Soil Environmental Chemistry - SJTUsese.sjtu.edu.cn/web/upload/200752313066491.pdf · Soil...

Soil Environmental ChemistrySoil Environmental Chemistry

YUAN TaoYUAN TaoDr., Associate Professor Dr., Associate Professor taoyuan@sjtu.edu.cntaoyuan@sjtu.edu.cn517#, Building of Environment , SJTU 517#, Building of Environment , SJTU

22Dr. Yuan T, Room 517, Env. Building, Minhang campus, SJTU. (Email: taoyuan@sjtu.edu.cn)

Perceptions of SoilAgriculture

Environment

Science

Course Objectives

• Comprehend the physical, chemical, and biological processes functioning within soils

• Obtain an appreciation for soils as dynamic, non-renewable natural resources

Outline Outline

General introduction General introduction Soil components Soil components Soil taxonomy Soil taxonomy Properties of soil Properties of soil Soil pesticides pollution Soil pesticides pollution Soil heavy metal contamination Soil heavy metal contamination Soil remediationSoil remediation

General introductionGeneral introduction

Soil developmentSoil developmentSoil roleSoil roleGlobal soil issues Global soil issues Soil pollution and healthSoil pollution and healthResearch briefing Research briefing

Soil DevelopmentSoils are formed by the weathering of parent rocks as the result of interactive geological, hydrological and biological process.

Soil Profile Development

The BeginningThe Beginning

Soil Forming Factors

•Time

•Parent Material

•Climate

•Biota

•Topography

•Time

•Parent Material

•Climate

•Biota

•Topography

Soil roleSoil role(open system that undergo continual exchange (open system that undergo continual exchange

of matter and energy with atmosphere, of matter and energy with atmosphere, hydrosphere, and biosphere. )hydrosphere, and biosphere. )

1.1. Most fundamental requirement for agriculture Most fundamental requirement for agriculture

2.2. Receptor of large quantities of pollutants Receptor of large quantities of pollutants

Global soil issuesGlobal soil issuesSoil acidification Soil acidification Soil Soil salificationsalification and and alkalificationalkalificationDesertification Desertification Soil loss and degradation Soil loss and degradation

Acid Soils

Salt Affected Soils

Soil pollution and health Soil pollution and health Sources of soil pollution Sources of soil pollution Human activitiesHuman activities: wastewater, solid waste , : wastewater, solid waste ,

pesticide , fertilizer, recycling of wastes pesticide , fertilizer, recycling of wastes atmospheric sedimentation atmospheric sedimentation

Natural sourcesNatural sources : mine areas, mineral : mine areas, mineral degradation and weathering degradation and weathering

Soil pollution and healthSoil pollution and healthHealth concern Health concern

Crop growth and nutrients loss Crop growth and nutrients loss Food chain Food chain Pollutants releasing to water body Pollutants releasing to water body

Research briefing Research briefing

Some topics of soil researchSome topics of soil research–– Degradations and behaviors of toxic Degradations and behaviors of toxic

organics organics –– Forms and transformations of heavy metals Forms and transformations of heavy metals –– SolidSolid--liquid interface actions of pollutants liquid interface actions of pollutants –– Emissions and fates of green houseEmissions and fates of green house–– Chemical remediation Chemical remediation –– BioBio--remediation remediation

Outline Outline

General introduction General introduction Soil componentsSoil taxonomy Soil taxonomy Properties of soil Properties of soil Soil pesticides pollution Soil pesticides pollution Soil heavy metal contamination Soil heavy metal contamination Soil remediationSoil remediation

Soil Profile DevelopmentSoil Profile Developmentcontains characteristic contains characteristic

layers called layers called horizonshorizons

BedrockBedrock

development

Soil profileSoil profile

BedrockBedrock

A horizon, topsoil (typically several inches in thickness, maximum biological activity, contains most of the soil organic matter, metal ion

and clay particles leaching )

B horizon, subsoil (receives material such as organic matter, salts and clay particles

leached form topsoil)

C horizon, weathered parent rock (composed of weathered parent rocks

from which the soil originated)

Bedrock

Soil componentsSoil components

Major components Major components Solid phaseSolid phaseLiquid phaseLiquid phaseGas phaseGas phase

Major ComponentsMajor Components

mineral45%

air25%

water25%

organic 5%

Major ComponentsMajor Components

mineral45%

air25%

water25%

organic 5%

Other populations in soils: bacteria, virus, fungi, animals such as earthworm

Soil components Soil components

Minerals Minerals Original: physical weathering Original: physical weathering Secondary: chemical weatheringSecondary: chemical weathering

Depends on chemical element and Depends on chemical element and crystal structure crystal structure

Organic matterOrganic matterHumusHumus : the residue left when bacteria and : the residue left when bacteria and fungi biodegrade plant material.fungi biodegrade plant material.

BaseBase--soluble , soluble , humichumic acid, acid, fulvicfulvic acid acid Insoluble , Insoluble , huminhumin

NonNon--humus:humus:Fats, resins and waxes Fats, resins and waxes SaccharideSaccharide (cellulose, starches, (cellulose, starches, hemicellulosehemicellulose, gums), gums)NN--organics (Norganics (N--humus, amino acid, amino sugars)humus, amino acid, amino sugars)PP--compounds (phosphate ester, compounds (phosphate ester, inositolinositol phosphate, phosphate,

phospholipids ) phospholipids )

Organic matter Organic matter –– Determines soil productivity Determines soil productivity –– Serves as food for microorganism Serves as food for microorganism –– Undergoes chemical reactions Undergoes chemical reactions –– Sorbs solutes in soilSorbs solutes in soil

Soil solution Soil solution

WaterWater →→ plants (Rain , snow, irrigation , plants (Rain , snow, irrigation , groundwater (2groundwater (2--3m) )3m) )

Solutes Solutes ↔↔ soil particles soil particles

Note: Plant root nutrients Note: Plant root nutrients ↔↔ solid soilsolid soil(waterlog)(waterlog)

Soil componentsSoil components

Soil air Soil air Basic components are same with atmosphere Basic components are same with atmosphere

((NN22, O, O22, CO, CO22))Differences to atmosphere Differences to atmosphere

Uneven and Uneven and incontinuousincontinuousHigher COHigher CO22, lower O, lower O22, higher moisture, higher moistureReductive gases, such as CHReductive gases, such as CH44, H, H22S, HS, H22

Other components in soilsOther components in soils

Plant nutrients Plant nutrients Macronutrient Macronutrient CC, , HH, , OO, N, P, K, Ca, Mg and S , N, P, K, Ca, Mg and S Micronutrient Micronutrient B, B, ClCl, Cu, Zn, , Cu, Zn, MnMn, iron. , iron. Pollutants (details will be discussed in Soil Pollutants (details will be discussed in Soil pollution section)pollution section)

Fertilizer

Nitrogen,Phosphorus,Potassium...

* Soils act as a storagebank for plant nutrients

* retain water

* filter contaminants

Retention within Soils

Outline Outline

General introduction General introduction Soil components Soil components

Soil taxonomySoil taxonomyProperties of soil Properties of soil Soil pesticides pollution Soil pesticides pollution Soil heavy metal contamination Soil heavy metal contamination Soil remediationSoil remediation

Long history Long history Many pathways ( application, color, texture, Many pathways ( application, color, texture, hardness, region, etc. )hardness, region, etc. )Trend, Q, S, I, Trend, Q, S, I,

Soil taxonomySoil taxonomy

Soil Color Originates from the Molecular Framework

Soft soil

Mollisol

Grey soil

SpodosolSpodosol

Oxide soil

(Soils of the Tropics)

Oxisol

Organic soil

(Soils from Wetlands )

Histosol

Inception (initial) soil

Soils from Recent Landscapes

InceptisolInceptisol

Arid soil (Soils Near Recent Volcanic Activity)

AridisolsAridisols

Soil classification Soil classification

Soil texture:Soil texture:Soil condition represented by the different Soil condition represented by the different

degrees of fine and rough particles degrees of fine and rough particles

Physical properties are influenced by particle size

Size Classification (USDA):

Soil < 2 mm

Sand, 2 - 0.05 mm

Silt, 0.05 - 0.002 mm

Clay, <0.002 mm

Sandy Soils(coarse textured)

SandLoamy

Sandy Loam

Outline Outline

General introduction General introduction Soil components Soil components Soil taxonomy Soil taxonomy

Properties of soil Properties of soil Soil pesticides pollution Soil pesticides pollution Soil heavy metal contamination Soil heavy metal contamination Soil remediationSoil remediation

Properties of soil Properties of soil

Physical propertiesPhysical propertiesAdsorption (colloid)Adsorption (colloid)AcidAcid--base base RedoxRedox (reduction(reduction--oxidation)oxidation)

Ion exchange adsorptionIon exchange adsorption

Keynotes Keynotes –– Same charge exchangeSame charge exchange–– Dynamic balance (or kinetic equilibrium)Dynamic balance (or kinetic equilibrium)–– Mass balance Mass balance –– Equivalent exchange based on ionic valenceEquivalent exchange based on ionic valence

Cation exchange adsorptionCation exchange adsorptionWhat is What is cationcation? ?

----Any element with a positive chargeAny element with a positive chargeTwo groups of Two groups of cationscations in soilsin soils----Basic (electropositive )Basic (electropositive )cationscations: Ca: Ca+2+2, Mg, Mg+2+2, K, K+1+1 and and

NaNa+1+1

----Acidic Acidic cationscations: H: H+1+1 and Aland Al+3 +3

5050Dr. Yuan T, Room 517, Env. Building, Minhang campus, SJTU. (Email: taoyuan@sjtu.edu.cn) BACK

Notes for CECNotes for CECAn indication of the soils potential to hold plant nutrients An indication of the soils potential to hold plant nutrients ( the larger this number, the more ( the larger this number, the more cationscations the soil can the soil can hold)hold)Including both mineral and organic portions (e.g., clay Including both mineral and organic portions (e.g., clay and humus)and humus)Different Different cationscations with different exchange ability (e.g., with different exchange ability (e.g., higher charges with higher exchange ability, Fehigher charges with higher exchange ability, Fe3+ 3+ > Ca> Ca2+2+))Factors affecting CECFactors affecting CEC–– Soil colloid, e.g., organic colloid > Soil colloid, e.g., organic colloid > kaolinekaoline–– Soil texture, e.g., fine particles with higher CEC Soil texture, e.g., fine particles with higher CEC –– Soil condition, e.g., low pH Soil condition, e.g., low pH ------hydroxyl ( OH) dissociation hydroxyl ( OH) dissociation

decreaseddecreased------ negative charge reducednegative charge reduced------CEC decreased CEC decreased

A related concept to CECA related concept to CECPercent base saturationPercent base saturation (electropositive (electropositive saturabilitysaturability ))--------tells what percent of the exchange sites are occupied tells what percent of the exchange sites are occupied

by the basic by the basic cationscations. .

PBS (%)= (exchangeable basic PBS (%)= (exchangeable basic cationscations/ CEC) / CEC) ××100%100%FYI: FYI: ☺☺----Basic (electropositive )Basic (electropositive )cationscations: Ca: Ca+2+2, Mg, Mg+2+2, K, K+1+1 and Naand Na+1+1

----Acidic Acidic cationscations: H: H+1+1 and Aland Al+3 +3

Note: PBS depends on matrix of soil and the climate, etc. Note: PBS depends on matrix of soil and the climate, etc. WHY ? WHY ?

Cation exchange adsorption Cation exchange adsorption Anion exchange adsorptionAnion exchange adsorption

Anion exchange adsorptionAnion exchange adsorption

{Soil colloid{Soil colloid++} A} A-- + {Soil solution} B+ {Soil solution} B--

{Soil colloid{Soil colloid++} B } B -- + {Soil solution} A + {Soil solution} A --

Anions exchanges occur between positively charged soil colloid Anions exchanges occur between positively charged soil colloid and soil solutionand soil solution

Anion exchange adsorptionAnion exchange adsorption–– Strongly adsorptionStrongly adsorption----precipitationprecipitation------

{ PO{ PO4433-- , HPO, HPO44

22-- }+ {Ca}+ {Ca2+2+, Fe, Fe3+3+, Al, Al+3+3}}

–– Less adsorption Less adsorption ClCl--, NO, NO33

--, NO, NO22--, hard to form insoluble salt , hard to form insoluble salt

(any indication? )(any indication? )

CationCation exchangeexchangeNitrification Nitrification OM. DecompositionOM. DecompositionBasic Basic cationscationsAcid rain Acid rain Hydrogen and aluminum Hydrogen and aluminum cationscationsOxidation of sulfur (S) or pyrite (FeS2) Oxidation of sulfur (S) or pyrite (FeS2) Acid residue of inorganic fertilizer Acid residue of inorganic fertilizer

……

Sources of acidSources of acid--base in soil base in soil

Soil Soil acidacid--base scalebase scale

AcidAcid--base property base property

Overview Overview –– Why acidWhy acid--base property occurs in soil?base property occurs in soil?–– Grades of acidGrades of acid--base scalebase scale–– Significance of acidSignificance of acid--base in soilbase in soil

Overview Overview –– Why acidWhy acid--base property occurs in soil?base property occurs in soil?–– Grades of acidGrades of acid--base scalebase scale–– Significance of acidSignificance of acid--base in soilbase in soilAcidity and Acidity and basicitybasicity of soilof soil

(several concepts and buffering effect )(several concepts and buffering effect )

Acidity and Acidity and basicitybasicity of soilof soilActive acidity– is that acidity found in the soil solution or [H+]. Active

acidity is measured by the glass electrode and pH meter.

Exchangeable acidity– is that acidity found on colloid surfaces in soil that are

displaced into solution by a salt solution (usually 1 MKCl).

E.g. Al3+, Al(OH)2+, Al(OH)2+ and other hydroxy compounds on clay surfaces

Al complexed by soil OM carboxyl groups on soil OM

Acidity and Acidity and basicitybasicity of soilof soilNon-exchangeable acidity– is acidity (H+, Al3+) that is not displaced or displaced

very slowly by a salt solution. E.g., weak acid groups on soil OM

organically complexed Al Al- hydroxy cations retained strongly on colloid surfaces

Reserve acidity– is all titratable acidity associated with the solid phase.

It is equal to the sum of exchangeable and non-exchangeable acidity and represents the buffer capacity of a soil.

Percent base saturation vs. reserve acidityWhen PBS =100%, there is no reserve acidity

Acidity and Acidity and basicitybasicity of soilof soil

Active acidity Vs. reserve acidity reserve acidity >> active acidity

e.g., in sand soil, 1000 timesin clay soil (with organic matters), 5X104-1X105 times

Buffering effect{Soil colloid {Soil colloid -- } Na} Na+ + ++HClHCl {Soil colloid {Soil colloid -- } H+ +} H+ +NaOHNaOH

{Soil colloid {Soil colloid -- } H} H+ + + + NaClNaCl {Soil colloid {Soil colloid -- } Na} Na+ + + H+ H22O O

Overview Overview Acidity and Acidity and basicitybasicity of soilof soilAdjustment of soil pH (supplement)Adjustment of soil pH (supplement)

–– Adding acid: FeAdding acid: Fe+3+3, Al, Al3+3+, S, S–– Adding alkali: liming (CaCOAdding alkali: liming (CaCO33))

Oxidant and reductants

Oxidants Oxidants i.i. OO22

ii.ii. NONO33--

iii.iii. MMxx+ + (with higher ionic valences)(with higher ionic valences)

ReductantsReductantsi.i. Organic mattersOrganic mattersii.ii. MMy+ y+ (with lower ionic valences)(with lower ionic valences)

OthersOthersplant roots ; soil biota plant roots ; soil biota ……

RedoxRedox property property

Redox reaction Oxidant and reductantsEEh of soil h of soil

Potential of soil Potential of soil redoxredox ( to evaluate the condition ( to evaluate the condition of of redoxredox ))

Factors affecting redox condition

RedoxRedox property property

Redox reaction Oxidant and reductantsEEh of soil h of soil

Factors affecting redox condition

Significance

Properties of soil Properties of soil

Physical propertiesPhysical properties

AdsorptionAdsorptionAcidAcid--base base RedoxRedox (reduction(reduction--oxidation)oxidation)

Biological property (supplement)Biological property (supplement)

Just for fun Just for fun ☺☺Aoccdrnig to a rscheearch at Cmabrigde

Uinervtisy, it deosn't mttaer inwaht oredr the ltteers in a wrod are, the olny

iprmoetnt tihng is tahtthe frist and lsat ltteer be at the rghit pclae. The

rset can be a totalmses and you can sitll raed it wouthit porbelm.

Tihs is bcuseae thehuamn mnid deos not raed ervey lteter by istlef,

but the wrod as a wlohe.

Soil Environmental Chemistry - SJTUsese.sjtu.edu.cn/web/upload/200752313066491.pdf · Soil...

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