BIOMI 2900 Lecture 30

Overview of the Carbon Cycle

Decomposition is the breakdown of?

dead biomass (ie: organic carbon, (CH2O)n)

Decomposition: Organic C is oxidized to? It releases?

CO2

Nutrients (N, P, S, etc)

Decomposition is mediated by what type of organisms? through what 3 ways?

chemo-organo-heterotrophs

1. Aerobic Resp

2. Anaerobic resp

3. Fermentation

Simplified Global Carbon Cycle

Mauna Loa Monthly Mean Carbon Dioxide

Overview of the Carbon Cycle: Ice core Data

Composting and Wastewater Treatment: Aerate the plant matter to promote?

decomposition

Wastewater Treatment: Goals are to elimiante what from water? reduce what demand? and remove?

1. Pathogens

2. Biological oxygen demand (BOD)

3. Nutrients and contaminants (eg N, P, metals)

What are the three stages of wastwater treatment

1. Primary Treatment (Physical): -screens, sedimentation,

2. Secondary Treatment (Biological) : -activated sludge -anaerobic digestion

3. Tertiary Treatment (Chemical) : -e.g. chlorination, UV, chemical flocculation

Anaerobic Digestion: What are 4 things in relation

Anaerobic respiration

Fermentation

Denitrification

Methanogenesis

Aeration (activated sludge): What are two things in relation?

1. Aerobic resp

2. Nitrification

Anoxic Habitats Where do we find anoxic environments (and anaerobic organisms)?

Anywhere there is stagnant water and microbial O2 consumption.

What are 4 examples of anoxic habitats?

1. Anaerobic digestion

2. Gut communities

3. Wet soil

4. Wetlands and sediments

Even 100 microns of water is enough to result in an anoxic environment if O2 consumption is high

Anaerobic Food Webs

What are Syntrophs?

eating together, ie: cross-feeding; chemo-organo-heterotrophs, obligate anaerobes)

Syntrophs, carry out fermentation reactions that are? under standard conditions

ENERGETICALLY UNFAVORABLE

Syntrophs: Reactions are made favorable by the consumption of what two things by other organisims?

1. H2

2. Acetate

Free Energy

Methanogens (Archaea) Are what type of organisms?

1. Chemo-litho-autotrophs

2. Chemo organo heterotrophs

Obligate anaerobes

Electron donor

Carbon source

Habitats of Methanogens?

Methane in the Biosphere

The Methane Budget Methane has 20x? of CO2?

GWP

Aerobic Methanotrophs are what organisms?

CH4 + 2O2 → CO2 + 2H2O

Chemo-organo-heterotrophs*, obligate aerobes

What are the habitats of aerboic methanotrophs?

anoxic/oxic interface of freshwater habitats and soils

Methane in the Biosphere