Geoscience Reference
In-Depth Information
Placic horizons
Fe
d
-Fe
o
dominant
¼
ferrihydrite; some Al
o
Al
p
and Al
d
Al
o
Extractable Fe, Al; micromorphology
Two stages: (1) water is perched
between E and B due to
textural discontinuity; (2) Fe
in upper part of pedon is
reduced, then immobilized
and reoxidized at E-Bsm
interface
Wu and Chen (
2005
)
High Fe
o
/Al
o
; ferrihydrite and goethite dominant Extractable Fe, Al; micromorphology
Fe reduced in organic-rich
horizon under wet conditions
then reox-idized in drier
horizon below
Pinheiro et al. (
2004
)
High Fe
o
Fe
p
¼
ferrihydrite
Extractable Fe, Al
Ping et al. (
1989
)
Wide Fe
o
/Al
o
; high Fe
o
Extractable Fe, Al; elemental composition
of C
h
,C
f
Valentine (
1969
) and
Bonifacio
et al. (
2006
)
Ferrihydrite, goethite
>
lepidocrocite from
DXRD
Differential XRD; selective dissolution
Campbell and
Schwertmann (
1984
)
Fe-C
f
complex; wide Fe
o
/Al
o
; abundant Fe
o
Micromorphology; differential thermal analysis,
extractable Fe, Al; functional analysis SOM
McKeague et al. (
1967
)
Narrow Fe
o
/Al
o
; high Al
o
Extractable Fe, Al, SOC
Lavkulich et al. (
1971
)
Fe-OC complexes; isotropic microfabric; wide
Fe
o
/Al
o
; high Fe
o
Micromorphology; extractable Fe, Al
Forms due to redox processes
enhanced by high water table
Hseu et al. (
1999
)
Lepidocrocite & ferrihydrite from DXRD; wide
Fe
o
/Al
o
Scanning electron microscopy; energy dispersive
spectrometry; differential XRD; extractable
Fe, Al; micromorphology
Clay eluviation followed by
podzolization creates textural
discontinuity that enforces
episaturation; topsoil Fe is
reduced and mobilized, then
illuviated with clay &
organics
Jien et al. (
2010
)
High Fe
o
; wide Fe
o
/Al
o
Extractable Fe, Al, Si
Fe precipitates at depth in profile
due to higher oxidation, pH
potential
Lapen and Wang (
1999
)
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