Transcript Lecture 2 STEMx

Lecture 2
Impact of Human Activities on Ecosystem
Lisa Antoniacci Ph.D.
Marywood University
18.5 Human Effects on the
Biosphere
• The increasing size of the human
population and its increasing
industrialization have far-reaching effects
on the biosphere
• Effects range from extinction of individual
species to global climate change
Increasing Species Extinctions
• Humans are increasing the rate of species
extinctions by degrading, destroying, and
fragmenting natural habitats, by
overharvesting species, and by introducing
exotic species
Increasing Species Extinctions
• Endangered species
– Faces extinction in all or part of its range
• Threatened species
– Likely to become endangered in the near future
• Endemic species
– Evolved in one place and is found nowhere else
The Global Impact of Human
Activities
• Human activities threaten entire ecosystems
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Desertification
Deforestation
Air pollution and acid rain
Water pollution
Trash in aquatic ecosystems
Air pollution and the ozone hole
Greenhouse gases and global warming
Desertification
• Poor agricultural practices turn grasslands
or woodlands into deserts
– US Great Plains (the Great Dustbowl)
– Sahara Desert
• Desertification
– Conversion of grassland or woodlands to
desertlike conditions
Deforestation
• Human activities strip woodlands of trees
– Flooding
– Landslides
– Increases atmospheric CO2
– Decreases atmospheric oxygen
• Deforestation
– Removal of all trees from a large tract of land
Pollution
• Human activities generate pollutants that kill
animals and damage ecosystems
• Pollutant
– Natural or man-made substance released into the
environment in greater than natural amounts, and
that damages the health of organisms
Acid Rain
• Acid rain
– Rainfall contaminated by acidic pollutants
– Burns trees, kills fish, leaches nutrients from soil
• Caused by pollutants that combine with water
vapor in the atmosphere to form acids
– Sulfuric acid from sulfur dioxides from coalburning power plants and factories
– Nitric acid from nitrogen oxides from vehicles and
power plants that burn gas and oil
Other Sources of Water Pollution
• Pollution from point sources may be
identified; dealing with pollution from nonpoint
sources is more difficult
– Industrial chemicals and heavy metals
– Oil from vehicles
– Runoff of fertilizers, pesticides, herbicides, and
animal wastes
– Sewage and excreted prescription drugs
– Sediments
Some Results of Water Pollution
• Bioaccumulation
– Concentration of toxins such as mercury as they
move up through the food chain
• Eutrophication
– Nutrient enrichment by sewage and fertilizers,
resulting in toxic algal blooms or oxygen depletion
• Turbidity
– Clouding of water by sediment runoff, blocking
sunlight and choking animals
The Trouble With Trash
• Human activities generate plastics and other
trash that kill animals and damage
ecosystems
– Chemicals from buried trash contaminate
groundwater
– Wastes dumped or washed into the ocean
damage marine ecosystems
– Plastics can persist more than 100 years
Air Quality
• Pollution from airborne particles damages
respiratory systems of humans and animals
– Burning of fossil fuels and industrial processes
• Some pollutants have global effects
– CFCs cause thinning of the ozone layer
– Rising levels of greenhouse gases contribute to
climate change
The Ozone Hole
• Ozone is a pollutant near the ground, but
depletion of the ozone layer is a global threat
caused by the use of CFCs
– Global agreement to phase out CFC use
• Ozone layer
– Atmospheric layer with a high concentration of
ozone that prevents much ultraviolet radiation
from reaching Earth’s surface
Global Climate Change
• Climate change caused by rising
concentrations of greenhouse gases is
another global threat
– Results in extremes in rainfall patterns and
drought, increased hurricane intensity
• Global climate change
– Global warming and other changes in the current
climate and weather patterns
ACTIVITY #1
POLLUTION LAB
Using Kit:
Water Pollutants and a Living Organism
Pre-Lab Instructions
POLLUTION LAB
 Determining the effects of water pollutants
on a living organism
 Examining 6 known water pollutants
 Regulatory agencies control pollutant
dumping and concentrations in water….. BUT
worry about Biological Magnification
 Also need to assess positive synergy between
pollutants
Pre-Lab Instructions
POLLUTION LAB
Procedure
 Gather all materials (working in groups of 2-3)
 6 pollutants labeled A, B, C, D, E, F
 Depression slide
 Plastic pipettes
 Distilled water
 Microscope
Pre-Lab Instructions
POLLUTION LAB
Procedure – Part 1
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Prepare control by placing 2 drops of distilled water in depression slide. Then add
1 drop of organism
Use microscope to observe organism in the control conditions
Place 1 drop of distilled water in 6 depression slides
Add 1 drop of Bottle A and then 1 drop of living organism
Start timer and observe the organism under the microscope.
Record amount of time it takes to lose ability to swim (form coils)
Wait 5 minutes – if no changes in movement record a negative result
Repeat by adding 1 drop of each pollutant (B-F) to the remaining depression
slides and record results.
Pre-Lab Instructions
POLLUTION LAB
Procedure – Part 1
Bottle A – Silver Nitrate
Bottle B – Mercury Nitrate
Bottle C – Nickel Nitrate
Bottle D – Lead Nitrate
Bottle E – Aluminum Nitrate
Bottle F – Copper Nitrate
Pre-Lab Instructions
POLLUTION LAB
Procedure – Part 2 (Synergy)
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Place 1 drop of Pollutant B 4 depression slides
Add 1 drop of Bottle C and then 1 drop of living organism to first slide
Start timer and observe the organism under the microscope.
Record amount of time it takes to lose ability to swim (form coils)
Wait 5 minutes – if no changes in movement record a negative result
Repeat by adding 1 drop of each pollutant (D-F) to the remaining depression
slides(containing a drop of B and record results.