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Group 5B: N, P, As, and Sb
part of speciation and general behavior
21
Chemistry
Undergraduate 4
01/10/2017

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Term
about 75-80% of N in soil is found in...
Definition
organic matter
Term
2 common valence states for soil N
Definition
-N-III -NV
Term
behavior of ammonia (NH3) in solution
Definition
strong base that's hydrolyzed to produce hydroxide and the the ammonium ion
Term
what happens to ammonium (NH4+) in aerated systems?
Definition
gets oxidized to nitrate (NO3-), which is a microbially mediated process
Term
how NH4+ and NO3- are relatively conservative in soils
Definition
-they don't form mineral precipitates
-they don't participate in aqueous complexation rxns
Term
where ammonium fixation can occur
Definition
in soils containing vermiculite
Term
valence state of P in soils
Definition
V
Term
amount of P in soil that's organic P
Definition
19-70% of total soil P
Term
the basic inorganic P species
Definition
orthophosphate (PO43-)
Term
when orthophosphate (PO43-) occurs as H2PO4-
Definition
when the soil solution pH is < 7.2
Term
how orthophosphate (PO4-3) is affected by pH
Definition
releases protons as the pH increases
Term
the orthophosphate (PO4-3) species that form stable aqueous complexes with numerous mono- and divalent metal cations
Definition
-H2PO4- -HPO4-2
Term
the phosphate species that can become strongly, if not irreversibly, adsorbed by Al and Fe oxyhydroxides and clay minerals and how this happens
Definition
-H2PO4- -HPO42- -this happens via ligand exchange mechanisms
Term
the commonly occurring oxidation states of As and Sb
Definition
III and V
Term
why As and Sb may be able to isomorphically substitute in primary and secondary minerals
Definition
similarities in ionic radii
Term
how AsIII exists in soil solution
Definition
as arsenite, a hydroxyanion (As(OH)3)
Term
where the AsV oxidation state is stable
Definition
in oxic and suboxic environments
Term
when neither AsIII nor SbIII are stable
Definition
when in the presence of FeIII or MnIV oxyhydroxides thus, they are readily oxidized
Term
will As or Sb form stable secondary minerals in soil?
Definition
no, neither of them will
Term
why As and Sb won't form stable secondary minerals in soil
Definition
because of their innately low soil concentrations
Term
the primary retention mechanism for As and Sb
Definition
adsorption by Fe oxyhydroxides
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