impacts of dirt and gravel road dust 9-22-09
TRANSCRIPT
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Impacts of Dirt and Gravel Impacts of Dirt and Gravel
Road Dust on Roadside Road Dust on Roadside
Organic Forest SoilsOrganic Forest Soils
& &
Roadside VegetationRoadside Vegetation
Introduction
• Study - effects of imported limestone driving
surface aggregate (DSA) and native driving
surface aggregate on roadside forest soils and
vegetation in central PA
• Dirt & Gravel Roads are an important part of
PA’s Road system
– Tourism
– Agriculture
– Mining
– Forestry
Introduction
• Causes of Dust
– Vehicles
• Tires pulverize road aggregate
• Dust becomes airborne due to turbulent
wind
• Suspended dust deposits alongside
roadways
–Less than 2.5 micrometers stays
suspended
–Greater than 2.5 micrometers settle
back to ground
Introduction
• Dust variables
– Vehicle
• Weight
• Speed
• Linear relationship (Sanders & Addo 1993)
– Road surface
• Aggregate abrasion resistance
• Silt content
• Moisture Content
Introduction
• Dust
– Impacts on roadside vegetation
• Covers foliage & blocks sunlight
• Clogs plant pores (Addo et al. 2004)
• Increases leaf temperature
• Increases water loss
• Decreases photosynthesis (L. Frazer 2003)
Introduction
• Research
• Machian and Navas 2000 – Spain - magnesite calcination factory increased the soil pH from a value of 7 to 9.5 pH over 40 years
• Viskari et al., 1997– Snow samples & mossbags to assess airborne pollutants
– Results showed inverse relationship between concentrations & distance from road
– Most pollutants deposited within 30 meters
– Calcium & Chloride deposited out to 60 meters
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Introduction
• Hagen et al. 2006
– Wind erosion from a small field with erodible
Amarillo fine sand loam soils
– 30% of the dust deposited within fifty (50)
meters
– 12-15% deposited within the 10 meters
Introduction
• Center for Dirt & Gravel Road Studies (CDGRS)
– Dust Suppressant Study utilizing dustfall jars
– Jars placed at 30’ (9.14 m), 60’ (18.28 m) & 120’(36.57 m) from road edge.
– Greatest amount of dust collected at 30’
• 66% decrease at 60’
• 83% decrease at 120’
Introduction
• Literature Review Indications
– Input of dust over time can affect soil chemistry
– Dust is capable of being transported by wind
– Majority of dust falls within 200m of road
Focus of Research
• Does limestone Driving Surface Aggregate
(DSA) Dust & Native Aggregate Surface Dust
have an effect on roadside forest soil chemistry?
• Does dust impact roadside vegetation?
Driving Surface Aggregate (DSA)
• Limestone DSA
– CDGRS Specification
– 5 size gradations
• Maximum – 1 ½”
• Minimum – 1/200th (#200 sieve) of an inch
• Compacts densely & long wearing
• Still produces Dust
Crowfield Rd. Limestone DSA
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Sand Mt. Rd. Limestone DSA Driving Surface Aggregate (DSA)
• Native Driving Surface Aggregate
– Outcropping bedrock
– Derived from physiographic region where
road is located
Methods
• Soil samples collected along 4 different road
segments
– 2 surfaced with limestone DSA
– 2 surfaced with native aggregate
• Located within Seven Mts. Region of Central PA
– Bald Eagle State Forest
– Rothrock State Forest
Methods
• Road selection criteria
– Geological province (ridge and valley)
– Similar soils
– Similar vegetative cover
– Aligned in the same general compass direction
– Suitable surface aggregate
• Limestone DSA in place min. of 4 years
– Traffic – low volume roads
Methods Road Segments
• Crowfield Road
• Limestone DSA & Native Aggregate
• Sand Mountain Road
– Limestone DSA
• Pine Swamp Road
– Native aggregate
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Crowfield Road
Limestone DSA
Native Aggregate
Sand Mountain Road
Limestone DSA
Pine Swamp Road
Native Aggregate
Road Locations
Pine Swamp Rd
Sand Mt. Rd.
Crowfield
Rd
Soil Samples
• Samples collected along road segments
– Organic soil layer (O horizon)
– Most likely to show evidence of dust impacts
• 3 samples collected at each sampling point
– 1 Oi consisting of fallen leaves from previous fall
– 2 Oe & Oa combined
• Analyzed at Agricultural Analytical Services Laboratory
Sampling LayoutCross-sections and Sampling Layout
200m
1m
10m
100m
200m
1m
10m
100m
245m
90m
Beginning of
Road Segment
Soil sampling locations
Aggregate sampling locations
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Soil Samples
• 3 cross sections per road segment
– Cross sections spaced 90 meters apart
• Samples collected perpendicular to road
– 1 meter
– 10 meters
– 100 meters
– 200 meters
• Each side of segment sampled to account for wind
Soil Samples
• 200 meter sampling point on each cross-section
used as reference
– Minimal dust impact predicted at 200 meters
– Determined from CDGRS dust fall jar sampling
• ***1 meter sampling points located within disturbed
area
Soil Sample Analysis• Oi Samples
– Foliar Analysis, Dry Ash Method (Miller 1998)
– Ca, Mg, Mn, Fe, Cu
• Oe & Oa Samples
– Soil Fertility Test
• pH, Ca, Mg, P, K
– Aluminum Stress Test
• CA & Al, Ca:Al ratio
• Potential stress of Al on forest tree species when grown on soils with a pH less than 5.5
Soil Sample Analysis
• Samples weighed prior to analysis
• Elemental analyses for all three testing methods
was performed using a Thermo 61E ICP
• pH was obtained with a Thermo Orion electrode
• High Ca concentrations in 80 of the Soil Fertility
Tests indicated probable presence of soluble Ca
Aggregate Samples
• Composite aggregate samples of each road
segment were collected for mineral analysis.
• Composite samples were composed of three
separate samples of road aggregate taken on
each cross-section.
• X-ray diffraction for mineral composition
Soil Sample Statistical Analysis
• Analysis of Variance General Linear Model
– Determine what effects surface treatments of
the road segments had on adjacent soils
• Test Limestone DSA vs. Native Aggregate
• Determine if road surface, wind, distance, or a
combination was significant
• Statistical alpha of 0.05
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Soil Sample Statistical Analysis• Dunnett’s Multiple Comparison with reference point
• After testing for significant effects caused by the road segments, i.e. side and distance
• Compare 1m, 10m, & 100m to 200m point
• Inter-comparisons of sampling distances to the 200 m reference site
– Analyze each distance individually along road segments
• Test results at one distance would not have any effect on statistical significance for the other distances when tested against reference point.
• Statistical alpha of 0.05
Vegetation
• Sampled at the 10-meter sampling sites along each
road cross-section in May 2006
• 10x10m & 1m square plot sampled
– 10-meter point center of the plot.
• 10x10-meter plot was used for sampling woody plant
species
• 1x1 meter plot was for seedling and herbaceous plant
species
Vegetation
• Did not sample:
– Soil moisture,
– canopy density
– micro-climate
– micro-topography
• Time Constraints
Vegetation Statistical Analysis
• Statistical analysis of the vegetation was
performed using Analysis of Variance (ANOVA)
One-way General Linear Model
– Compare limestone vs. native aggregate
segments
• Test Limestone DSA vs. Native Aggregate
• An alpha value of 0.05 was used to determine
the statistical significance of the results.
RESULTS
Road Surface Aggregate• Composite samples analyzed
• X-ray diffraction used to determine aggregate
mineral components
• Verify limestone DSA & Native Aggregate
10 20 30 40 50 60 70
Two-Theta (deg)
0
250
500
750
1000
Inte
ns
ity
(Co
un
ts)
00-046-1045> Quartz - S iO200-047-1743> Calc ite - CaCO3
00-036-0426> Dolomite - CaMg(CO3)200-025-0649> Mus c ovite-2M2 - (K ,Ca,Na)(A l,Mg,Fe)2(S i,A l)4O10(OH)2
Sand Mt. Road Limestone DSA
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Crowfield Road
– Crowfield Limestone DSA
• Calcite (CaCO3), Dolomite (Ca Mg (CO3)2, and Quartz (SiO2)
– Crowfield Native Driving Surface Aggregate
• Contained calcite (CaCO3), and dolomite (Ca Mg (CO3
• Not native aggregate
Sand Mountain Road
• Limestone DSA
– Calcite, dolomite, quartz and muscovite
(KAl2Si3AlO1O[OH}2)
– Similar to Crowfield limestone DSA segment
Pine Swamp Road
• Native Aggregate Driving Surface
– Quartz and muscovite
• Not impacted by limestone aggregate
General Linear Model Results
• Limestone DSA vs. Native Aggregate Comparison
• Road segment, direction (wind) & distance tested in
General Linear Model against soil test results
General Linear Model Results
• Distance & Segment statistically significant
– Influence roadside soil chemistry
• Limestone DSA has greater effect than native aggregate on roadside soils
– Ph, Ca, Mg, Mn higher
– Fe & Zn not significantly different between segments
• **Direction (wind) not significant**
Soil Fertility Tests
Mean pH vs. Distance
Oe & Oa Horizons
0
1
2
3
4
5
6
7
8
9
10
1m 10m 100m 200m
pH
Crowfield limestone DSA
Crowfield Native
Sand Mt. limestone DSA
Pine Swamp Native
Segment Arranged by Distance
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Soil Fertility Tests
Mean Mg vs. Distance
Oe & Oa Horizons
0
500
1000
1500
2000
2500
1m 10m 100m 200m
Mg. (ppm)
Crowfield limestone DSA
Crowfield Native
Sand Mt. limestone DSA
Pine Swamp Native
Mean Ca vs. Distance
Oe & Oa Horizons
0
5000
10000
15000
20000
25000
1m 10m 100m 200m
Mean Ca (ppm)
Crowfield limestone DSA
Crowfield Native
Sand Mt. limestone DSA
Pine Swamp Native
Soil Fertility Tests
Rd. Segment Mean Ca:Al Ratio vs. Distance
Oe & Oa Horizons
0
2000
4000
6000
8000
10000
12000
14000
1m 10m 100m 200m
Crowfield limestone DSA
Crowfield Native
Sand Mt. limestone DSA
Pine Swamp Native
Al. Stress Test
Rd. Segment Mean Extractable Al vs. Distance
Oe & Oa Horizons
0
0.2
0.4
0.6
0.8
1
1.2
1m 10m 100m 200m
Al (m
g/kg)
Crowfield limestone DSA
Crowfield Native
Sand Mt. limestone DSA
Pine Swamp Native
Al. Stress Test
Dunnet’s Multiple Comparisons Results
• General Linear Model showed Distance
significant
• Further analysis of Distance
– How significant is it?
– How far out from the road edge does road
dust effect soil chemistry?
• Segment specific
– Compare 10m & 100m sampling points to
200m reference point
Dunnet’s Multiple Comparisons Results
• Native aggregate driving surface
– No significant differences in soil composition
between sampling points
– Observed increases in pH & Ca not significant
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• Limestone DSA
– Significant differences between 200m
reference point
– Inverse relationship - closer to the road the
higher the concentrations
– Direct relationship for Oe & Oa Extractable Al
Dunnet’s Multiple Comparisons Results Mean pH of Oe and Oa Horizon vs.
Distance from Road Surface
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
Crowfield
limestone DSA
Crowfield Native Sand Mt.
limestone DSA
Pine Swamp
Native
Me
an
pH
1m
10m
100m
200m
Mean Ca of Oa and Oa Horizons vs.
Distance from Road Surface
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Crowfield
limestone DSA
Crowfield Native Sand Mt.
limestone DSA
Pine Swamp
Native
Me
an
Ca
(p
pm
)
1m
10m
100m
200m
Mean Ca of Oa and Oa Horizons vs.
Distance from Road Surface
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Crowfield
limestone DSA
Crowfield Native Sand Mt.
limestone DSA
Pine Swamp
Native
Me
an
Ca
(p
pm
)
1m
10m
100m
200m
Oi Horizon Mg vs. Distance from Road
Surface
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Crowfield
limestone DSA
Crowfield Native Sand Mt.
limestone DSA
Pine Swamp
Native
Me
an
Mg
(p
pm
)
1m
10m
100m
200m
% Base Saturation vs. Distance
from Road Surface
0
20
40
60
80
100
120
140
Crowfield limestone
DSA
Crowfield Native Sand Mt. limestone
DSA
Pine Swamp Native
Percent (%
) Base Saturation
1m
10m
100m
200m
10
Oe and Oa Horizon Extractable Al vs.
Distance from the Road Surface
0
0.2
0.4
0.6
0.8
1
1.2
Crowfield
limestone DSA
Crowfield
Native
Sand Mt.
limestone DSA
Pine Swamp
Native
Mean Al (m
g/kg)
1m
10m
100m
200m
Mean Ca:Al Ratio in Oe & Oa Horizon vs. Distance
from the Road Surface
Dunnet’s Multiple Comparison
0
50
100
150
200
250
300
350
400
Crowfield
limestone DSA
Crowfield Native Sand Mt.
limestone DSA
Pine Swamp
Native
Ca
lciu
m (
mg
/kg
)
1m
10m
100m
200m
Mean Mn in Oi Horizon vs. Distance from
the Road Surface
0
1000
2000
3000
4000
5000
6000
7000
Crowfield limestone
DSA
Crowfield Native Sand Mt. limestone
DSA
Pine Swamp Native
Mn (ug/g) 1m
10m
100m
200m
Vegetation Results
• Statistically Significant difference between plant
spp. & Road Segments
• Limestone DSA Segments
– Higher counts of Japenese barberry (Berberis
thunbergii) & multiflora rose (Rosa multiflora)
• Prefer neutral soil pH
– Crowfield Rd. Limestone DSA had highest mean #
of tree seedling per cross-section
Vegetation Results
• Native Aggregate Driving Surface
– Higher number of native plant spp.
– Mt. laurel (Kalmia latifolia), lowbush blueberry
(Vaccinium augustifolium a
• Like acidic soils
• Pine Swamp Road had highest mean # of
trees/shrubs per cross-section
Mean # Tree/Shrubs per Cross-Section
0
10
20
30
40
50
60
70
80
90
Crowfield Road DSA Crowfield Road Native
Aggregate
Sand Mt. Road DSA Pine Swamp Road
Native Aggregate
# Tree/Shrubs
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Mean # Tree Seedlings per Cross-Section
0
20
40
60
80
100
120
Crowfield Road
DSA
Crowfield Road
Native Aggregate
Sand Mt. Road
DSA
Pine Swamp Road
Native Aggregate
Sand Mt. Road Limestone DSA Segment
Sand Mt. Road Limestone DSA Segment
Pine Swamp Road
Pine Swamp Road
Conclusions
• Dirt & gravel road dust from both limestone
DSA and native aggregate segments affect
the chemistry of roadside forest soils.
• Limestone driving surface aggregate had a
significantly greater effect.
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Conclusions
• Overall inverse relationship between soil
chemistry change and distance from road
edge
• Chemical changes to roadside soils from
limestone DSA dust appeared to increase
presence of invasive/exotic plant specie