Science 8, Unit E: Fresh and Saltwater Systems

Earth is sometimes called the _____ because __ % of its surface is water

water planet, 74

Drinkable water must be ____ but, __________

Fresh Water, not all fresh water is drinkable.

potable water

water that is safe for human's to drink.

Where is most fresh water located?

icecaps and sea ice in the Arctic and the Antarctic far from population centres

77% ice

22% groundwater

1% water in lakes, rivers, and wetlands

Freshwater only makes up __ % of all the water on Earth. Of that, only __ % of all the water on Earth is available for humans to drink.

3

0.003

Where is the remaining fresh water?

1) too far below the Earth's surface

2) located too far from human habitats

Water Quality

measure of the amount of substances besides water in a water sample; description of how pure a water sample is.

Water in nature is never ___________ it always contains organisms, organic material, minerals, and other chemicals.

pure

Most of the substances dissolved in fresh and salt water are called ___________.

salts

what is the most common salt dissolved in water?

sodium chloride (same mineral we use for table salt)

salinity

total amount of dissolved salt in water

how does sea water compare to fresh water in salinity?

it has a significantly higher salinity than fresh water.

its average salinity is 3.5%.

how many of the world's population are resorted to drinking dirty water? What are the consequences?

1 billion people. Over 3 to 5 million people worldwide die each year from unsafe water.

how is disease commonly spread in water?

by water contaminated with feces of infected animals or people

as fresh water flows, it...

dissolves minerals from the soil and rocks it passes through, like salt.

hard water

contains high concentration of the minerals calcium and magnesium

how can you tell if you have hard water?

if soap doesn't lather properly.

It may also leave mineral deposits in appliances such as kettles and hot water heaters.

fresh water

contains organisms and organic matter, which is sometimes harmful

scale

mineral deposits

does fresh water contain organisms and other organic matter?

yes, some are harmful and some are not. most minerals dont pose serious health problems.

water in wells

are rarely treated because its location far underground protects it from most pollutants, both natural and human-made.

most towns and cities get their drinking water from...

surface sources, either lakes or rivers.

city water

they filter water from the source and treat it with chemicals.This processing brings it to a level of quality that is safe for human use.

-has to be tested regularly to make sure it's potable

one of the first things that a technician does when testing water is..

looking at its appearance, as well as its smell.

dissolved hydrogen sulphide gas can give water a...

rotten egg smell (and it is unsafe for human consumption)

what would clear water indicate?

when it comes to water quality, nothing, as it is not a sign of clean water

(ocean water can be clear but cant be used because of high salt content.)

how can we ensure that our water is safe to drink?

it must be tested regularly.

what occurs after testing water?

water is filtered and treated with chemicals, such as chlorine, to kill any dangerous organisms.

testing water quality (9)

o Taste & odour

o Turbidity (cloudiness) and colour

o Toxic substances and other pollutants

o Bacteria

o Hardness or mineral content

o pH (how acidic or basic the water is)

o Dissolved oxygen

o Solids, including floating materials

o dissolved solids

what are the two most common processes used for producing fresh water from salt water?

distillation and reverse osmosis

distillation

produces pure water (distilled water) from water that may contain minerals, such as salt, and other substances.

Process of distillation

the solution is boiled so that the water evaporates and leaves the salt behind. Liquid fresh water is then formed from the water vapour.

Reverse Osmosis

operates by forcing salt water through a filter or membrane with holes too small for the salts to pass through

Recall: osmosis

movement of water particles through a membrane from a HIGH concentration TO LOW concentration

reverse osmosis

movement of water through a membrane from an area of lower water concentration to one of higher water concentration.

In this way, the water leaves behind the unwanted dissolved substances.

Section

2

waves

changes in patterns that move along the water's surface.

does water in waves move?

the water itself does not move very far, but waves can move thousands of kilometres across the surface of the ocean.

what mostly causes waves?

the wind. The stronger the wind, the bigger the waves.

how do waves appear? How is this felt?

out in open water, waves appear as up and down water movements. If you were in a boat, you would feel this up and down movement as the waves passed under your boat.

how do waves react with the shore?

near the shore, the water becomes shallower, and the lower part of the waves drags on the bottom of the ocean or lake. This slows the waves down, and the tops of the waves rise up and eventually break, crashing onto the shore. this is where the most damage is caused.

where do waves do the most damage?

when the tops of the waves rise up and break, crashing onto the shore.

what effect do waves have on the shoreline?

it can change the shape of the shore.

Large waves erode away the shore.

Small waves just move gently onto the shore.

Waves can deposit sand or other materials near the shore.

tide

daily change in water level of the oceans

if a place is on the shore of the ocean, that water level along its coast would...

change regularly every day. people who live beside the ocean are used to seeing and working around high and low tide.

in most places, there are __ high tides and __ low tides

2, 2.

high tide

highest water level along the coast

low tide

lowest water level along the coast

what are the main cause of tides?

the gravitational force of the moon

The side of the earth that is closest to the moon feels..

the strongest pull from the moon's gravity. This is where the bulge of water is the largest.

How are high tides caused specifically?

The side of Earth closest to the moon feels the strongest pull from the moon's gravity. This is where the bulge of water is the largest.

Other forces are also at work, resulting from Earth's and moon's rotations. These forces cause another, smaller bulge on the other side of Earth at the same time. The two large bulges, on either side of Earth, are the high tides

As the moon orbits Earth, what occurs?

it pulls the large bulge of water along. At the same time, earth is spinning in its rotation, and orbiting around the sun. All of these movements combine to create two low tides and two high tides

these movements combine to create tides.

earth spinning it its rotation, and orbiting around the sun.

the movements of earth spinning in its rotation, and orbiting around the sun create...

two low tides and two high tides every 24 hours and 50 minutes. Because every day is 24 hours, this mean that low tide or high tide is 50 minutes later every day

tide tables

guides to tell when tides occur, and how high or low they will be that day.

the side _____ to the moon feels a strong pull from the moon creating a _____. The opposite has a _____ _____

closest, bulge

smaller bulge

the bulge on each side are

the high tides

as the Earth _____ the points of the ____ tides also change along with the movement

rotates, high

stream characteristics

characteristics used to describe a stream or river; includes volume and rate of flow, slope and shape of the bed

identifying stream characteristics is important because...

1. scientists can understand types of organisms

2. scientists hypothesize the impact of human activities

3. engineers use them to build bridges and dams

moving water is a ______ ______

powerful force

waves can ____ a ______

shape, shoreline

where do rivers mostly begin

may start in the mountains where a glacier is melting. This is its source.

In the river's early stage, how does it flow?

swiftly and fairly straight.

what occurs when a river reaches its later stages?

The river reaches lower elevations, and the ground becomes more level. The river flows more slowly here. This causes it to move in large curves, called meanders. The flatland on other side of the river becomes covered with water whenever the river overflows its banks. This area is called the floodplain.

The speed of the river's current depends on...

its volume of water, the greater the volume, the greater the speed.

what occurs in the last stages of a river?

At its mouth, the river enters a lake or the ocean. The flow of water slows done much more, and drops much of the sediment it carries. This sediment forms a fan-shaped deposit called a delta.

how did rivers start out?

the water collects in a channel that forms a small stream . The volume of water in the stream increases as other streams flow into it. Rivers can also start from lakes that are fed by other streams and rivers.

floodplain

the flat land on either side of the river that becomes covered with water whenever the river overflows its banks.

meanders

large curves where the water from the river flows.

delta

fan-shaped deposit formed from sediment

the water is at its slowest near the ____ in ____

mouth of the river, deltas

erosion

wearing away and transporting of rock fragments and soil.

sediments

eroded rock fragments and soil

sediment load

the amount of water-borne materials, such as soil, rocks, and organic matter that it carries

deposition

the laying down or depositing of sediments

the slower water flows, the ___ load it can carry. as it slows down, what occurs? when it stops flowing?

less. it deposits some of its sediment load,

it can't carry any load, so it deposits all the sediment it still carries.

how do caves form?

when rainwater and streams dissolve limestone and other rocks. the water collects in cracks and holes in the rock. As it sits there, it gradually dissolves more and more of the rock until large caverns form. streams and rivers flowing through these caverns cause even more erosion.

chemical weathering

The process that breaks down rock through chemical changes

mechanical weathering

The breaking up of rocks by physical forces

water shed

area of land that drains into one main lake or river.

most drain into lakes and rivers that drain into other lakes and rivers.

the location of the highest land on the continent determines...

the direction that a watershed drains

continental divide

highest point of land on a continent

in north america the continental divide is ___

the rocky mountains

lithosphere

solid outer layer of the Earth. it is made out of rock which is broken into huge, moving pieces called tectonic plates.

plate tectonics

move constantly and slowly because of convection currents within Earth. This movement has shaped the geological features on the ocean floors and many of those on the continents

mid ocean ridges

form where molten rock pushes up from the interior of the Earth.

On either side of the ridge are two different plates which are slowly moving away from each other as the molten rock hardens into new crust.

continental shelves

shallow areas around the edges of continents. they are mainly sedimentary deposits of materials eroded off the continents. They are largest on the edges of oceans that are opening up

volcanic islands

formed by volcanoes that grow up from the ocean's floors

seamounts

underwater volcanoes that do not come all the way to the ocean's surface

trenches

form where two plates are moving toward each other. the thinner oceanic plate is pushed down below the thicker continental plate

are long, deep depressions in the ocean bed

continental drainage system

shaped by mountains, and another major force, ice.

glaciers

large moving bodies of ice

continental glaciers or ice caps

glaciers that cover vast areas of land, form in Earth's coldest regions.

valley glaciers

glaciers that form high up in mountain ranges

as glaciers move, what occurs?

pieces of rock become imbedded in the ice. these pieces range in size.

It is these pieces combined with the massive glacier, that grind down and shape the land they pass over.

movement of glaciers depend on the

climate

colder =

little melting, snow build up (glacier moves forward/advance)

warmer weather=

more melting, (glacier moves backward/retreat)

leaves behind the soil, rock, and boulders it once contained

ice ages

times when a vast area of the Earth was covered with glaciers