ANALYSIS and MODELING OF ACID NEUTRALIZING CAPACITY
in The MID-ATLANTIC HIGHLANDS AREA
Brett R. Kellum, Jennifer A. Hoeting, and N. Scott Urquhart
STARMAP, Department of Statistics, Colorado State University
 Values can be positive or negative
 Elevation
 Negative values mean the solution is already acidic
 Thirteen Thematic Mapper Satellite Imagery Classifications
 Low, positive values indicate sensitivity to acidification (0 to 200)
of Acid Neutralizing Capacity - DARM Data Set
 Strahler Histogram
Stream Order
HISTOGRAM OF
ANC
Complete Observations in VA & WV
0.20
0.00
0.20
n = 238
0.0
0
 Mid-Atlantic Highlands Area (MAHA) Region 3: PA, VA, WV, DE, MD
 Data collected by EPA’s EMAP
1000
2000
3000
4000
5000
6000
 ANC sampled at 579 sites
AVAILABLE
PREDICTORS
 Elevation
 Strahler Stream Order
 Bedrock Geology
Available only for VA, WV at the
time of analysis
Not Available
Argillace
Siliceous
Carbonate
Felsic
Mafic
Unclassified
1.5
2.0
2.5
 Anisotropic spatial correlation was found in the
residuals of this multiple regression model.
 It is possible to model ANC using remotely
sensed predictors using
0.05
MODEL SELECTION
0.0
0.5
1.0
1.5
2.0
2.5
Euclidean distance between stream sites
 Leaps and Bounds selection procedure using Minimum
 Sites sampled from 1993 through 1996
1.0
CONCLUSIONS
ANC
AVAILABLE DATA
0.5
Euclidean distance between stream sites
0
 Goal: Predict ANC at unobserved sites using remotely sensed predictors
SEMIVARIOGRAM OF RESIDUALS
0.15
that are “at risk”?
 Also referred to as omni-directional correlation
Semi-Variance
 Can this monitoring be done from a distance, or can we identify locations
distance.
20
acidification of lakes and streams
# of observations
40
 The Clean Air Act Amendments of 1990 mandated the monitoring of
60
WHY MODEL ANC?
 Looks at relationship between sites separated by a given
0.05
80
Isotropic Correlation
0.15
 Five Bedrock Geologic Classes
Angle of correlation = 45° and span = 30°
0.10
 Measure of a solution’s ability to buffer itself against acidification
EXPLORING SPATIAL
CORRELATION
Semi-Variance
ACID NEUTRALIZING CAPACITY (ANC)
EXPLORATORY DATA
ANALYSIS
0.10
CONTEXT
ANISOTROPIC SEMIVARIOGRAM
OF RESIDUALS
Mallow’s Cp criterion
ANISOTROPIC SPATIAL CORRELATION
 Efroymson’s Forward Stepwise procedure
 Looks at relationship between sites separated by a given
“Best” Regression Model of ln(ANC+500)
distance in a given direction.
 Also referred to as directional correlation
Predictor
(Intercept)
Probable
ln(Pasture)
ln(Urban High
Density)
ln(Emergent
Wetlands)
ln(Woody
Wetlands)
ln(Quarry)
Carbon
Felsic
Elevation
Coefficient
7.506
0.012
0.051
Standard Error
0.157
0.004
0.011
P-value
<0.001
<0.001
<0.001
0.063
0.019
<0.001
0.046
0.021
0.033
-0.073
0.020
0.542
-0.273
-0.001
R2 = 0.5781
0.019
0.012
0.101
0.102
<0.001
= site not correlation
with site (x,y)
= site correlated with
site (x,y)
DEFINITIONS
Overall p-value < 0.0001
FUTURE WORK
 Expand to all of EPA’s Region 3
 Summarize geology above sample point
 Investigate model uncertainty
 Expand to small area estimation
FUNDING/DISCLAIMER
Angle of Span (d)
The work reported here was developed under the STAR Research Assistance Agreement CR829095 awarded by the U.S. Environmental Protection Agency (EPA) to Colorado State
University. This poster has not been formally reviewed by EPA. The views expressed here are
solely those of the authors and STARMAP, the Program they represent. EPA does not endorse
any products or commercial services mentioned in this poster.
<0.001
0.084
<0.001
0.008
<0.001
 Multiple regression model with
 Anisotropically correlated residuals (in Virginia and West Virginia)
Site (x,y)
Angle of Correlation ()
This research is funded by
U.S.EPA – Science To Achieve
Results (STAR) Program
Cooperative # CR - 829095
Agreement