Download Matter Cycles Through The Biosphere Mr. Alvarez September 29, 2014

Matter Cycles Through The
Biosphere
Mr. Alvarez
September 29, 2014
Biosphere
Biosphere- the region of our planet where life
resides
Biogeochemical Cycles- the movements of
matter within and between ecosystems
involve biological, geological, and chemical
processes.
The Hydrologic Cycle
Hydrologic Cycle- The movement of water
through the biosphere
Transpiration- The release of water from leaves
during photosynthesis
Evapotranspiration- the combined amount of
evaporation and transpiration
Runoff- Water moving across the land surface and
into streams and rivers, eventually reaching the
ocean
Carbon Cycle
• There are 4 main types of processes that
move carbon through its cycle
1. Biological processes, such as photosynthesis,
respiration and decomposition, that take up
and release Carbon and Oxygen
Carbon Cycle cont.
2. Geochemical processes, such as erosion and
volcanic activity, release CO2 to the
atmosphere and oceans
3. Mixed processes, such as the burial and
decomposition of dead organisms and their
conversions under pressure into coal and
petroleum (fossil fuels), store carbon
underground
Carbon Cycle cont.
4. Human activities such as mining, cutting and
burning forests, and burning fossil fuels,
release carbon dioxide into the atmosphere
Top Carbon Storage Reservoirs:
1. Marine sediments & rocks (& shells)
2. Oceans (dissolved)
3. Fossil Fuels
4. Soil organic matter
5. Forests
Macronutrients
Macronutrients- Six key elements that
organisms need in relatively large amounts
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Nitrogen
Limiting Nutrient- a nutrient required for
growth of an organism but available in a lower
quantity than other nutrients
Nitrogen is used to form amino acids, building
blocks of proteins and nucleic acids (DNA and
RNA)
Make up 3 percent of total body weight
Nitrogen Fixation
• Earth’s atmosphere is 78 percent Nitrogen by
volume
– Most of this is in gaseous form, N2, which is
unusable
Nitrogen Fixation- converting N2 gas directly
into ammonia (NH3)
First step in the nitrogen cycle
Occurs in organisms such as cyanobacteria and
certain bacteria that live within the roots of
legumes (peas, beans, some trees)
Nitrogen Fixing Organisms
• Nitrogen-fixing organisms use the fixed nitrogen
to synthesize their own tissues, then excrete
excess
– Cyanobacteria = water
– Bacteria living within plant roots = soil
• Plant provides glucose to bacteria
• Organisms that fix nitrogen can break N2 bond
using enzymes
– Also adds hydrogen to make NH3
– NH3 is converted into its ionic form, ammonium
(NH4+) in the soil
Two Abiotic Ways of Nitrogen Fixation
1. Lightning or combustion reactions convert N2
into Nitrate (NO3-), which is usable by plants
– Nitrate is carried to earth’s surface during
precipitation
2. Humans synthesizing Nitrogen Fertilizers
– Humans now fix more nitrogen than is fixed in
nature
Nitrogen Cycle continued
• After producers obtain fixed nitrogen, the
assimilate it into their tissues (step 2)
• Consumers obtain nitrogen by eating producers
• Then, producers and consumers die and
decompose (step 3)
– Ammonification- fungal and bacterial decomposers
use nitrogen-containing wastes and dead bodies as a
food source and excrete ammonium
Nitrogen Cycle cont.
 Nitrification- nitrifying bacteria converts
ammonium into nitrite (NO2-) and then into
nitrate (NO3-) (step 4)
 Leaching- the transportation of dissolved
molecules through the soil via groundwater
Nitrate ions are repelled by negatively charged soil
particles
 Denitrification- bacteria convert nitrate in a
series of steps into gases nitrous oxide (N2O) and
eventually N2. This is emitted into the
atmosphere
Human Impacts on N cycle:
1. Commercial fertilizer overuse
(fixed-N) = mobility
–
–
Eutrophication & fish kills
Groundwater contamination
Human Impacts on N cycle
2. Combustion of Fossil Fuels




NOx emissions from autos
Global warming & Ozone depletion
Photochemical smog
Acid rain
Phosphorus
• Phosphorus is a major component of DNA and
RNA as well as ATP
• Limiting Nutrient second only to Nitrogen
• Also added to soil in the form of fertilizer
• Weathering of rocks is a natural source of
phosphorus
The Phosphorus Cycle
Excess Phosphorus
 Algal Bloom- rapid growth of algae
– Can result from adding even small amounts of
Phosphorus to aquatic ecosystems
• Algal Blooms quickly increase the amount of
biomass in the ecosystem
• Algae eventually dies, initiating a massive amount
of decomposition, which consumes a large
amount of oxygen which leads to Hypoxic
Conditions
– Hypoxic Conditions- areas of low oxygen
Disturbance
• Disturbance- an event caused by physical,
chemical, or biological agents that results in
changes in population size or community
composition
Types of Disturbances
Natural
• Hurricanes
• Ice storms
• Tsunamis
• Volcanic Eruptions
• Forest Fires
Anthropogenic Disturbances
• Human Settlements
• Agriculture
• Air pollution
• Clear-cutting of Forests
• Removal of entire
Mountaintops for Coal
Mining
Watershed Studies
• Watershed- all of the land in a given
landscape that drains into a particular stream,
river, lake or wetland
Resistance versus Resilience
• Resistance- the measure of how much a disturbance
can affect the flows of energy and matter
– When a disturbance influences populations and
communities, but has no effect on the overall flows of
energy and matter = high resistance
• Resilience- the rate at which an ecosystem returns to
its original state after a disturbance
– A highly resilient ecosystem returns to its original state
rapidly
• Restoration Ecology- A new scientific discipline that is
interested in restoring damaged ecosystems
Intermediate Disturbance Hypothesis
• Intermediate Disturbance Hypothesisecosystems experiencing intermediate levels
of disturbance are more diverse than those
with high or low disturbance levels
Ecosystem Services
• Instrumental Value- something that has worth
as an instrument or a tool that can be used to
accomplish a goal
– The value of items such as lumber or
pharmaceutical drugs
• Intrinsic Value- something that has worth
independent of any benefit it may provide
humans
– Moral value of an animal’s life
Provisions
Provisions- goods that
humans can use directly
Lumber
Food crops
Medicinal plants
Natural rubber
Furs
Regulating Services
Regulating Services- The service provided by
natural systems that helps regulate
environmental conditions.
Support Systems
Support Systems- The support services that
natural ecosystems provide such as
pollination, natural filters and pest control.
Resilience
Resilience- Resilience
of an ecosystem
ensures that it will
continue to provide
benefits to humans.
This greatly depends
on species diversity.
Cultural Services
Cultural services- Ecosystems provide cultural
or aesthetic benefits to many people