Biogeochemical Cycles - MHHS 2016-2017mhhsmsbean.weebly.com/uploads/3/7/6/7/37679777/... ·...
Transcript of Biogeochemical Cycles - MHHS 2016-2017mhhsmsbean.weebly.com/uploads/3/7/6/7/37679777/... ·...
Biogeochemical Cycles
Objectives:
Identify and describe the flow of nutrients in
each biogeochemical cycle.
Explain the impact that humans have on the
biogeochemical cycles.
Chapter Overview Questions
What happens to energy in an ecosystem?
What happens to matter in an ecosystem?
What Sustains Life on Earth?
Solar energy,
the cycling of
matter, and
gravity sustain
the earth’s life.
Figure 3-7
Two Secrets of Survival: Energy Flow
and Matter Recycle
An ecosystem
survives by a
combination of
energy flow and
matter recycling.
Figure 3-14
MATTER CYCLING IN
ECOSYSTEMS
Nutrient Cycles: Global Recycling
Global Cycles recycle nutrients through the
earth’s air, land, water, and living organisms.
Nutrients are the elements (CHNOPS) and
compounds that organisms need to live, grow,
and reproduce.
Biogeochemical cycles move these substances
through air, water, soil, rock and living
organisms.
• Water, Nitrogen, Carbon, Phosphorus, Sulfur Cycles
Water’s Unique Properties
There are strong forces of attraction between
molecules of water.
Water exists as a liquid over a wide
temperature range.
Liquid water changes temperature slowly.
It takes a large amount of energy for water to
evaporate.
Liquid water can dissolve a variety of
compounds.
Water expands when it freezes.
Fig. 3-26, p. 72
Precipitation Precipitation
Transpiration
Condensation
Evaporation
Ocean storage
Transpiration
from plants
Precipitation
to land
Groundwater movement (slow)
Evaporation
from land Evaporation
from ocean Precipitation
to ocean
Infiltration and
Percolation
Rain clouds
Runoff Surface runoff
(rapid)
Surface
runoff
(rapid)
Effects of Human Activities
on Water Cycle
We alter the water cycle by:
Withdrawing large amounts of freshwater.
Clearing vegetation and eroding soils.
Polluting surface and underground water.
Contributing to climate change.
Fig. 3-27, pp. 72-73
Effects of Human Activities
on Carbon Cycle
We alter the carbon cycle by adding excess CO2 to the atmosphere through:
Burning fossil fuels.
Clearing vegetation faster than it is replaced.
Figure 3-28
Effects of Human Activities
on the Nitrogen Cycle
We alter the nitrogen cycle by:
Adding gases that contribute to acid rain.
Adding nitrous oxide to the atmosphere through
farming practices which can warm the
atmosphere and deplete ozone.
Contaminating ground water from nitrate ions in
inorganic fertilizers.
Releasing nitrogen into the troposphere through
deforestation.
Effects of Human Activities
on the Nitrogen Cycle
Human activities
such as
production of
fertilizers now fix
more nitrogen
than all natural
sources
combined.
Figure 3-30
Fig. 3-31, p. 77
Dissolved in Ocean
Water
Marine Sediments Rocks
uplifting over
geologic time
settling out weathering sedimentation
Land Food Webs
Dissolved in Soil Water, Lakes, Rivers
death,
decomposition
uptake by
autotrophs
agriculture
leaching, runoff
uptake by
autotrophs
excretion
death,
decomposition
mining Fertilizer
weathering
Guano
Marine Food Webs
Effects of Human Activities
on the Phosphorous Cycle
We remove large amounts of phosphate from
the earth to make fertilizer.
We reduce phosphorous in tropical soils by
clearing forests.
We add excess phosphates to aquatic
systems from runoff of animal wastes and
fertilizers.
Fig. 3-32, p. 78
Hydrogen sulfide
Sulfur
Sulfate salts
Decaying matter
Animals
Plants
Ocean
Industries
Volcano
Hydrogen sulfide
Oxygen
Dimethyl
sulfide
Ammonium
sulfate
Ammonia
Acidic fog and precipitation Sulfuric acid
Water Sulfur
trioxide
Sulfur dioxide
Metallic
sulfide
deposits
Effects of Human Activities
on the Sulfur Cycle
We add sulfur dioxide to the atmosphere by:
Burning coal and oil
Refining sulfur containing petroleum.
Convert sulfur-containing metallic ores into free
metals such as copper, lead, and zinc releasing
sulfur dioxide into the environment.
The Gaia Hypothesis:
Is the Earth Alive?
Some have proposed that the earth’s various
forms of life control or at least influence its
chemical cycles and other earth-sustaining
processes.
The strong Gaia hypothesis: life controls the
earth’s life-sustaining processes.
The weak Gaia hypothesis: life influences the
earth’s life-sustaining processes.
What do you think?
Does life on earth control earth’s life-
sustaining processes or does life merely
influence these life-sustaining process?
Free Response
Objectives:
Identify and describe the flow of nutrients in
each biogeochemical cycle.
Explain the impact that humans have on the
biogeochemical cycles.