chemical weathering. i. introduction chemical weathering i. introduction ii. process of...
TRANSCRIPT
Chemical Weathering
Chemical Weathering
Chemical Weathering
I. Introduction
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview:
Decomposition alters minerals into more stable minerals or substances at the earth’s surface.
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction
an element loses electrons to an Oxygen ion
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction
an element loses electrons to an Oxygen ion
2Fe2++ 4HCO3 -1 + 1/2O2 + 2H20 >>>> Fe2O3 + 4H2CO3
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction
an element loses electrons to an Oxygen ion
2Fe2++ 4HCO3 -1 + 1/2O2 + 2H20 >>>> Fe2O3 + 4H2CO3
Ferrous bicarbonate ferric carbonic acid Iron Iron
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution
The process of chemical weathering by which earth material passes into solution by removal of its atoms.
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution
The process of chemical weathering by which earth material passes into solution by removal of its atoms.
Most well-known:
CO2 + H2O = H2CO3
Carbon dioxide water carbonic acid
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution
The process of chemical weathering by which earth material passes into solution by removal of its atoms.
Most well-known:
CO2 + H2O = H2CO3
Carbon dioxide water carbonic acid
CaCO3 + H2CO3 = Ca+ + HCO3-
Limestone + carbonic acid = calcium ions + bicarbonate
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution
The process of chemical weathering by which earth material passes into solution by removal of its atoms.
Most well-known: Limestone + water + carbonic acid = calcium ions + CO2 + bicarbonate
pH controls solubility….
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis
Describes the reaction between minerals and hydrogen“converting primary minerals into secondary minerals”
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis
Describes the reaction between minerals and hydrogen“converting primary minerals into secondary minerals” 2 KAlSi3O8 + 2H+ + 9H2O >>>> H4Al2Si2O9 + 4H4SiO4 + 2K+
orthoclase kaolinite silica acid
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange
involves the substitution of ions in solution for those held by mineral grains.
Cation exchange capacity (CEC): the capability for absorbing cations
“High Base Saturation”…..the % of exchange sites occupied by cationsother than H+.”
In acid soils, H+ replaces the cations; but in basic soils, H+ replace by cations.
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview * Mobility of cations
(Ca+2, Mg2+, Na+) > K+ > Fe2+ > Si4+ > Ti 4+> Fe 3+> Al 3
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview * Mobility of cations
(Ca+2, Mg2+, Na+) > K+ > Fe2+ > Si4+ > Ti 4+> Fe 3+> Al 3
* All related to the ionic potentialvalence (z) / ionic radius
valence (z) / ionic radiusvery mobile = less than 3very immobile + greater than 9.5
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview B. Leaching“The separation, selective removal, or dissolving out of soluble constituents from a rock by the natural action of percolating water”
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview B. Leaching“The separation, selective removal, or dissolving out of soluble constituents from a rock by the natural action of percolating water”
The process is dependent on CLIMATE and SOIL PROPERTIES
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview B. Leaching C. pH
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview B. Leaching C. pH
* The mobility of ions is controlled by pH
pH controls solubility….
Chemical Weathering III. Mobility A. Overview B. Leaching C. pH D. Fixation/Retardation
Chemical Weathering
III. Mobility A. Overview B. Leaching C. pH D. Fixation/Retardation E. Chelation
Chemical WeatheringIV. Degree and Rate of Decomposition A. Mineral Stability
Chemical Weathering
I. Introduction II. Process of Decomposition A. Overview: B. Oxidation and Reduction C. Solution D. Hydrolysis E. Ion Exchange III. Mobility A. Overview B. Leaching C. pH D. Fixation/Redardation E. Chelation IV. Degree and Rate of Decomposition A. Mineral Stability B. Secondary Minerals
Chemical WeatheringIV. Degree and Rate of Decomposition A. Mineral Stability B. Secondary Minerals C. Estimates based on chemical analysis