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Science 8/9 Notes
Unit 1 Water Systems on Earth (pg 190)
1.1 Water in Our World (pg 193 sec 7.1)
 Consider two different views from space, one looking down on Europe and
Asia, the other on the Pacific Ocean. In the first case it looks like the Earth
has lots of land, in the second like the earth is mostly water. Water is not
distributed evenly on the Earth.
 Most of the Earth’s liquid water
is salt water in the oceans. Only
3% of the world’s liquid water is
fresh water.
 Fresh water is any water that
has a low enough dissolved salt
content that you can drink it
safely. Not all fresh water is
available to drink though. Some
of it is frozen into ice and some
is in the clouds and air.
 It does not take much salt to turn fresh water into salt water. The ocean’s
salinity is only 3.5%. Most of this salt comes from the land. As freshwater
travels through the soil to the ocean’s it dissolves the salt that is in the soil
and carries it to the oceans. It can also carry other minerals and pollutants.
 Where a river empties into the ocean is called an estuary. When the tide is
high the ocean pushes salt water back into the river creating slightly salty
water called brackish water.
 Wetlands (swamps, marshes, and bogs) are important to fresh water
because they can clean out impurities and because they can store water
and release it during droughts. Canada is fortunate to have lots of wetlands
and lakes. Canada has about 9% of the worlds fresh water and only 0.5% of
its population.
 Just because humans need water in liquid form does not mean that all
organisms do. Many plants also benefit from the water in the air. Recall
that water has three phases: solid (ice), liquid (water), and gas (vapour).
1.2 The Water Cycle (pg 197 sec 7.3)
 Water moves through nature a lot. All of us can think of streams, rivers,
oceans and clouds drifting by that we have seen. The way that water moves
though out the environment is referred to as the water cycle.
 The water cycle influences our weather, keeps our rivers and lakes full,
purifies water, and sustains life.
 The steps of the water cycle can be summarized as:
o Evaporation – This is when the sun heats water up until it turns into a
gas. Water can evaporate off of people (perspiration) and plants
(transpiration). This leaves behind the pollutants.
o Condensation – This is when warm air containing water vapour cools.
If there are dust particles in the air it can easily form a cloud that we
can see.
o Precipitation – When enough condensation has happened to form
droplets the water falls either as rain, snow, hail, sleet, etc.
o Sublimation – When precipitation happens in the form of snow you
can get large snow banks and if it builds up yearly, glaciers. Some of
this snow will melt, but some will go straight from a solid to a gas
again. This is sublimation.
o Wetlands – When the rain falls and snow melts the water runs off in
rivers and travels through marshes and swamps. These are called
wetlands and they filter the water.
o Ground water – The water that soaks into the ground eventually
finds its way back to rivers, lakes, and oceans. It can also collect
underground into something called an aquifer. As the water travels it
can dissolve chemicals, minerals and pollutants.
1.3 The Water Table (Sec 7.4 pg 199)
 When you look at a piece of glass that has steam condensing on it you can
see two things happening. Some water builds up and then rolls down the
window, this is because of gravity. Other water sticks to the glass for a
while, this is because of the force of attraction of the glass on the water.
 Water has a chemical structure that gives it an attraction or stickiness for
many materials. This stickiness is called adhesion.
 Each water molecule has a positive and a negative side to
it. These charges cause a cohesive force among groups of
molecules that attract each other. This allows them to stick
to objects like glass.
 Rain water that does not find its way into a river or lake
eventually finds its way into groundwater. Water that is
underground experiences adhesion with the dirt particles around it. This
allows water to spread out moistening the ground. As it spreads out it
moves between soil particles. This is called percolation.
 Eventually water hits a layer of dirt that it cannot percolate through. The
water then starts to saturate the dirt above this layer. The top of the layer
of saturated dirt is called the water table.
 Water can be pulled out of the dirt by capillary action if the dirt above it is
dry enough. This will cause the water table to drop. Also if rivers or lakes
are losing too much water then the water will flow from the water table to
the lakes. This again lowers the water tables. Also if all the water is
funneled into a river or lake then it does not have a chance to enter the
water table.
1.4 The Power of Water (Sec 7.5 Pg 202)
 Fast moving rain water often appears dirty or muddy. This is because it
carries little particles of dirt called sediment with it. If there is a lot of
sediment being moved in the water it can drastically alter the landscape
and habitat.
 A stone from the beach is usually smooth. This is because water slowly
wears down the rough edges of rocks. This is called weathering and is
where dirt originally comes from. Water can also freeze in the cracks of
rocks splitting them apart.
 Sometimes water can wear away the land slowly through many gentle
rains, other times it can quickly flood an area weakening the soil and
washing it away quickly. When water wears away soil we call it erosion.
Removing vegetation (cutting down trees, etc) removes plants and the
roots that help hold the soil in place. This can speed up erosion.
 Once the sediment in a river settles we call it deposition. Heavier particles
settle first while finer particles like sand are carried further. The settling
particles can make up a flat area of land near the mouth of a river called a
delta. (Example Delta in Vancouver is the delta of the Frasier river)
 Sometimes rivers must be dredged to allow ships through. This is when the
sediment is dug up off of the bottom of the river to make it deeper.
 If a river receives too much water too quickly it can flood. This is when the
water goes over the banks of the river and covers the surrounding flat land
called the flood plain with water. This often happens annually to a certain
extent but there can be worse floods that come from heavy rains, fast
melting snow, or too much ground cover that prevents percolation.
1.5 The Human Side of Water Systems (sec 7.6 pg 209)
 Imagine going down to your favourite beach and finding it closed. This is
becoming a greater reality as humans use water for more things. Safe water
can become unsafe because of pollution, and bacteria.
 Almost all water in nature contains some microorganisms and your body
can usually digest them easily. They become a problem when there gets to
be too many of them. A common bacteria that can close down a beach is
Coliform. They normally live in the intestine and in the water in small
amounts, but when too much untreated sewage is added to water they can
multiply in the water supply. They can cause nausea, vomiting, and
diarrhea.
 Another water hazard caused by humans is acid precipitation. This is when
water in the clouds reacts with pollution to form sulphuric and nitric acid.
These can then fall in the form of rain or snow. This precipitation can slow
plant growth, kill aquatic life, and even eat away at buildings and rocks.
 The problems that acid precipitation causes can also cost money. Failed
crops, less lumber, and fewer fish all mean less to sell. Also damaged
buildings means more to fix. This is one reason to try and prevent acid
precipitation.
1.6 Water Treatment and Disposal (sec 7.7 pg 211)
 Most of the water that we use comes form a river or a lake. This water is
taken in through big pipes that have screens on them to prevent garbage
and fish from entering. The water then goes through a multi-stage process
to get it ready to drink:
o Pumped into a reservoir where sediment can settle.
o Passed through finer and finer screens getting out particles.
o Sent to a treatment plant where even more particles are removed.
o Chlorine or ultraviolet light is then used to kill dangerous
microorganisms.
 Water then goes through large pipes to get to each house and building in
town.
 There are two kinds of waste water to treat.
o Sanitary sewage comes from sinks, baths, toilets, etc.
o Storm water come from precipitation
 Some older sewer systems combine these two waters in the sewers and
pump them into lakes and oceans.
 Newer systems keep the water separate. Storm water goes back into the
environment while the sanitary water gets treated to make it safe.
 This treatment includes
o Removing the solids as a sludge and burning it or using it as a
fertilizer.
o Air is then bubbled through the water to speed up biodegradation.
o It is filtered through gravel again.
o Chlorine is added to kill bacteria.
o Released into a river, lake or ocean and called effluent.
 In rural areas there are not treatment plants, they need to provide their
own water and treat their own water.
o A well provides the farm with water.
o Waste is pumped into a septic tank were the sludge settles and the
effluent flows out the top down a pipe.
o The effluent flows into a drainage field downhill from the well.
1.7 Geological Features at Sea and on Land (sec 8.1 pg 219)
 About 100 years ago a scientist noticed that the continents fit together like
pieces of a puzzle. Later it was discovered that the continents move. This
led to the theory of tectonic plates, that the crust of the Earth moves about
the core.
 The ocean floor slopes down gently away from shore as you enter the
ocean. This is called the continental shelf. These shelves while underwater
are part of the continent.
 The largest mountains on Earth are underwater. They form ridges in the
middle of the oceans. When a volcano underwater erupts it can form a
growing seamount, when it breaks the surface it is called a volcanic island.
If it ever gets weathered down below the water again it is called a guyot.
 A canyon is a deep sided valley carved by a river. The river sometimes
keeps carving the continental crust even when it enters the ocean. A trench
forms where the ocean crust and continent crust meet. They are very deep.
 More common water features that we all know about are lakes and rivers.
A lake is when water collects in a basin in the land. If there is no output
from the lake then it can become salty over time. A river is a flowing body
of water. Fast moving rivers often carve steep banks. Slow moving rivers
often meander.
 Water on one side of the mountains flows towards the Pacific, the water on
the other side flows to the Atlantic. The land area that has all of the water
flowing to the same body of water is called a watershed. The part of the
continent where the division between the Pacific watersheds and the
Atlantic watersheds is called the continental divide.
1.8 Glaciers: Rivers of Ice (sec 8.2 pg 226)
 A glacier is a pack of snow and ice that does not completely melt in the
summer. They can happen high up in the mountains, or in the extremely far
north and south.
 As snow builds up into thick layers the bottom layers get squeezed into
clear ice by the huge weight of the snow. This weight also pushes glaciers
downhill. Cracks in the top of a glacier are called a crevasse.
 Most of Antarctica and Greenland are covered by glaciers. The ones in
Greenland are over 2700m thick. These glaciers gradually flow out from
the center at a rate of a few cm a day. Many glaciers are shrinking year to
year but some are growing year to year.
 Cold air flows off of glaciers cooling the surrounding areas. This sucks
moisture out of the air and keeps everything cold with little precipitation.
 The great weight of glaciers can erode mountains. Rocks, and sand get
dragged along as glaciers slowly slide downhill. Over time glaciers can
change the shape of the landscape. Some of the most prominent are.
o Cirques are U shaped valleys in the side of a mountain where a
glacier is flows down from.
o Arêtes are the knife like ridge in between 2 cirque valleys.
o A horn is made when two or more arêtes meet to form a sharp peak.
o A hanging valley forms when two glacial valleys meet with one being
deeper than the other.
o A fjord is when a cirque ran into the ocean and the ocean flooded it.
 Today’s glaciers are tiny compared to the ones that we think used to be on
the Earth. Most of North America and Eurasia was at one time covered.
1.9 Currents (sec 8.4 pg 232)
 Remember from the experiment with the ice cubes that cold water sinks
and warm water rises. This means that as cold water sinks it pushes warm
water out of the way. This creates a circular movement in the water called
a convection current.
 Convection currents help to move nutrients and oxygen throughout lakes
and the oceans.
 Cold waters from the poles sink and move south and as they go they warm
up and start to rise. Warm waters from the equator rise even more pushing
out towards the poles. As they do they cool and sink. This, the wind, the
gravitational pull from the moon and sun, and much more all affect how
currents form.
 Currents in the oceans form circular patterns called gyres. Gyres are made
up many smaller currents.
1.10 Water, Weather and Climate (sec 8.5 pg 236)
 When you take a sheet of cookies out of the oven you need oven mitts to
touch the cooking sheet but you can usually touch the cookies without
burning yourself. The reason for this is that some materials cool down
faster than other materials. This is because some materials need to absorb
more heat energy to heat up by the same amount. This means that they
will also give off more heat energy as they cool back down. The amount of
heat something can absorb is called the specific heat.
 Water has a higher specific heat than land. This means that it will take
longer to heat up a body of water than the surrounding land. It also means
it will take longer to cool it down.
 The difference in temperature over the land and the water creates
convection currents in the air (breezes). In the night the cooler air over the
land pushes out to the sea and the warmer air over the sea rises up and
pushes inland. The opposite happens during the day.
 A combination of the wind, temperature, and humidity makes up what we
call the climate.
 Currents in the ocean can affect climate a lot. This is because they move
warm or cold water into an area. This then cools or warms the air. In BC the
Pacific ocean warms the air. This causes a lot of rain on the coast.
1.11 Waves (sec 8.6 pg 240)
 A tsunami is what we used to call a tidal wave. They start deep in the ocean
from a landslide, earthquake or volcano. Originally they may only create a
wave 0.5m tall, but this wave is lifting the weight of the all of the water in
that part of the ocean and it might be travelling at 800km/h. As this wave
hits shallow waters all of the energy causes it move the much lighter
shallower water to very high heights (+10m).
 Most waves are not tsunamis. Many waves are caused by wind. The wind
pushes down unevenly on the water and soon it forms a wave. The top of a
wave is called the crest. The bottom is called the trough. The distance
between two crests is called the wavelength.
 We you float on a wave in the water you are not going to get pushed
continually towards shore. Instead you move in a circular motion. Up and
towards shore and then down and out to sea. The forward motion of a
wave in a movement of energy not water.
 Since a wave is a movement of energy they can do a lot of work on the
shape of the shore. Over time waves can more the sand on a beach around,
carve out rocks and pile up sediment.
 A breakwater is a structure that will absorb or block a lot of the energy to
keep it from hitting shore. This can be done to protect a harbour, keep
beach sand from moving down shore, etc. Protecting one beach or piece of
shore may cause another to become more damaged.
1.12 Tides (sec 8.7 pg 244)
 When you walk alone the beach you likely notice a line of debris. This
debris is evidence of a high tide that pushes things ashore. When the
tide goes out the debris is left at the highest point of the water.
 Tides are caused by the gravitational pull of the Moon and Sun and
the rotation of the Earth. The difference between the high tide and
low tide mark is called the tidal range.
 The primary cause of tides is the Moon’s gravity. The water on the
Earth bulges the most on the side closest to the Moon. It also bulges
on the side opposite of the Moon due to the Earth’s rotation.
 Most places on Earth experience 2 high tides and 2 low tides in a day
as the Earth rotates.
 The Sun also contributes a little to the tides but not as much since it
is so far away. If the Sun and Moon are pulling together then we call
it a spring tide (it can happen any time of year). If they are pulling
against each other we call it a neap tide.
 The shape of the shore and the shallowness of the beach can also
affect tides. A long shallow beach that narrows into an inlet will have
higher tides because it forces the water to “pile up”.
1.13 Exploring the Deep (sec 9.1 pg 253-254)
 Humans love to explore and learn what about what is around them. To
explore the ocean deeps though you need some special equipment. In the
1940s the SCUBA (self contained underwater breathing apparatus) was
invented and it allowed for greater exploration. Another invention that
helps is the NEWT suit made in BC. It has a hard shell that allows divers to
go to depths of more than 300m.
 Starting in the 1700s humans had ideas of how to build boats that would
travel underwater. These submersibles have allowed us to explore the
oceans to great depths. They have to be specially designed to be able to
withstand the incredible pressures in deep water. This means thick outer
hulls and small thick windows.
 The French submersible Nautilus can go to depths of 6000m for up to 5
hours at a time.
 The ocean can also be explored from the surface. In order to do this you
need a boat that has sonar (Sound Navigation And Ranging) to map the
bottom of the ocean. Many ocean exploring boats also have remote subs
with video for exploring the ocean floor and depths. Some send drilling
platforms to the bottom of the ocean to drill out samples of the ocean floor
to see what it is made of. They also take samples of the water to measure
the nutrient contents, oxygen levels and pollution levels.
 The oceans can also be studied from the air or space. This allows scientists
to see if the coastlines are changing or if storms are coming.
1.14 Oil: Wealth from the Ocean Floor (sec 9.2 pg 255-257)
 Oil is the remains of organisms that lived millions of years ago. The
organisms were buried in silt and mud which eventually hardened into
rock. The pressure caused the organisms to turn into oil. Some were turned
into natural gas which is usually found floating above the oil in
underground pockets.
 To find the Oil on the ocean floor geologists send shockwaves through the
ocean floor. They can measure the speed of the shock waves and figure out
the kind of material in the ocean floor. This allows them to locate oil. Once
they find the oil they drill a test well to see if there is enough to make a
profit off of.
 Once a profitable well has been located oil companies move a drilling
platform over the site. This drills a well using the same technology that they
use on land. Once a well is dug they move a production platform over the
well. This houses all of the workers and equipment.
 As the Oil comes up they can load it onto oil tankers or send it through
pipelines to shore. They sometimes burn off some of the natural gas to
relieve the pressures in the well and to keep them from exploding.
 There is a risk of oil leaks with every well that is dug. Most of the risk comes
from the oil tankers. They could hit a reef or iceberg and develop a leak. BC
has a large amount of tanker traffic off of its coast.
 Recently a whole oil platform sprung a leak in the Gulf of Mexico leading to
one of the worst environmental disasters in history.
 If there is a leak the oil floats on the top of the water coating everything it
touches in sticky hard to remove layers. This coats and kills wildlife.
1.15 Biodiversity (sec 9.4 pg 261 -266)
 We know that almost all life on Earth lives in the oceans. Biodiversity is a
reference to the number of different kinds of organisms that live in an area.
Each different watery biome contains different kinds of aquatic organisms.
o A tidal pool is a puddle near the shore that gets filled with new water
when the tide comes in and becomes a mini lake when the tide goes
out. Each tidal pool is a mini ecosystem. They offer a glimpse into the
life of ocean animals.
o The waters of the Pacific Ocean are cooler by 4oC when compared to
the Atlantic. The continental shelf is also smaller and covered in mud
and silt. The few rocky places grow kelp forests where starfish,
urchins and oysters live. Otters love to feed there.
o The ocean surface away from shore supports phytoplankton, which
are eaten by zooplankton. These act as food for small fish and large
whales.
o Most animals live in the top 200m of the ocean. Those that live
deeper often travel to the surface to eat at night, or they eat the
scraps that drift downwards.
o The deep dark abyss of the ocean supports fewer animals but they
often glow to attract prey or find each other.
o Hydrothermal vents are like mini volcanoes on the ocean floor. They
give off heat and nutrients. Many bacteria live off of them and are
food for giant tube worms and hairy snails.
o Coral reefs are made of the skeletons of small sea creatures. They
support a huge biodiversity but are very fragile. Pollution, bleaching,
and temperature changes can easily kill coral.
o Reefs made from the skeletons of sponges are called sponge reefs.
Some of the only known ones are off the Coast of BC.
o Saltwater marshes and estuaries have especially hardy organisms
due to the struggles of surviving both salt water and fresh water
conditions.