Effects of Acidic Deposition and Calculating Critical Loads of Acidic Deposition

in the Adirondack Region of New York

By Charles T. Driscoll

Syracuse University

Outline

Data sets

Model calculations

Critical load calculations

Conclusions

Collaborators

Syracuse University– Wei Wu– Jing Zhai– Richard Warby– Chris Johnson– Brenden McNeil

NYDEC/ALSC– Karen Roy

SUNY ESF– Myron Mitchell

E&S– Tim Sullivan

Univ. Virginia– Jack Cosby

USDA FS– Linda Pardo– Natasha Duarte

Data Sets and Tools

Survey– ALSC (chemistry, fish)– EMAP/Time (chemistry)– DDRP (chemistry, soil,

foliage)

Monitoring– ALTM (chemistry, soil)– RPI (aquatic biota?)

GIS– Atmospheric deposition– Vegetation– Land disturbance

Models– PnET-BGC (dynamic)– MAGIC (dynamic)– VSD (steady-state)

Cumulative Frequency Diagram for Exch. Al (cmolc/Kg)

Exch. Al Normalized to C (Oa Horizon)

Exchangeable Aluminum (cmolc/Kg)

0 20 40 60 80

% L

es

s t

ha

n E

xc

h. A

cid

ity

0

20

40

60

80

100

19842001

Cumulative Frequency Diagram for Ca (cmolc/Kg)

Ca Normalized to C (Oa Horizon)

Ca (cmolc/Kg)

0 20 40 60 80 100 120 140

% L

es

s t

ha

b C

a

0

20

40

60

80

100

19842001

% L

ess

than C

a

Climatic data•Solar radiation•Precipitation•Temperature

PnET Water balance Photosynthesis Living biomass Litterfall

Net Mineralization

BGC – Surface water Aqueous reactions

Uptake

Deep water flow

Shallow water flow

Weathering

Wet Deposition

Dry Deposition

BGC• Aqueous reactions• Surface reactions

• Cation exchange• Adsorption• Humic binding• Aluminum dissolution/precipitation

Total Nitrate Deposition

1850 1900 1950 2000 2050 2100

g N

/m2 -y

r

0.0

0.2

0.4

0.6

0.8

1.0

Year

Total Sulfate Deposition

1850 1900 1950 2000 2050 2100

g S/

m2 -y

r

0.0

0.5

1.0

1.5

2.0

2.5

Base CaseModerate ControlsAggressive Controls

Indian Lake

SO42-

ueq/

L0

50

100

150

200

250

Base CaseModerateAggressiveMeasured

Ca2+ + Mg2+ue

q/L

0

50

100

150

200

250

year vs ca+mg base year vs Ca+Mg observed year vs Ca+Mg mod year vs Ca+Mg agg

ANC

ueq/

L

-20

0

20

40

pH

Year1850 1900 1950 2000 2050 2100

pH u

nits

4

5

6

7

Indian Lake

SO42-

ueq/

L0

50

100

150

200

250

Base CaseModerateAggressiveMeasured

Ca2+ + Mg2+ue

q/L

0

50

100

150

200

250

year vs ca+mg base year vs Ca+Mg observed year vs Ca+Mg mod year vs Ca+Mg agg

ANC

ueq/

L

-20

0

20

40

pH

Year1850 1900 1950 2000 2050 2100

pH u

nits

4

5

6

7

Model simulated median concentrations for lake chemistry and soil % BS at the 44 EMAP sites for pre-industrial and current conditions.

Pre-industrial conditions (1850)

Current conditions

(1990)

SO42- (μeq/L) 15.9 88.8

NO3- (μeq/L) 3.8 20.0

ANC (μeq/L) 67.7 27.8

pH 6.63 5.95

Soil %BS 12.3 7.9

Indian Lake

SO42-

ueq/

L

0

50

100

150

200

250

Base CaseModerateAggressiveMeasured

Ca2+ + Mg2+ue

q/L

0

50

100

150

200

250

year vs ca+mg base year vs Ca+Mg observed year vs Ca+Mg mod year vs Ca+Mg agg

ANC

ueq/

L

-20

0

20

40

pH

Year1850 1900 1950 2000 2050 2100

pH u

nits

4

5

6

7

The mean water concentrations from model for the 44 EMAP sites in 2000 and 2100 for three future scenarios. Values are expressed as ueq/L, except pH.

20002100

Base Case2100

Moderate2100

Aggressive

SO42-+NO3

- 92.3 79.8 55.7 46.0

ANC 48.0 47.8 62.1 68.4

pH 5.90 5.86 6.10 6.19

pH

pH

4.5 5.0 5.5 6.0 6.5 7.0 7.5

0.0

0.2

0.4

0.6

0.8

1.0

NO3-

0 10 20 30 40 50

0.0

0.2

0.4

0.6

0.8

1.0

185019802100 base case2100 mod case2100 agg case

SO42-

0 20 40 60 80 100 120 140 160 180

Cum

ulat

ive

Pop

ulat

ion

of L

akes

0.0

0.2

0.4

0.6

0.8

1.0

Mg2++Ca2+

0 100 200 300 400

Cum

ulat

ive

Pop

ulat

ion

of L

akes

0.0

0.2

0.4

0.6

0.8

1.0ANC

0 50 100 150 200

Cum

ulat

ive

Po

pula

tion

of L

akes

0.0

0.2

0.4

0.6

0.8

1.0

%BS

0 5 10 15 20 25 30

0.0

0.2

0.4

0.6

0.8

1.0

Very Simple Dynamic ModelAtmospheric deposition

Net nutrient uptake

RootingZone

Soil leachingSoil weathering

Biomass removal

N ImmobilizationN leaching = f(soil C:N)

BC Exchange(Gapon or Gaines-Thomas)

Conclusions

Soils and surface waters in the Adirondacks have been impacted by acidic deposition

Databases, data layers and tools are available to facilitate critical load calculations

Regional scale applications of PnET-BGC have been conducted to quantify past and potential future response of soil and lakes to changes in acidic deposition

Preliminary efforts are underway to investigate critical load calculations in the Adirondacks