Lecture 26 Global Anthropogenic Impacts Flashcards
Threats to Biodiversity
Local and global scale processes lead to biodiversity loss
slide 16
Pollution
- Pollutants are harmful materials
that damage the quality of air,
water, and land - Pollution can be:
- Chemical (industrial
compounds, pesticides,
pharmaceutical) - Plastic
- Environmental (light and
sound) - Pollution can spread globally
from source
Pollution: Chemical
- Some toxins are metabolized or excreted,
others accumulate in tissues - Chlorinated hydrocarbons and inorganic
compounds (e.g., mercury) are found in
industrial chemicals and pesticides - Pollutants enter ecosystems through
industrial waste, sewage, and combustion - They are often endocrine disruptors that
interrupt normal physiological functions
(including in humans) - They can also accumulate and magnify in
ecosystem…
Pollution: Biological Magnification
- Bioaccumulation: Pollutants (toxins) are stored
in tissues - Biomagnification: pollutants become more
concentrated at each higher trophic level
slide 19
Pollution: Acid Rain
Combustion releases sulfur and nitrogen oxides
that react with water in air to make acids
slide 20
Pollution: Ozone Depletion
- Atmospheric ozone (O3) provides UV
protection - Has been thinning since 1970’s because of
ozone-destroying pollutants like
chloroflurocarbons (CFCs) - Worst in the south pole because cold air
allows ozone-depleting reactions to continue
year round - Global regulations have stabilized ozonedepleting chemicals, but pollutants already in
the atmosphere will continue depleting
ozone for 50+ years
Pollution: Plastics
- 11-28 billion pounds of
plastic waste end up in the
ocean every year - Plastic can persist for 100’s
of years! - How does it harm wildlife?
- Animals eat it & get
entangled by it - Can carry bacterial
pathogens - Many unknown effects of
consuming microplastics
Pollution: Environmental
Noise and light pollution impact animal communication, behavior, and physiology
Nutrient Enrichment
- Nutrient enrichment
(mainly N & P) from:
industrial pollution, sewage,
agriculture, and crop fertilizers - Problems arise when nutrients
exceed the critical load:
the amount of nutrients that
can be absorbed by plants - Excess nutrients leach into
aquatic systems to contaminate
water supply and cause
eutrophication
slide 24
Nutrient Enrichment: Agriculture
- Agricultural practices affect
nutrient reserves in soil: - Crop harvesting removes
nutrients leading to depletion
of natural reserves over time - Fertilizers supplement
nutrients, but excess
nutrients remain in the soil - Nitrate concentrations in
groundwater are elevated in
agricultural regions sometimes
reaching unsafe levels for
drinking
Nutrient Enrichment: Eutrophication
- Nutrient levels in an aquatic ecosystem exceed critical load leading to
explosive growth of primary producers - Primary producer growth leads to “dead zones” and harmful algal blooms
slide 26
Nutrient Enrichment: Dead Zones
Algal blooms deplete oxygen as plant matter decomposes
* Hypoxic (oxygen depleted) water kills wildlife
slide 27
Nutrient Enrichment: Harmful Algal Blooms
- Harmful algal blooms produce elevated
levels of toxins that kill wildlife - HAB toxins can bioaccumulate!
slide 28
Climate Change
- Instrumental records
of sea surface and land
temperatures have
been recorded since
1800s – there has
been a steady increase - Scientific consensus is
that warming is due to
increased
concentrations of
greenhouse gases
slide 30
Climate Change: Greenhouse Gases
- Human activities have
increased multiple
greenhouse gases:
Methane, Nitrous
Oxide, Carbon Dioxide - Greenhouse gases
reflect heat that would
otherwise escape to
space back toward
Earth
slide 31
