8.E.1
The Hydrosphere
Earth Systems, Structures and Processes
8.E.1 Understand the hydrosphere and the impact of humans on local systems and the effects of the hydrosphere on humans.
8.E.1.1 Explain the structure of the hydrosphere including: Water distribution on earth Local river basin and water availability
8.E.1.2 Summarize evidence that Earth’s oceans are a reservoir of nutrients, minerals, dissolved gases, and life forms: Estuaries Marine ecosystems Upwelling Behavior of gases in the marine environment Value and sustainability of marine resources Deep ocean technology and understandings gained
8.E.1.3 Predict the safety and potability of water supplies in North Carolina based on physical and biological factors, including: Temperature Dissolved oxygen pH Nitrates and phosphates Turbidity Bio-indicators
8.E.1.4 Conclude that the good health of humans requires: Monitoring of the hydrosphere Water quality standards Methods of water treatment Maintaining safe water quality Stewardship
8.E.1.1, Distribution of Water
Students know that water is one of the most common substances on the surface of the Earth. They know that water has unique properties that impact the role it plays on the Earth in all the spheres (hydrosphere, lithosphere, atmosphere, and biosphere). These properties include: polarity, cohesion, adhesion, high surface tension, density, high specific heat, high heat of vaporization.
Water is the only substance on Earth that occurs naturally as a solid, a liquid, and a gas. It is often referred to as ‘the universal solvent’ because so many other substances dissolve in it. This characteristic is one reason that the water encountered on Earth is rarely pure. Water covers approximately 71% of the Earth’s surface (USGS). Most of this water (97%) is not drinkable because it is saltwater. The majority of freshwater (3%) exists in ice caps, glaciers, and oceans. 77% of the freshwater is frozen. Of the 23% that is not frozen, approximately a half of a percent is available to supply living organisms with what they need to survive. The availablilty of water varies with local geography and allows humans to utilize water as a resource.
The ocean is salty because of dissolved chemicals eroded from the Earth's crust and washed into the sea. Solid and gaseous ejections from volcanoes, suspended particles swept to the ocean from the land by onshore winds, and materials dissolved from sediments deposited on the ocean floor have also contributed. Salinity in ocean waters is increased by evaporation or by freezing of sea ice and it is decreased as a result of rainfall, runoff, or the melting of ice. The average salinity of seawater is 35 parts per thousand. Salinities are much less than average in coastal waters, in the polar seas, and near the mouths of large rivers.
Hydrothermal vents are recently-discovered features on the crest of oceanic ridges that release dissolved minerals into the oceans. These vents are the exit point on the ocean floor from which sea water that has seeped into the rocks of the oceanic crust (heated and containing dissolved materials from the crust) flows back into the ocean. This super-heated water brings large amounts of dissolved minerals with it. Estimates of the amount of hydrothermal fluids now flowing from these vents show that the entire volume of the oceans could seep through the oceanic crust in about 10 million years. Thus, this process has a very important effect on salinity.
That the ocean is an integral component of the world's climate due to its capacity to collect, drive and mix water, heat, and carbon dioxide. The ocean can hold and circulate more water, heat and carbon dioxide than the atmosphere although the components of the Earth's climate are constantly exchanged. Because the ocean can store so much heat, seasons occur later than they would and air above the ocean is warmed. Heat energy stored in the ocean in one season will affect the climate almost an entire season later.
The ocean and the atmosphere work together to form complex weather phenomena like the North Atlantic Oscillation and El Niño. The many chemical cycles occurring between the ocean and the atmosphere also influence the climate by controlling the amount of radiation released into ecosystems and our environment.
Air temperatures all over the world are regulated by the circulation of heat by the oceans. The ocean stores heat in the upper two meters of the photic zone. This is because seawater has a very high density and specific heat and as a result can store vast quantities of energy in the form of heat. The ocean can then buffer changes in temperature by storing heat and releasing heat. Evaporation cools ocean water which cools the atmosphere. It is most noticeable near the equator and the effect decreases closer to the poles.
That the water cycle is the continuous movement of water in and around the Earth. The sun drives the entire water cycle and is responsible for its two major components: condensation and evaporation. When the sun heats the surface of water, it evaporates and ends up in the atmosphere as water vapor. It cools and rises, becoming clouds, which eventually condense into water droplets. Depending on the temperature of the atmosphere and other conditions, the water precipitates as rain, sleet, hail or snow. Some of this precipitation is captured by tree canopies and evaporates again into the atmosphere.
The precipitation that falls to the ground becomes runoff, which courses over the surface of the earth in streams. (Runoff also comes from snowmelt, which occurs when the sun and climate changes melt snow and ice.) Runoff can accumulate and freeze into snow caps or glaciers. Runoff can also infiltrate the ground and accumulate, becoming groundwater.
Permeability is a measure of the ability of a rock or sediment to transmit water or other liquids. Water does not pass through impermeable materials. A substantial amount of water is stored in permeable soil and rock underground.
An aquifer is a large deposit of groundwater that can be extracted and used. Finally, runoff makes its way back into lakes and oceans, where it is again evaporated by the sun.
That a river basin is the portion of land drained by a river and its tributaries. It encompasses the entire land surface drained by the various streams and creeks that flow downhill into one another, and eventually into one river. The final destination of the water drained by a river basin is an estuary or an ocean. A river basin sends all the water falling on the surrounding land into a central river and out to the sea. That for land-dwellers, everyone lives in a river basin. Even if they do not live near the water, land-dwellers live on land that drains to a river or estuary or lake, and their actions on that land affect water quality and quantity far downstream. There are 17 river basins in North Carolina. The topography of each basin determines the area that it drains, and whether that water - from creeks, rivers, springs, and aquifers - flows into the Atlantic Ocean or Gulf of Mexico.
8.E.1.2, Water Habitats
Students know: that the ocean is a dynamic system in which many chemical, biological, and physical changes are taking place. The ocean is an important source of food and mineral resources as well as a venue for human recreation and transportation. Students know that the ocean is the largest reservoir of water on the surface of the Earth.
They also know that the ocean is the single largest reservoir of heat at Earth’s surface. The stored heat in the ocean drives much of Earth’s weather and causes climate near the ocean to be milder than climate in the interior of continents. Many of the cycles that circulate materials between the atmosphere, lithosphere and hydrosphere originate in the ocean. Ocean currents are a source of large scale distribution of energy and resources on the Earth.
That estuaries are areas where fresh and salt water mix, producing variations in salinity and high biological activity. Estuaries trap nutrients and sediment that are carried from the land by rivers and from the ocean by tides. In an estuary, these nutrients are constantly being mixed, due to tidal action and river flow. These conditions create a fertile repository of plant and animal life. Estuaries are one of the most productive ecosystems on earth. Because estuarine waters are shallow (in North Carolina, less than thirty feet deep), sunlight penetrates to the bottom. This promotes plant growth. The rivers that feed estuaries deposit sediments rich in nutrients, which settle onto the sand and mud of the estuary floor. These conditions create unique habitats for both plants and animals, and provide the basis for great biological diversity in species (of fish, shrimp, crabs, clams and oysters) that are able to adapt to the brackish conditions. Estuaries are also good nurseries as they provide a protected environment for species to hatch and grow in before they migrate to the sea to live out their adult lives. Estuaries are numerous in North Carolina. The largest North Carolina estuary is Pamlico Sound. Water drains into this system from eastern North Carolina and southeastern Virginia, from the Chowan, Roanoke, Pasquotank, Pamlico, and Neuse Rivers, from marshes, swamps, forests, and grasslands. Estuaries help control erosion and reduce flooding of the mainland. Sand bars buffer the impact of waves, while plants and shellfish beds anchor the shore against tides. Swamps and marshes take the initial impact of high winds moving in from the ocean, soak up heavy rain and storm surges, and release the extra water gradually into rivers and groundwater supplies.
Estuaries are a type of environmental filter. Plants and animals in estuaries filter pollutants out of the water. For instance, salt marsh plants trap some of the chemicals and pathogens carried by rivers and move them into soils where they can be neutralized. Oysters filter impurities out of water as they eat, collecting the contaminants in their bodies. One oyster can filter twenty-five gallons of water per day. Bacteria eat organic matter found in the sediment and in turn release carbon dioxide, hydrogen sulfate and methane into the atmosphere preventing these gases from being excessively stored up in the estuary. However, toxins can accumulate in estuaries causing many environmental and health problems. Chemical pollution and sedimentation are great threats to the well-being of estuaries and oceans. that from the seashore to the deepest depths, oceans are home to some of the most diverse life on Earth.
Oceanographers divide the ocean into zones according to how far down sunlight penetrates. Plants are found only in the sunlit zone where there is enough light for photosynthesis, however, animals are found at all depths of the oceans. As far as we know, nearly all life in the ocean is dependent on plants. Only plants have the ability to manufacture food out of inorganic substances.
Algae in the ocean are an important food source as well as an important source of atmospheric oxygen. The most abundant plants in the ocean are known as phytoplankton. To grow, phytoplankton needs nutrients from sea water and an abundance of sunlight. Currents in the ocean recycle and circulate a variety of organic and inorganic materials. This makes nutrients, minerals, and gases available to organisms. that in the ocean there are innumerable individual food chains overlapping and intersecting to form complex food webs. Most marine creatures eat a variety of foods. If one link in a chain is depleted, the other consumers in the chain have alternate food sources.
Ocean organisms generally belong to several different food chains that are linked to form a food web. Ocean food chains and webs are also connected to land-dwelling organisms.
How winds have a powerful effect on the oceans and are an important force in creating ocean currents. From global circulation to microscopic patterns of turbulence, winds move water and its resident animals and plants. Under certain conditions, a special kind of ocean event known as upwelling can occur. Upwelling happens when warm surface water near coastal areas is blown offshore by winds. This creates a condition in which the cold water along the bottom of the ocean near the shore rises, carrying sediment and organic material to the surface. Phytoplankton uses these nutrients to grow and reproduce at a rapid rate. This attracts organisms that rely on the phytoplankton as food and their consumers in turn. As a result, areas of upwelling tend to become areas of rich biological activity, providing resources to a great diversity of ocean organisms. Approximately half of the fish caught in the world come from areas where there is upwelling.
That seawater has many different gases dissolved in it, especially nitrogen, oxygen and carbon dioxide. The action of ocean wind and waves agitates the ocean surface, stimulating the exchange of these gases between the ocean and the atmosphere. Marine plants depend on dissolved carbon dioxide in order to perform photosynthesis. Photosynthesis releases oxygen into ocean water which is in turn used by ocean organisms for respiration. Respiration releases energy from stored carbohydrates and produces carbon dioxide and water as byproducts. Some properties of seawater affect how much gas can be dissolved in it: Cold water holds more gas than warm water. Seawater with low salinity holds more gas than high salinity water. Deep water, which has a high pressure, holds more gas than shallow water.
That carbon dioxide is one of the most important gases that dissolve in the ocean. Some of it remains as dissolved gas, but most reacts with the water to form carbonic acid or reacts with carbonates already in the water to form bicarbonates. This reaction removes dissolved carbon dioxide from the water. Many marine organisms use the bicarbonate to form calcium carbonate shells. When these organisms die, some of the bicarbonate is returned to the water, but a lot of it settles down to the sea bed. This process locks up, for long periods of time, carbon that originated in carbon dioxide in the atmosphere. As atmospheric levels of gases rise, so do the levels of the same gases dissolved in ocean water rise.
That the ocean is one of Earth's most valuable natural resources. Marine resources include biotic, mineral and energy resources. The ocean provides food. It is used for travel and shipping. It provides a source of recreation for humans. It is mined for minerals and drilled for crude oil.
The ocean plays a critical role in removing carbon from the atmosphere and providing oxygen. It regulates Earth's climate. The ocean is an increasingly important source of biomedical organisms with potential for fighting disease. The ocean is very important to life on land. The oceans have been fished for thousands of years and are an integral part of human society.
Fish have been important to the world economy for a very long time. Fisheries today provide about 16% of the total world's protein with higher percentages occurring in developing nations.
The word shipping refers to the activity of moving cargo with ships in between seaports. Wind-powered ships exist, but more often ships are powered by steam turbine plants or diesel engines. The various types of ships include container ships, tankers, crude oil ships, chemical ships, bulk carriers, cable layers, general cargo ships, ferries, gas and car carriers, tugboats, barges and dredgers.
Tourism is the fastest growing division of the world economy and is responsible for more than 200 million jobs all over the world. The tourism industry is based on natural resources present in each country and tourism often has a negative impact on coastal and ocean ecosystems. However, sustainable tourism can actually promote conservation of the environment. The negative effects of tourism originate with the over development of coastal habitats and the annihilation of entire ecosystems. Garbage and sewage generated by natives and visitors can add to an already existing solid waste and garbage disposal issue. Often visitors produce more waste than locals, and much of it ends up as untreated sewage dumped in the ocean. This causes eutrophication because it results in excessive algal bloom. It can also lead to disease epidemics.
Ecotourism and cultural tourism are a new trend that favors low impact tourism and fosters a respect for local cultures and ecosystems.
Humans began to mine the ocean floor for diamonds, gold, silver, metal ores like manganese nodules and gravel in the 1950's. Sands and gravels are often mined for in the United States and are used to protect beaches and reduce the effects of erosion. Mining the ocean can be devastating to natural ecosystems. Dredging of any kind pulls up the ocean floor and a cloud of sediment rises up in the water, interfering with photosynthetic processes of phytoplankton and other marine life. Dredging also introduces previously benign heavy metals into the ocean food chain. Drilling for oil is another activity that extracts resources from the ocean. Before an offshore oil well can be drilled, it must first be located. Geologists locate potential oil wells beneath the ocean floor through the use of magnetic and seismic surveys. This surveying does not indicate for certain whether a site contains oil until exploratory drilling takes place. In order to drill exploratory wells, government permission must first be obtained. An environmental impact assessment may be carried out at this stage. Then, using an exploratory drilling rig, geologists drill temporary wells to find out if there's a source of oil. If they think they've found a good source of oil, then more drilling takes place to substantiate the findings. Once oil or gas is discovered, then a production well is drilled and a production oil rig is built to replace the exploratory drilling rig. An average well will last from ten to twenty years, and even after it has run dry an oil rig may still be used for processing or storage of petroleum from other wells, so the production oil rig is built to last. The platforms are normally made of steel and are secured to the seabed using concrete or metal foundations. Initially the pressure from the reservoir is enough to pump the oil or gas, but as the pressure decreases various techniques are used to increase the pressure in the reservoir. These techniques include pumping in gas, water, compressed air or steam. The crude oil obtained from the well is then refined at oil refineries onshore. Drilling for oil under the ocean has many different environmental impacts. The rigs themselves impact living creatures, the actions and processes of drilling affect the oceans and ocean life, and the danger of accidental release of petroleum into the oceans is constant.
Conservation of ocean resources and thoughtful long term cost /benefit analyses with regard to the use of the ocean’s many natural resources are an integral part of sustaining our oceans well into the future. that the deep ocean has long been of interest to scientists. In order to understand the ocean, scientists must gain access for themselves or their instruments to very specific parts of it. Traditionally, scientists have used ships to photograph the depths, to drop floats and drifters into the currents, and to collect samples of water, rock, and marine life. In recent years, the spectrum of available observing tools has grown to include human-occupied submersibles, remote-controlled vehicles, and autonomous robots. At one time, scientists thought that life could not exist on the deep ocean floor.
In 1977, scientists diving in Alvin to the Galápagos Rift discovered a new community of organisms. These organisms can withstand tremendous pressure, high temperatures, utter darkness, and toxic chemicals. These organisms are called extremophiles because of the extreme nature of their living conditions. The discovery of life at vents and seeps revolutionized what scientists understand about how and where life can exist on Earth. The organisms that thrive at deep-sea vents and seeps have to survive freezing cold, perpetual darkness, high-pressure, and toxic chemicals. Hydrothermal vents and cold seeps are places where chemical-rich fluids emanate from the seafloor, often providing the energy to sustain lush communities of life in some very harsh environments. Studying the organisms at hydrothermal vents and cold seeps expands our understanding of how life first took hold and slowly evolved on our planet as well as where it might exist elsewhere in the solar system and beyond.
On land and near the ocean surface, sunlight provides the energy that allows photosynthetic plants to convert carbon dioxide and water into the organic carbon, the fundamental source of nutrients for animals higher up the food chain. Below the photic zone (the sunlit, upper reaches of the ocean) many microbes have evolved chemosynthetic (instead of photosynthetic) processes that create organic matter by using oxygen in seawater to oxidize hydrogen sulfide, methane, and other chemicals present in vent and seep fluids. Animals such as clams, mussels, snails, and shrimp feed on the microbes, and in turn, provide food for fish and other predators. Some vent and seep animals, such as tubeworms and shrimp, also host chemosynthetic microbes on or within their bodies, providing a place for the microbes to live in exchange for nutrients produced by the microbes.
Cold seeps and hydrothermal vents differ from one another in the underlying conditions that form and drive them. This has implications for the kinds of animals that are able to survive at each. Hydrothermal vents are driven by heat from volcanism beneath the seafloor. In this environment, chemical reactions take place as seawater percolates through cracks in the seafloor to produce hot (more than 400°C or 750°C), acidic fluids that eventually rise back to the seafloor. Vents, and the ecosystems they support, are created and destroyed as underlying volcanic activity waxes and wanes over tens or hundreds of years. On land and near the ocean surface, sunlight provides the energy that allows photosynthetic plants to convert carbon dioxide and water into a fundamental source of nutrients for organisms in proximal food chains and webs. Below the photic zone many microbes have evolved chemosynthetic (instead of photosynthetic) processes that create organic matter by using oxygen in seawater to oxidize hydrogen sulfide, methane, and other chemicals present in vent and seep fluids. Animals such as clams, mussels, snails, and shrimp feed on the microbes, and in turn, provide food for fish and other predators.
Cold seeps are a little bit different. They produce a diffuse flow of lower-temperature fluids, often composed of natural gas and a mixture of hydrocarbons, at slower rates for longer periods. The methane seeping from the seafloor sustains microbes that serve as the base of the food chain for communities of animals which thrive in the sunless depths. Far more natural gas is sequestered on the seafloor—or leaking from it—than can be drilled from all the existing wells on Earth. Some seeps may be thousands of years old.
8.E.1.3, Water Safety
Students know: that the health of a water system is determined by the balance between physical, chemical and biological variables.
Physical variables include temperature, turbidity, and water movement.
Chemical variables include dissolved oxygen and other gases, pH, nitrates, and salinity. Both natural and man-made forces are constantly changing these variables. Freshwater systems are of particular concern because they are the source of most of the potable water consumed by humans. Testing for the occurrence of chemicals and other factors that can influence water quality, such as nutrients and pesticides in water resources is a normal part of public health maintenance and stewardship of freshwater resources.
Water that is safe to drink is called potable water, or drinking water, in contrast to safe water, which can be used for bathing or cleaning. In the United States, the Environmental Protection Agency sets maximum levels for the 90 most commonly occurring contaminants.
That the temperature of water in rivers and lakes determines the kinds of organisms that can survive there. Particular aquatic species have preferred water temperature ranges within which they will live and thrive. Warm water dissolves more of a solid substance as it gets warmer, but it also dissolves less of important gases like oxygen and carbon dioxide. Very warm water may not contain enough dissolved oxygen for aquatic life to survive.
That measuring dissolved oxygen is an important factor in determining water quality. Dissolved oxygen (commonly called DO, pronounced dee-oh) is oxygen that is dissolved in water. Dissolved oxygen (DO) is a measure of the amount of oxygen in water that is available for chemical reactions and for use by aquatic organisms. In the aquatic ecosystem, dissolved oxygen balance in water is important for the survival of certain microorganisms and higher organisms such as zooplankton and fish. Normally oxygen in water gets there through diffusion with the air and as a waste product of photosynthesis by aquatic plants. Dissolved oxygen in surface water is used by all forms of aquatic life; therefore, it is measured to assess the "health" of lakes and streams. Dissolved oxygen levels vary with seasons, and over 24 hour cycles. When dissolved oxygen levels in a body of water decline, sensitive animals may move away, weaken, or die. High DO levels in potable water usually make it taste better.
That pH is a measure of how acidic or basic water is. pH is important because it controls many chemical and biological processes that occur in the water. pH is measured on a scale that ranges from 0 to 14, with 7 considered neutral. Values of pH less than 7 are acidic, while values higher than 7 are basic. The pH scale ranges from 0 (high concentration of positive hydrogen ions, strongly acidic) to 14 (high concentration of negative hydroxide ions, strongly basic). In pure water the pH measures exactly 7. Students know that the pH of a body of water is important because pH has a synergistic effect. This means that the impact of other materials in a body of water - such as iron, aluminum, ammonia, or mercury - is amplified or diminished depending on the pH of the water. For example, when acidic waters come into contact with certain chemicals and metals, it makes these chemicals and metals more poisonous than normal. This has special significance in water treatment processes, because specific water treatment processes require specific pH ranges.
That nitrogen and phosphorous are essential plant nutrients. The nitrates and phosphates derived from them are chemicals that pose possible health risks to humans if their presence in drinking water is not controlled. The major sources of nitrates in surface water include runoff contaminated with fertilizers, septic tank leakage, sewage, and erosion of natural deposits. Phosphates, on the other hand, usually enter waterways from human and animal waste, laundry, cleaning and industrial effluents.
That turbidity is a measure of how clear water is. The more suspended solids there are in a water sample, the less transparent it is. Turbidity is considered a good measure of water quality. In drinking water, high turbidity is generally not considered a favorable sign because it can be associated with organic pollution that might include pathogenic materials. In surface bodies of water, high turbidity can lead to increased water temperatures, low dissolved oxygen, and even physical impairment of aquatic organisms.
That the water quality of a body of water can also be assessed by using bioindicators (macroinvertebrates). The presence, condition, and numbers of the types of fish, insects, algae, plants and other aquatic life provide accurate information about the health of freshwater, coastal and marine waters. Bioindicators include living macroinvertebrates. Macroinvertebrates are easy for people to collect and identify. Because many macroinvertebrates are sensitive to pollution in water, they are a good indicator of whether or not a body of water is livable. Good water quality is indicated by a variety of macroinvertebrates. Poor water quality is indicated by a few of one type of macroinvertebrates in one place.
8.E.1.4, Water Treatment
Students know that water quality is a term used to describe the chemical, physical, and biological characteristics of water. Scientifically, an array of chemical, physical, and biological measurements is used to define water quality. Water quality is also described in terms of the purpose for which water is intended to be used. Water that is safe to drink is called potable water, or drinking water, in contrast to safe water, which can be used for bathing or cleaning. In the United States, the Environmental Protection Agency sets maximum levels for the 90 most commonly occurring contaminants.
That water quality standards outline the water quality pollution control program that is mandated and regulated by local, regional and federal agencies. Standards outline the goals for a body of water by identifying its uses, establishing how to protect those uses and establishing provisions to protect and preserve the water bodies in the long term. Point and non-point environmental stressors such as urban and/or agricultural runoff, industrial inputs and over-fishing can impact a variety of aquatic and land-based populations. Because the water quality of a given water body is so closely linked to the surrounding environment and land use, monitoring and regulation at local, regional, and national levels is important.
Clear water may contain odorless, tasteless, and colorless harmful contaminants. Water must be tested for specific contaminants such as bacteria, nitrates, arsenic and others. Natural supplies of potable water are very limited and do not exist in sufficient quantities to meet human needs. Because of this, humans have developed water treatments that process water so that it can be used for a particular purpose.
Drinking water treatment requires some basic steps: Water collection, coagulation, during which lime and alum are added to the water, causing particulates to clump together. Next, the water is shaken to form larger clumps, called flocs. During the sedimentation process water stands for approximately 24 hours, which allows the clumps to settle to the bottom. The water is then filtered, disinfected (usually with chlorine) and aerated. The substances removed during the drinking water treatment process include suspended solids, bacteria, algae, viruses, fungi, minerals, and chemical pollutants. that water is essential to life. Water quality determines the sustenance of ecosystems, human activity such as agriculture, fishing, and recreation, as well as public health of human societies. Water quality supports healthy environments in which rich and varied communities of organisms can be found. The importance of monitoring and maintaining water quality cannot be overstated. Cultivating an awareness of their connection to North Carolina’s hydrologic system is the first step towards developing stewardship skills and dispositions in students.