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Animation: Water Pollution from Nitrates

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Rivers and lakes are an important part of any ecosystem, providing water for people, plants, and animals. Unfortunately, human activity often results in water pollution, which can affect all of these living things. In this animation, we will concentrate on one of the main pollutants: nitrate. Animals need nitrogen because it is found in proteins and DNA. Although the air around us contains a lot of nitrogen gas, we cannot use this gas directly. Instead, we get proteins and DNA from the food that we eat, after plants incorporate the nitrogen into these molecules. Plants take in nitrate from the soil. The nitrate is produced by bacteria from the nitrogen gas in the air. Decomposers complete the cycle by breaking down proteins in dead organisms and producing other nitrogen-containing molecules. So in a natural ecosystem nitrogen atoms are continually being recycled. Humans affect the nitrogen cycle in many ways. Burning fossil fuels (mainly coal and oil) in power stations and cars can add nitrogen to the air. Factories can produce water pollution in the form of nitrate. Farm animals produce manure, which contains nitrates. Farmers and homeowners use fertilizers containing nitrate. Why do farmers have to use fertilizers, even though natural ecosystems do not need fertilizer? The nitrate in fertilizer is used to replace the nutrients that are removed from the farm in harvested crops. The Environmental Protection Agency, or EPA, found in its National Water Quality Inventory that animal wastes and fertilizers were the main sources of water pollution. Most fertilizers contain nitrate, and farmers and homeowners often use too much fertilizer or fertilize just before it rains. Rainwater then washes the nitrates into nearby waterways. Nitrate in water causes many problems. High levels of nitrate in rivers, lakes, and the ocean can cause algal blooms during which algae grow very rapidly. As the algae dies, the accompanying rapid bacterial growth depletes the water of oxygen. This state of low oxygen level in the water kills fish and other organisms. Many states, such as North Carolina, keep records of fish kills. These may involve tens of thousands of fish that are killed in a particular river or lake, and are often caused by low oxygen levels. In addition, a particular dinoflagellate, called Pfiesteria, sometimes increases in numbers in polluted water. Unlike most dinoflagellates, which are photosynthetic, Pfiesteria feeds on the skin of fish and kills them. This map shows the site of fish kills in North Carolina between January and September 2000. During the summer months, a dead zone covering up to 7,000 square miles forms in the Gulf of Mexico off the coast of Louisiana. This is probably caused by nitrates that are washed down the Mississippi River. Livestock that are given drinking water with nitrates dissolved in it suffer from a variety of ailments. The symptoms of nitrate poisoning in animals include a bluish or brownish discoloring of the areas around the mouth and eyes. Animals may have a sluggish, staggering gait, rapid heartbeat, frequent urination, and labored breathing followed by collapse. In severe cases, convulsion and coma may occur, followed by death one to three hours after the first signs appear. Even moderate levels of nitrate in drinking water can cause livestock to grow more slowly than normal, and pregnant animals with nitrate poisoning have more stillbirths. Nitrate in human drinking water reduces the amount of oxygen being carried to the brain, and causes blue baby syndrome in infants less than 6 months old. The blood sample of an affected baby is a chocolate brown color instead of red. Nitrate poisoning can be treated, and in most cases the baby makes a full recovery. It is crucial, however, to deal with the problem immediately, because without treatment a baby can die. Recent studies have shown a link between nitrate in drinking water and goiter, a condition characterized by swelling in the neck. There is also increased risk of developing insulin-dependent diabetes associated with moderate levels of nitrate in water supplies. The recommended EPA limit for nitrates in drinking water is a maximum of 10 parts per million: in other words, 10 nitrate molecules mixed in a million water molecules. In 1995, 9 percent of drinking water wells tested had higher levels of nitrate than this. Nitrates are a common problem throughout the country. In 1996, the EPA found that in almost a third of the regions studied nationwide, less than 20 percent of the rivers met the standards for all designated uses. For example, almost 40 percent of lakes and rivers assessed by states were unsafe for fishing and swimming. Let's look at how this problem is being addressed at the individual, city, state, and federal level. At an individual level, you can reduce water pollution by following these tips for fertilizing your lawn and garden. Most of these tips are designed to reduce the amount of nitrate being washed into rivers and lakes. Some examples of easy ways to reduce water pollution include: 1. Test the soil before you fertilize to make sure that fertilizer is really necessary. 2. Do not fertilize close to streams or lakes. 3. Use a mulching mower for lawns, or leave grass clippings on the lawn to encourage natural recycling of nitrate. 4. Sweep grass clippings off driveways and concrete surfaces, as these often wash into storm drains and then into rivers. 5. Use a slow-release fertilizer that will last for several months. 6. Do not fertilize just before a heavy rain. Next, we will look at how the problem of nitrate pollution is addressed at the city level. People contribute to the problem of nitrate pollution mainly by using fertilizers incorrectly and by inadequately treating sewage. Fifty years ago, most sewage treatment plants pumped raw sewage into rivers, and leaking septic tanks are still a major contributor to high nitrate levels in many areas. One innovative solution to both of these problems was worked out in 1926. The city of Milwaukee used a new process to treat its sewage: air was bubbled through the liquid sewage, and the water was removed to produce a solid that contained nitrogen. This solid was called Milorganite, for Milwaukee Organic Nitrogen, and sold as a fertilizer, particularly for lawns. One of the advantages of Milorganite is that it is a slow-release fertilizer, so even in heavy rains there is very little problem with nitrate washing into rivers. So human sewage has been turned into a useful fertilizer! Each state has its own programs to combat water pollution. One example in California was Proposition 12. In March 2000, voters approved Proposition 12, which provided a 2.1 billion-dollar bond issue with a significant proportion of the money being dedicated to protecting water quality, both by buying land around rivers and by reducing water pollution. In the last 10 years, states have improved their water monitoring programs and have significantly cut pollution, especially from factories and power plants. This is why most nitrate pollution now comes from farms and lawns. Water quality has become an important political issue particularly in coastal states, partly because the number of pollution-related beach closings nationwide increased 50 percent between 1997 and 1999. Many states now have programs to both educate farmers and consumers about the problems of water pollution, and also to suggest simple ways to reduce the amount of nitrate that gets into water supplies. Every year the federal government spends over 2 billion dollars implementing the Clean Water Act. Some of this money is spent protecting pristine areas, and some is spent reducing pollution at its source. Animal manure is a major source of nitrate pollution. Nationwide, farm animals produce 130 times as much fecal waste as humans. Farms produce 5 tons of animal manure a year for every man, woman, and child in the country. Some of this animal manure is stored in romantically named manure lagoons. Federal grants to farmers encourage them to cut down on the amount of nitrate that gets into rivers. For example, since 1983 the amount of nitrate washed into the Mississippi River has declined. Even simple ideas such as fencing off streams so that animal wastes cannot easily get into them can have a dramatic effect in reducing pollution. Although 40 percent of rivers are still unsafe to swim in, this is an improvement over the 70 percent of rivers that were unsafe when the Clean Water Act was first implemented in 1972. Many individual rivers and bays are now much cleaner than in the past. Examples include Long Island Sound, Tampa Bay, Galveston Bay, and San Francisco Bay. If you would like to find out more about water quality, the EPA and U.S. Geological Survey (USGS) provide websites with water-quality information and data.
Rivers and lakes are an important part of any ecosystem, providing water for people, plants, and animals. Unfortunately, human activity often results in water pollution, which can affect all of these living things. In this animation, we will concentrate on one of the main pollutants: nitrate. Animals need nitrogen because it is found in proteins and DNA. Although the air around us contains a lot of nitrogen gas, we cannot use this gas directly. Instead, we get proteins and DNA from the food that we eat, after plants incorporate the nitrogen into these molecules. Plants take in nitrate from the soil. The nitrate is produced by bacteria from the nitrogen gas in the air. Decomposers complete the cycle by breaking down proteins in dead organisms and producing other nitrogen-containing molecules. So in a natural ecosystem nitrogen atoms are continually being recycled. Humans affect the nitrogen cycle in many ways. Burning fossil fuels (mainly coal and oil) in power stations and cars can add nitrogen to the air. Factories can produce water pollution in the form of nitrate. Farm animals produce manure, which contains nitrates. Farmers and homeowners use fertilizers containing nitrate. Why do farmers have to use fertilizers, even though natural ecosystems do not need fertilizer? The nitrate in fertilizer is used to replace the nutrients that are removed from the farm in harvested crops. The Environmental Protection Agency, or EPA, found in its National Water Quality Inventory that animal wastes and fertilizers were the main sources of water pollution. Most fertilizers contain nitrate, and farmers and homeowners often use too much fertilizer or fertilize just before it rains. Rainwater then washes the nitrates into nearby waterways. Nitrate in water causes many problems. High levels of nitrate in rivers, lakes, and the ocean can cause algal blooms during which algae grow very rapidly. As the algae dies, the accompanying rapid bacterial growth depletes the water of oxygen. This state of low oxygen level in the water kills fish and other organisms. Many states, such as North Carolina, keep records of fish kills. These may involve tens of thousands of fish that are killed in a particular river or lake, and are often caused by low oxygen levels. In addition, a particular dinoflagellate, called Pfiesteria, sometimes increases in numbers in polluted water. Unlike most dinoflagellates, which are photosynthetic, Pfiesteria feeds on the skin of fish and kills them. This map shows the site of fish kills in North Carolina between January and September 2000. During the summer months, a dead zone covering up to 7,000 square miles forms in the Gulf of Mexico off the coast of Louisiana. This is probably caused by nitrates that are washed down the Mississippi River. Livestock that are given drinking water with nitrates dissolved in it suffer from a variety of ailments. The symptoms of nitrate poisoning in animals include a bluish or brownish discoloring of the areas around the mouth and eyes. Animals may have a sluggish, staggering gait, rapid heartbeat, frequent urination, and labored breathing followed by collapse. In severe cases, convulsion and coma may occur, followed by death one to three hours after the first signs appear. Even moderate levels of nitrate in drinking water can cause livestock to grow more slowly than normal, and pregnant animals with nitrate poisoning have more stillbirths. Nitrate in human drinking water reduces the amount of oxygen being carried to the brain, and causes blue baby syndrome in infants less than 6 months old. The blood sample of an affected baby is a chocolate brown color instead of red. Nitrate poisoning can be treated, and in most cases the baby makes a full recovery. It is crucial, however, to deal with the problem immediately, because without treatment a baby can die. Recent studies have shown a link between nitrate in drinking water and goiter, a condition characterized by swelling in the neck. There is also increased risk of developing insulin-dependent diabetes associated with moderate levels of nitrate in water supplies. The recommended EPA limit for nitrates in drinking water is a maximum of 10 parts per million: in other words, 10 nitrate molecules mixed in a million water molecules. In 1995, 9 percent of drinking water wells tested had higher levels of nitrate than this. Nitrates are a common problem throughout the country. In 1996, the EPA found that in almost a third of the regions studied nationwide, less than 20 percent of the rivers met the standards for all designated uses. For example, almost 40 percent of lakes and rivers assessed by states were unsafe for fishing and swimming. Let's look at how this problem is being addressed at the individual, city, state, and federal level. At an individual level, you can reduce water pollution by following these tips for fertilizing your lawn and garden. Most of these tips are designed to reduce the amount of nitrate being washed into rivers and lakes. Some examples of easy ways to reduce water pollution include: 1. Test the soil before you fertilize to make sure that fertilizer is really necessary. 2. Do not fertilize close to streams or lakes. 3. Use a mulching mower for lawns, or leave grass clippings on the lawn to encourage natural recycling of nitrate. 4. Sweep grass clippings off driveways and concrete surfaces, as these often wash into storm drains and then into rivers. 5. Use a slow-release fertilizer that will last for several months. 6. Do not fertilize just before a heavy rain. Next, we will look at how the problem of nitrate pollution is addressed at the city level. People contribute to the problem of nitrate pollution mainly by using fertilizers incorrectly and by inadequately treating sewage. Fifty years ago, most sewage treatment plants pumped raw sewage into rivers, and leaking septic tanks are still a major contributor to high nitrate levels in many areas. One innovative solution to both of these problems was worked out in 1926. The city of Milwaukee used a new process to treat its sewage: air was bubbled through the liquid sewage, and the water was removed to produce a solid that contained nitrogen. This solid was called Milorganite, for Milwaukee Organic Nitrogen, and sold as a fertilizer, particularly for lawns. One of the advantages of Milorganite is that it is a slow-release fertilizer, so even in heavy rains there is very little problem with nitrate washing into rivers. So human sewage has been turned into a useful fertilizer! Each state has its own programs to combat water pollution. One example in California was Proposition 12. In March 2000, voters approved Proposition 12, which provided a 2.1 billion-dollar bond issue with a significant proportion of the money being dedicated to protecting water quality, both by buying land around rivers and by reducing water pollution. In the last 10 years, states have improved their water monitoring programs and have significantly cut pollution, especially from factories and power plants. This is why most nitrate pollution now comes from farms and lawns. Water quality has become an important political issue particularly in coastal states, partly because the number of pollution-related beach closings nationwide increased 50 percent between 1997 and 1999. Many states now have programs to both educate farmers and consumers about the problems of water pollution, and also to suggest simple ways to reduce the amount of nitrate that gets into water supplies. Every year the federal government spends over 2 billion dollars implementing the Clean Water Act. Some of this money is spent protecting pristine areas, and some is spent reducing pollution at its source. Animal manure is a major source of nitrate pollution. Nationwide, farm animals produce 130 times as much fecal waste as humans. Farms produce 5 tons of animal manure a year for every man, woman, and child in the country. Some of this animal manure is stored in romantically named manure lagoons. Federal grants to farmers encourage them to cut down on the amount of nitrate that gets into rivers. For example, since 1983 the amount of nitrate washed into the Mississippi River has declined. Even simple ideas such as fencing off streams so that animal wastes cannot easily get into them can have a dramatic effect in reducing pollution. Although 40 percent of rivers are still unsafe to swim in, this is an improvement over the 70 percent of rivers that were unsafe when the Clean Water Act was first implemented in 1972. Many individual rivers and bays are now much cleaner than in the past. Examples include Long Island Sound, Tampa Bay, Galveston Bay, and San Francisco Bay. If you would like to find out more about water quality, the EPA and U.S. Geological Survey (USGS) provide websites with water-quality information and data.