Biogeochemical Cycling Flashcards
1
Q
Carbon cycle
A
- CO2 is the starting point
- C fixed to photoautotrohic and chemoautotrophic
- organic matter mineralized by respiration and fermentation
- CO 2 formed again
2
Q
Anaerobic products of C cycle
A
- acetate, CO2 and H2 can be used in methanogenesis
- resulting methane can be used as C source by methanotrophes
- oxidized to CO2 again
3
Q
Degradation of organic matter is influenced by (4)
A
- nutrients
- abiotic conditions
- microbial community
- organic matter
4
Q
Aerobic Carbon use
A
mineralization products are oxidized by other chemoautotrophs during energy metabolism
5
Q
Anaerobic Carbon use
A
fermentation products are used by methanogens to produce energy during methanogenesis
6
Q
Nitrogen Cycle
A
- anaerobic conditions by Rhizobium
- N-rich organic compounds
- mineralized into ammonia
7
Q
Ammonia Transformation
A
- Annamox to N gas
- Nitrification to nitrite and nitrate
8
Q
Denitrification
A
nitrate and terminal electron acceptor during anaerobic respiration of Thiobacillus and Clostridium
9
Q
Nitrate assimilation
A
- nitrogen gas
- protein
10
Q
Sulfur Cycle
A
- mineralization of organic matter forms H2S (e- donor for energy metabolism)
- aerobic (Thiobacillus) or anaerobic (p & g sulfur bacteria)
- elemental sulfur oxidized by sulfite to sulfate (reduced to H2S)
- sulfate reduced through assimilation into organisms
- forms sulfur-containing compounds
11
Q
Iron Cycle
A
- linked to Mn and Hg cycles by microbes
- ferrous to ferric iron interchange
- Fe3+ as terminal e- acceptor in anaerobic dissimilatory iron reduction
- Fe2+ as e- donor for lithotrophic microbes
12
Q
Manganese Cycle
A
- Manganous ion to oxidized manganic oxide
- Mn2+ as e- donor with O2 or nitrate as e- acceptor
- Mn reduction carried out by chemoorganotrophs
13
Q
Mercury Cycle
A
- atmosphere, aerobic water and anaerobic sediment
- Desulfovibrio transform mercury into methylated forms (toxic)
- undergoes biomagnification
- elemental Hg can react with sulfide to produce HgS
