Biogeochemical Cycling

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Biogeochemical Cycling from a microbial
perspective how do elements (e.g. carbon)
cycle and support ecosystem function? Conversio
n and movement of materials Mediated by
BIOCHEMICAL FORCES Through the Ecosphere
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Biogeochemical Cycling Energy flows -
(increasing entropy) BUT Materials Cycle by
characteristic pathways Major C, H, O, N,
P, S Minor Fe, Mn, Ca, Si, Se (Redox
Fe, Mn)
Low Entropy
High Entropy
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Scale e.g. Carbon Global Carbonate rock,
CO2, Org C, Living C Ecosystem Chesapeake Bay,
Lakes Local Farm Field Microhabitat N2
fixation (by BG heterocysts) bacteria
associated anoxia (org driven)
Forces Physical Dissolution, Precipitation,
Volatile Chemical - Oxidation,
Reduction BIOLOGICAL all orgs BUT Microbes
play major role MO - everywhere, gtgtrates,
special types
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Microbially Mediated Cycles are crucial For
survival and growth of plants and
animals Environment pH, Dissolved O2,
H2S Nutrients N2 fixation (legumes) mycorrhy
sal associations nitrification/denitrification
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Out In
Combustion 5.4
3.4/yr
5.4 0.0 Combust. 1.9 0.0 Deforest. 100 102.6
Land 90.6 92.0 Ocean 197.9 194.6 Total
750
5 in
550
0.4/yr
1,020
6 org
Sediment Ocean Inorg Fossil Fuel Organic
dead Atmosphere Land Biota
4 org
10,000 Coal Oil deposits
1.6/yr
2 in
38,100
4 org
3 org
1 in
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Reminders Biochemical Processes Glycolysis and
TCA Cycles RuBISCO (ribulose bis phosphate
carboxylase) Calvin Cycle C3 plants PEPcase
(phosphoenolpyruvate carboxylase) C4 plants
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RuBISCO
Heterotrophs C4
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Carbon Flow / Food Web Reservoir Most C in CO2,
HCO3 Most Org C Dissolved (DOC)
Flow Most to 1o Prod Large to from Bact
Org Detritus particles gt Bacterial Biomass
Small (??)
Why large bidirectional exchange at detritus?
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Phenylpropane
Lignin 50 of Woody Plants Complex 3D
structure Resistant
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Energy Flow Silver Spring Florida
Note gtgt energy Through decomposers
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Bact Biomass Small But Most Energy through
?? this
CO2 N S CH4
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Labile Carbon Forms and Conc
Chesapeake Bay 1 uM 180 ug/l
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OLD BUT Assimilable C vs Culturable s
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Winter Spring Summer
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Feb May Aug Nov Jan
Organics??
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More Carbon Cycling focused On Chesapeake
Bay And adjacent waters Later.