section 2.1 the role of water in cycles of matter

Section 2.1Section 2.1

The Role of Water in Cycles of The Role of Water in Cycles of MatterMatter

Water in the BiosphereWater in the Biosphere

• Because Earth is a closed system, Because Earth is a closed system, matter must cycle within itmatter must cycle within it

• The water that we see in surface The water that we see in surface water sources may have come from water sources may have come from snow and ice, from oceans, or it may snow and ice, from oceans, or it may have been a product of cellular have been a product of cellular respirationrespiration

Water in the BiosphereWater in the Biosphere

• Water in our atmosphere acts as a Water in our atmosphere acts as a greenhouse gas, trapping heat and greenhouse gas, trapping heat and warming the Earthwarming the Earth

• The transfer of heat throughout our The transfer of heat throughout our biosphere is also mostly due to biosphere is also mostly due to water’s ability to absorb large water’s ability to absorb large amounts of heat energyamounts of heat energy

The Hydrologic CycleThe Hydrologic Cycle

http://www.buffer.forestry.iastate.edu

The Universal SolventThe Universal Solvent

• Water is a polar moleculeWater is a polar molecule

• When an ionic compound is placed in When an ionic compound is placed in water, it pulls apart the ions and water, it pulls apart the ions and makes it dissolvemakes it dissolve

http://academic.brooklyn.cuny.edu

• As well, there is attraction formed As well, there is attraction formed between nearby water molecules as between nearby water molecules as a a hydrogen bondhydrogen bond forms forms

• This allows water molecules to This allows water molecules to surround compounds while dissolving surround compounds while dissolving themthem

http://antoine.frostburg.edu

Hydrogen Bonding and Water’s Hydrogen Bonding and Water’s PhasesPhases

• Because water molecules have relatively Because water molecules have relatively strong hydrogen bonds between them, it strong hydrogen bonds between them, it requires a large amount of energy to break requires a large amount of energy to break these bonds so that the molecules can move these bonds so that the molecules can move freelyfreely

• This means that water will have very high This means that water will have very high heats of fusion and vaporizationheats of fusion and vaporization

• It also means that water has high melting and It also means that water has high melting and boiling points when compared to similar boiling points when compared to similar hydrogen compoundshydrogen compounds

• These hydrogen bonds and the These hydrogen bonds and the forces of repulsion between the forces of repulsion between the oxygen atoms contributes to the oxygen atoms contributes to the open spacing seen in the crystal open spacing seen in the crystal structure of icestructure of ice

http://www.lsbu.ac.uk

• Because ice is less Because ice is less dense than water, dense than water, lakes always freeze lakes always freeze from the top downfrom the top down

• This prevents most This prevents most lakes and ponds lakes and ponds from freezing solidfrom freezing solid

• As well, it As well, it contributes to the contributes to the cycling of oxygen cycling of oxygen and nutrients during and nutrients during the spring and fall in the spring and fall in bodies of waterbodies of water http://www.islandnet.com

• The hydrogen bonds in water The hydrogen bonds in water produce produce cohesioncohesion between between molecules, which gives water its molecules, which gives water its surface tensionsurface tension

• AdhesionAdhesion also occurs between water also occurs between water molecules and molecules of other molecules and molecules of other substances (such as glass)substances (such as glass)

• The force of adhesion is responsible The force of adhesion is responsible for the capillary action that occurs in for the capillary action that occurs in the xylem of plantsthe xylem of plants

Water and HeatWater and Heat

• The hydrogen bonds between water The hydrogen bonds between water molecules means that water has a high molecules means that water has a high specific heat capacityspecific heat capacity

• As a result, water stores huge amounts of As a result, water stores huge amounts of heat energyheat energy

• Large bodies of water will moderate Large bodies of water will moderate temperatures because of thistemperatures because of this

• At the level of the individual organism, the At the level of the individual organism, the high specific heat capacity of water high specific heat capacity of water prevents body temperatures from prevents body temperatures from changing too quicklychanging too quickly

Water and OrganismsWater and Organisms

• Organisms gain water from their Organisms gain water from their environment through eating, environment through eating, drinking, absorption, and cellular drinking, absorption, and cellular respirationrespiration

• Organisms lose water through Organisms lose water through breathing, sweating, and in their breathing, sweating, and in their wastewaste

Water as a ResourceWater as a Resource

• When ecosystems lack water, the When ecosystems lack water, the producers that use it during producers that use it during photosynthesis quickly disappearphotosynthesis quickly disappear

• Therefore, droughts in areas can be Therefore, droughts in areas can be devastating to ecosystemsdevastating to ecosystems

• If global temperatures rise, then droughts If global temperatures rise, then droughts will become more common in areas such will become more common in areas such as Alberta, which will greatly affect our as Alberta, which will greatly affect our economy economy

Water QualityWater Quality

• Not all freshwater is suitable for useNot all freshwater is suitable for use

• In many areas, the water is In many areas, the water is contaminated with toxic chemicals or contaminated with toxic chemicals or pathogenspathogens

• Even if the pathogens can be killed Even if the pathogens can be killed by chemical treatment or boiling, by chemical treatment or boiling, some toxins are extremely difficult to some toxins are extremely difficult to remove from polluted waterremove from polluted water

Water and EcosystemsWater and Ecosystems

• Changes in the amount of water Changes in the amount of water available in an ecosystem will affect available in an ecosystem will affect the growth of producersthe growth of producers

• Research carried out in the rainforest Research carried out in the rainforest shows that trees exposed to drought shows that trees exposed to drought conditions will extend their roots conditions will extend their roots deeper than normal in search of deeper than normal in search of waterwater

• As well, the rate of growth of the As well, the rate of growth of the trees decreased, and some of the trees decreased, and some of the largest trees diedlargest trees died

• This could contribute further to This could contribute further to climate change as less COclimate change as less CO22 would be would be absorbed from the atmosphereabsorbed from the atmosphere

• The lack of growth in trees and other The lack of growth in trees and other producers due to drought will also producers due to drought will also affect other chemical cycles in our affect other chemical cycles in our biospherebiosphere

Section 2.2Section 2.2

Biogeochemical CyclesBiogeochemical Cycles

The Necessity of CyclesThe Necessity of Cycles

• Again, because there is a limited Again, because there is a limited amount of matter in our ecosystem, amount of matter in our ecosystem, chemicals must be recycled chemicals must be recycled constantlyconstantly

• The main biogeochemical cycles are The main biogeochemical cycles are the oxygen, carbon, nitrogen, sulfur, the oxygen, carbon, nitrogen, sulfur, and phosphorusand phosphorus

The Carbon and Oxygen The Carbon and Oxygen CycleCycle

• Carbon and oxygen are closely Carbon and oxygen are closely related in our ecosystemrelated in our ecosystem

• As a result, they can often be As a result, they can often be illustrated in the same cycleillustrated in the same cycle

Carbon-Oxygen CycleCarbon-Oxygen Cycle

http://kentsimmons.uwinnipeg.ca

Slow vs. Rapid Cycling of Slow vs. Rapid Cycling of CarbonCarbon

• Organisms are involved in the rapid Organisms are involved in the rapid cycling of carbon through cycling of carbon through photosynthesis and cellular respirationphotosynthesis and cellular respiration

• However, some larger producers (like However, some larger producers (like large trees) also store carbon for long large trees) also store carbon for long periods of time in their tissues, and the periods of time in their tissues, and the carbon is not recycled until the tree dies carbon is not recycled until the tree dies and is broken down by decomposersand is broken down by decomposers

Carbon SinksCarbon Sinks

• A carbon sink is a storehouse of carbon in A carbon sink is a storehouse of carbon in the biospherethe biosphere

• The largest stores of carbon in the The largest stores of carbon in the biosphere are Earth’s oceansbiosphere are Earth’s oceans

• The water in the ocean contains billions of The water in the ocean contains billions of tonnes of dissolved carbon dioxidetonnes of dissolved carbon dioxide

• Other carbon sinks include forests, Other carbon sinks include forests, limestone rock (calcium carbonate) and limestone rock (calcium carbonate) and petroleum depositspetroleum deposits

The Sulfur CycleThe Sulfur Cycle

• Sulfur is an important component of Sulfur is an important component of proteinsproteins

• Many bacteria use sulfur compounds Many bacteria use sulfur compounds in photosynthesis or certain types of in photosynthesis or certain types of cellular respirationcellular respiration

• Bacteria also release sulfur that is in Bacteria also release sulfur that is in forms that cannot be used by other forms that cannot be used by other organismsorganisms

Sulfur CycleSulfur Cycle

http://web.missouri.edu

Acid DepositionAcid Deposition• The combustion of fossil fuels that contains The combustion of fossil fuels that contains

sulfur releases sulfur oxides into the sulfur releases sulfur oxides into the atmosphereatmosphere

• Sulfur dioxide reacts with oxygen and water Sulfur dioxide reacts with oxygen and water vapour in the atmosphere to form sulfuric vapour in the atmosphere to form sulfuric acid and sulfurous acidacid and sulfurous acid

• When this acid condenses, it falls as acid When this acid condenses, it falls as acid precipitationprecipitation

• The acid can change soil and water pH, The acid can change soil and water pH, making it impossible for organisms to survivemaking it impossible for organisms to survive

The Nitrogen CycleThe Nitrogen Cycle

• Nitrogen is required by organisms to Nitrogen is required by organisms to form the amino acids that form form the amino acids that form proteins and to make up the proteins and to make up the structure of DNAstructure of DNA

• However, the nitrogen gas in our However, the nitrogen gas in our atmosphere cannot be used for this atmosphere cannot be used for this purposepurpose

• The nitrogen gas must therefore be The nitrogen gas must therefore be converted into other formsconverted into other forms

Nitrogen CycleNitrogen Cycle

http://www.epa.gov

Processes in the Nitrogen Processes in the Nitrogen CycleCycle• Nitrogen fixation is the conversion of Nitrogen fixation is the conversion of

atmospheric nitrogen into ammonium atmospheric nitrogen into ammonium (NH(NH44

++))• This is carried out by nitrogen-fixing This is carried out by nitrogen-fixing

bacteria found in nodules attached to bacteria found in nodules attached to the roots of legumesthe roots of legumes

• Ammonification also produces Ammonification also produces ammonium as bacteria break down ammonium as bacteria break down organic matterorganic matter

• During denitrification, bacteria During denitrification, bacteria complete the cycle by breaking down complete the cycle by breaking down nitrogen compounds and releasing nitrogen compounds and releasing nitrogen gas back into the nitrogen gas back into the atmosphereatmosphere

• Denitrification typically occurs in Denitrification typically occurs in anaerobic environmentsanaerobic environments

The Phosphorus CycleThe Phosphorus Cycle

• Phosphorus is required for cellular Phosphorus is required for cellular materials such as DNA, phospholipids, materials such as DNA, phospholipids, and ATPand ATP

• Phosphorus does not cycle in the Phosphorus does not cycle in the atmosphere, but is found in soil and atmosphere, but is found in soil and waterwater

• Large amounts of phosphorus are stored Large amounts of phosphorus are stored in rocks and released during erosionin rocks and released during erosion

Phosphorus CyclePhosphorus Cycle

Overabundance of Overabundance of PhosphorusPhosphorus• Because most of the world’s Because most of the world’s

phosphorus is locked in rocks and phosphorus is locked in rocks and sediments, the growth of plants is sediments, the growth of plants is limitedlimited

• However, adding excess phosphorus However, adding excess phosphorus can cause uncontrolled growth of algae can cause uncontrolled growth of algae and plant life, which reduces available and plant life, which reduces available oxygen in aquatic ecosystemsoxygen in aquatic ecosystems

Energy and Matter TransferEnergy and Matter Transfer

• Remember that energy is involved in Remember that energy is involved in each step of these cycleseach step of these cycles

• As well, water is also a necessary As well, water is also a necessary component of these cycles, so the component of these cycles, so the biogeochemical cycles are all linked biogeochemical cycles are all linked together through energy and watertogether through energy and water

2.3 – The Balance of Matter 2.3 – The Balance of Matter and Energy Exchangeand Energy Exchange

• The amount of sunlight an area The amount of sunlight an area receives often determines its receives often determines its productivityproductivity

• Productivity rates are often Productivity rates are often expressed as energy or biomassexpressed as energy or biomass

• As well, moisture plays a significant As well, moisture plays a significant role in the productivity of an role in the productivity of an ecosystemecosystem

Balance in the BiosphereBalance in the Biosphere

• Inside our own bodies, we maintain Inside our own bodies, we maintain homeostasishomeostasis

• To do this, we must use energyTo do this, we must use energy• In 1979, James Lovelock proposed In 1979, James Lovelock proposed

the Gaia Hypothesis, which is the Gaia Hypothesis, which is homeostasis on a global levelhomeostasis on a global level

• In essence, this hypothesis suggests In essence, this hypothesis suggests that the Earth is self-regulatingthat the Earth is self-regulating

The Gaia Hypothesis and Living The Gaia Hypothesis and Living ThingsThings

• Life itself plays a large role in the balance Life itself plays a large role in the balance we see in our biospherewe see in our biosphere

• The composition of our atmosphere, for The composition of our atmosphere, for instance, would be very different if living instance, would be very different if living things had not modified it through cellular things had not modified it through cellular respiration and photosynthesisrespiration and photosynthesis

• As well, some of the sediments that make As well, some of the sediments that make up our geological features come from up our geological features come from biological sourcesbiological sources

• Stromatolites are formations of Stromatolites are formations of sedimentary rocks that are composed sedimentary rocks that are composed partly of the cellular debris of partly of the cellular debris of organismsorganisms

• Early stromatolite layers show that Early stromatolite layers show that there was large amounts of oxygen there was large amounts of oxygen trapped in iron oxidestrapped in iron oxides

• Later layers indicate that this oxygen Later layers indicate that this oxygen was no longer being trapped – it had was no longer being trapped – it had moved out of the oceans and into the moved out of the oceans and into the atmosphereatmosphere

Replicating Earth’s Replicating Earth’s BiosphereBiosphere• Scientists have tried Scientists have tried

to replicate the to replicate the biosphere on a small biosphere on a small scalescale

• However, these However, these experiments were not experiments were not very successful very successful because our biosphere because our biosphere is extremely complexis extremely complex

http://www.mistershape.com

http://www.theoctobergallery.com

Future ProjectsFuture Projects

• NASA programs such as ALS NASA programs such as ALS (Advanced Life Support) are being (Advanced Life Support) are being studied to see how plants may be studied to see how plants may be grown in a space colony for food and grown in a space colony for food and oxygenoxygen

• Such programs also look for ways to Such programs also look for ways to recover usable resources from wasterecover usable resources from waste

The Haughton-Mars ProjectThe Haughton-Mars Project

• In the Canadian Arctic, In the Canadian Arctic, NASA sponsors a NASA sponsors a research station that is research station that is intended to simulate intended to simulate the conditions of Mars’ the conditions of Mars’ surfacesurface

• The purpose of such The purpose of such research is to study research is to study what factors need to what factors need to be in place for be in place for sustainable manned sustainable manned missions to other missions to other planetsplanets

http://www.space.gc.ca

Human InterferenceHuman Interference

• Humans have significant ability to change Humans have significant ability to change our surroundingsour surroundings

• However, sometimes these changes cause However, sometimes these changes cause a disruption in the flow of matter and a disruption in the flow of matter and energy, which interrupts the delicate energy, which interrupts the delicate natural balance of ecosystemsnatural balance of ecosystems

• Therefore, much work is being done into Therefore, much work is being done into looking for ways to reduce our looking for ways to reduce our environmental impactenvironmental impact

Preserving Natural BalancePreserving Natural Balance

• The development of alternative The development of alternative energy sources is one possible energy sources is one possible method of reducing the impact we method of reducing the impact we have on our planethave on our planet

• As well, we may need to reconsider As well, we may need to reconsider how we use land and resources to how we use land and resources to prevent damage to the ecosystems prevent damage to the ecosystems around usaround us