10 for examples of decomposi0on steps how do we

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Unformatted text preview: rtment of biopolymers Micro- organisms •  Decompose SOM (complete decomposi0on releases CO2) •  Various biopolymers range in their ease and rate of decomposi0on •  Cellulose – structural fibres of many plants •  Hemicelluloses – more complex chemically than cellulose •  Lignin – gives wood its rigid structure; most resistant plant compounds to decomposi0on •  (See box 4.10 for examples of decomposi0on steps) How do we measure CEC? •  Measured in milliequivalents (meq) per 100 grams of soil •  Standard measurement is the number of charges occupied by 1 milligram of H+ per 100 grams of soil •  1 meq = 1mmol/ionic charge •  1mmol = 1/1000 mol = 6.023 x 1020 monovalent ca0ons (+1 charge) •  For a divalent ca0on (+2 charge) 1 meq = 1mmol/2 = 0.5 mmol •  We’ve seen that soil materials vary in their CEC •  Next ques0on: Are there differences in how readily ca0ons are adsorbed? •  YES •  Func0on of: charge, radius, concentra0on… Order of displacement: Al 3+ > H+ > Ca 2+ > Mg 2+ > K+ > NH4+ > Na + (assuming equal molar concentra0ons) In dealing with environmental issues: •  Ohen helpful to have a measure of charges occupied by H+ and Al3+ versus base ca0ons Na+, Mg2+, K+ an...
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This note was uploaded on 01/30/2014 for the course ESCI 271 taught by Professor Lisakellman during the Fall '12 term at St. Francis Xavier, Antigonish.

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