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Lecture 3

Lecture 3 Nutrients etc

Environmental Science
Course Code
Marnie Branfireun

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ES1021F Lecture 3 September 28, 2011
Part 1: Flows & Cycles of Nutrients
What are nutrients?
Nutrients are any chemicals that are required for the proper functioning of organisms
Autotrophs use inorganic nutrients in their nutrition
Animals require organic nutrition – the biomass of other organisms
Examples of inorganic nutrients:
Gaseous carbon dioxide (CO2)
Ionic nitrate (NO3-) and ammonium (NH4+)
Ionic phosphate (PO4-3)
Ionic sulphate (SO4-2) & gaseous sulphur dioxide (SO2)
Ionic calcium (Ca2+), magnesium (Mg2+), potassium (K+)
Nutrient flows and cycles
Nutrient cycling refers to the transfers, transformations, and recycling of nutrients
A nutrient budget is a quantitative estimate of the quantities present in compartments and
the fluxes (rates of movement) between them
The Soil Ecosystem
Soil is an ecosystem comprised of inorganic material, organic matter, and a great
diversity of organisms
It is derived from original parent materials, which over time are modified by climatic
factors (especially percolating water) and organisms
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ES1021F Lecture 3 September 28, 2011
Mature soils develop distinctive features that are dependent on local climatic conditions
and the kind of ecological community in which they have developed
Factors that determine soil types
Chernozem – a soil that develops in natural grasslands
Podzol – develops in coniferous boreal forest
Brown forest soil – develops in temperate hardwood forest
Gleysol – develops in cool temperate habitats that are periodically waterlogged
Solonetz – develops in desert communities
Organic – develops in fens and bogs
Soil Horizons
Soil horizons are distinctive layers that vary in their physical and chemical properties:
Litter layer – organic matter identifiable as plant litter
Duff layer – litter fragments still visible
Humus layer – well-humified organic matter
A horizon – a zone of eluvation (out-leaching) of organics, Fe, Al, Ca, Mg
B horizon – a zone of eluviation (deposition) of materials leached from the A horizon
C – parent materials
R – the regolith, or underlying rock
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ES1021F Lecture 3 September 28, 2011
Nutrient cycles
Carbon Cycle:
Carbon is the most abundant building block of life, accounting for about ½ of dry
The largest store of C is in carbonate rocks, such as limestone (CaCO3) and dolomite
The most abundant atmospheric form is CO2 (~385 ppm in 2009)
Photosynthetic autotrophs fix CO2 into simple sugars, which is used to drive the
metabolic production of all biochemicals
Organic-carbon is eventually returned to the atmosphere via decomposition, mostly as
CO2, and some CH4
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