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Environmental Science Chapter 14: Water Pollution
Mrs. Blackwell Environmental Science AP
Terms in this set (45)
Generally defined as the contamination of streams, rivers, lakes, oceans, or groundwater with substances produced through human activities and that negatively affect organisms. This is a broad definition that encompasses a wide range of substances that vary in their sources, prevalence, and impact. Since there are many ecological connections between aquatic and terrestrial ecosystems, water pollution has the potential to impact both aquatic and terrestrial organisms. Pollution can come from point sources and non-point sources.
They are distinct locations such as a particular factory that pumps its waste into a nearby stream or a sewage treatment plant that discharges its wastewater from a pipe into the ocean.
They are more diffuse areas such as an entire farming region, a suburban community with many lawns and septic systems, or storm runoff from parking lots.
The Importance of distinguishing between point and non-point sources
The distinction can help in controlling pollutant inputs into waterways. For example, if a municipality determines that the bulk of water pollution is coming from one or two point sources, it can target those specific sources to reduce their pollution output. It can be more difficult to control pollution from non-point sources.
Pollutants that can be found in water
The broad range of pollutants that can be found in water includes human and animal waste, inorganic substances, organic compounds, synthetic organic compounds, and non chemical pollutants.
It is the water produced by human activities including human sewage from toilets and gray water from bathing and washing clothes and dishes. One of the biggest challenges has been to keeping this water from contaminating human drinking water. This can be difficult because throughout the world many people routinely use the same water source for drinking, bathing, washing, and disposing of sewage.
The Effects of wastewater on the environment
1. Wastewater dumped into bodies of water naturally undergoes decomposition by bacteria, which creates a large demand for oxygen in the water. 2. The nutrients that are released from wastewater decomposition can make the water more fertile. 3. Wastewater can carry a wide variety of disease-causing organisms.
It is organic matter that enters a body of water and feeds the growth of the microbes that are decomposers. Because these microbes require oxygen to decompose the waste, the more waste that enters the water, the more the microbes grow and the more oxygen they demand. This type of waste is measured in terms of biochemical oxygen demand.
Biochemical Oxygen Demand
BOD, It is the amount of oxygen a quantity of water uses over a period of time at a specific temperature. Lower BOD values indicate that a water body is less polluted by wastewater, whereas higher BOD values indicate that a water body is more polluted by wastewater. If we were to test the BOD of natural waters over a five-day period in a liter of water, for example, we might find a BOD of 5 to 20 mg of oxygen coming from the decomposition of leaves, twigs, and perhaps a few dead organisms. In contrast, domestic wastewater might have a BOD of 200 mg of oxygen.
When bodies of water have a high oxygen demand due to microbial decomposition, the amount of oxygen remain gin for other organisms can be very low. Low oxygen concentrations are lethal to many organisms that cannot move, such as many plants and shellfish. In some areas, there is so little oxygen, and therefore so little life, creating theses areas. These areas can be self-perpetuating, with the dying organisms subsequently decomposing and causing continued oxygen demand by microbes.
An abundance of fertility in a water body that can be caused by the decomposition of wastewater. The Chesapeake Bay experiences this problem of nutrients from wastewater decomposition as well as from nutrients that are leached from agricultural lands during periods of precipitation. This initially causes a rapid growth of algae, known as an algal bloom. This enormous amount of algae eventually dies, microbes rapidly begin digesting the dead algae, and the increase in microbes consumes most of the oxygen in the water. In short, the release of nutrients from wastewater initiates a chain of events that eventually leads to a lack of oxygen and the creation of dead zones once again.
This is when a body of water experienced an increase in fertility due to anthropogenic inputs of nutrients.
One of the most impressive dead zones in the world occurs where the ___________ _____ dumps into the Gulf of Mexico. This river receives water from 41% of the land of the continental US. Each summer there is an influx of wastewater and fertilizer that causes late algal blooms followed by substantial decreases in oxygenated water and massive, die-offs of fish.
Human wastewater can carry a variety of illness-causing viruses, bacteria, and parasites that we collectively call _________. _________ in wastewater are responsible are responsible for a number of diseases that can be contracted by humans or other organisms that come in contact with or ingest the water. These _________ cause cholera, typhoid fever, various types of stomach flu, and diarrhea. Worldwide, the major waterborne diseases are cholera and hepatitis.
An organism that indicates whether or not disease-causing pathogens are likely to be present. The bed indicators for potentially harmful water are fecal coliform bacteria.
Fecal Coliform Bacteria
A group of generally harmless microorganisms that live in the intestines of human beings and other animals. One of the most common species of this is Escherichia coli, abbreviated E. coli. Most strains of E. coli live naturally in humans and are not harmful, although there are strains that can be deadly to people who are very young, very old, or possess weak immune systems. Given that E. coli is commonly found in human intestines, detecting E. coli in a body of water indicates that human waste has entered the water. This does not necessarily mean that the water is harmful to drink, but the presence of E. coli does indicate that there is an increased risk of the other wastewater pathogens being in the water.
Testing water supplies
Public water supplies, such as drinking water sources and swimming pools, are routinely tested. homeowners with a single-family well might test their water less frequently or not at all. Public health authorities recommend declaring water unsuitable for human consumption if any bacteria are present. For safe swimming and fishing, the acceptable level of E. coli is higher; for example, swimming at a public beach or in a river is considered safe as long as the fecal coliform bacteria elves are less that 500 to 10,000 colonies per 100 mL of water. A pool, beach, or campground with contaminated water likely would be posted with a sign such as "The Department of Health has closed this water supply because of the presence of fecal coliform bacteria."
This is a private household sewage treatment system in rural areas of low population density. The environmental advantages to this is that because most of these rely on gravity - water from the house flows downhill to the septic tank,and water from the septic tank flows downhill to the leach field - no electricity is needed to run a septic system. However, sludge from the septic tank must be pumped out periodically (every 5 to 10 years) and taken to a sewage treatment plant.
A large container tat receives wastewater from the house. having a capacity of 1,900 to 4,700 liters (500-1,250 gallons), this tank is buried underground adjacent to the house. Wastewater from the house flows into the tank at one end and leaves the tank at the other. After the tank has been operating for some time, 3 layers develop. Anything that will float rises to the top of the tank and forms a scum layer.
The bottom layer that is formed of anything that is heavier than water and sinks to the bottom of the tank.
The middle layer in a septic tank. It is a fairly clear water layer. The seepage contains large quantities of bacteria and also may contain pathogenic organisms and inorganic nutrients such as nitrogen and phosphorus. This moves out of the septic tank by gravity into several underground pipes laid out across a lawn below the surface.
The combination of underground pipes laid out across a lawn below the surface and lawn makes up this. The pipes contain small perforations so the water can slowly seep out and spread across this. The septage that seeps out of the pipes is slowly absorbed and filtered by the surrounding soil. The harmful pathogens scan settle and become part of the sludge, be outcompeted by other microorganisms in the septic tank and therefore diminish in abundance, or be degraded by soil microorganisms in the leach field. The organic matter is broken down into carbon dioxide and inorganic nutrients. Eventually, the water and nutrients are taken up by plants or enter a nearby steam or aquifer.
Sewage Treatment Plants
Household septic systems work well for rural areas in which each house has sufficient land for a leach field. This is not a feasible solution for more developed areas with greater population densities and little open land. In developed countries, municipalities use centralized sewage treatment plants that receive the wastewater from hundreds or thousands of households via a network of underground pipes. In a traditional sewage treatment plant, wastewater is handled using a primary treatment followed by a secondary treatment/
Primary Treatment of Sewage
The goal of the primary treatment in a sewage plant is for the solid waste material to settle out of the wastewater. This solid material is then dried and classified as sludge. To reduce the volume of material and help remove many of the pathogens, sludge is typically exposed to bacteria that can digest it. Most of the water is then removed from the sludge to reduce its volume and wight prior to transporting it away form the sewage treatment plant. This final form of sludge can be placed into a landfill, burned, or converted into fertilizer pellets for agricultural fields, lawns, and gardens. After the sludge has settled out of the wastewater and been treated, the remaining wastewater undergoes a secondary treatment.
Secondary Treatment of Sewage
The goal of he secondary treatment is to use bacteria to break down 85-90% of the organic matter in the water and convert it to carbon dioxide and inorganic nutrients such as nitrogen and phosphorus. The secondary treatment typically includes aeration of the water to promote the growth of aerobic bacteria, which emit less offensive odors than anaerobic bacteria. This treated water sits for several days to allow particles to settle out. These settled particles are added to the sludge from a primary treatment. the remaining water is disinfected, using chlorine, ozone, or ultraviolet light to kill any remaining pathogens. The treated water is then released into a nearby river or lake, where it is once again part of the global water cycle
Tertiary Treatments of Sewage
Large sewage treatment plants are now developing tertiary treatments that remove nitrogen and phosphorus from the wastewater. The ultimate goal is to release wastewater similar in quality to the waterway receiving it.
Legal Sewage Dumping
Sewage treatment plants are critical to human health b/c they remove a great deal of harmful organic matter and associated pathogens that cause human illness. It might surprise you to know that even in the most developed countries, raw sewage can sometimes be directly pumped into rivers and lakes. Sewage treatment plants are typically built to handle wastewater from local households and industries. However, many older sewage treatment plants also receive water ad wastewater form storm-water drainage systems. During periods of heavy rain, the combined volume of storm water and wastewater overwhelms the capacity of the plants. When this happens, the treatment plants are allowed to bypass their normal treatment protocol and pump vast amounts of water directly into an adjacent body of water.
They are large, human-made ponds lined with rubber to prevent the manure from leaking into the groundwater. After the manure has been broken down by bacteria - the same process that occurs in sewage treatment plants - the manure can be spread onto farm fields to serve as a fertilizer. A major risk of these is the possibility of developing a leak in the liner. A leak would allow the waste to seep into the underlying groundwater, contaminating it. A possible overflow into adjacent water bodies is mother danger. The application of manure as fertilizer can create runoff that moves into nearby water bodies.
It is a heavy metal that poses a serious health threat. It is rarely found in natural sources of drinking water. It contaminates water when the water passes through the pipes of older homes that contain lead-lined pipes, brass fittings containing lead, and lead-containing materials such as solder used to fasten pipes together. Fetuses and infants are the most sensitive and exposure can damage the brain, nervous system, and kidneys. A series of federal guidelines for building construction implemented during the past 3 decades now requires the installation of lead-free pipes, pipe fittings, and pipe solders.
It is a compound that occurs naturally in Earth's crust and can dissolve into groundwater. As a result, naturally occurring arsenic in rocks can lead to high concentrations of arsenic in groundwater and drinking water. Human activity also contributes to higher arsenic concentrations in groundwater. For example, mining breaks up rocks deep underground, and industrial uses of arsenic for items such as wood preservatives can add to the amount arsenic found in drinking water. Fortunately, arsenic can be removed from water via fine membrane filtration, distillation, and reverse osmosis.
A naturally occurring heavy metal found in increased concentrations in water as a result of human activities. These activities are burring fossil fuels and the incineration of garbage, hazardous waste, medical supplies, and dental supplies. One of the less well-known sources of mercury comes for the raw materials that go into the manufacturing of cement for construction. The limestone used to make cement can contain mercury that is release during the heating process. The source of heat is often coal that ask releases mercury when it is burned.
It was inorganic mercury that went under a chemical transformation. It is toxic to humans.
acids deposited on Earth as rain and snow or as gases. It reduced the pH of water bodies from 5.5 or 6 to below 5, which can be lethal to many aquatic organisms, leaving these water bodies devoid of many species. To combat the problem of acids being released into the atmosphere, many coal-burning facilities have installed coal scrubbers.
Occurs as gases and particles that attach to the particles
They pass the hot gases through a limestone mixture. the limestone reacts with the acidic gases and removes them from the hot gases that subsequently leave the smokestack.
Synthetic Organic Compounds
They can enter the water supply either from industrial point sources where they are manufactured or from non point sources when they are applied over very large areas. these organic compounds include pesticides, pharmaceuticals, and industrial cleaners. They have a variety of effects on organisms. They can be toxic, cause genetic defects, and, in the case of compounds that resemble animal hormones, interfere with growth and sexual development.
Polychlorinated biphenyls. They represent one group of industrial compounds that has caused many environmental problems. They were used in manufacturing plastics and insulating electoral transformers until 1979. Ingested PCBs are lethal and carcinogenic, or cancer-causing. One particularly high-profile case revolves around 2 General Electric manufacturing plants in New York State that dumped 590,000 kg (1.3 million pounds) of these into the Hudson River from 1947 to 1977. In 2002, the EPA ruled that General Electric must pay for the dredging and removal of approximately 2.03 million cubic meters of this contaminated sediment.
Polybrominated biphenyl ethers. They are most commonly known as flame retardants added to a wide variety of items including construction materials, furniture, electrical components, and clothing. They make buildings and their contents considerably less flammable tan they would be otherwise. Since the 1990s, however, scientists have been detecting these in some unexpected places, including fish, aquatic birds, and human breast milk. Exposure to some types of these can lead to brain damage, especially in children.
Solid waste pollution
Consists of discarded materials from households and industries that do not pose a toxic hazard to humans and other organisms. Much solid waste is what we call garbage. It is also coal ash and coal slag
the result of human activities that can substantially increase the amount of sediment entering natural waterways.
Occurs when human activities cause a substantial change in the temperature of water. Although temperature can become either warmer or cooler, the most common cause of thermal pollution occurs when cold water is removed from a natural supply, used to absorb heat as part o some industrial process, and then returned as heated water back to the natural supply.
Since species in a given community are generally adapted to a particular natural range of temperatures, a dramatic change in temperature can kill many species. High temperatures also cause organisms to increase their respiration rate, yet warmer water does not contain as much dissolved oxygen as cold water, when both effects are present, many animals will simply suffocate.
Sounds emitted by ships and submarines that interfere with animal communication are the major concern. Especially loud sonar could negatively affect species such as whales that rely on low-frequency, long-distance communication.
Clean Water Act
Water quality in much of the US was bad in the 1960s but growing awareness of the problem encouraged a series of laws to fight water pollution. The Federal Water Pollution Control Act of 1948 was the first major piece of legislation affect in water quality, and it was substantially expanded in 1972 into what is now known as the Clean Water Act. The Clean Water Act supports the "protection and propagation of fish, shellfish, and wildlife and recreation in and on the water" by maintaining and, when necessary, restoring the chemical, physical, and biological properties of natural waters.
Safe Drinking Water Act
The EPA is responsible for establishing maximum contaminant levels (MCL) for 77 different elements or substances in both surface water and groundwater. This list includes some well known microorganisms, disinfectants, organic chemicals, and inorganic chemicals. These maximum concentrations consider both the concentration of each compound that can cause harm as well as the feasibility and cost of reducing the compound to such a concentration.
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