Critical Loads Meeting at Mission Inn, Riverside CA February 15-18 2005 Jack Cosby University of Virginia Scientific Justification for Using the Critical

Critical Loads Meeting at Mission Inn, Riverside CACritical Loads Meeting at Mission Inn, Riverside CA

February 15-18 2005February 15-18 2005

Jack CosbyJack Cosby

University of VirginiaUniversity of Virginia

Scientific Justification for Using the Critical Loads Scientific Justification for Using the Critical Loads ApproachApproach

Geochemical ProcessesGeochemical Processes

Patterns of ResponsePatterns of Response

Dynamics of ResponseDynamics of Response









Atmosphere

Soil andSoil Water

Stream Water

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

ANC > 0.0ANC > 0.0

Atmosphere

Soil andSoil Water

Stream Water

Al-X

Al(OH)3

HCO3

H+ Al 3+

Al 3+

CO2

Al(OH)3

CO2 Al 3+HCO3

H+ OH -

ANC = 0.0ANC = 0.0

Atmosphere

Soil andSoil Water

Stream Water

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

Primary Mineral

BC+ Weathering

Long-term Steady-Long-term Steady-state Conditionstate Condition

Weathering rate = Weathering rate = ANC production rateANC production rate

ANCANCSSSS > 0.0 > 0.0

Atmosphere

Soil andSoil Water

Stream Water

Effects of Acidic Effects of Acidic Deposition on Deposition on

Soils and Soils and Drainage WatersDrainage Waters

H2SO4

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

BC+ Weathering

ANCANCSSSS > 0.0 > 0.0

Atmosphere

Soil andSoil Water

Stream Water

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

BC+ Weathering

H+ OH-

H2SO4

SO42-

SO4 -X

Initial Response to Initial Response to Acidic DepositionAcidic Deposition

- without mobile anion -- without mobile anion -

Buffering by adsorption Buffering by adsorption of sulphate anionof sulphate anion

ANC > 0.0ANC > 0.0

Atmosphere

Soil andSoil Water

Stream Water

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

BC+ Weathering

H+

H2SO4

SO42-

SO4 -X

SO42-

SO42-

Initial Response to Initial Response to Acidic DepositionAcidic Deposition

- with mobile anion -- with mobile anion -

Buffering by cation Buffering by cation exchangeexchange

ANC > 0.0ANC > 0.0

( neutral salt ( neutral salt of sulphate )of sulphate )

Atmosphere

Soil andSoil Water

Stream Water

Long-term Response Long-term Response to Acidic Depositionto Acidic Deposition

depletion of soil depletion of soil base saturationbase saturation

Al-X

CO2

Al(OH)3

BC+

BC+

H+ Al 3+

HCO3

Al 3+

BC+ Weathering

Al(OH)3

CO2 Al 3+HCO3

H+ OH -

H+

H2SO4

SO42-

SO4 -X

SO42-

SO42-

???

Final ANC Final ANC depends on depends on

relative relative magnitudes of magnitudes of

BC and SOBC and SO44

Atmosphere

Soil andSoil Water

Stream Water



Al-X

CO2

Al(OH)3

BC+

BC+

H+ Al 3+

HCO3

Al 3+

BC+ Weathering

Al(OH)3

CO2 Al 3+HCO3

H+ OH -

H+

H2SO4

SO42-

SO4 -X

SO42-

SO42-

HCO3

If BC > SOIf BC > SO44

ANC > 0.0ANC > 0.0

( but < ANC( but < ANCSS SS ))

Atmosphere

Soil andSoil Water

Stream Water



Al-X

CO2

Al(OH)3

BC+

BC+

H+ Al 3+

HCO3

Al 3+

BC+ Weathering

Al(OH)3

CO2 Al 3+HCO3

H+ OH -

H+

H2SO4

SO42-

SO4 -X

SO42-

SO42-

H+ Al3+

If SOIf SO44 > BC > BC

ANC < 0.0ANC < 0.0

Atmosphere

Soil andSoil Water

Stream Water

Initial Recovery from Initial Recovery from Acidic DepositionAcidic Deposition

replenishment of replenishment of soil base saturationsoil base saturation

Al-X

CO2

Al(OH)3

BC+

H+ Al 3+

HCO3

Al 3+

BC+ Weathering

Al(OH)3

CO2 Al 3+HCO3

H+ OH -

ANC ~ 0.0ANC ~ 0.0

( ANC < ANC( ANC < ANCSSSS ) )

Atmosphere

Soil andSoil Water

Stream Water

Final Recovery from Final Recovery from Acidic DepositionAcidic Deposition

soil base saturation soil base saturation restoredrestored

Al-X

BC-X

CO2

Al(OH)3

HCO3

BC+

BC+

H+ Al 3+

HCO3

BC+ Weathering

ANC = ANCANC = ANCSSSS









Use Dynamic Model for Use Dynamic Model for Quantitative Understanding Quantitative Understanding

of Changes in Soil of Changes in Soil Properties Responsible for Properties Responsible for Time Scales of Acidification Time Scales of Acidification

and Recoveryand Recovery

-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%


of Changes in Soil Acid-of Changes in Soil Acid-Base Properties During Base Properties During

Acidification and RecoveryAcidification and Recovery

-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B




-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C




-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D




-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

-60

-30

0

30

60

0 50 100 150 200

SO4 ueq/L

AN

C u

eq/L BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D

4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%4.5

5.5

6.5

7.5

0 50 100 150 200

SO4 ueq/L

Soi

l pH

BS = 20%

BS = 15%

BS = 10%

BS = 5%

A

B

C

D









Recovery delay time

From the UN ECE ICP mapping and

modeling (Max Posch)

DDT:Damage delay time

RDT:Recovery delay time

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5

Critical load

Critical response

Chemical target (ANC)B

iolo

gic

al

res

po

ns

eA

cid

de

po

sit

ion

Ch

em

ica

l re

sp

on

se

t1 t2 t3 t4 t5 t6

RDTDDT

Documents

Critical Loads Meeting at Mission Inn, Riverside CA February 15-18 2005 Jack Cosby University of Virginia Scientific Justification for Using the Critical