Science 8 Unit E Study guide
Section 1: Fresh & saltwater system
Section 1.1 water, water, everywhere
Living things need water to survive. Water can be a powerful force that shapes landscapes & ecosystems. 74% of the Earth’s surface is covered in water.
Distribution of water: The earth is covered in water, but we can drink very little of it.
Water that is safe to drink is called potable water. Potable water must be fresh water, not saltwater.
Section 1.2 Water quality
Define the following terms:
Water quality describes how pure water is.
Water in nature is never 100% pure. We test water for various contaminants.
Contaminants are substances that don't belong in something and make it dirty, unsafe, or unhealthy. They can be in air, water , soil, or even food.
Dissolved slats:
We test the dissolved substances in water. Most commonly these substances are slats. This includes sodium chloride (table salt) & other types of salt.
Salinity: the total amount of all salts in water is called salinity.
Salinity is usually measured as a % of water.
Hard & slat water:
Hard water is water that is high in dissolved minerals.
Hard water has calcium (Ca) and magnesium (Mg) - those are the main minerals that make water hard.
Soft water is water with high amounts of sodium salts.
Hard water isn't bad for you but it can cause mineral buildup on plumbing.
Organisms in Drinking water
Fresh water contains organisms & organic matter.
Some are harmful. Water from below ground is protected from this hazard. (protected from harmful organisms because soil & rock naturally filter it)
Cities that get their drinking water from surface sources treat it with chemicals to kill organisms.
Water testing Criteria:
-Tate & color -Mineral content (hardness)
-pH (acidity or basicness -Dissolved solids
–Dissolved -Turbidity (cloudiness)
-Pollutants -Bacteria
Changing Saltwater to Freshwater
Distillation – Process where water is turned into a vapour (steam) & dissolved particles are left behind.
Reverse Osmosis: Forces water through a filter. This membrane allows water to pass but does not allow large salt particles through.
Section 2 Waves & tides
Section 2.1 waves & Tides
What are waves?
Waves are movements on the surface of bodies of water.
The actual particles of water in a wave do not move very far but the physical movement of a wave can stretch for kilometers.
What Causes Waves?
Most waves are caused by wind.
Stronger wind = bigger waves
In the open ocean, a wave feels like an up & down motion.
Close to the shore in shallow water, the bottom of the wave drags along the ground. This causes waves to smell up & crash.
What are Tides?
A change in water level in a body of water is called a tide.
High tide = highest water level on the coast.
Low tide = lowest water level on the coast
Remeber Gravity:
Gravity acts on the mass of an object. Understanding that the Moon & Sun have gravitational pull helps explain tides.
Section 2.2 Erosion & Deposition
Steam Characteristics
When we describe a stream of water we can use different categories:
The rate of flow
The slope of the stream
TThe direction of flow
Erosion & deposition
Weathering: the wearing away of materials like rock & soil by things like wind & water.
Erosion: the removal of the weathered pieces (carried away by a river, for example).
Deposition: the depositing or placing of weathered particles in a new location.
We refer to weathered particles as sediment.
Rivers & Deposition
Rivers often weather, erode, & deposit at the same time
The sediment load of materials like soil, rocks, & organic matter that the river carries.
As the flow of a river slows, it can carry less sediment, so it deposits some of its sediment load!
Chemical Weathering
Chemical weathering is the weathering of landscapes by chemical change. This often involves water.
Flowing water can dissolve limestone and other rocks.
Watersheds
-Watersheds ( also called drainage basins) are regions of connected rivers & streams that drain into one main lake or river.
The location of the highest point of land on the continent determines the direction a watershed will drain. ( this is due to gravity).
The highest point is called the continental divide. In North America this is the Rocky Mountains.
Alberta Rivers
-Most of Alberta’s rivers run through the prairies & into hudson’s bay.
The Milk River is southern Alberta drains into the Mississippi River Drainage system.
Two of Alberta’s major rivers run through urban centres.
The north saskatchewan river runs through Edmonton..
The bow river runs through Calagray.
Section 2.3 Process that shapes ocean basin & continental drainage.
The cuter layer of earth’s crust is called the lithosphere. It is broken into chunks called tectonic plates.
Continental ridges/slopes: areas where the continental shelf drops steeply.
Seamounts: understand volcanoes that do not come all the way to the surface.
Abyssal plain: flat vast area on the deep ocean floor.
Mid-ocean ridge: form where molten rock pushes up from the interior of earth. Two plates moving away from each other.
Ocean features
Volcanic islands: formed by volcanoes that grow from the ocean floor post the surface of the water.
Continental shelf: shallow are around the edges of the continents mainly sedimentary deposits.
Trenches: from where two plates move toward each other.
Glaciers: large moving bodies off ice.
Ice Caps: glaciers that cover large area of continents (also called continental glaciers)
Antarctica & Greenland are covered by continental glaciers
Glaciers shape land as they move because the rocks they pick up & their icy bottoms grinded down their path.
Eskers: From when parts of the glaciers melt. These meltwater flaws in tunnels water the ice. The melting releases sand & gravel from the glacier. These sediments are deposited by the meltwater in the pattern of the winding river.
Braided stream: it's a type of river that has multiple shallow channels.
Kettles: is a hole formed when a block of ice detouches from a glacier.
Retreating glacier: a glacier moving backwards, because of the amount of ice lose, due to melting.
Moraine: A moraine is a pile of rocks, soil, & broken pieces of earth that were carried and left behind by a glacier as it moved or melted.
drumlins: a smooth, oval-shaped hill made of sand, gravel and still (mixed rocks and soil) that was left behind by a moving glacier.
Section 2.4 Water & Climate
What is climate?
Climate is the average weather measured over a long time in a specific area.
Bodies of water can affect climate.
- Water has a high heat capacity compared to similar substances.
This means it can hold onto kinetic energy for longer. Because of this, large bodies of water take a long time to heat up and cool down. (this prevents extreme temperature changes)
Currents: Currents are streams of water that move within large bodies of water
Caused by : Wind, Earth’s rotation, temperature differences, salinity difference.
Currents are different from waves because the water in currents actually moves from place to place
How currents affect Climate?
☀Warm currents (from equator)>warm water >wind picks up moisture >land= wetter & milder.
❄Cold currents (from poles) > cold water >wind stay dry >land= cooler & drier.
Wind over warm water = moist air
Wind over cold water = dry air
Section 3 : Diversity of organisms in freshwater
Section 3.1
Aquatic Zones: A rich variety of organisms living and interacting within a water ecosystem indicates a healthy ecosystem. More species = more oxygen & less pollutants.
Diversity refers to the variety of different organisms species ( both plants & animals) living in a particular ecosystem or environment.
Large bodies of water like oceans and lakes have layers or zones.
Some organisms live in only one or two zones, while other organisms can live in all three.
Canadians diversity
In Canada lakes are affected by extreme changes in temperature
Organisms living in the freshwater ecosystem of a lake or pond must be able to adapt to these changes in order to survive.
Ocean diversity
zones experience greater differences in water movement, salinity and depth.
Ocean diversity is much greater.
Adaptation of organisms
An adaptation is a physical characteristic or behaviour of a species that increases that species’ chances of survival in a particular environment.
All living things are adapted to live in particular environments.
As changes occur within their environment, those organisms that can adapt to the changes have a better chance of surviving than those organisms that cannot adapt to the changes.
Section 3.2 Populations.
A population = a group of organisms of the same species living in the same area. (Ex: all frogs in one pond)
Why Population Change matters:
Populations naturally increase & decrease over time.
But rapid declines can mean something is wrong in the ecosystem ( like pollution, loss of food, or invasive species).
Population Changes
Population change means:
Number of individuals changes (more or less)
Change in males & females
Change in young & old
3 types of population Changes
Seasonal Changes
It happens during certain seasons (usually due to temperature).
Some animals hibernate (sleep through cold months).
Examples of animals that hibernates:
Box turtles
Wood frogs
Bats
Common poorwills
Fat-tailed dwarf lemur
Groundhogs
Snakes
Snails
Bumblebees
Skunks
hedgehogs
Tip: Hibernation = short-term drop in visible population but not extinction!
2. Short-term changes
Happens suddenly & lasts a short time.
Caused by natural disasters ( floods, fires etc.) or human activities ( like oil spills)
Ex: Oil spill - can hurt animals fast, & sometimes the effects last longer if cleanup is bad.
3. Long - term Changes
Happen slowly & last a long time.
Caused by natural events ( climate change, volcanoes) or human activity ( pollution , deforestation, invasive species).
Tip: Invasive species = animals or plants that don't belong in an area & harm native ones.
Section 3.3 Water Quality & living things.
Water Quality Changes
Water quality can change from:
Natural events (like flooding or volcanoes)
Human activity (pollution, acid rain, waste)
Effect on populations:
Some species can handle small changes - this called their range of tolerance
Other die off if the water becomes too polluted or acidic
Acid Laked & algal blooms
Acid lakes happen when pollution (like acid rain) lowers the water’s pH.
This can kill plants & animals & cause algal blooms
Algal Bloom process:
1.Algae grows fast & covers the lake surface.
2.Sunlight can’t reach underwater plants > they die
3.Plants rot > oxygen in water drops
4. Fish & other animals die due to low oxygen
5. The food chain collapses.
Section 4
Section 4.1 Human Water Use
Water Use Overview
Water is recycled around the world through the water cycle.
The amount of water an area gets can change from year to year.
Human activities can hurt Earth’s water supply by causing:
Pollution of surface or groundwater
Depletion (using up) of groundwater.
Major Uses of water
Key Factors in Water Pollution
Cities
City water often has oil & salt > harms plants & animals.
Can contains toxic chemicals that cause:
Tumors
Birth defects
Sterility (can’t reproduce)
Death
Add too thermal pollution (too much heat in water)
Habitat Destruction
When pollution or construction damages aquatic habitats ( where plants & animals live).
Ex: power stations release warm water into rivers/lakes > this is called thermal pollution
Thermal pollution = warmer water > kills organisms that can’t handle high temperatures.
Sewage
Sewage has lots of nitrogen
Nitrogen causes microorganisms to grow quickly.
These microorganisms use up oxygen, leaving little for fish & other life.
Result > Many organisms die because of low oxygen.
Oil spills
Happen when ships carrying oil leak or spill.
Oil coats animal (like birds or seal), blocking their breathing & movement
Harms plants & animals in & near the water