Role of Biology in Transferring Energy and Mass Through the

Earth System

RememberConservation of Energy

& Conservation of Mass

3 Basic Steps in Photosynthesis

• Light reactions- energy capture: chemiosmosis generation of ATP from harvested sunlight

• Dark reactions- fixation of carbon: enzyme catalyzed reactions using the ATP formed in the light reactions to “fix” CO2 into sugars

• Pigment regeneration- electron replacement from the splitting of H2O in oxygenic photosynthesis

Light Reactions:A very specific energy is required for photochemistry since only photons of a certainwavelength can dislodge electrons from an object

Most common range of wavelengthfrom the sun is the most sensitiverange for photosynthesis

Carbon enters water leaves the plant through the same pore; thus theexchange of the two substances is linked. This processes is known as

transpiration.Stoma

Chlorophyll

Nutrients

Chemicals required for life processes but often in short

supply and thus may limit growth

The Essential Elements Necessary for Plant Growth: 1. the bulk mass (95%)

Element Available from Present in Essential Role in Plants

Carbon, C CO2 Air, water All organic molecules

Hydrogen, H H2O Air, water All organic molecules

Oxygen, O CO2, H2O Air, water Most organic molecules

Nitrogen, N NO3-, NH4

+ Soil, water All proteins and

nucleic acids

N2 (only by

nitrogen fixation)

Air

Sulfur, S SO42- Soil, water Most proteins

Phosphorous, P PO43- Soil, water Nucleic acids and

energy transfer

The Essential Elements Necessary for Plant Growth: 2. minor constituents

available from soil minerals or dissolved in water

Element Role in Plants

Potassium, K Water balance, essential for certain enzymes

Calcium, Ca Membrane function, essential of cell walls of most plants

Magnesium, Mg Essential in chlorophyll

Iron, Fe Photosynthesis, energy release reactions

Mn, B, Z, Cu, Mo, Co Essential for function of certain enzymes

Chlorine, Cl Essential for photosynthesis

Interactions Between Biology and Climate

Climate Controls on Biology

&

Biology Controls on Climate

Climate Controls on Biology

TemperatureLight

CO2

WaterClimate variability

Levitus94 Annual Phosphate (micromolar) at Surface

Blue lowest (~0); Pink highest (~2)

Source: SeaWiFS Project of the NASA Goddard Space Flight Center

Data aquired between Noverber 1978 and June 1986

Climate variability and ecosystem structure(greater variability = lower diversity)

Biological Controls on Climate

Albedo

Interception of rainfall

Cloud formation

Surface roughness

Greenhouse gasses

Long-term atmospheric change

Albedos for Various Terrestrial Biomes

• Equatorial forest 0.18

• Savannah 0.18-0.24

• Mid-latitude forest 0.14-0.46

• Tundra 0.18-0.80

• Desert 0.35

(In general vegetated surfaces reflect less than bare soil and rock.Tall vegetation prevents snow from making surface completely white)

Possible chain of events set off by overgrazing

Interception of Rainfall

Cloud Formation

Aerosols are cloud condensation nuclei

Increased terrestrial vegetation leads to decrease dust (aerosol)Ocean plankton release a sulfur compound (aerosol)

Surface Roughness

• Vegetation roughens the surface of the earth, causing air to flow less smoothly.

• This increase in turbulence near the surface increases the efficiency of mixing of heat and moisture between the surface and rest of troposphere

• Additionally, the rough surface causes surface winds to blow in a different direction from winds at high levels.

Greenhouse Gasses

Long-term Atmospheric Change

The CO2 Content of the atmosphere is critical to maintianing the earth’s mean surface temperture. The CO2 content is controled by the biosphere. It has not

always been as it is today.

Role of Biology

• Photosynthesis

• Respiration

• Transpiration

• Nutrient

• Climate controls on Biology

• Biology controls on Climate