Energy Resources

Energy Resources Humans depend on electrical energy in order to perform a large percentage of their everyday tasks. There are different sources that can be used to generate this energy, each of which has environmental consequences. Some types of environmental impacts are longer-lasting than others. Nonrenewable Energy Sources Any resource that is used at a faster rate than it can be replaced is called a nonrenewable resource. Most of the energy that is currently used comes from non-renewable sources. Fossil fuels and nuclear energy are both considered to be nonrenewable resources, and if they continue to be used at the current rate, these resources will eventually run out. Fossil Fuels- The most common method for obtaining energy is through the burning of fossil fuels, such as coal, oil, and natural gas. These fuels can be converted to other forms of energy in many ways, including the production of electricity through coalburning power plants. Fossil fuels are abundant and cheap, and coal-burning power plants are currently the most effective way for generating widespread electricity where and when it is needed. However, coal-fired power plants cause large amounts of pollution and can affect the Earth's natural greenhouse effect. Power plants burn coal in order to produce electricity. While coal is plentiful and cheap, it produces a significant amount of air pollution. Measures are being taken to reduce the amount of pollution released by coal burning, but it is impossible to completely eliminate it. Nuclear Energy- Nuclear energy is produced by splitting atoms of certain elements, such as uranium. The energy released by this process is then used to heat water to produce steam. Nuclear power plants generate electricity by capturing the energy of the rising steam, which turns the turbines that run generators. The main environmental drawback to using nuclear energy is that it produces radioactive waste, which is harmful to organisms and may remain harmful for thousands of years. Also, nuclear energy is a nonrenewable energy resource because it relies on materials that are limited in supply. However, many scientists believe nuclear energy could remain viable for more than 1,000 years at current usage rates. Renewable Energy Sources Some resources are replaced more quickly, or about as quickly as we can use them. These resources are called renewable. One drawback to the usage of many renewable energy sources is that technology and infrastructure for efficiently storing and transferring energy generated from these sources is not yet in place. Hydroelectric Energy- Hydroelectric energy is sometimes considered an inexhaustible resource, which means humans cannot deplete supplies no matter how much of it we use. However, hydroelectricity can also be classified as renewable. Dams have been constructed to control rivers all over the world. The held-back water contains potential energy, which is converted to kinetic energy as it is then released through tunnels. Hydroelectric dams were designed to convert the kinetic energy of falling water into electrical energy. As the water flows across the dam, it spins a turbine. And the turbine runs a generator that produces the electrical current. Hydroelectric energy is much cleaner than fossil fuels, but the construction of dams is extremely disruptive to natural ecosystems, especially where it prevents fish and other aquatic animals from moving up or down a river. Hydroelectric energy can also be harnessed from the motion of tidal waters, but such examples are not as common as those that use river dams. Solar Energy- Solar energy is in inexhaustible resource. Human use of the solar energy has no effect on the supply of energy produced by the Sun. Solar power has far fewer environmental consequences than fossil fuels. On-site solar heating systems (the type that produce energy very close to where the energy is needed) are generally composed of a fluid system to move the heat from the collector to its point of usage, and a reservoir to stock the heat for future use. The negative effects of using solar energy are minor and are primarily related to the manufacturing and disposing of the solar panels which convert solar energy into electrical energy. Cost is the main reason that the technology is not more widespread. Solar energy is very expensive to harness in useful quantities. One other negative effect of using solar-generated electricity is that the large collections of panels needed to create a solar power station can significantly impact local ecosystems. Solar energy is also not as reliable as energy derived from fossil fuels, because weather is inconsistent, and the amount of sunlight available on any given day may not be sufficient to produce the needed amount of energy from solar panels. In addition, some latitudes and geographic locations may be more suitable for solar power than others. While California and Colorado might be excellent places for solar power plants, Wisconsin and Michigan might not be. But as the technology continues to improve, solar energy costs decrease, and more solar panels are being implemented. Solar energy can be harnessed using solar panels. While this process results in far less pollution or waste than burning fossil fuels, it is currently very expensive and therefore not yet used widely across the world. Wind Energy- Wind energy is an inexhaustible resource that comes from the movement of air heated by the Sun. As with solar energy, wind energy has very few negative environmental consequences, and these are mostly related to the manufacture and disposal of wind turbines. Wind turbines also pose hazards for birds and bats, and some communities may not embrace the establishment of wind farms because some people find the appearance of the large turbines off-putting. Unlike the technologies related to solar energy, wind technologies are relatively inexpensive. In terms of electricity prices, wind energy is able to compete with fossil-fuel generated electricity, but there are limitations to wind as well. Wind turbines are used to convert blowing wind energy into electricity. This process offers a much cleaner alternative to burning fossil fuels, but not every location is suitable for wind power. And wind power is unreliable, since the wind does not blow in consistent patterns. The inconsistency of wind patterns is one of the challenges facing the expansion of wind power. It is not always easy to predict when and where the wind will be blowing. And there is not enough wind in many locations to generate electricity. It is estimated that the U.S. has enough wind to supply about 20% of its current electricity demand, if wind energy is used to its full potential. Biomass Energy- Biomass energy is perhaps the oldest form of energy used by humans. Biomass is simply plant or animal material, such as wood, manure, grass, and hay. The difference between biomass and fossil fuels is that biomass is from living or recently living organisms, while fossil fuels come from long-dead organisms. Consequently, biomass is considered renewable as long as it is used at the same rate (or slower) than it is replaced. Biomass resources are used throughout the world, and in many portions of the world, biomass is the primary source of energy. Biomass is traditionally burned for heating and cooking, but it can also be used to generate electricity. Burning biomass releases many pollutants into the air. A cleaner way to use biomass is to let it decompose and capture the gases it releases, called biogas. Decomposition produces methane, the main ingredient in natural gas, which can be burned relatively cleanly for fuel. Biomass-generated electricity can be relatively inexpensive, but most available materials are already used for other purposes in the U.S., such as in construction, agriculture, and food production. Biomass resources are considered renewable because new biomass can be grown quickly. Fossil Fuels Fossil fuels are energy resources that are created by natural processes including the decomposition of dead organisms. The most common fossil fuels are petroleum, coal, and natural gas. Fossil Fuel Formation There are a number of very useful resources that can be found at or near Earth's surface. Sometimes, these resources are right at the surface and are easy to collect. At other times, these resources are located underground, and mines must be built in order to acquire them. Some of these resources are known as fossil fuels. Millions of years ago, large areas of jungle, forest, swamp, and wetlands left behind huge amounts of dead plant and animal material. This material decomposed through a number of different processes over the next several million years and was exposed to great temperatures and pressures in the Earth. The result is that, today, this material has been transformed into fossil fuels such as coal, which forms from plant matter, and oil and natural gas, which form from all kinds of dead organisms. Just like the animals living today, animals that lived millions of years ago got their energy by eating plants or by eating animals that had eaten plants. All of these plants got their energy from the Sun. Since fossil fuels were made from decomposing plant and animal materials, the energy contained in fossil fuels originally came from the Sun, as well. Uses of Fossil Fuels Fossil fuels are very useful for a number of reasons. One of these reasons is that they can be burned for energy. Coal, petroleum, and natural gas are each used to generate electricity. Coal is also sometimes used in steam engines to power trains. Large amounts of coal are mined out of the ground and burned in power plants to generate electricity. This image shows coal that is about to be shipped to a power plant for this purpose. Natural gas is sometimes burned in furnaces that heat homes and other types of buildings. Petroleum or oil, of course, is used to make gasoline, which powers cars, trucks, and other automobiles. People also use fossil fuels for purposes other than just the production of energy. Fossil Fuels Are Nonrenewable Fossil fuels are known as nonrenewable resources, because there is a limited supply of them on Earth. At the rate that humans use them, these fuels will run out some day. It will take many millions of years for more fossil fuels to form, if they ever do. Resource Use & Conservation Many natural resources, such as coal and oil, are nonrenewable. Nonrenewable resources are depleted faster than they can be replenished. Since many countries use these resources as their primary source of energy, it is important to try to conserve them and manage their usage, so that these resources will be still be available for future generations. 2 The Hydrosphere The hydrosphere is composed of the Earth's supply of moisture in all its forms: liquid, frozen, and gaseous. Hydrosphere Components & their Locations The hydrosphere includes surface water, underground water, frozen water, and water vapor in the atmosphere. Most of the hydrosphere is composed of liquid water and ice. Only a small amount of the hydrosphere is water vapor. The frozen water on Earth makes up the cryosphere, which is usually considered to be part of the hydrosphere. The hydrosphere covers about 71% of the Earth's surface. The water in the hydrosphere changes from liquid water to water vapor and moves from one location to another through a process called the water cycle. The water cycle keeps a constant amount of water in the hydrosphere as water changes state (liquid to gas, etc.) and location in the atmosphere. The cycle is mainly driven by solar energy. Most of the water in the hydrosphere is saltwater and is contained in the oceans and seas (97%). The next largest amount of water is found as ice in glaciers and the icecaps (2%). Of the freshwater, which is the water that is not in oceans or seas, thirty percent is groundwater. Rivers, lakes, and streams make up less than one percent of freshwater found in the hydrosphere. (see figure below) The Water Cycle Water and energy are transferred throughout the hydrosphere, lithosphere, and atmosphere during the water cycle. The amount of water on Earth remains constant, but it continuously changes forms as energy from the Sun drives the cycle. Movement of Water During the Water Cycle The water cycle describes the continuous movement of water on, above, and below the surface of the Earth. This movement of water in the cycle can have a great influence on weather patterns. There is much more water being stored at any given time than is moving through the cycle. Water may be stored for a short time as water vapor in the atmosphere, for days or weeks in a lake, or for thousands of years in a polar ice cap. However, most of the Earth's water is stored in the oceans. The water cycle is a cycle with no beginning or end. It includes the following processes:  Condensation is the changing of gas to a liquid (water vapor to water) and is crucial for the formation of clouds. Clouds form in the atmosphere when air containing water vapor rises and cools. Water vapor can be present in the air even when clouds are not visible. Clouds become visible when water particles combine with each other around tiny particles of dust to form water droplets.  Water returns to the Earth as precipitation. Precipitation is the process by which water vapor in the air condenses to form drops heavy enough to fall to the Earth's surface.  During infiltration water fills the porous spaces in the rock and soil that makes up the lithosphere. This is one of the main sources of groundwater.  Surface runoff occurs when no more water can be absorbed into the ground and gravity pulls it downhill until it joins a body of surface water, such as a river, stream, or lake. Some of this surface water may seep downward and become groundwater. The rest of the water in a flowing water body, such as a river, eventually empties into the ocean.  Evaporation takes place largely from the oceans. It often happens as a result of heat produced by the radiant energy from the Sun–liquid water is heated until it turns to a gas (water vapor) and is released into the atmosphere.  Transpiration is similar to evaporation in that it is the process by which water is carried through plants, from roots to leaves, where it changes to water vapor and is released to the atmosphere.  Sublimation is the changing of water from a solid directly to a gas with no intermediate liquid stage. The opposite of sublimation is deposition, when water vapor changes directly to a solid. Snowflakes and frost are examples of deposition. Life and the Water Cycle Ecosystems and living organisms depend on the water cycle. Most living organisms, including humans, depend on the water cycle and actually take part in it. Land animals, for example, need to consume fresh water to remain hydrated. Without fresh water to drink, land animals quickly die. But the vast majority of water on Earth is saltwater and undrinkable. Fortunately, the water cycle supplies fresh water on land through the process of evaporation and precipitation. When water from the Earth's saltwater oceans evaporates, it leaves the salt behind. The freshwater travels by wind over land and falls as precipitation. This process makes it possible for animals to survive on land. Animals, including humans, make use of the water cycle in other ways as well. When a person sweats (perspires) the water on his or her skin evaporates. This has the effect of keeping the person cool. Many other animals, including dogs, use panting to keep cool, which also involves the evaporation of water. 3 Watershed Systems A watershed is a region of land where rain or snow (along with sediments and dissolved materials) drains downhill into a particular body of water, such as a river, lake, sea, ocean, or wetland. Watershed Structure The area of land where water is drained downhill into a body of water is known as a drainage basin, or watershed. When precipitation falls onto land surfaces, it can either soak into the ground or become runoff, which is surface water that travels downhill and drains into streams and rivers. The components of a watershed include lakes, streams, rivers, wetlands, and groundwater. Water can flow among all of the components of a watershed, including between groundwater and surface features, such as lakes. Watersheds are separated from adjacent watersheds by a water divide, which is the high ground between two watersheds. At the point of the divide, water that falls on one side of the divide will drain into one watershed, while water that falls on the other side will drain into another. A divide is often a geographical feature, such as a ridge, hill, or mountain. Often, the body of water into which a watershed drains is a river basin. Eventually, all rivers, and therefore all watersheds, drain into the ocean. Water as a Solvent Water is an excellent solvent because of the shape of its molecules and the presence of small electrical charges on each of the molecules' atoms. Water is known as the universal solvent because it dissolves such a large number of substances. More substances are soluble in water than in any other liquid. The partial electrical charges on the different parts of a water molecule allow water to dissolve many different substances. As water flows downhill in a watershed, either underground or on the surface, it dissolves and carries away some of the substances it passes over or through. Water passing over or through limestone rock may dissolve some of the calcium and magnesium that compose the rock. Water passing through cultivated land may dissolve and carry away soluble components of fertilizers, such as potassium and phosphorous compounds. Use & Importance of Water Earth is a unique planet because of the presence of water. Water is essential to support life on Earth. Plants, animals and humans all rely on water for survival. Locations & Characteristics of Water Water exists on Earth in many different places and forms. Liquid water can be found underground in aquifers. Liquid, solid, and gaseous water can be found in the atmosphere, and liquid and solid water can be found on Earth's surface. Water found in oceans and seas is salt water. This water is rich in dissolved nutrients and salts. It is too concentrated in these materials for humans to use for drinking. Water found in streams, rivers, ponds, and most lakes is fresh water. Fresh water contains minerals but does not have high levels of dissolved salt. Once it has been purified, is suitable for human consumption. The most common sources of drinking water are aquifers and lakes. However, not all cities are located close enough to one of these for it to be a practical drinking water source. To solve this problem, some cities build reservoirs, or artificial lakes, often by damming a river as shown in the photo. Much of the drinking water for North Carolina's cities comes from reservoirs and groundwater. Drinking water for more rural communities comes from wells. Water Usage Humans need to drink water in order to survive. But in addition to consuming water for life processes, humans use water in many other ways. Power plants account for almost half of the water usage in the United States. Coal-burning and nuclear power plants require water to generate power. Both types of power plants capture rising steam to create electricity. The second largest use of water in the United States is agriculture. The use of water for crops, or irrigation, requires trillions of gallons of water each year. The amount of fresh water that communities have available determines how they use their water. For example, a city near a river may choose to build a dam and use the river to generate electricity with a hydroelectric power plant. They can also choose to allow industries to build factories on the river and use water from the river for cooling or waste disposal. Communities that have lakes and rivers nearby may use them for recreation, allowing citizens to swim, ski, boat, and fish in the water. Where water supplies are plentiful, lawns and landscapes may be watered regularly. However, in places where water supplies are finite, people must landscape with native, drought-tolerant plants that do not need to be watered with an irrigation system. Water Usage in the United States (2005) 4 The Ocean The ocean is the dominant physical feature of our planet. There is one ocean with many ocean basins, such as the North Pacific, South Pacific, North Atlantic, South Atlantic, Indian, and Arctic. The ocean covers about 70% of the Earth or about 225 million square kilometers. The ocean can be divided up into three main regions: the shore, the open ocean, which is the surface layer at the top of the ocean, and the deep ocean, which is the area located toward the ocean's floor in deeper waters. A fourth distinctly different, but related, region is the estuary. An estuary is an area where fresh water and salty ocean waters mix together. These areas may include bays, mouths of rivers, salt marshes, and lagoons. Shore The shore, or the intertidal zone, is the area of the ocean where the water meets the land. This area is exposed to the air during low tide and is covered in water during high tide. This part of the ocean receives high exposure to sunlight. This area includes only the part of the ocean floor that lies between tide markers and is alternately submerged and exposed based on the ebb and flow of the tide. Open Ocean The open ocean, or pelagic zone, is any water in the ocean that is not close to the bottom. This zone includes all of the water in the ocean from the surface almost to the bottom. The pelagic zone can be further divided into layers based on depth. Deep Ocean The deep ocean, or abyssal zone, ranges from 2,000-6,000 meters in depth. Sunlight cannot penetrate this deep in the ocean, so it is constantly in darkness. Many organisms that live in this layer are blind or have their own sources of light. The organisms that live in this layer must also be able to withstand the extremely high pressure and low temperature of these ocean depths. Since little sunlight can penetrate to the depths of the oceans, photosynthetic organisms cannot survive there. Many organisms in this layer of the ocean survive on whatever falls from above. However, other organisms, living near hydrothermal vents, submarine hot springs, and methane cold seeps survive by performing chemosynthesis. Chemosynthesis is the process by which organisms, such as bacteria without access to sunlight, use chemical energy to produce food. Estuary An estuary is an area in which fresh water and salty ocean water mix together at salt marshes, mouths of rivers, bays or lagoons. These brackish (salt mixed with fresh) water ecosystems are affected by tides. Each high tide brings a new supply of nutrients and small organisms. Marsh grasses take up these nutrients and thrive in the environment. The dense clumps of plants and their roots create shelter for marine life, birds, and other wildlife. Often, sea animals go to estuaries to breed and produce their young. The young sea animals live within the relative safety of the estuaries during the first parts of their lives, until they are strong enough to survive in the open ocean. Estuaries perform functions that help to promote the health of the environment and human populations. They help protect the environment by filtering sediment and pollutants from river and ocean water. They also produce more plant and animal life than many other types of ecosystems on Earth. Many of the animal species that are fished as human food sources spend at least part of their lives in estuaries. The Ocean as a Reservoir Earth's ocean is a reservoir of life forms, minerals, nutrients, and dissolved gases. Biological Diversity Earth's ocean is a major reservoir of life forms. About 80% of all of the life forms on Earth live in the ocean or on its floor. Coral reefs, found in shallow ocean waters, are some of the most biologically rich ecosystems in the world, containing thousands of different species of fish, coral, and sponges. Minerals The ocean is a major reservoir of salts and minerals. It contains a large amount of sodium chloride (3.5%), resulting in the salty nature of ocean water, which is called salinity. Other minerals found in the ocean include potassium, magnesium, sulfur, and calcium. Most elements found in the ocean were carried there in water after the weathering of rocks. This process, along with emissions from underwater volcanoes and hydrothermal vents, help keep the ocean's salinity levels relatively constant. However, humans extract salt from ocean water for use in cooking and manufacturing. Sea salt, as shown in the photo, is obtained from sea water by evaporating the water from holding tanks. Ocean water also contains nutrients such as phosphates and nitrates that are critical to plant growth. In a process called upwelling, warm surface water is blown out to sea by prevailing winds and cold, nutrientrich water from the deep ocean rises to the surface to take its place. Many of the organisms living in areas where upwelling takes place feed off of the nutrients brought to the surface by the upwelling. The presence of these organisms provides scientists with strong proof that deep ocean water is rich in minerals and other nutrients. These nutrients are not only important to the plants and animals found within the ocean, but also to the estuaries near the ocean. Upwelling, ocean currents, tides and surface winds all play a role in distributing gases and nutrients to estuaries and different parts of the ocean. Microorganisms Just 100 mL of ocean water contains millions of bacteria and hundreds of thousands of phytoplankton, such as algae. Phytoplankton and many kinds of marine bacteria are photosynthetic producers. These two kinds of producers are at the base of almost every aquatic food web in the world. 5 Dissolved Gases The ocean is a major reservoir of gases. The ocean absorbs gases from the atmosphere or gives off gases to the atmosphere to help the concentration of gases to stay in equilibrium. The gases dissolved in the ocean include nitrogen (N), carbon dioxide (CO 2), argon (Ar), and oxygen (O2). The amount of gases dissolved in ocean water depends on the gas's solubility as well as the water's depth and temperature. The solubility of gases can be determined by looking at the amount and ratio of gases present in the air as compared to the amount and ratio of the same gases dissolved in the surface layer of the ocean. Oxygen and argon appear in approximately the same proportions in ocean surface water as in the air; this indicates high solubility. Contrastingly, there is about half as much nitrogen found in ocean surface water as in the air; this indicates lower solubility of nitrogen than of oxygen and of argon. The amount of dissolved gases in the ocean also changes with distance under the ocean's surface. Plants and other photosynthetic organisms live primarily near the surface of the ocean because that layer of the ocean receives more sunlight than those deeper in the ocean. As plants grow, they take in carbon dioxide and give off oxygen. Therefore, there is more oxygen near the surface of the water, because the plants living there have more sunlight to use for growth. Some of the oxygen stays in the water, and the rest enters the atmosphere. The photosynthetic organisms in the ocean produce 70% to 80% of the world's oxygen. Another property of gases is that they dissolve more easily in cold water than in warm water. Therefore, water in colder regions of the world contains larger amounts of dissolved gases. When the water warms, the ocean releases gases into the atmosphere. Humans & the Oceans Earth's ocean is rich in resources, such as minerals, nutrients, and dissolved gases. Many aspects of modern human life depend on resources obtained from the ocean. The Ocean as a Resource Earth's ocean is a valuable source of resources. The following list includes some of the ways the ocean influences human lives. o Transportation: For most of human history, the oceans have been the main routes used for exploration, trade and shipping, and even warfare. o Air: Half the oxygen in the entire world is produced in the ocean. o Minerals: Materials that can be extracted from ocean water or mined from the bottom of the ocean include salt, potassium, magnesium, gold, tin, titanium, and diamonds. Salt from the ocean or from old ocean deposits is used in many industries, including textiles and dying, metal processing, rubber manufacturing, oil and gas drilling, paper making, animal hide processing, leather tanning, and soap making. o Weather and Climate: The ocean controls weather patterns across the entire world. It is the site of much of the evaporation that begins the water cycle and provides fresh water for people and animals living on land. o Medicines: The ocean, and coral reefs in particular, are sources of minerals and chemical compounds that may have utility as the active ingredients in medicines. o Food: The ocean is the primary source of food for people in some nations. Some organisms that can be used for food include seaweed, algae, fish, shrimp, and crabs. Threats to Oceans The ocean provides natural resources that benefit humans, plants, and animals. The most obvious natural resources from the oceans are the fish and other marine life that provide food for humans and animals. There are several other marine resources that are less obvious, such as sand and gravel for building; salt for seasoning; and tidal motion, oil, and gas for energy production. Many of the ocean's resources, such as electrical energy produced from tidal motion, are renewable. However, even renewable resources such as fish can be over-harvested, or their environments can be polluted, resulting in reduced numbers. Some fish species are now very difficult to find because their numbers are so low. Populations of some types of marine animals—such as turtles, dolphins, and sharks—are also shrinking because the animals get caught in drift nets that are used for fishing. The photo shows a drift net that has accidentally caught a sea turtle. Coral reefs are also being endangered by human activity. Runoff carrying soil eroded as a result of farming and construction enters the ocean and deposits the soil onto coral reefs. This blocks sunlight that the algae living in the coral needs to survive. The ocean plays a vital role in recycling energy and matter; many earth materials and geochemical cycles originate in the ocean. In addition, ocean waters can, to some extent, absorb air and water pollutants produced by human activities. However, the capacity of the ocean to absorb these materials without being affected is limited. When this limit is reached, environmental consequences become apparent. In response to the changes that have been observed and are believed to result from human activities, efforts have been made in the United States to help protect marine animals and create National Marine Sanctuaries with laws protecting natural areas and resources. Technology for Exploring the Ocean Sonar Sonar is a measuring instrument that sends out an acoustic pulse (sound) in water and measures distances in terms of the time for the echo of the pulse to return. Sonar is an acronym that stands for "sound navigation ranging." Sonar is very good for providing underwater explorers with information about the shape or makeup of underwater structures or objects. This information is usually displayed on a computer screen, where it can be interpreted. But sometimes an actual visual image is needed. This can be provided with a submarine or submersible Submarines Submarines are watercraft capable of navigating to specific depths beneath the surface of the water. They are used in deep oceanic explorations to not only see the ocean floor but also to see the creatures that live at these great depths. Some of these submarines are capable of holding people, but some are entirely robotic. Many of them have robotic arms that can be used for obtaining samples of sea life from the ocean depths. LIDAR LIDAR is a technology that is currently being used to map the bottom of the ocean. LIDAR data is collected by satellite or aircraft by sending a laser beam to the Earth and measuring the depth of the ocean. Computer programs can use this data to map the features of the ocean floor. 6 Water Quality Water monitoring is a necessary step in ensuring good water quality for all living things in a watershed. Monitoring the water allows scientists and public health officials to make necessary changes to improve water quality. Types of Water Pollution Point source pollution is that which can be traced back to its origin. It occurs when harmful substances are added directly to a body of water. An example of point source pollution is when pipes delivering wastewater from factories or sewage treatment facilities discharge directly into a lake, stream, or the ocean. Sewage from septic tanks and broken or inadequate sewage systems is a common source of groundwater pollution. This pipe delivering waste water directly into the river is an example of point source pollution. Non-point source pollution can be far more difficult to treat because it cannot be traced back to one source. It is most often the accumulation of runoff containing various substances from different locations. When rain water carries substances such as lawn chemicals, fertilizers, motor oil, or animal waste into storm sewers or rivers, this is non-point source pollution. The heavy growth of algae in this pond could be the result of non-point source pollution, such as runoff containing fertilizer or animal wastes. Stormwater runoff is a serious problem in many urban and suburban areas. The problem is complicated by artificial surfaces, such as buildings, parking lots, and paved roads. These impervious areas not only decrease the groundwater quality by prohibiting natural filtration through the soil, they also increase the risk of flooding and contamination of surface water by allowing leaves and other organic debris to accumulate. Dirt, oil, and debris that collect in parking lots and paved areas can be washed into the storm sewer system and eventually enter local water bodies. Water Quality Characteristics Water quality can be affected by biotic and abiotic factors. Water can be tested and characterized with regard to these factors. Testing often includes evaluation of dissolved oxygen, conductivity, clarity, pH, temperature, nutrients, and life forms.         Dissolved oxygen indicates how much oxygen is available for animals and plants living in the water to use for respiration. A low dissolved oxygen level is a sign of poor water quality, because it can result in reduced animal or plant population size. Conductivity is a measure of the amount of nutrients in the water in the form of dissolved solids. This measurement can show high or low levels of salts or minerals in a water body. Clarity is a measure that indicates how much light is able to penetrate the water. Light penetration is a requirement for photosynthesis of bottom-dwelling plants. This water quality characteristic is also called turbidity. Water is turbid if it contains high levels of suspended solids, such as fine particles of silt or large amounts of algae or bacteria. Increased turbidity can increase water temperature at the surface and decrease temperature in deeper waters. pH is a measure of how acidic or basic the water is. Healthy, natural water systems usually have a pH of between 6.5 and 8.5. Low (acidic) pHs can be damaging to water-dwelling animals and plants. Certain pollutants and acid rain can cause the pH of a body of water to be lowered. Water temperature can greatly affect aquatic life. Temperature affects the rate of photosynthesis and the metabolic rates of aquatic organisms. Temperature can further affect aquatic organisms by influencing the amount of dissolved solids and gases the water can hold. Gases are less soluble in warm water and more soluble in cooler water. In contrast, salts and minerals tend to be more soluble in warm water and less soluble in cooler water. Nitrates and phosphates are nutrients that come from both natural and human sources (e.g. fertilizer runoff, septic systems, improperly treated wastewater). Their presence determines the productivity of a water body. Although needed in small amounts in a healthy aquatic environment, too much of either of these nutrients will result in eutrophication. During eutrophication, excess nutrients in the water cause rapid growth in algae populations. In large quantities, the algae may produce substances that can be toxic to people and animals. In addition, after the large algae population depletes the excess nitrates and phosphates, it quickly dies off. As bacteria in the water work to decompose the dead algae, they use up a large fraction of the oxygen dissolved in the water. As a result, the aquatic plants and animals may not have access to enough oxygen to perform respiration, and they may die. The presence of some types of bacteria can indicate pollution is entering the body of water. For example, coliform bacteria can mean that untreated human or animal wastes are entering the water. Farms located near streams, lakes, or rivers can be sources of this type of pollution. Since it is impossible to see bacteria and some other types of pollution with the naked eye, water in streams or other bodies of water should not be assumed to be safe for consumption. Macroinvertebrates, including aquatic insects, crustaceans, and other visible invertebrates can be strong indicators of the presence or absence of certain types of water quality issues. Every species has a certain range of physical and chemical conditions in which it can survive. Some organisms can survive in a wide range of conditions and are more tolerant of pollution. When pollution enters a system, some types of these organisms disappear, while other types become more abundant. Thus, these living "indicators" are referred to as indicator organisms. Water quality can be determined by comparing the number of pollution-tolerant organisms with the number of pollutionintolerant species. However, the mere presence of pollution-tolerant organisms does not imply that the system is unsafe. These organisms can be found in both polluted and unpolluted waters. 7 Measuring Water Quality Water quality can be measured using a variety of methods and with many different tools. Research scientists and professionals commonly use a digital water quality instrument that records different characteristics such as dissolved oxygen, conductivity or salinity, turbidity or clarity, pH, and temperature when placed in the water. Wetlands and Water Quality Wetlands are capable of improving water quality and are very important ecosystems in a watershed. Wetlands hold water during floods and slowly release it after flood events. These valued ecosystems restore the groundwater while holding water. Wetlands contain plants that are specialized to grow in water. These plants add oxygen to the water, reduce water temperature through shade, and remove pollutants or extra nutrients from the water. Water Quality Regulation Water is valuable to human populations because humans use water for drinking, household use, industry, manufacturing, and recreation. However, water loses its value economically and aesthetically when it becomes polluted. Pollution in water supplies can threaten our health and even our food supply. There are ways to monitor and improve the health and purity of our water. For example, most cities in the U.S. now treat their sewage at a wastewater treatment plant, whereas in the past, raw sewage was sent directly into a nearby body of water. Regulatory agencies have helped to promote healthy water by setting minimum water quality standards. Water quality standards help to prevent water pollution and to identify water quality problems and correct them. These standards dictate, according to the United States' Clean Water Act, maximum allowable toxicity levels of waste discharge. There are three types of criteria: biological criteria describe the desired aquatic community, based on the populations of organisms expected to be present in a healthy body of water; nutrient criteria protect against over-enrichment of water due to excess nutrients; sediment criteria outline conditions that will avoid detrimental amounts and types of sediments. There are many reasons to strive for improving water quality; however, there are also economic hurdles to addressing water pollution issues. The Clean Water Act tries to protect our clean water, but some individuals and groups find it cost prohibitive to treat wastewater to meet current standards. Sometimes groups or companies can be excused from adhering to water quality standard requirements if they can demonstrate that the cost of the required water treatment will result in significant negative social and economic impact. Individuals, especially those obtaining water for drinking and household use from wells, can take responsibility for maintaining safe water quality. It is recommended to have drinking water tested regularly at a certified lab. Water quality can be affected by either primary contaminants (chemicals/organisms that may cause disease or long-term health problems) or secondary contaminants (contaminants causing bad odors or tastes or other problems that do not pose a health risk). 8