Soils Flashcards
organic soils
decomposition of organic matter from bogs and marshes
higher (60%) of organic matter
soil formation
needs 1000s of years to reach a mature soil profile
microbial activity, and other physical processes contribute
-Acids dissolve out rock material
-Water wind etc, erode
-Biological processes
-Microbes can live, using sun, are autotrophic, use rock minerals, produce organic matter and allow for more microbial activity
O horizon
in the open air
in soils, its often not there as we often change it
A horizon
organic matter, some nutrients, microbes, root zone, minerals
B horizon
less organic matter
C
mostly bed rock
not a lot of organic matter
can have microbes / living in the bed rock
D
can have microbes living in the bedrock
rhizosphere
richer than normal soil, absorbs acids, etc.
-surround plant roots
determinants of microbial activity in soil
- water availibility, affecting O2 availibility
- nutrient status, can limit microbes with C,N,P
- adding fungals metabolize and release material helping bacterials for food
Cold water and microbes
cold water is more soluble and hence is used up by aerobes and becomes anoxic
Congregation
cells congregate near edges of pores as theres more nutrients there
rhizoplane
root surface, source of root exudates (sugar, aa, hormones, vitamins)
phyllosphere
surface of plant leaf
Deep terrestrial surface is a microbial habitat
- primarily prokaryotes
- low nutrient habitat, v.low metabolic activity
- 10km below ground surface
Aquatic environments: Freshwater - lakes
O2 produced near surface, depleted further down due to low solubility and consumption
anaerobic inhabitants are in deeper regions
Epilimnion
oxygenic area of lake
hypolomnion
anoxic region of lake
Aquatic environments: Freshwater - Rivers
re-oxygenation is affected, organic matter, nutrient inputs affect productivity, leading to O2 depletion
-Biochemical Oxygen Demand (BOD) is the change in dissolved oxygen after 5 days at 20deg C (the measure of organic matter that can be oxidized by microorganisms)
Aquatic environments: Marine - Open ocean
low primaryproductivity, often limiting N, P, Fe resulting in low heterotrophic activity
Aquatic environments: Marine - Inshore area
nutrient rich, resulting in greater productivity
Aquatic environments: Deep Sea
- cold, high hydrostatic pressure, low nutrient input
- low microbial activity; inhabitants are psychrotolerant or psychrophilic, piezotolerant (barotolerant) or piezophilic (barophilic)
Hydrothermal vent communities
driven by geothermal energies
- free living organisms
- include S-oxidizing chemolithotrophs (Thiothrix, Beggiatoa, Thiobacillus)
- may also be H2-, Fe2+-, Mn2+-oxidizers, methanotrophs, nitrifiers
- may also be methanogens, S0-reducers, sulfate-reducers, Fe(III)-reducers
- microbe-animal symbioses
- S-oxidizers & tube worms, clams, mussels
-animals that graze directly on the microbiota
tube worms
- possess a trophosome - spongy tissue packed with S granules and S-oxidizing bacteria
- tube worm traps O2, H2S in blood and delivers to bacteria
- bacteria grow on H2S, thiosulfate and CO2
- products of bacterial metabolism support tube worm growth
