Chapter 5 The Biogeochemical Cycles In all things there is a law of cycles. -Pubilus Cornelius Tacitus (Roman Historian)

Lake Washington

5.1 How Chemicals Cycle Chemical- an element like C or P or a compound like NH 3. Chemical- an element like C or P or a compound like NH 3. Biogeochemical cycle- complete path a chemical takes through Earth’s major reservoirs (bio- involves life; geo- include atmos., water, rock, soil; chemical- chemicals are cycled) Biogeochemical cycle- complete path a chemical takes through Earth’s major reservoirs (bio- involves life; geo- include atmos., water, rock, soil; chemical- chemicals are cycled) –Atmosphere –Hydrosphere (ocean, lake, river, groundwater, glacier) –Lithosphere (rock & soil) –Biosphere (plants & animals)

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Rate of transfer/flux: the amount per unit time of a chemical that enters or leaves a storage compartment Rate of transfer/flux: the amount per unit time of a chemical that enters or leaves a storage compartment Sink: the compartment that receives the chemical Sink: the compartment that receives the chemical –Ex: forests (measured in units – billions of metric tons) Residence time: the average length of time that an atom is stored before its transfered Residence time: the average length of time that an atom is stored before its transfered

5.3 Biogeochemical Cycles and Life: Limiting Factors Macronutrients Macronutrients –Elements required in large amounts by all life –Include the “big six” elements that form the fundamental building blocks of life: carbonoxygen hydrogenphosphorus nitrogensulfur Micronutrients Micronutrients –Elements required either in  small amounts by all life or  moderate amounts by some forms of life and not all by others Limiting factor Limiting factor –When chemical elements are not available at the right times, in the right amounts, and in the right concentrations relative to each other

Micronutrients (human body)

5.4 The Geologic Cycle 5.4 The Geologic Cycle The Geologic Cycle: The Geologic Cycle: –The processes responsible for formation and change of Earth materials –Best described as a group of cycles:  Tectonic  Hydrologic  Rock  Biochemical

© 2008 John Wiley and Sons Publishers Geologic cycle

Tectonic Cycle Tectonic cycle: Tectonic cycle: –Involves creation and destruction of the solid outer layer of Earth, the lithosphere  Lithosphere: 100 km (60 mi) thick and is broken into plates Plate tectonics: Plate tectonics: –The slow movement of these large segments of Earth’s outermost rock shell –Boundaries between plates are geologically active areas  Float on denser material and move 2-15 cm/year (as fast as fingernails grow)

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Tectonic Cycle: Plate Boundaries Divergent plate boundary: Divergent plate boundary: –Occurs at a spreading ocean ridge, where plates are moving away from one another –New lithosphere is produced (seafloor spreading)

Divergent…

Tectonic Cycle: Plate Boundaries Convergent plate boundary Convergent plate boundary –Occurs when plates collide  Produces linear coastal mountain ranges or continental mountain ranges Result: upfolded mountains Example: Himalyas and Appalacian Mts. Result: trench and volcanic island arcs Example: Aleutian Trench and Aleutian Islands

Tectonic Cycle: Plate Boundaries Transform fault boundary Transform fault boundary –Occurs where one plate slides past another  San Andreas Fault in California

Wallace Creek- Carrizo Plains Offset 100 yards

All 3…

Hydrologic Cycle “Water Cycle”

Water Cycle Role of Water? Role of Water? –Terrestrial ecosystems: major factor determining distribution of organisms –Aquatic ecosystems: literally matrix that surrounds & serves as environment of aquatic organisms –Flows of water are major means for material & energy transfer –Water Is critical for human activities: agriculture, industry, and municipal use Water is the driver of nature. - Leonardo da Vinci

Water Cycle: Main Processes Evaporation: conversion from liquid to vapor (surface to atmosphere) Evaporation: conversion from liquid to vapor (surface to atmosphere) Transpiration: evaporation of water from leaves Transpiration: evaporation of water from leaves Condensation: conversion of vapor to liquid (ex: water droplets of water on cold soda can) Condensation: conversion of vapor to liquid (ex: water droplets of water on cold soda can) Precipitation: movement as rain, sleet, hain, & snow (atmosphere to surface) Precipitation: movement as rain, sleet, hain, & snow (atmosphere to surface) Infiltration: movement into soil Infiltration: movement into soil Percolation: downward flow through soil to aquifers Percolation: downward flow through soil to aquifers Runoff: surface flow down slope to ocean, river, or lake. Runoff: surface flow down slope to ocean, river, or lake.

Water Cycle Withdraw large quantities of freshwater- water diversion, ground water depletion, wetland drainage Withdraw large quantities of freshwater- water diversion, ground water depletion, wetland drainage Clear vegetation- increase runoff, decrease infiltration & groundwater recharge, increase flooding & soil erosion. Clear vegetation- increase runoff, decrease infiltration & groundwater recharge, increase flooding & soil erosion. Modify water quality- add nutrients (P, N, K,…) and pollutants Modify water quality- add nutrients (P, N, K,…) and pollutants

The Water Cycle Condensationconversion of gaseous water vapor into liquid water Transport overland: net movement of water vapor by wind Evaporation from the ocean Evaporation Evaporation from inland lakes and rivers Evaporatio n from the land Lakes Ocean storage 97% of total water Transpiration Transpiration from plants Rivers Water locked up in snow and ice Groundwater movement (slow) Surface runoff (rapid) Infiltration: movement of water into soil Aquifers: groundwater storage areas Percolation: downward flow of water Precipitation over the ocean Rain clouds Precipitation (rain, sleet, hail, snow, fog) Precipitatio n to land

The hydrological (water) cycle, collects, purifies, and distributes the Earth’s water. Over the oceans, evaporation exceeds precipitation. This results in a net movement of water vapor over the land. On land, precipitation exceeds evaporation. Some precipitation becomes locked up in snow and ice for varying lengths of time. Most water forms surface and groundwater systems that flow back to the sea. Water Transformations Precipitation Rivers and streams

Humans intervene in the water cycle by utilizing the resource for their own needs. Water is used for consumption, municipal use, in agriculture, in power generation, and for industrial manufacturing. Industry is the greatest withdrawer of water but some of this is returned. Agriculture is the greatest water consumer. Using water often results in its contamination. The supply of potable (drinkable) water is one of the most pressing of the world’s problems. The Demand for Water Hydroelectric power generation… Irrigation… Washing, drinking,bathing…

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The Rock Cycle The rock cycle: The rock cycle: –Numerous processes that produce rocks and soils –Depends on other cycles:  tectonic cycle for energy  Hydrologic cycle for water –Rock is classified as  Igneous  Sedimentary  Metamorphic

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Element Main nonliving storehouse Main forms in living organisms Other nonliving storehouse Carbon(C) Atmospheric: Carbon dioxide (CO 2 ) Carbohydrates: organic molecules Hydrologic: dissolved carbonate (CO 3 2- ) and bicarbonate (HCO 3 - ) Sedimentary: carbon containing minerals in rocks Nitrogen(N) Atmospheric: Nitrogen gas (N 2 ) Proteins and other nitrogen-containing organic molecules Hydrologic: dissolved ammonium (NH 4 + ) and nitrate (NO 2 - ) in water and soils Phosphorous(P) Sedimentary: Phosphate (PO 4 3- ) containing minerals in rocks DNA. Other nucleic acids (ATP) and phospholipids Hydrologic: dissolved phosphate (PO 4 3- ) Sulfur(S) Sedimentary: rocks (e.g., Iron disulfide & pyrite) and minerals e.g., sulfate [SO 4 2- ]) Sulfur- containing amino acids in most proteins, some vitamins Atmospheric: hydrogen sulfide (HgS), sulfur dioxide (SO 2 ), sulfur trioxide (SO 3 ), and sulfuric acid (H 2 SO 4 ) Hydrologic: sulfate (SO 4 2- ) and sulfuric acid

Carbon Cycle

Building block of organic molecules (carbohydrates, fats, protein, & nucleic acids)- essential to life Building block of organic molecules (carbohydrates, fats, protein, & nucleic acids)- essential to life Currency of energy exchange- chemical energy for life stored as bonds in organic compounds Currency of energy exchange- chemical energy for life stored as bonds in organic compounds Carbon dioxide (CO 2 ) greenhouse gas- traps heat near Earth's surface & plays a key role as “nature’s thermostat” Carbon dioxide (CO 2 ) greenhouse gas- traps heat near Earth's surface & plays a key role as “nature’s thermostat”

Carbon: Main Processes Movement in atmosphere: atmos. C as CO 2 (0.036% of troposphere) Movement in atmosphere: atmos. C as CO 2 (0.036% of troposphere) Primary production: photosynthesis (=carbon fixation) moves C from atmos. To organic molecules in organisms Primary production: photosynthesis (=carbon fixation) moves C from atmos. To organic molecules in organisms Movement through food webs: C movement in organic form from organism to organism Movement through food webs: C movement in organic form from organism to organism Aerobic respiration: organic molecules broken down to release CO 2 back to atmos. Aerobic respiration: organic molecules broken down to release CO 2 back to atmos. Combustion: organic molecules broken by burning down to release CO 2 back to atmos. Combustion: organic molecules broken by burning down to release CO 2 back to atmos. Dissolving in oceans: C enters as to form carbonate (CO 3 2- ) and bicarbonate (HCO 3 - ) Dissolving in oceans: C enters as to form carbonate (CO 3 2- ) and bicarbonate (HCO 3 - ) Movement to sediments: C enters sediments, primarily as calcium carbonate (CaCO 3 ) Movement to sediments: C enters sediments, primarily as calcium carbonate (CaCO 3 )

Carbon- Terrestrial

Carbon- Aquatic

Carbon cycles between the living (biotic) and non-living (abiotic) environments. Gaseous carbon is fixed in the process of photosynthesis and returned to the atmosphere in respiration. Carbon may remain locked up in biotic or abiotic systems for long periods of time, e.g. in the wood of trees or in fossil fuels such as coal or oil. Humans have disturbed the balance of the carbon cycle through activities such as combustion and deforestation. Processes in Carbon Cycling Burning fossil fuels Petroleum

The Carbon Cycle

Carbon: Human Influences? Removal of vegetation- decreases primary production (decrease carbon fiation) Removal of vegetation- decreases primary production (decrease carbon fiation) Burning of fossil fuels & biomass (wood)- increase movement of carbon into the atmos. Burning of fossil fuels & biomass (wood)- increase movement of carbon into the atmos. The resulting increase concentration of atmos. CO 2 is believed to be sufficient to modify world climate through global warming The resulting increase concentration of atmos. CO 2 is believed to be sufficient to modify world climate through global warming

© 2008 John Wiley and Sons Publishers

Carbon Sink Units are PgC.- One Pg [petragram]= on ebillion metric tonnes=1000 x one bilion kg

Carbon-Silicate Cycle

The Carbon-Silicate Cycle The carbon-silicate cycle: The carbon-silicate cycle: –A complex biogeochemical cycle over time scales as long as one-half billion years. –Includes major geological processes, such as:  Weathering  Transport by ground and surface waters  Erosion  Deposition of crustal rocks –Believed to provide important negative feedback mechanisms that control the temperature of the atmosphere.

The Archean atmosphere was a mix of gases including nitrogen, water vapor, methane (CH4), and CO2. The Archean atmosphere was a mix of gases including nitrogen, water vapor, methane (CH4), and CO2. "Atmospheric Oxygen," free oxygen did not accumulate in the atmosphere until more than two billion years after Earth was formed. "Atmospheric Oxygen," free oxygen did not accumulate in the atmosphere until more than two billion years after Earth was formed. Volcanoes emitted CO2 as a byproduct of heating within the Earth's crust. Volcanoes emitted CO2 as a byproduct of heating within the Earth's crust. But instead of developing a runaway greenhouse effect like that on Venus, Earth's temperatures remained within a moderate range because the carbon cycle includes a natural But instead of developing a runaway greenhouse effect like that on Venus, Earth's temperatures remained within a moderate range because the carbon cycle includes a natural This sink involves the weathering of silicate rocks, such as granites and basalts, that make up much of Earth's crust. This sink involves the weathering of silicate rocks, such as granites and basalts, that make up much of Earth's crust.

4 basic stages: 4 basic stages: –First, rainfall scrubs CO2 out of the air, producing carbonic acid (H2CO3), a weak acid. –Next, this solution reacts on contact with silicate rocks to release calcium and other cations and leave behind carbonate and biocarbonate ions dissolved in the water. cations  This solution is washed into the oceans by rivers, and then calcium carbonate (CaCO3), also known as limestone, is precipitated in sediments. (Today most calcium carbonate precipitation is caused by marine organisms, which use calcium carbonate to make their shells.) –Over long time scales, oceanic crust containing limestone sediments is forced downward into Earth's mantle at points where plates collide, a process called subduction. subduction –Eventually, the limestone heats up and turns the limestone back into CO2, which travels back up to the surface with magma. Volcanic activity then returns CO2 to the atmosphere.

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Nitrogen Cycle

Nitrogen cycle Role of Nitrogen? Role of Nitrogen? –Building block of various essential organic molecules- especially proteins & nucleic acids –Limiting nutrient in many ecosystems- typically addition of N leads to increased productivity

How is Nitrogen Cycled?

Nitrogen Cycle: Main Processes Nitrogen fixation: conversion of N 2 (nitrogen gas) to NH 4 + (ammonuim), atmospheric by lightning, biological by bacteria & blue-green algae (anaerobic), e.g., Rhizobium in legumes Nitrogen fixation: conversion of N 2 (nitrogen gas) to NH 4 + (ammonuim), atmospheric by lightning, biological by bacteria & blue-green algae (anaerobic), e.g., Rhizobium in legumes Nitrification: conversion of NH 4 + to NO 2 - (nitrite) to NO 3 - (nitrate) by microbes Nitrification: conversion of NH 4 + to NO 2 - (nitrite) to NO 3 - (nitrate) by microbes Uptake by plants, forms proteins and other N containing organic compounds, enters food chain Uptake by plants, forms proteins and other N containing organic compounds, enters food chain Ammonification: returned NH 4 + inorganic forms by saprophytes (fungi) and decomposers Ammonification: returned NH 4 + inorganic forms by saprophytes (fungi) and decomposers Denitrification: conversion of NH 4 + to N 2 by combustion or microbes Denitrification: conversion of NH 4 + to N 2 by combustion or microbes

FUNGI -all are heterotrophs, and eukaryotes (they contain a nucleus), they can be most are multi-cellular, most are decomposers and feed on dead things (saprophytes). pics1-04m.jpg pics1-04m.jpghttp:// pics1-04m.jpg

Nitrogen cycles between the biotic and abiotic environments. Bacteria play an important role in this transfer. Nitrogen-fixing bacteria are able to fix atmospheric nitrogen. Nitrifying bacteria convert ammonia to nitrite, and nitrite to nitrate. Denitrifying bacteria return fixed nitrogen to the atmosphere. Atmospheric fixation also occurs as a result of lightning discharges. Humans intervene in the nitrogen cycle by producing and applying nitrogen fertilizers. Nitrogen in the Environment

Nitrogen Transformations The ability of some bacterial species to fix atmospheric nitrogen or convert it between states is important to agriculture. Nitrogen-fixing species include Rhizobium, which lives in a root symbiosis with leguminous plants. Legumes, such as clover, beans, and peas, are commonly planted as part of crop rotation to restore soil nitrogen. Nitrifying bacteria include Nitrosomonas and Nitrobacter. These bacteria convert ammonia to forms of nitrogen available to plants. NH 3 NO 2 - NO 3 - Nitrosomonas Nitrobacter Root nodules in Acacia Nodule close-up

Nitrogen Cycle

Nitrogen Cycle: Human Influences? Emit nitric oxide (NO), which leads to acid rain- huge quantities of nitric oxide emitted; contributes to photochemical smog; forms nitrogen dioxide (NO 2 ) in atmosphere, which can react with water to for nitric acid (HNO 3 ) & cause acid deposition (“acid rain”) Emit nitric oxide (NO), which leads to acid rain- huge quantities of nitric oxide emitted; contributes to photochemical smog; forms nitrogen dioxide (NO 2 ) in atmosphere, which can react with water to for nitric acid (HNO 3 ) & cause acid deposition (“acid rain”) Emit nitrous oxide into the atmosphere- nitrous oxide (N 2 O) is a potent greenhouse gas & also depletes ozone in stratosphere Emit nitrous oxide into the atmosphere- nitrous oxide (N 2 O) is a potent greenhouse gas & also depletes ozone in stratosphere

Nitrogen Cycle: Human Influences? (continued…) Mine nitrogen- containing fertilizers, deplete nitrogen from croplands, & leach nitrate from soil by irrigation- leads to modification of nitrogen distribution in soils Mine nitrogen- containing fertilizers, deplete nitrogen from croplands, & leach nitrate from soil by irrigation- leads to modification of nitrogen distribution in soils Remove N from soil by burning grasslangs & cutting forest- leads to decreased N in soils Remove N from soil by burning grasslangs & cutting forest- leads to decreased N in soils Add excess N to aquatic systems- runoff of nirates & other soluble N- containing compounds stimulates algal blooms, depletes oxygen, & decreases biodiversity Add excess N to aquatic systems- runoff of nirates & other soluble N- containing compounds stimulates algal blooms, depletes oxygen, & decreases biodiversity Add excess N to terrestrial systems- atmospheric deposition increase growth of some species (especially weeds) & can decrease biodiversity Add excess N to terrestrial systems- atmospheric deposition increase growth of some species (especially weeds) & can decrease biodiversity

Phosphorous Cycle

Role of Phosphorous? Role of Phosphorous? –Essential nutrient for plants & animals: especially building block for DNA, other nucleic acids (including ATP; ATP stores chemical energy), various fats in cell membrane (phospholipids), & hard calcium-phosphate compounds (in bone, teeth, & shells) –Limiting nutrient in many ecosystems- typically, addition of P leads to increased productivity, especially for fresh water aquatic systems

Phosphorus cycling is very slow and tends to be local; in aquatic and terrestrial ecosystems, it cycles through food webs. Phosphorous is lost from ecosystems through run-off, precipitation, and sedimentation. A very small amount of phosphorus returns to the land as guano (manure, typically of fish-eating birds). Weathering and phosphatizing bacteria return phosphorus to the soil. Human activity can result in excess phosphorus entering water ways and is a major contributor to eutrophication. Phosphorus Cycling Deposition as guano… Loss via sedimentation… Fertilizer production

Phosphorous: Main Processes Weathering: P slowly released from rock or soil minerals as phosphate (PO 4 3- ), which dissolves in H 2 O & is readily leached Weathering: P slowly released from rock or soil minerals as phosphate (PO 4 3- ), which dissolves in H 2 O & is readily leached Uptake: by plants to form organic phosphates Uptake: by plants to form organic phosphates Movement through food web: nucleic acids (including DNA 7 ATP), certain fats in cell membranes (phospholipids), bones/teeth/shells (calcium- phosphate) Movement through food web: nucleic acids (including DNA 7 ATP), certain fats in cell membranes (phospholipids), bones/teeth/shells (calcium- phosphate) Break down of organic forms: to phosphate (PO 4 30 ) by decomposers Break down of organic forms: to phosphate (PO 4 30 ) by decomposers Leaching: PO 4 3- from soil Leaching: PO 4 3- from soil Burial in ocean sediments: not cycled in short time scale, only over geologic time Burial in ocean sediments: not cycled in short time scale, only over geologic time

The Phosphorus Cycle Guano deposits

Phosphorous: Human Influences? Mine large quantities of phosphate rock: used for organic fertilizers & detergents; can cause local environmental effects from mining & releases more P into environement Mine large quantities of phosphate rock: used for organic fertilizers & detergents; can cause local environmental effects from mining & releases more P into environement Sharply decrease P available in tropical forests & other ecosystems where P is limiting: deforestation & certain agricultural practices decrease available P Sharply decrease P available in tropical forests & other ecosystems where P is limiting: deforestation & certain agricultural practices decrease available P Add excess P to aquatic ecosystems: leads to excessive algal growth, depletion of oxygen, & decrease in biodiversity; such eutrophication (“over nourishment”) will be discussed later Add excess P to aquatic ecosystems: leads to excessive algal growth, depletion of oxygen, & decrease in biodiversity; such eutrophication (“over nourishment”) will be discussed later

Sulfur Cycle

Role of Sulfur? Role of Sulfur? –Component of some proteins & vitamins: essential for organisms –Limiting nutrient in some ecosystems

Sulfur Cycle: Main Processes Storage in rocks: much of Earth’s S is in rock form (e.g., iron disulfides or pyrites) or minerals (sulfates) Storage in rocks: much of Earth’s S is in rock form (e.g., iron disulfides or pyrites) or minerals (sulfates) Atmospheric input from volcanoes, anaerobic decay, & sea spray: S enters atmosphere in form of hydrogen sulfide (HS), sulfur dioxide (SO 2 ), and sulfates (S) 4 2- ) Atmospheric input from volcanoes, anaerobic decay, & sea spray: S enters atmosphere in form of hydrogen sulfide (HS), sulfur dioxide (SO 2 ), and sulfates (S) 4 2- ) Combustion: sulfur compounds released to the atmosphere by oil refining, burining of fossil fuels, smelting, and various industrial activities Combustion: sulfur compounds released to the atmosphere by oil refining, burining of fossil fuels, smelting, and various industrial activities Movement through food web: movement through foor web & eventual release during decay Movement through food web: movement through foor web & eventual release during decay

Biotic flow of sulfur through ecoystems Biotic flow of sulfur through ecoystems

Abiotic flow of sulfur through ecosystems Abiotic flow of sulfur through ecosystems

Sulfur Cycle: Human Influences? Contribute about 1/3 of atmospheric sulfur emissions: Contribute about 1/3 of atmospheric sulfur emissions: –Burning S- containing oil and coal –Refining petroleum –Smelting –Other industrial processes

Rock Cycle