Nutrient Pollution

About Nutrient Pollution

Nutrient pollution is one of America's most widespread, costly and challenging environmental problems, and is caused by excess nitrogen and phosphorus in the air and water.

Nitrogen and phosphorus are nutrients that are natural parts of aquatic ecosystems. Nitrogen is also the most abundant element in the air we breathe. Nitrogen and phosphorus support the growth of algae and aquatic plants, which provide food and habitat for fish, shellfish and smaller organisms that live in water.

But 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.

Nutrient pollution in ground water - 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.

• Phosphorus - Depending on your soil type, phosphorus from wastewater can be absorbed and retained in the soil. Unabsorbed phosphorus can travel in groundwater toward a waterbody and become a source of contamination.

• Nitrogen - Some nitrogen may be removed as wastewater flows through the septic system and soil. But the remaining nitrogen can enter the underlying groundwater and flow towards a surface water body. If there are many septic systems in a small area, the nitrogen flowing through groundwater could overload a waterbody, causing eutrophication. Saltwater is more vulnerable to nitrogen pollution.

Nutrient Polution Sources and Solutions

The primary sources of excess nitrogen and phosphorus are:

Agriculture Nutrient Pollution

Farmers apply nutrients on their fields in the form of chemical fertilizers and animal manure, which provide crops with the nitrogen and phosphorus necessary to grow and produce the food we eat. However, when nitrogen and phosphorus are not fully utilized by the growing plants, they can be lost from the farm fields and negatively impact air and downstream water quality.

This excess nitrogen and phosphorus can be washed from farm fields and into waterways during rain events and when snow melts, and can also leach through the soil and into groundwater over time. High levels of nitrogen and phosphorus can cause eutrophication of water bodies. Eutrophication can lead to hypoxia (“dead zones”), causing fish kills and a decrease in aquatic life. Excess nutrients can cause harmful algal blooms (HABs) in freshwater systems, which not only disrupt wildlife but can also produce toxins harmful to humans.

Fertilized soils, as well as livestock operations, are also vulnerable to nutrient losses to the air. Nitrogen can be lost from farm fields in the form of gaseous, nitrogen-based compounds, like ammonia and nitrogen oxides. Ammonia can be harmful to aquatic life if large amounts are deposited from the atmosphere to surface waters. Nitrous oxide is a potent greenhouse gas.

Stormwater Nutrient Pollution

In undeveloped areas precipitation typically soaks into the ground. However, when buildings, parking lots, roads and other hard surfaces are added to the landscape, the ground cannot absorb the water. Water from rain or snow storms, known as stormwater, instead flows over streets, parking lots and roofs and into a water body or storm drain. Urban and suburban areas produce much more stormwater runoff due to the high amount of paved and hard surfaces.

Stormwater runoff can contain nitrogen and phosphorus pollutants from fertilizers and pet and yard waste. During periods of heavy rainfall or snowmelt some wastewater systems are designed to occasionally overflow and discharge excess untreated sewage directly to nearby streams, rivers or other water bodies. These discharges are known as combined sewer overflows and are common in many cities nationwide.

Green Infrastructure Stormwater Solutions

Green infrastructure can be used to address stormwater runoff and sewer overflow problems. Green infrastructure works by slowing down the runoff, spreading it out over the land, and slowly soaking it into the ground, or in some cases reusing the water onsite. Green infrastructure is also sometimes referred to as "low impact development." These techniques also help to remove pollutants from runoff by allowing plants to filter out pollutants as the water slowly infiltrates into the ground. Some examples of green infrastructure techniques include rain gardens, pervious pavement, rain barrels and green roofs.

• Green Infrastructure Tips:
  • Plant a rain garden of native plants, shrubs and trees that reduce the amount of fertilizer needed and provide a way for water to soak into the ground.
  • Install a rain barrel to collect rainwater; the rainwater can later be used to wash your car or water your plants and lawn.
  • Adopt techniques that utilize natural processes to manage stormwater runoff and reduce the impact of impervious surfaces on water quality.
  • Use pervious pavers for walkways and low traffic areas to allow water to soak into the ground.
  • Install a green roof on your home or business.
  • Incorporate best management practices, such as grassed swales, filter strips, or buffer strips on your property to control and temporarily store stormwater runoff.
  • Use yard waste, which includes grass clippings and leaves, in mulch or compost for your garden. If this is not an option, prepare all clippings and leaves for community composting, or in barrels or secured papers bags for disposal, which keeps them from washing into streams.

Residential Nutrient Pollution

Our homes, through appliances, yards, driveways and even pets, contribute to nutrient pollution. Roadside storm drains often lead directly to local streams and rivers, so anything that flows into them makes it to local waterways without treatment.

Residential areas can be a significant source of excess nitrogen and phosphorus pollution from fertilizers. Over-fertilizing and overwatering a yard is a common practice among homeowners and landscaping services and can lead to fertilizer being washed away more easily. Additionally, pet waste contributes nitrogen, phosphorus, parasites and bacteria to water bodies when it is not disposed of properly. Pet waste that is not properly disposed of can lead to conditions in local water bodies that are unsafe for human recreation.

There are also sources of nutrient pollution inside our homes. Many laundry, dish and car washing soaps contain a form of phosphorus called phosphates, which are carried from our homes into the water system through our drains. We also add excess nitrogen to the atmosphere through the use of electricity in our homes. Most of our electricity comes from the burning of fossil fuels, which release pollutants into the environment.

Residential Run-off Solutions

Fertilizers, yard clippings and pet waste contain nitrogen and phosphorus, and can contribute to nutrient pollution if not properly used or disposed. The amount of hard surfaces and type of landscaping can also increase the runoff of nitrogen and phosphorus during wet weather.

• Apply fertilizers only when necessary and at the recommended amount.
• Don't apply fertilizer before windy or rainy days.
• Apply fertilizer as close as possible to the period of maximum uptake and growth for grass and other plants, which is usually spring and fall in cool climate, and early and late summer in warm climates.
  • The sale of lawn fertilizer is banned during summer months in many Florida counties.
• Avoid applying fertilizer close to waterways.
• Do not overwater lawns and garden; use a soaker hose, a porous hose that releases water directly to the ground, which can reduce overwatering that carries away fertilizers that would otherwise enrich lawns and gardens.
• Fill fertilizer spreaders on a hard surface so that any spills can be easily cleaned up.
• Properly store unused fertilizers and properly dispose of empty containers.
• Maintain your lawn mowers, snow blowers, chain saws, leaf vacuums and similar outdoor power equipment to reduce nitrogen oxide emissions.
• Blow grass clippings back into yard, the mulch will help it grow.
  • Do not blow clippings or leaves into the street or storm drain gutters.

Fossil Fuel

Airborne nitrogen pollution affects not only the quality of the air we breathe, but also the land and the water. Nitrogen is the most abundant element in the air and is essential to plant and animal life. Sources of nitrogen from human activities, such as electric power generation, industry, transportation and agriculture, can upset the natural balance of nitrogen in the environment.

When fossil fuels are burned, they release nitrogen oxides into the atmosphere, which contribute to the formation of smog and acid rain. The most common nitrogen-related compounds emitted into the air by human activities are collectively referred to as nitrogen oxides. Ammonia is another nitrogen compound emitted to the air, primarily from agricultural activities, but also from fossil fuels. Most of the nitrogen oxides released in the U.S. due to human activity are from the burning of fossil fuels associated with transportation and industry.

Major sources of nitrogen oxide emissions include:

• Cars and trucks
• Coal-fired power plants
• Large industrial operations
• Ships and airplanes

Solutions for Fossil Fuel Pollution

Businesses: There are many ways that businesses can reduce nutrient pollution, including:

• Manage and Reduce Emissions - Leading businesses are taking steps to understand and manage their greenhouse gas emissions by preparing annual greenhouse gas inventories and setting long-term targets to reduce emissions.
• Increase Energy Efficiency - Improving energy efficiency not only reduces greenhouse gas emissions into the atmosphere, it is good for a corporation's bottom line. Developing and implementing an effective corporate energy management program allows companies to manage energy with the same expertise used to manage other aspects of their business.
• Buy Renewable Energy - Your organization's purchased electricity use can be a significant source of air pollution and greenhouse gas emissions. Buying renewable energy, can help reduce your organization's environmental impact while also providing a number of other valuable benefits.

Individuals:

• Conserve Energy - Air pollution from energy production leads to acid rain, excess greenhouse gases, and health risks. One important step you can take to minimize airborne nutrient pollution is to conserve energy. You can do this by:

Turning off lights, computers, televisions, video games and other electrical equipment when you're not using them. Buying equipment that uses less electricity, including lights, air conditioners, heaters, refrigerators and washing machines. Energy Star-certified products and buildings use at least 10 less energy than standard models.

• Limiting the use of air conditioning.
• Installing a programmable thermostat.
• Minimize the Miles - Driving cars and trucks also produces significant amounts of nitrogen oxide emissions. To help cut down on air pollution from cars, you can consolidate driving trips, carpool or take public transportation, such as buses and trains. When possible, consider walking or biking instead of driving.

The presence of excess nitrogen in the atmosphere in the form of nitrogen oxides or ammonia is deposited back onto land, where it washes into nearby water bodies. These excess nutrients contribute to pollution, harmful algal blooms and oxygen-deprived aquatic zones. Excess ammonia and low pH in these areas are toxic to aquatic organisms and affect their survival.

Nutrient Pollution Effects

The presence of excess nutrients in air and water can affect human health, the environment and the economy. Federal, state and local governments spend billions of dollars per year to minimize these effects.

Human Health Effects

Excess nutrients and harmful algal blooms create toxins and compounds in water that pose danger for human health. There are several ways that people (and pets) can be exposed to these compounds.

Direct exposure to toxic algae

A hand filling a clear glass with water from a sink faucet Drinking water can be a source of exposure to chemicals caused by nutrient pollution. Drinking, accidentally swallowing or swimming in water affected by a harmful algal bloom can cause serious health problems including:

• Rashes
• Stomach or liver illness
• Respiratory problems
• Neurological effects

Nitrates in drinking water

Nitrate, a compound found in fertilizer, can enter drinking water in agricultural areas. A 2010 report on nutrients in ground and surface water by the U.S. Geological Survey found that nitrates were too high in 64 percent of shallow monitoring wells in agricultural and urban areas.

Infants are more susceptible to the health effects posed by nitrates, which can be serious and sometimes fatal.

Byproducts of water treatment

Stormwater runoff can carry nutrients directly into rivers, lakes and reservoirs, which serve as sources of drinking water for many people. When disinfectants used to treat drinking water react with toxic algae, harmful chemicals called dioxins can be created. These byproducts have been linked to serious health problems, including reproductive and developmental health risks.

Nutrient Pollution Environmental Effects

Nutrient pollution fuels the growth of harmful algal blooms which have negative impacts on aquatic ecosystems.

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 waterbodies 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.

Nutrient Pollution Economic Effects

Nutrient pollution has diverse and far-reaching effects on the U.S. economy, impacting tourism, property values, commercial fishing, recreational businesses and many other sectors that depend on clean water.

Drinking water costs

Nitrates and algal blooms in drinking water sources can drastically increase treatment costs. For example, nitrate-removal systems in Minnesota caused supply costs to rise from 5-10 cents per 1000 gallons to over $4 per 1000 gallons.

It can also cost billions of dollars to clean up polluted water bodies. Every dollar spent on protecting sources of drinking water saves in water treatment costs.

Tourism losses

The tourism industry loses close to $1 billion each year, mostly through losses in fishing and boating activities, as a result of water bodies that have been affected by nutrient pollution and harmful algal blooms.

Airborne nutrient pollution can also affect visibility at popular outdoor destinations like national parks. This kind of pollution can also damage buildings and other structures, especially those made of marble and limestone.

Commercial fishing and shellfish losses

Fishing and shellfish industries are hurt by harmful algal blooms that kill fish and contaminate shell fish. Annual losses to these industries from nutrient pollution are estimated to be in the tens of millions of dollars.

Real estate losses

Clean water can raise the value of a nearby home by up to 25 percent. Waterfront property values can decline because of the unpleasant sight and odor of algal blooms.