Download scientific inquiry: si1 - Mrs. Spurling 7th Grade Science

WATER
Textbook Reference: Chapter 11
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Water is a limited resource because less than 1% of Earth’s water is available for consumption and a growing
population means water is being used more than ever before.
Fresh water exists as surface water or ground water.
o Surface water is water found in rivers, lakes, streams, and wetlands.
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A river system is a flowing network of rivers and streams draining a river basin. The amount of water
entering a river system can vary depending on how much rain and melting snow occurs.
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A watershed is the area of land that is drained by a river system.
o Pollution that occurs on the land within a watershed can run off the land into the
river system. Wetlands can filter out some water pollution and are also important to
control flooding.
o Ground water is fresh water stored beneath Earth’s surface.
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People dig wells to access groundwater. The wells need to be deep enough so there is always
enough water, even during dry seasons.
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The water table is the point below ground where soil is saturated with water. Groundwater should
not be taken from aquifers faster than it is replaced. Groundwater is replaced when water seeps
down through a permeable surface.
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Pollution can seep into groundwater. Groundwater pollution is difficult to clean because it is hard to
get to and may cling to sediments below the surface.
Dams and canals are important water management systems.
o Canals divert rivers to places that need it for irrigation. Dams are structures built across rivers to control the
flow of water.
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Dams create reservoirs of water behind the dam. The reservoirs can be used as a fresh water
source. However, dams cause several problems: they destroy the original ecosystem where the
reservoir forms, they displace people from their homes where the reservoir forms, and they trap
fertile sediment which harms agriculture.
o Desalination, which is a process that removes salt from water, is not widely used because it requires too
much energy and is therefore too expensive for most nations.
Pollution can be either point-source (coming from a specific site, such as a leaking landfill or septic tank or a factory)
or nonpoint-source (coming from many sources such as roads or farmland).
o Wastewater needs treatment after it leaves homes and businesses so that it is clean enough to return to a
river or lake. Water treatment also includes the removal of toxins and pathogens (viruses, bacteria, or other
microorganisms that can cause disease).
o In addition to releasing toxic chemicals, factories can also cause thermal pollution (a temperature increase
in a body of water. Thermal pollution can lead to hypoxia (too little oxygen dissolved in water) because
warm water cannot hold as much oxygen as cold water. Hypoxia can kill aquatic life because there isn’t
enough oxygen in the water.
o Farmers often use synthetic fertilizers containing phosphorus and nitrogen. These fertilizers run off the land
into surface water, causing too much algae to grow (a process called artificial eutrophication). The process
of algae decaying causes hypoxia.
o Biomagnification is the accumulation of pollutants at successive levels of the food chain. Pollutants become
concentrated in animals as they eat contaminated animals; therefore, the animals highest in the food chain
have the highest levels of pollutants. People need to limit the amount of fish they eat for this reason.
The Clean Water Act was designed to restore and maintain the chemical, physical, and biological integrity of the
nation’s waters. Although not all waterways have become fishable and swimmable, the act has allowed the
government to limit water pollution and require the clean up of polluted waterways. It also led the way in water
quality legislation and there have been many new laws created to continue to improve water quality.
AIR
Textbook Reference: Chapter 12
A primary pollutant is put directly into the air by human activity.
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Health effects include respiratory problems, cancer and death.
A secondary pollutant forms when a primary pollutant comes into contact with other primary pollutants or with naturally
occurring substances such as water vapor and a chemical reaction takes place.
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An example of a secondary pollutant is ground-level ozone, which forms when the emissions from vehicles react with
the UV rays of the sun and then mix with the oxygen in the atmosphere.
The Clean Air Act, passed in 1970 and strengthened in 1990, gives the Environmental Protection Agency (EPA) the authority
to regulate air pollution.
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The EPA required the elimination of lead in gasoline, reducing lead pollution by 90%.
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Cars are required to have catalytic converters to clean pollutants out of car exhaust before the exhaust leaves
the tailpipe.
Cars and industries in cities create smog, and air pollution is trapped near Earth’s surface by temperature inversions.
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Smog is urban air pollution that is a mixture of smoke and fog made from industrial pollutants and burning fossil
fuels.
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Smog results from chemical reactions that involve sunlight, air, automobile exhaust, and ozone.
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Smog hangs over urban areas and reduces visibilities.
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Temperature inversion – the air above is warmer than the air below. The cooler air does not rise and can’t take
air pollutants away from Earth’s surface.
Air quality inside a home or building is sometimes worse than the air outside.
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Buildings with very poor air quality have a condition called sick-building syndrome.
o Sick-building syndrome is most common in hot climates where buildings are tightly sealed to keep out
the heat.
o Ventilation (mixing outdoor air with indoor air) is necessary for good air quality.
o Finding and removing sources of indoor air pollution can also improve indoor air quality.
Noise pollution is any noise that affects human health and the quality of human life.
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Some sources of noise pollution include airplanes, construction equipment, city traffic, factories, home
appliances, and lawnmowers.
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Health problems that can be caused by noise pollution include loss of hearing, high blood pressure, stress, loss of
sleep, and decreased productivity at work and in the classroom.
Light pollution does not present a direct hazard to humans; however, it negatively affects our environment.
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The use of inefficient lighting in urban areas is diminishing our view of the night sky because the sky is much
brighter than the natural sky. Inefficient lighting wastes energy.
Acid precipitation is precipitation such as rain, sleet, or snow that contains a high concentration of acids
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Burning fossil fuels releases oxides of sulfur and nitrogen into the air. These oxides combine with water in the
atmosphere to form sulfuric acid and nitric acid, which fall as acid precipitation
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If acid precipitation falls on a lake and changes the water’s pH, acid can kill aquatic plants, fish, and other
aquatic animals.
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Solving the problem of acid precipitation is difficult because pollutants may be released in one geographical
area and fall to the ground in another area.
CLIMATE
Textbook Reference: Chapter 13
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Climate is different from weather because climate is the long-term prevailing conditions of an area and weather is
current short-term atmospheric conditions.
Climate is affected by:
o Latitude (areas closer to the equator receive more direct sunlight and are therefore warmer)
o Atmospheric circulation (large-scale circulation of air that distributes heat on Earth’s surface).
o Oceanic circulation patterns (distribute heat across the Earth).
o Topography (higher elevations experience cooler climates; mountain ranges affect precipitation).
o Solar effects (the sun sometimes emits more UV rays).
o Volcanic activity (can cause a haze that decreases global temperature).
El Nino and La Nina are oceanic circulation patterns that change the normal temperature and precipitation
patterns in many places on Earth.
Many places on Earth experience seasonal changes because of Earth’s tilt on its axis. While the Northern hemisphere
is tilted toward the sun, it is experiencing more sunlight and therefore warmer temperatures (summer). At the same
time, the Southern hemisphere is tilted away from the sun and therefore experiencing cooler temperatures (winter).
Seasons change as Earth revolves around the sun and different parts of the Earth experience being tilted toward or
away from the sun.
The ozone layer is an area of concentrated ozone in the stratosphere that absorbs harmful UV rays released by the
sun.
o The ozone layer is important because it blocks UV radiation which damages the DNA of cells and can cause
cancer, damage to plankton and amphibian eggs, and disruption to photosynthesis in plants.
o The ozone layer is being destroyed by a chemical called chlorofluorocarbon (CFCs) which were used in
aerosols and refrigerants. The chlorine from the CFCs breaks apart ozone (O 3) molecules.
o Although ground-level ozone is an air pollutant that is unhealthy to breath, the ozone layer is in the
stratosphere which is too high above the Earth for us to breathe.
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Greenhouse gases trap the sun’s heat near Earth’s surface. Greenhouse gases are naturally occurring in Earth’s
atmosphere; however, human burning of fossil fuels has greatly added to the amount of greenhouse gases in the
atmosphere, causing global warming.
o Global warming refers to the recent and ongoing rise in global average temperature near Earth’s surface.
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During the 20th century, the average global temperature has increased (although it has varied from
year to year and sometimes decreased).
o Global warming is causing global climate change. Global climate change causes the following effects:
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Melting polar ice and rising sea levels (increased flooding).
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Stronger and more frequent storms (such as hurricanes and typhoons).
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Human health problems.
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Increased droughts and agricultural problems when droughts occur.
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Negative impacts on plants and animals whose habitats would change as climate changes.
o Citizens can slow global climate change by reducing the emission of greenhouse gases. People can burn
fewer fossil fuels (which emits greenhouse gases) by:
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Driving less (carpool, use public transportation, bike, or walk).
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Using less electricity (turn thermostat up in the summer (less A/C), unplug appliances when not in
use, turn off computers and TVs when not in use, turn off lights that nobody is using).
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Use less fuel for heating (turn down thermostat in the winter (less heat), wash clothes and dishes in
cold water.
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Buy fewer goods (buying less means fewer fossil fuels were burned to create the products you own).
LAND USE
Textbook Reference: Chapter 14 & 15.2
Humans use land for a variety of purposes (in the United States):
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Rangeland (26%) – animal grazing
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Forestland (28%) – harvesting wood
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Cropland (20%) – agriculture (food and fiber)
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Parks and preserves (13%) - recreation
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Urban land (6%) – houses, industry, roads
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Other (7%) – wetlands, mountains, deserts – land difficult for human use
Urban land is land that is covered mainly with buildings and roads; population 2,500+ and a governing body.
Rural land is land that contains few people and large open spaces (any area not urban is rural)
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Rural lands produce ecosystem services, which are resources produced by ecosystems.
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Urban areas depend on resources produced in rural areas.
Infrastructure is all the things that a society builds for public use.
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Includes roads, sewers, railways, bridges, schools, libraries, etc…
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Rapid population growth can overwhelm an infrastructure leading to traffic jams and poor living conditions.
Urban sprawl is the rapid expansion of a city into the surrounding rural area.
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Suburbs are built on land previously used for food.
Cities generate and trap more heat than rural areas and are called heat islands.
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Planting trees for shade and installing rooftops that reflect heat reduces heat in cities.
Urban planning considerations:
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Mass transit systems – include buses and trains – reduce energy, traffic and air pollution.
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Open space is land in cities set aside for scenic and recreation enjoyment.
o Provides ecosystem services for an urban area.
Land management and conservation is important to a rapidly growing human population.
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More rural resources are needed to support the growing population.
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It is important to reduce rural land being overused and polluted.
Fertile soil is soil that can support the growth of healthy plants
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Fertile topsoil is rich in organic matter (living and dead organisms), rock particles, water, and air
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Human activities such as farming and grazing livestock threaten fertile soil.
Desertification is the process where land becomes more desert-like because of human activities
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Farmers can rotate crops and periodically allow the land to lie fallow (remain unplanted) for several years.
Soil conservation is an important agricultural practice because is protects topsoil and reduces erosion.
WASTE
Textbook Reference: Chapter 19
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Solid waste is any discarded solid material such as garbage, refuse or sludge.
Biodegradable waste can be broken down by natural processes. Ex: paper, food and yard waste.
Cities are running out of space to dispose of waste. As the population grows, we have less land available for landfills
and more waste produced.
Solid waste can be disposed of in landfills or incinerators.
o Landfills are areas of land where waste is permanently disposed of.
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Landfills must be lined so waste does not contaminate soil or water. Leachate is a hazardous liquid
from waste chemicals that can flow into groundwater. For this reason, leachate must be monitored,
collected, and stored.
o Incinerators are used to burn waste so that it takes up less space.
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Incinerators are expensive to operate and may produce air pollution and toxic chemicals.
It is important for individuals to reduce, reuse, and recycle.
o People can “reduce” buy purchasing fewer goods, purchasing goods made from recycled materials, and
purchasing goods with less packaging. Easy ways to reduce are using cloth grocery bags, using a refillable
water bottle, and buying food in one large container rather than several small containers.
o People can “reuse” items before discarding them. Look for ways to reuse items such as using an empty
peanut butter jar as a storage container.
o People can “recycle” by following the procedures in their area for recycling pick-up or drop-off. Recycling
turns materials from waste into new products. It is important to only place recyclable materials in recycling
containers. Composting is recycling biodegradable material, such as yard waste.
Hazardous waste is any waste that is a risk to the health of humans or other living things in the environment.
o Hazardous waste can be disposed of by storing it, incinerating it, or exporting it.
o Hazardous waste should not be disposed of by placing it in the garbage or pouring it down the drain.
MINING
Textbook Reference: Chapter 16
Essential Information:
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A mineral is an inorganic solid with an orderly internal structure and characteristic chemical composition and
physical properties.
o Minerals are used to make goods such as electronics, jewelry, glass, cell phones, and toothpaste. Minerals
are also used to build roads and buildings and make building materials such as wiring and plumbing.
o Minerals can be metallic (shiny, bendable solids that are good conductors of heat and electricity) or
nonmetallic (brittle solids, gases, or liquids that are good insulators).
In order to find minerals, mining companies use technology, like satellite and air imagery, radiation detectors,
magnetometers, gravity differences, seismic surveys and chemical analyses.
The mining process incudes the following steps: site preparation, mining, processing and reclamation.
o Site preparation: storing topsoil and constructing roadways, sediment traps, and equipment.
o Mining: Can be surface mining (occurs at the surface of the Earth) or subsurface mining (occurs below the
surface of the Earth).
o Processing: Minerals are crushed to sizes needed and sorted by size.
o Reclamation: The Surface Mining and Reclamation Act of 1977 requires mining companies to return mined
land to a beneficial use and as close to normal grade as possible.
Mining causes the following environmental damage:
o Disruption of land surfaces: displaces wildlife and destroys ecosystems
o Subsidence: regions of the ground sink when abandoned subsurface mines collapse
o Erosion and sedimentation: excess rock from mines is eroded and builds up sediment in rivers and streams
o Acid mine drainage: water in mines can carry sulfuric acid into streams and groundwater which destroys
aquatic life.
o Air and noise pollution: dust produced during mining and transportation create air pollution; mining
equipment creates noise pollution.
o Storage and leakage of liquid mining waste: creates water and soil pollution
States can regulate mining by requiring mining companies to get a permit and to have a plan for reclamation of the
land. If a mining company does not reclaim the land it can be fined.