environmental Protection Agency, 4 Feb. 2019, www.epa.gov/nutrientpollution/sources-and-solutions.
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