Biogeochemical CyclesBiogeochemical Cycles

life-earth-chemical cycleslife-earth-chemical cycles• Water cycleWater cycle• Carbon cycleCarbon cycle• Nitrogen cycleNitrogen cycle• Phosphorus cyclePhosphorus cycle• Sulfur cycleSulfur cycle

Water CycleWater Cycle

How are humans affecting the How are humans affecting the water cycle?water cycle?

How are humans affecting the How are humans affecting the water cycle?water cycle?

Using large quantities of freshwater Using large quantities of freshwater from rivers, lakes, and underground from rivers, lakes, and underground aquifersaquifers

Clearing vegetation and replacing it Clearing vegetation and replacing it with impermeable materials (like with impermeable materials (like concrete), which increases runoffconcrete), which increases runoff

Adding pollutants and excess Adding pollutants and excess nutrients to the waternutrients to the water

Water CycleWater Cycle

What can people do to improve the What can people do to improve the water cycle?water cycle?

Water conservationWater conservation Use more permeable materials on Use more permeable materials on

the groundthe ground Reduce the amount of runoff and the Reduce the amount of runoff and the

chemicals it containschemicals it contains

DistillationDistillation

Carbon CycleCarbon Cycle

Where is carbon stored?Where is carbon stored?

Where is carbon stored?Where is carbon stored?

Air – 0.037% is COAir – 0.037% is CO22

Vegetation – during photosynthesis, plants Vegetation – during photosynthesis, plants convert COconvert CO22 into C into C66HH1212OO66 (glucose) (glucose)

Fossil fuels – plant matter that’s been Fossil fuels – plant matter that’s been subjected to heat and pressuresubjected to heat and pressure

Ocean – dissolves COOcean – dissolves CO22

Marine organisms – used to make shellsMarine organisms – used to make shells Rocks – limestone is primarily CaCORocks – limestone is primarily CaCO33

Fossil FuelsFossil Fuels

White Cliffs of DoverWhite Cliffs of Dover

How are humans affecting the How are humans affecting the carbon cycle?carbon cycle?

How are humans affecting the How are humans affecting the carbon cycle?carbon cycle?

By cutting down trees and clearing By cutting down trees and clearing vegetation that naturally absorbs COvegetation that naturally absorbs CO22

Burning fossil fuels (especially coal) Burning fossil fuels (especially coal) releases their stored carbon into the releases their stored carbon into the atmosphereatmosphere

Effects of disrupting the carbon Effects of disrupting the carbon cyclecycle

Global WarmingGlobal Warming – more – more COCO22 in the atmosphere will in the atmosphere will lead to a stronger lead to a stronger greenhouse effectgreenhouse effect

Acidification of the oceansAcidification of the oceans – more dissolved CO– more dissolved CO22 in in the water creates more the water creates more carbonic acidcarbonic acid

NitrogenNitrogen

NitrogenNitrogen

78% of the air is 78% of the air is nitrogen (Nnitrogen (N22))

Nitrogen is Nitrogen is essential for essential for organisms to make organisms to make DNA, protein, DNA, protein, amino acids, etc.amino acids, etc.

Yet, NYet, N22 is useless to is useless to plants and animalsplants and animals

How do organisms get nitrogen?How do organisms get nitrogen?

Two natural processes Two natural processes convert nitrogen gas convert nitrogen gas into usable nitrogen:into usable nitrogen:• LightningLightning• Nitrogen cycleNitrogen cycle

Nitrogen CycleNitrogen Cycle

5 main processes cycle nitrogen 5 main processes cycle nitrogen through the atmosphere, biosphere, through the atmosphere, biosphere, and lithosphere:and lithosphere:• Nitrogen fixationNitrogen fixation• NitrificationNitrification• AssimilationAssimilation• AmmonificationAmmonification• Denitrification Denitrification

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

Nitrogen fixationNitrogen fixation• Bacteria (such as Bacteria (such as RhizobiumRhizobium) convert gaseous ) convert gaseous

nitrogen into ammonia, which is taken up by nitrogen into ammonia, which is taken up by plantsplants

• NN22 + 3H + 3H22 2NH 2NH33

Rhizobium nodules

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

NitrificationNitrification• Ammonia in soil converted by bacteria into Ammonia in soil converted by bacteria into

nitrite ions (NOnitrite ions (NO22--) and nitrate ions (NO) and nitrate ions (NO33

--))

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

AssimilationAssimilation• Plants use ammonia Plants use ammonia

(NH(NH33), ammonium ions ), ammonium ions (NH(NH44

++), and nitrate ions ), and nitrate ions (NO(NO33

--))

• Make DNA, amino Make DNA, amino acids, and proteinacids, and protein

• Animals get their Animals get their nitrogen from eating nitrogen from eating plantsplants

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

AmmonificationAmmonification• Animals excrete excess nitrogen in their Animals excrete excess nitrogen in their

urine and fecesurine and feces• Additional nitrogen is added to the soil Additional nitrogen is added to the soil

when organisms diewhen organisms die• Decomposing bacteria and fungi convert Decomposing bacteria and fungi convert

the nitrogen in their waste into usable the nitrogen in their waste into usable ammonia (NHammonia (NH33) and ammonium ions ) and ammonium ions (NH(NH44

++))

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

DenitrificationDenitrification• Bacteria in the soil convert usable Bacteria in the soil convert usable

ammonia (NHammonia (NH33) and ammonium ions ) and ammonium ions (NH(NH44

++) back into nitrogen gas (N) back into nitrogen gas (N22) and ) and nitrous oxide gas (Nnitrous oxide gas (N22O)O)

Nitrogen CycleNitrogen Cycle

How are humans affecting the How are humans affecting the nitrogen cycle?nitrogen cycle?

Burning fuels Burning fuels release nitric oxide release nitric oxide (NO) into the (NO) into the atmosphereatmosphere• Creates acid rainCreates acid rain

Harms vegetationHarms vegetation Harms aquatic Harms aquatic

ecosystemsecosystems Damages materials Damages materials

(metal, stone, etc.)(metal, stone, etc.)

How are humans affecting the How are humans affecting the nitrogen cycle?nitrogen cycle?

Excess livestock Excess livestock waste and fertilizer waste and fertilizer adds nitrous oxide adds nitrous oxide (N(N22O) to the O) to the atmosphereatmosphere• NN22O is a greenhouse O is a greenhouse

gasgas• May lead to global May lead to global

warmingwarming

How are humans affecting the How are humans affecting the nitrogen cycle?nitrogen cycle?

Runoff from Runoff from agricultural lands agricultural lands and sewage and sewage facilities adds facilities adds nitrogen to aquatic nitrogen to aquatic ecosystemsecosystems• Results in algal Results in algal

bloomsblooms• Leads to “dead Leads to “dead

zones”zones”

Nitrogen SummaryNitrogen Summary

1.1. What allows nitrogen to be used by What allows nitrogen to be used by plants?plants?

2.2. How do animals get their nitrogen?How do animals get their nitrogen?

3.3. What makes the What makes the nitrogen cyclenitrogen cycle a a cycle?cycle?

4.4. How are humans affecting the How are humans affecting the nitrogen cycle?nitrogen cycle?

PhosphorusPhosphorus

PhosphorusPhosphorus

Phosphorus is an Phosphorus is an essential nutrient essential nutrient for plant growthfor plant growth

It does not exist as It does not exist as a gas, but is mainly a gas, but is mainly found in water, found in water, soil, and sedimentsoil, and sediment

Phosphorus CyclePhosphorus Cycle

Phosphorus is Phosphorus is found naturally in found naturally in rocksrocks

Erosion by rainfall, Erosion by rainfall, weathering, and weathering, and runoff allows runoff allows phosphorus to be phosphorus to be available to plantsavailable to plants

Phosphorus CyclePhosphorus Cycle

Phosphorus is absorbed by roots in Phosphorus is absorbed by roots in plantsplants

Animals eat the plants and it is Animals eat the plants and it is passed up the food chainpassed up the food chain

Phosphorus is returned to the soil by Phosphorus is returned to the soil by animal excretion and decompositionanimal excretion and decomposition

How are humans affecting the How are humans affecting the phosphorus cycle?phosphorus cycle?

Humans mine phosphate rocks to Humans mine phosphate rocks to make fertilizers and detergentsmake fertilizers and detergents

Increasing erosion by removing Increasing erosion by removing vegetationvegetation

Adding excess phosphorus to water Adding excess phosphorus to water from runoff from fertilizers and from runoff from fertilizers and livestock waste livestock waste

Sulfur CycleSulfur Cycle

Most sulfur is Most sulfur is buried in rocks and buried in rocks and minerals minerals undergroundunderground

Hydrogen sulfide Hydrogen sulfide (H(H22S) and sulfur S) and sulfur dioxide (SOdioxide (SO22) are ) are released by released by volcanoesvolcanoes

Rotorua, New Zealand (aka – “Sulfur City”)Rotorua, New Zealand (aka – “Sulfur City”)

Sulfur CycleSulfur Cycle Sulfur is taken up Sulfur is taken up

by plants and is by plants and is passed through the passed through the food chainfood chain

As organisms die As organisms die and decompose, and decompose, the sulfur then the sulfur then again becomes again becomes available for plantsavailable for plants

How do humans affect the sulfur How do humans affect the sulfur cycle?cycle?

Burning coal and Burning coal and processing metals processing metals release SOrelease SO22 into into the atmospherethe atmosphere

SOSO22 reacts with reacts with water in the water in the atmosphere to atmosphere to form Hform H22SOSO44, sulfuric , sulfuric acidacid