Transcript Cycling of matter

Cycling of matter
IB Syllabus: 2.5.4
Syllabus Statements
• 2.5.4: Describe and explain the transfer
and transformation of materials as they
cycle within an ecosystem
Biogeochemical cycles
• Nutrients needed for life are continuously
cycled between living and nonliving things
• Life  Earth  Chemical cycles
• Driven by incoming solar energy
• Connect past – present – future by
recycling chemical compounds
• Oxygen, Carbon, Nitrogen, Phosphorous,
and water
Water Cycle
• Collects, purifies and distributes earth’s
constant water supply
– Evaporation – converts water into vapor
– Transpiration – evaporation from plant leaves
– Condensation – vapor to liquid
– Precipitation – rain, sleet, snow, hail
– Infiltration – movement of water into soil
– Percolation – flow of water to aquifers
– Runoff – movement of water over land surface
Hydrologic cycle
Water cycle
• Sun powers the cycle – 84% vapor from
ocean
• Warmer air holds more water
• Relative humidity = amount of water vapor
in a mass of air expressed as a % of the
maximum the air could support at that
temp
• Wind and air masses transport water
around the earth
Water cycle II
• Precipitation – needs condensation nuclei to
occur
– Soil dust, volcanic ash, smoke, sea salt, particulates
• Some locked in glaciers, most into oceans as
surface runoff
• Runoff sculpts earth’s surface & transports
nutrients
• Water purification happens at many steps
Hydrologic Cycle
Human Influences
1. Withdrawing large quantities of fresh water
from surface and ground water
•
Aquifer depletion and saltwater intrusion
2. Clearing vegetation for agriculture, mining,
construction
•
Increase runoff, flooding, erosion, Decrease
infiltration
3. Modifying water quality
•
Adding nutrients, changing natural processes
Carbon cycle
• “C” is the basic building block of life
• Global gaseous cycle based on CO2
• Producers remove CO2 from the
atmosphere in photosynthesis
• Respiration of organisms puts CO2 back
into atmosphere
• Organic carbon stored in living tissues and
fossil fuel deposits
Terrestrial Carbon cycle
Carbon storages
1. Organisms store most of the carbon
•
organic compounds
2. Sedimentary rocks such as limestone
•
Carbon reenters cycle when sediments dissolve
naturally or by acid rain
3. Oceans
•
•
Gas dissolves into ocean at surface
Removed by marine algae in photosynthesis
4. Marine organisms
•
Reaction of CO2 with Ca in organisms to produce
CaCO3 for shells and
Aquatic Carbon Cycle
Human effects
1. Adding Carbon to the Atmosphere
– Clearing trees and plants that absorb CO2
through photosynthesis
– Burning fossil fuels and wood increasing
CO2
2. Enhance the greenhouse effect
•
•
•
Raise sea level
Disrupt food production
Destroy habitats
Nitrogen cycle
1. Nitrogen Fixation
• Specialized bacteria convert atmospheric
N2 into NH3
– N2 + 3 H2  2 NH3
Done by
• Cyanobacteria – in soil and water
• Rhizobium – bacteria living in root nodules
of a variety of legume plants
2. Nitrification
• A two step process
• Ammonia in soil converted to nitrite and
nitrate
• Aerobic bacteria complete this process
– NH3 NO2- (toxic to plants)
– NO2- NO3- (easily taken up by plants as
nutrient
3. Absorption / Assimilation
• Plant roots absorb inorganic nitrogen ions
– nitrates, ammonium
• Ions used to make nitrogen containing
organic molecules
– DNA, amino acids, proteins
• Animals get nitrogen by eating plants or
other plant-eating animals
4. Ammonification
• After N has been used in living things and
it leaves as waste or death…
• Bacterial decay results
• Producing
– Simpler inorganic compounds like NH3
– Water soluble salts containing NH4+
5. Denitrification
• Anaerobic bacteria in waterlogged soils
and bottom sediments
• Convert nitrogen compounds back into
gas forms and release into the
atmosphere
NO2-
NH3

NH4+
NO3-
N2

N2O
Human effects on the N-cycle
1. Inputs of commercial inorganic fertilizer
2. Adding NO to the air through combustion
of fuels
• Enters water cycle  Acid Rain
3. Removing “N” from the crust by mining
4. Removing “N” from soil
• Harvest crops, irrigation, deforestation
5. Adding “N” to aquatic systems from
runoff
The Phosphorous cycle
• Through water  organisms  earth’s crust
• Very little in the atmosphere
• Found as phosphate salts in terrestrial rocks and
ocean sediments
• Into organisms by uptake & assimilation by
plants, consumption & assimilation by animals,
then animal waste returns it to water or to the
land (guano)
• Often a limiting factor in plant growth both
terrestrial and aquatic
Phosphorous cycle
Human effects
1. Mining large amounts of phosphate rock
• Inorganic fertilizers, Detergents
2. Reducing available phosphate in tropical
forests by removing trees
• Soil nutrients washed away w/out trees
3. Adding excess phosphate to aquatic
systems
• Runoff of animal waste, commercial fertilizer
from farmland, municipal sewage discharge
Florida Phosphate mining
The sulfur cycle
• Most “S” stored underground in rocks and
minerals including salts in ocean sediment
• Enters the atmosphere from volcanoes,
sea spray, decomposition in aquatic
habitats
• Marine algae may produce DMS sulfur
compounds in large quantities
• In atmosphere it may mix into hydrologic
cycle to form sulfuric acid – acid rain
Sulfur cycle
Human effects
1. Burning “S” containing coal and oil for
electricity production
• 2/3 of human SO2 inputs
2. Refining “S” containing petroleum into
gasoline, heating oil, etc.
3. Smelting of “S” compounds of metallic
minerals producing pure metals
• Copper, Lead, Zinc
Cycle types
• With all cycles common features allow
grouping
• Groups based on storages
–Sedimentary cycle – major storage in
the ground
• E.x. phosphorous cycle
–Atmospheric cycle – major storage in
the atmosphere
• E.x. nitrogen cycle
You should be able to create a
flow diagram of Carbon, Water
and Nitrogen cycles
• http://www.colorado.edu/GeolSci/courses/
GEOL1070/chap04/chapter4.html