Nutrient (aka nitrogen and phosphorus) pollution is one of America’s most widespread, costly, and challenging environmental problems. It is caused by excess nitrogen and phosphorus in the air and water.
Nutrients are chemical elements that all living organisms—plants and animals—need to grow. When too much nitrogen and phosphorus enter the environment—usually from a wide range of human activities—the air and water can become polluted.
Sources of Nutrient Pollution
The primary sources of nutrient pollution are fertilizer, animal manure, sewage treatment plant discharge, detergents, stormwater runoff, cars and power plants, failing septic tanks, and pet waste. In the Mississippi River Basin, which spans 31 states and ultimately drains into the Gulf of Mexico, nutrients from row crops, large farms, and concentrated animal feeding operations contribute the most nutrient pollution.
Effects of Nutrient Pollution
Excessive nitrogen and phosphorus in water and the air can cause health problems, damage our land and water, and take a heavy toll on the economy.
Nutrients can lead to a massive overgrowth of algae, known as an algae bloom. Certain types of algae emit toxins absorbed by shellfish; consuming these tainted shellfish can lead to stomach illness and short-term memory problems. Drinking or coming into contact with toxins from algae blooms can cause stomach aches, rashes, and more serious problems.
Excess nitrogen is a common drinking water contaminant in agricultural areas and can pose a particular risk to infants younger than six months old. Chemicals used to treat nutrient-polluted drinking water can pose additional risks to human health. These chemicals, including chlorine, can react with the algae in the water to form disinfection by-products that have been associated with reproductive and developmental health problems. Nitrogen pollutants in the air from burning fossil fuels can contribute to various respiratory problems for children, the elderly, and lung ailments.
There is another type of consumption that nearly all groups agree is detrimental to the environment: land consumption. The per capita rate at which we convert land from resource use of forestry or agriculture to nonproductive commercial or residential use has been steadily increased since World War II.
A few places are trying to slow the rate of land conversion, but few are succeeding, and none have stopped the loss of resource lands. Today, once we develop the land, we only know how to make it more developed. It is lost from the resource base “forever.”
There is a view that we should preserve forest land and let them develop the farmland. Farmland is a major source of nutrient pollution, while forests are our least polluting land use.
Farmland is better than developed land, but it can be sacrificed to protect the forest. We must preserve as much farmland as possible for two good reasons. First, as long as the land is in agriculture, it can be converted to forest if society deems that appropriate. If we produce too much food, we can selectively remove small to large amounts of land from production and plant it to trees or other less polluting resource uses.
We can selectively remove land that provides the greatest environmental benefit and is marginal for crop production. We may even wish to remove large tracts of agricultural lands in specific important watersheds.
The second reason to preserve both forest and farmland is that, globally, as many environmental nay-sayers like to point out, we must produce enough crops to feed a growing world.
The more farmland, particularly prime land, that we preserve from development, the less marginal land must “be brought under the plow,” and alternatively, the more forest/native lands that can be held.
Residents of the United States currently represent less than 5% of the global population but are responsible for about one-quarter of the consumption of natural resources (including food). The global glut of agricultural products also suggests these assumptions are not valid in the short term. However, it must be recognized that the global population will expand, and agricultural production must meet whatever the food (diet) and fiber needs are for that population to exist reasonably. The best way to feed that population while addressing environmental concerns, including nutrient pollution, is to minimize the loss of all resource lands, including farmland.
Nutrient pollution damages the environment and harms water quality. Algal blooms consume large amounts of oxygen that fish, shellfish, and other organisms need to survive. Algal blooms can make the water cloudy, reduce the ability of aquatic life to find food, and clog the gills of fish. Some algal blooms produce toxins that can cause illnesses or death for animals like turtles, seabirds, dolphins, fish, and shellfish.
Airborne nitrogen can also pose environmental risks. Nitrogen compounds released into the air by burning fossil fuels can react with water, oxygen, and other chemicals to form nitric acid. When it falls to earth, acid rain can damage an entire ecosystem, including streams, estuaries, forests, and grasslands.
Airborne compounds like nitrogen oxides contribute to forming other air pollutants, such as ozone—a component of smog—which can restrict visibility. Wind and weather can carry ozone many miles from urban to rural areas, damaging trees.
The popularity of SUVs raises the question of personal/corporate ethics and responsibility instead of government regulation. During the last 30 years, it has been far too common for those who decry government regulation to exploit every loophole available to avoid addressing environmental issues.
It can be argued that many individuals and corporations have used government requirements as a substitute for ethics and responsibility. If the government does not say it cannot be done, then it is acceptable. This is usually rationalized by the need to remain competitive and produce at the lowest possible unit price.
Nutrient pollution has diverse and far-reaching effects on the U.S. economy, impacting many sectors that depend on clean water. The tourism industry loses close to $1 billion each year, mostly from losses in fishing and boating activities because of nutrient-polluted water bodies. In Mississippi alone, tourism in the three counties that border the Gulf Coast accounts for about $1.6 billion in visitor expenditures, 32 percent of state travel and tourism tax revenues, and 24,000 direct jobs.
Nutrient pollution causes annual losses to the commercial fishing and shellfish industry in the tens of millions of dollars. When oxygen levels are low, fishery yields are reduced. During harmful algal blooms, consumers become wary that seafood could be tainted by toxins. Algal blooms can also negatively impact waterfront property values.
Algal blooms in drinking water sources can drastically increase treatment costs and subsequently increase consumer utility bills. Costs to clean up polluted water bodies, such as the Chesapeake Bay, can cost billions of dollars. Airborne nutrient pollution can also affect visibility at outdoor tourist destinations, like national parks. Airborne nitrogen compounds can damage structures, especially ones made of marble and limestone.
Concentration and Intensification in Animal Agriculture
There has been a tremendous concentration of confined animal production, particularly poultry, in regional centers during the last fifty years. The number of animals per operation has also grown dramatically.
Poultry has seen major growth in total production and was the first animal industry to concentrate production in relatively small geographic regions. The concentration is driven by the integration and efficiencies of locating production near processing and feed mill facilities.
Regional concentration has provided production efficiencies, but it has also created regional nutrient imbalances. For example, a large part of the grain fed to poultry in Delmarva is grown outside the production area.
The result is that we have a surplus of waste nutrients in litter imported into feed grains. It may be possible to use all the litter for crop production on all of Delmarva, not just the poultry region, if an application is based on nitrogen.
There will be substantial excess litter when we go to phosphorus-based applications. This appears to be common in full production. Regional nutrient imbalances have principally developed since World War II.
As farms have become less diverse, we have substantially changed the nutrient cycle from a more local, farm-based cycle to a distant one-directional path. Lanyon (2000) suggested that “the supply of balanced nutrients from off-farm following World War II shifted farm organization from an emphasis on biological feedback to other considerations, primarily economic incentives based on market transactions, and encouraged specialization in agricultural production.”
If waste nutrients were of sufficient value to return to the crop production region, there might not be a problem. If there were local high-value alternative uses, there would be no problem. However, most animal waste nutrients are used on cropland near the production areas. High nutrient levels are common in both surface and ground waters in these areas.
Thus, many in and out of agriculture show that regional nutrient imbalances are an issue in concentrated animal production areas. Water pollution is the most damaging and widespread concern regarding production agriculture, including the poultry industry. While the individual bird has become more efficient in converting nutrients to meat or eggs, the large increase in animal units has led to an overall increase in environmental burden. Regional nutrient imbalances are an environmental concern because we have not fully included the cost of waste management as part of animal production.
How the Government Address the Nutrient Pollution
EPA is working with its many partners to address nutrient pollution across the country. EPA
- Provides technical guidance and resources to help states develop water quality criteria for nitrogen and phosphorus
- Awards grants to states, watershed groups, and wastewater facilities to address nutrient-driven water quality problems
- Oversees permits that restrict nutrient discharges from industries
- Conducts research
- Works with state and federal partners on the Mississippi River/Gulf of Mexico Watershed Nutrient Taskforce to reduce the dead zone in the Gulf
State environmental agencies are working to develop water quality criteria for nutrients. Some states have already developed statewide nutrient criteria for certain types of water bodies. Other states have developed site-specific nutrient criteria. Still, others are just beginning to develop criteria and have identified important milestones toward proposing and approving nutrient criteria.
What Can You Do?
We can all take action to reduce nutrient pollution through the choices we make on our farms, around our homes, with our pets, in lawn care, and transportation. Families, individuals, students, and teachers can access online resources to find out more about their local waterways' health and learn how to join community efforts to restore and protect them for the benefit of people and wildlife.
Technology and lifestyles have combined to immensely increase nutrient pollution in the U.S., and the developed world, during the last fifty years. Population growth and development and increased per capita resource consumption are the long-term factors that influence nutrient pollution.
Modern agricultural production systems are major sources of nutrient pollution due to their domination of the landscape in many watersheds and the inefficiency of nutrient use in a natural system. Concentration and intensification of animal production have created on-farm and regional nutrient imbalances.
Monitoring and soil test data suggest the regional production centers are substantial sources of nutrient pollution. Farmers have implemented many practices to address sediment and nutrient pollution.
However, these practices must be acceptable to farmers within current production systems and economic conditions. The costs of waste management and environmental control have not been fully included in the price of our food system. It isn't easy to extract these costs from farmers/producers without passing these costs up the food system.
Every person who lives in or visits a watershed contributes to nutrient pollution of its waters. We also each contribute to nutrient pollution through lifestyle choices and resource consumption. Agriculture is just one part of the problem, and solution, for nutrient pollution but an important one. We must work to address water quality issues so we can expect the same responsibility from all others.