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FIELD BIOLOGY & METHODOLOGYFall 2013 Althoff Lecture 07 Biogeochemical Cycles – Part IIGeneralized Compartment Model& the Role of Microorganisms
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
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
STEP 1: BASIC compartments BIOLOGICAL (faster, more-intensive processes) GEOLOGIC (slower, less-intensive Processes) CHEMICAL (with leaching)
STEP 1A: organic vs. inorganic forms BIOLOGICAL (faster, more-intensive processes) GEOLOGIC (slower, less-intensive Processes) Inorganic forms Organic forms CHEMICAL (with leaching)
STEP 2A: _____compartments BIOLOGICAL Animals Detritus Autotrophic bacteria, plants, & algae Microbes
STEP 2B: Subcompartments CHEMICAL Soil Atmosphere Water Sediments
STEP 2C: Subcompartments GEOLOGIC Indirectly Available organic compounds (peat, coal, oil) Indirectly available Inorganic compounds (limestone, various minerals)
STEP 3: interactions within subcompartments BIOLOGICAL Animals Detritus Autotrophic bacteria, plants, & algae Microbes
STEP 3: interactions within subcompartments CHEMICAL Soil Atmosphere Water Sediments
STEP 3: __________interactions GEOLOGIC Indirectly Available organic compountds (peat, coal, oil) Indirectly available Inorganic compounds (limestone, various minerals)
STEP 4: Interactions between compartments BIOLOGICAL (faster, more-intensive processes) GEOLOGIC (slower, less-intensive Processes) CHEMICAL (with leaching)
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
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
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
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
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