slide1 l.
Download
Skip this Video
Download Presentation
Soil Mineralogy and Chemistry

Loading in 2 Seconds...

play fullscreen
1 / 39

Soil Mineralogy and Chemistry - PowerPoint PPT Presentation


  • 287 Views
  • Uploaded on

Lecture 4. Soil Mineralogy and Chemistry. Phyllosilicate Minerals. tet. tet. tet. tet. tet. tet. oct. oct. oct. Phyllosilicates, NO layer charge. trioctahedral. dioctahedral. T:O (class). oct. octahedra. gibbsite. brucite. 1:1. oct. kaolinite. serpentine. oct. 2:1.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Soil Mineralogy and Chemistry' - alijah


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Lecture 4

Soil Mineralogy

and

Chemistry

slide4

tet

tet

tet

tet

tet

tet

oct

oct

oct

Phyllosilicates, NO layer charge

trioctahedral

dioctahedral

T:O

(class)

oct

octahedra

gibbsite

brucite

1:1

oct

kaolinite

serpentine

oct

2:1

talc

pyrophyllite

slide5

Building of Tetrahedral Sheets

* Linked SiO4 tetrahedra

slide7

z

y

x

slide17

Sharing of Apical Oxygens in Tetrahdral Sheet with

Hydroxyls of Octahedral Sheet

Serpentine (1:1 trioctahedral mineral)

tet

oct

slide18

Sharing of Apical Oxygens in Tetrahdral Sheet with

Hydroxyls of Two Octahedral Sheets

Talc (2:1 trioctahedral mineral)

tet

oct

tet

slide19

Short-hand Symbols

tet

oct

Short hand,

Block notation

slide20

tet

tet

tet

tet

tet

tet

oct

oct

oct

Phyllosilicates, NO layer charge

trioctahedral

dioctahedral

T:O

(class)

oct

octahedra

gibbsite

brucite

1:1

oct

kaolinite

serpentine

oct

2:1

talc

pyrophyllite

isomorphic substitution

Charge Development

Isomorphic Substitution

 permanent (layer) charge

slide22

Isomorphic Substitution

tet

Al3+

Si4+

oct

Al3+,

Fe3+

Mg2+

slide23

NET

Charge

- - - - - - -

0

++ ++ ++ ++ ++ ++ ++

- - - - - - -

Isomorphic substitution

- - - - - - -

-2

++ + ++ ++ ++ + ++

- - - - - - -

slide24

Charge Development

Terminal Bonds

  • pH-dependent charge

(ionizable functional groups)

slide25

Terminal Bonds

terminal

bonds

slide26

Terminal Bonds: Ionizable Functional Groups

O

Al

Al-OH2+ Al-OHo + H+  Al-O- + H+

Low pH

High pH

  • pH-dependent charge
  • edges of phyllosilicates; all surface on Fe- and Al-oxides
slide27

tet

tet

tet

tet

tet

tet

tet

tet

oct

oct

oct

oct

Phyllosilicates: 2:1 with layer charge

micas

2:1 clay minerals

K+

K+

K+

Ca2+

H2O

K+

H2O

H2O

1 unit of (-) layer charge

per formula unit

< 1 unit of (-) layer charge

per formula unit

slide30

Interlayer Status: d-spacing

d-spacing

Structure

K+

(and mica)

slide31

CEC

cmol/Kg

Properties of Clay Minerals

slide32

Accessory

Minerals

Kaolin and Oxide

Rich Soil

Western GA

Ultisol

slide33

Smectite Soil

Iron and Al-oxide Rich

?

NE Montana Vertisol

Hawaiian Oxisol

slide35

Clay mineralogy reflects weathering processes

Micas  Vermiculite  Smectite  Kaolinite  Al,Fe-Oxides

  • Young, weakly weathered soils
      • = fine-grained mica, chlorite, vermiculite
      • (Entisol, Inceptisol)
    • Intermediate weathering
      • = vermiculite, smectite, kaolinite
      • (Mollisol, Alfisol, Ultisol)
    • Strong weathering
      • = kaolinite, hydrous oxides
      • (Ultisol--> Oxisol)
slide36

Mol

E/I

E/I

Alf

Ult

slide37

Organic Matter

- reactive functional groups: carboxyl, hydroxyl, phenolic

* Humus, Humic Acid, Fulvic Acid

slide38

+

Flocculation (chemical)

Aggregation

Flocculation and Aggregation

(organic gluing)