1. FIELD BIOLOGY & METHODOLOGY Fall 2014 Althoff
Lecture 07
Biogeochemical Cycles – Part II Generalized Compartment Model & the Role of Microorganisms

2. MODELS
Models are ________….they can help clarify and organize what we think we know or understand about a process, procedure, etc.
Models are always _______…they simply cannot account for everything. And, sometimes they are unintentionally misleading because they are presented to simplify how a process or procedure or system is
Models can always be ___________ …as our understanding increases and more information (facts) come to our attention

3. Ecosystems can be modeled
Models may reflect basics by showing “compartments”
A series of ________________ highlights the ‘basics’….in this case we can use them to summarize basics about the biogeochemical cycles.
Ricklef presents a generalized model for cycling of elements (nutrients) within an ecosystem (Fig. 23.3, p485) with compartments and subcompartments

4. (faster, more-intensive processes) (slower, less-intensive
STEP 1: BASIC compartments
BIOLOGICAL
(faster, more-intensive processes)
GEOLOGIC
(slower, less-intensive
Processes)
CHEMICAL
(with leaching)

5. (faster, more-intensive processes) (slower, less-intensive
STEP 1A: organic vs. inorganic forms
BIOLOGICAL
(faster, more-intensive processes)
GEOLOGIC
(slower, less-intensive
Processes)
Inorganic forms Organic forms
CHEMICAL
(with leaching)

6. bacteria, plants, & algae
STEP 2A: _____compartments
BIOLOGICAL
Animals
Detritus
Autotrophic
bacteria, plants, & algae
Microbes

7. STEP 2B: Subcompartments
CHEMICAL
Soil
Atmosphere
Water
Sediments

8. STEP 2C: Subcompartments
GEOLOGIC
Indirectly
Available organic compounds (peat, coal, oil)
Indirectly available
Inorganic compounds (limestone, various minerals)

9. bacteria, plants, & algae
STEP 3: interactions within subcompartments
BIOLOGICAL
Animals
Detritus
Autotrophic
bacteria, plants, & algae
Microbes

10. STEP 3: interactions within subcompartments
CHEMICAL
Soil
Atmosphere
Water
Sediments

11. STEP 3: __________interactions
GEOLOGIC
Indirectly
Available organic compountds (peat, coal, oil)
Indirectly available
Inorganic compounds (limestone, various minerals)

12. (faster, more-intensive processes) (slower, less-intensive
STEP 4: Interactions between compartments
BIOLOGICAL
(faster, more-intensive processes)
GEOLOGIC
(slower, less-intensive
Processes)
CHEMICAL
(with leaching)

13. STEP 5: _____________ Model

14. Microorganisms: Big Role in Element Cycling
Many transformations in all the biogeochemical cycles are accomplished by bacteria
Without bacteria and other microorganisms performing these “transformations”, many element cycles would be _____________and _______________ of the ecosystem much reduced as a result

15. Microorganisms
For the most part, metabolism of sugars and other organic molecules are transformed the same way by microorganisms as they are by plants and animals
Bacteria and cynaobacteria are distinguished physiologically by their ability (most species) to metabolism under ________________ (i.e.,in the absence of O2) and to use substrates other than organic carbon as energy sources

16. 2 categories of AUTOTROPHS (i.e., those that assimilate C as CO2)
_______AUTOTROPHS—use sunlight (solar radiation) as their source of energy (i.e., carry on photosynthesis Ex. all green plants, algae, cyanobacteria
_______AUTOTROPHS—all use CO2 as a source of C but they obtain energy for its “reduction” by the aerobic oxidation of inorganic substrates (methane, hydrogen, ammonia, nitrite, hydrogen sulfide, sulfur, sulfite, or ferrous irons salts

17. Oxidation and Reduction
OXIDATION—removal of one or more electrons from an atom,ion, or molecule Ex. of oxidation: air reactions with metal to form metal oxides (i.e., rust) peroxides another group
REDUCTION—addition of one or more electionsto an atom, ion, or molecule Ex. of reducer nitrite producing nitrate

18. Chemoautotrophs Almost exclusively bacteria
Highly specialized biochemically a) to use inorganic substrates b) to efficiently dispose of waste products of chemoautotrophic metabolism
Example of a hydrothermal vent community that has as a base a chemoautotrophic sulfur bacteria (a food source for tubeworms