Transcript Grade 8 Science - Menihek Home Page

GRADE 8 SCIENCE
Unit 1:
Water Systems on Earth
Chapter 3
HEAT CAPACITY
A measure of how long it takes a material to
heat up or cool down.
Water has a high heat capacity... It takes a long
time to heat up and a long time to cool down.
Oceans can store large amounts of heat.
Currents will transfer this heat to other parts of
the world.
Heat Capacity ≠ Specific Heat Capacity
CONVECTION & WEATHER
Weather:
is described in terms of
temperature, wind speed and
direction, air pressure and
moisture.
Convection: heat transfer resulting
from circulation.
OCEANS & CLIMATE
Climate: refers to the main
characteristics of an area’s
weather.
Ocean temperatures can have an
effect on the climates of coastal
communities.
DUE TO ITS HIGH HEAT CAPACITY:
Oceans stay warmer through
the fall and into winter than
land masses.
Oceans remain cooler through
spring and into summer.
This keeps the climate of coastal
areas from being extremely hot in
the summer and extremely cold in
the winter.
This is called a Moderate Climate
EL NIÑO...
Occurs every 3-7 years
The trade winds do not increase after
having been slowed down.
The waters are warmer than usual.
Is responsible for changing rainfall
patterns around the world.
EL NIÑO ‘S EFFECT ON WORLD WEATHER
SYSTEMS
These warm waters force the
smaller ocean organisms
(phytoplankton) to move deeper
into cooler water. Fish and other
animals that eat these organisms
must follow.
LA NIÑA...
Often follows El Niño
The equatorial trade winds increase allowing
continuous upwelling of cooler water.
Brings heavy rains to Australia, Africa and
South America.
Marine life flourishes as the upwelling bring
nutrients for the phytoplankton.
OCEAN CURRENT & CLIMATE...
Our weather patterns are rapidly changing due to
the interaction of the Labrador Current and the
Gulf Stream.
Warm surface currents transfer tropical heat to
the atmosphere and colder currents remove heat
from the atmosphere.
When the warm, moist air above the Gulf Stream
blows over the colder water of the Labrador
Current, it cools and condenses, producing fog.
FOG IN NEWFOUNDLAND
Temperature fluctuations occur
rapidly in NL due to our location
between warm, tropical winds moving
north and cold, arctic winds moving
south.
Local atmospheric temperatures
depend on which of these prevail.
DESCRIBE SPECIES FOUND IN THE FOLLOWING FRESHWATER ENVIRONMENTS. BE
SURE TO INCLUDE INVERTEBRATES, VERTEBRATES, MICROORGANISMS AND PLANTS.
Freshwater Environments:
1.Lakes and ponds
2.Wetlands
3.Rivers and streams
4.Estuaries

Saltwater Environments:
1.Pelagic zone: the water
column
2.Benthic zone: the ocean floor
Refer to pages 90-93
LIVING IN WATER...
BIOINDICATOR SPECIES
WRITE THIS DOWN
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Species that are found in and around water systems can help us
determine how healthy the water is (the quality of the water)
Changes in the number of insects in a water system, for example,
can tell us about the amount of pollution present in the water (the
insects will always die first)
Birds, plants, fish, and clams can also help us monitor freshwater
systems.
We call these species bioindicator species because they help to
“indicate” the health of the water system
These species are often the best way to determine water quality,
because they are very sensitive to pollution. As soon as they are
gone from a system, it indicates that the water could be polluted.
ABIOTIC FACTORS THAT AFFECT PLANT AND
ANIMAL DISTRIBUTION:
WRITE THIS DOWN
Temperature:
Low temperature means more dissolved oxygen.
Dissolved Oxygen: levels should be ≥ 5mg/L
Phosphates: levels should be < 10μg/L
pH: level of acidity range should be 5 –8.5
Turbidity: how cloudy is the water
Pollution
ABIOTIC FACTORS THAT AFFECT PLANT AND
ANIMAL DISTRIBUTION:
Upwelling: the vertical motion of water in the
ocean by which subsurface water of lower
temperature and greater density moves toward
surface of the ocean bringing with it an
abundance of nutrients.
WRITE THIS DOWN
Salinity(marine)
Ocean currents (marine)
How do these factors affect productivity and species
distribution in both marine and fresh water
environments?
CORE LAB ACTIVITY
Activity 3.6 p. 108-111
“Water Health Test”
MARINE TECHNOLOGIES
For Example:
1.Confederation Bridge
2.Oil rigs
3.Sable Island gas development
4.Fundy tidal power
OVERFISHING... P. 105-6
Technologies that have contributed to overfishing
include:
1.Fish finding technologies such as radar
2.Factory freezer trawlers
Bottom Trawling
OFFSHORE OIL INDUSTRY...P. 104
Affects on the marine environments include:
1.Pollution
2.Scouring the ocean floor
3.Marine habitat destruction
4.Release of foreign species in bilge water
AQUACULTURE...P. 106-7
The growing and harvesting of marine species in a
controlled marine area.
Usually built in sheltered areas such as a bay.
May have accidental release of organisms and
spread of diseases.
ANSWERS P. 87
1. Convection is the process of heat transfer in air.
2. The heat transfer causes weather as the air
constantly moves up and down as winds blow it
from place to place.
3. El Nino is caused by the decline in trade winds
over several months. This event causes warm
water to stay in place, and prevents colder water
from upwelling.
4. La Nina is the opposite of El Nino; the trade winds
increase causing continuous upwellings of cooler
water.
ANSWERS P. 89
1. Specific heat capacity is the amount of heat it takes to increase the temperature of a
substance.
2. Since water has a high specific heat capacity, oceans act as heat reservoirs in the
winter, remaining warmer than nearby land and influencing local weather and, over
time, climate.
3. Weather can be described in terms of temperature, wind speed and direction, air
pressure, and moisture.
4. Weather describes short-term conditions in the atmosphere at a specific time and
place. Climate describes weather conditions in a particular region over a long period
of time, about 30 years.
5. Events such as El Nino can affect people in other parts of the world because
changing winds and ocean currents result in different weather patterns along their
path. When a part of the Pacific Ocean becomes warmer, then the currents that pass
through that part become warmer, and carry that warmer water to other parts of the
world. This process results in changes in temperature and rainfall.
6. The warm Gulf Stream Current passes by Great Britain. Due to the high specific heat
capacity of water, the ocean around Britain stays warmer in winter resulting in mild,
wet winters.
ANSWERS P. 89 CONTINUED
7. Some currents are warm because they originate from the
equator; others are cold because they originate from either
the Arctic or Antarctic.
8. The colder Labrador Current acts as a heat sink for
Newfoundland and Labrador in the summer, absorbing heat
from the air, and moderating the temperature.
9. The cold Labrador Current and the warm Gulf Stream
Current meet near
Newfoundland and Labrador, very often creating fog.
10. Prince Rubert, BC, has a warmer climate because it is
affected by the warm ocean currents nearby. The climate in
Happy Valley- Goose Bay, in Labrador, is affected by the cold
Labrador Current.
ANSWERS P. 99
1. The two types of plankton are phytoplankton and zooplankton.
Phytoplankton use photosynthesis to produce nutrients;
zooplankton are tiny animals that eat phytoplankton.
2. The two types of plankton are the first link in the lake or pond food
chain, and provide food for many organisms.
3. (a) A wetland is a lowland area that is saturated with water for part
or all of the year.
(b) Wetlands play an important role in the whole environment, acting
as filters for pollutants, helping to prevent flooding, providing a
resting point for migrating birds, and minimizing erosion.
4. Canada is home to one quarter of the world’s wetlands.
5. An estuary is a wetland that builds up where a river meets the
ocean.
ANSWERS P. 99 CONTINUED
7. Deep-ocean organisms use
bioluminescence to find
food, attract a mate, or
scare away predators.
8. Answers may vary.
Students may refer to the
phosphates in fertilizers
from farming, or
phosphates in detergents,
as being responsible. They
may also point to
manufacturers’ pollution.
ANSWERS P. 115
1. Humans can affect water quality directly (point sources) or indirectly
(non-point sources).
2. Human activities that affect the quality of water in a water system
include the following: using water systems for dumping sewage,
garbage, industrial waste, and waste water; landfill leaks; gas station
storage containers; run-off from roads; pesticides and fertilizers from
farmland and lawns; animal waste from parks and farms.
3. (a) Point source pollution comes from a specific area; non-point
source pollution comes from many different sources.
(b) point sources: landfill leaks; waste water from a factory or mill; oil
spills; underground storage containers for gas stations; sewage
systems; waste water treatment plants
non-point sources: run-off from roads; pesticides and fertilizers from
farms, lawns, and golf courses; and animal waste from parks and
farms
P. 115 CONTINUED
4. Point source pollution is easier to control because it can be traced back to
the source of the contamination. Non-point source pollution comes from
many different sources and is difficult, if not impossible, to trace.
5. Acid precipitation can affect people far away from where it falls by entering
waterways and contaminating them, killing plants and animals.
6. Using oceans as garbage dumps means that garbage gets washed up on
coastlines, beaches, and estuaries. Garbage that floats, such as plastic, can
kill sea life.
7. Factory freezer trawlers, deep-sea trawlers, and radar technology allow
fishers to catch enormous amounts of fish at a time, often with significant
bycatch.
8. Students’ answers may include the following: If a species, such as the green
crab, is suddenly added to an ecosystem, it can upset the ecosystem’s
natural balance by eating a significant number of another species, without
having a natural predator itself. If a species is suddenly taken away, the
balance will also be upset as this species could be the food source for other
species, or it could be a predator for anotherspecies.
ANSWERS P. 116-117
9. St. John’s, NL’s January temperature is affected by
the warm Gulf Stream Current.
10. If people were allowed to go on the island all the
time, they could frighten the birds away, damage
nesting sites or food sources for the birds, or leave
garbage that could harm the birds.
11. Pouring used oil along the side of the highway
could kill local plants and animals, and could
cause oil to eventually end up in the oceans
through run-off where it would harm marine life.
P. 116-117 CONTINUED
12. To determine if the river in my community were polluted, I
would do the following:
Step 1: Take a sample of the bottom sediment of the river, and
check in shallow parts under gravel or rocks.
Step 2: Examine the sediment with a magnifying glass.
Step 3: Identify and record any bioindicator organisms I found.
Step 4: Return the organisms to their natural habitat.
Step 5: Calculate the total biotic index.
15. Seismic testing kills aquatic life, such as eggs and larvae,
scares away fish, and changes migration patterns of whales.