12/30/2016
Evaluation of Traditional Soil
Testing Methods to Estimate Lead
(Pb) Hazard.
Health Consequences of Blood Lead
•
•
•
•
http:///
Shannon Plunkett, Douglas Soldat PhD
Dept. of Soil Science, University of Wisconsin- Madison
http://projects.seattletimes.com/2014/loaded-with-lead/3/
Seasonality of Blood Lead
Mean Monthly Blood Lead of
Wisconsin Children Younger
than Six (1996-2008).
Learning disabilities1
Reduced tests scores 2,3,4
Lower IQ scores 5,6,7
Antisocial behavior 8
Blood lead below 5μg/dL associated with:
• ADHD 9
• Behavior problems 9
• Decreased cognitive performance 9
1.
2.
3.
4.
5.
e.g. Nigg et al., 2010
Zahran et al., 2009
Chandramouli et al., 2009
Miranda et al., 2007
Canfield et al., 2003
6.
7.
8.
9.
Jusko et al., 2008
Surkan et al., 2007
e.g. Wright et al., 2008
e.g. NTP, 2012
Map of
Soil and
Blood Pb
in New
Orleans
Havlena et al., 2009
Zahran et al., 2011
In Situ Remediation of Pb Contamination
Problems with Soil Pb Remediation
Issue 1: The EPA regulates soil Pb using total Pb
• Cotter-Howells et al., (1991) publicized the
connection between pyromorphite ( a lead
phosphate) and poor human absorption.
• Phosphorus additions are common because
they can encourage pyromorphite formation
(e.g. Zia et al., 2011)
Barringer, 2011
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12/30/2016
Problems with Soil Pb Remediation
Problems with Soil Pb Remediation
Issue 1: The EPA regulates soil Pb using total Pb
Issue 1: The EPA regulates soil Pb using total Pb
Issue 2: Soil Pb remediation increasingly revolve around
Issue 2: Soil Pb remediation increasingly revolve around
altering Pb bioavailability
altering Pb bioavailability
Issue 3: Total Pb tests are not sensitive to Pb bioavailability
Problems with Soil Pb Remediation
Issue 1: The EPA regulates soil Pb using total Pb
Issue 2: Soil Pb remediation increasingly revolve around
altering Pb bioavailability
Issue 3: Total Pb tests are not sensitive to Pb bioavailability
Issue 4: Existing Pb bioaccessibility assays are expensive or
OBJECTIVE
The objective of this research is to
evaluate the ability of common,
inexpensive soil tests to estimate
bioaccessible lead.
not easily accessible
METHODS AND MATERIALS
METHODS AND MATERIALS
Incubation with Pb(NO3)2 and KCl:
Incubation with Pb(NO3)2 and KCl:
• Plano series silt loam spiked with Pb(NO3)2 solution in seven wet/dry cycles at room
• Plano series silt loam spiked with Pb(NO3)2 solution in seven wet/dry cycles at room
temperature. Target: 2000 mg Pb kg-1
• Soil incubated with KCl solution (10:1 soil: solution) to target ratio 5:2 Pb:Cl
temperature. Target: 2000 mg Pb kg-1
• Soil incubated with KCl solution (10:1 soil: solution) to target ratio 5:2 Pb:Cl
Phosphoric Acid Treatment:
• Divided into six treatment groups
• No Phosphorus
• 5:1 P:Pb
• 1:1 P:Pb
• 10:1 P:Pb
• 2:1 P:Pb
• 25:1 P:Pb
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METHODS AND MATERIALS
METHODS AND MATERIALS
Incubation with Pb(NO3)2 and KCl:
Phosphorus tests:
1.
2.
3.
• Plano series silt loam spiked with Pb(NO3)2 solution in seven wet/dry cycles at room
temperature. Target: 2000 mg Pb kg-1
• Soil incubated with KCl solution (10:1 soil: solution) to target ratio 5:2 Pb:Cl
Olsen (Olsen et al., 1954, 0.5 M NaHO3)
Mehlich 1 (Kamprath & Watson, 1980, 0.05 M HCl + 0.0125 M H2SO4)
Mehlich 3 (Mehlich, 1984, 0.2 N CH3COOH, 0.25 N NH4NO3, 0.015 N NH4F, 0.013 N HNO3,
0.001 M EDTA)
4.
Phosphoric Acid Treatment:
Bray (Bray & Kurtz, 1945, 0.025 M HCl in 0.03 M NH4F)
• Divided into six treatment groups
• No Phosphorus
• 5:1 P:Pb
• 1:1 P:Pb
• 10:1 P:Pb
• 2:1 P:Pb
• 25:1 P:Pb
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Amended with H3PO4 solution (1:1 soil: solution) and stirred daily until dry.
•
Added Ca(OH)2 to increase pH. Final pH 5.65-6.64.
METHODS AND MATERIALS
METHODS AND MATERIALS
Phosphorus tests:
1.
2.
3.
Phosphorus tests:
Olsen (Olsen et al., 1954, 0.5 M NaHO3)
Mehlich 1 (Kamprath & Watson, 1980, 0.05 M HCl + 0.0125 M H2SO4)
Mehlich 3 (Mehlich, 1984, 0.2 N CH3COOH, 0.25 N NH4NO3, 0.015 N NH4F, 0.013 N HNO3,
1.
2.
3.
0.001 M EDTA)
4.
0.001 M EDTA)
Bray (Bray & Kurtz, 1945, 0.025 M HCl in 0.03 M NH4F)
4.
Heavy metal test:
1.
DTPA
Olsen (Olsen et al., 1954, 0.5 M NaHO3)
Mehlich 1 (Kamprath & Watson, 1980, 0.05 M HCl + 0.0125 M H2SO4)
Mehlich 3 (Mehlich, 1984, 0.2 N CH3COOH, 0.25 N NH4NO3, 0.015 N NH4F, 0.013 N HNO3,
Bray (Bray & Kurtz, 1945, 0.025 M HCl in 0.03 M NH4F)
Heavy metal test:
1.
(Lindsay & Norvell, 1978, 0.005 M DTPA + 0.1 M TEA + 0.01 M CaCl 2)
DTPA
(Lindsay & Norvell, 1978, 0.005 M DTPA + 0.1 M TEA + 0.01 M CaCl 2)
Total Pb test:
1.
LEAD MINERALOGY VIA EXAFS
METHODS AND MATERIALS
Pb Bioaccessibility Assays:
1.
2.
Modified RBALP (Drexler & Brattin, 2007, 0.4 M glycine, pH 2.5)
0.4 M Glycine (Chaney, 2012, 0.4 M glycine, pH 2.5)
1 N HNO3 (Chaney & Sterett, 1984)
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Samples analyzed via x-ray absorption
fine structure spectroscopy at beamline
10- BM at the Advanced Photon
Source at Argonne National
Laboratory
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Ground samples combined with PVP,
pressed into pellets, mounted with
Kafton tape
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Fluorescence mode
All filtrates analyzed using ICP-OES at 200nm
http://www.mccormick.northwestern.edu/magazine/fall2011/northwestern-argonne.html
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Influence of Phosphorus Additions on Pb Extractability
Influence of Phosphorus Additions on Pb Extractability
1 N HNO3
100
RBALP
100
80
1 N HNO3
60
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•
•
•
Total Pb
Inexpensive
Accessible
Not sensitive
40
Relative Extractable Pb (%)
Relative Extractable Pb (%)
(Chaney & Sterett, 1984)
20
60
RBALP
• Expensive
• Inaccessible
• EPA Standard
40
0
0
5
10
15
20
25
0
5
10
Added P (P: Pb)
15
20
25
Added P (P: Pb)
Influence of Phosphorus Additions on Pb Extractability
Influence of Phosphorus Additions on Pb Extractability
0.4 M Glycine
100
1 N HNO3
RBALP
60
0.4 M Glycine
40
Relative Extractable Pb (%)
• Sensitive
• Inaccessible
80
Mehlich 3
100
1 N HNO3
Relative Extractable Pb (%)
(Drexler & Brattin, 2007)
20
0
20
80
(Mehlich, 1984)
RBALP
0.4 M Glycine
60
Mehlich 3
• Inexpensive
• Very common
• Moderately
sensitive
40
20
0
0
0
5
10
15
20
25
0
5
10
Added P (P: Pb)
15
20
25
Added P (P: Pb)
Influence of Phosphorus Additions on Pb Extractability
Influence of Phosphorus Additions on Pb Extractability
Mehlich 1
1 N HNO3
(Kamprath & Watson, 1980)
RBALP
80
0.4 M Glycine
Mehlich 3
60
Mehlich 1
40
20
• Inexpensive
• Very common
• Sensitive
DTPA
100
1 N HNO3
Relative Extractable Pb (%)
100
Relative Extractable Pb (%)
1 N HNO3
80
(Lindsay & Norvell, 1978)
RBALP
80
0.4 M Glycine
Mehlich 3
Mehlich 1
60
• Inexpensive
• Common
• Very sensitive
DTPA
40
20
0
0
0
5
10
15
Added P (P: Pb)
20
25
0
5
10
15
20
25
Added P (P: Pb)
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Influence of Phosphorus Additions on Pb Extractability
Influence of Phosphorus Additions on Pb Extractability
Olsen
RBALP
(Olsen et al., 1954)
Relative Extractable Pb (%)
80
0.4 M Glycine
• Inexpensive
• Very common
• Very sensitive
Mehlich 3
Mehlich 1
60
DTPA
Olsen
40
20
100
1 N HNO3
Relative Extractable Pb (%)
1 N HNO3
100
RBALP
0.4 M Glycine
80
Mehlich 3
Mehlich 1
60
DTPA
Olsen
40
20
0
0
0
5
10
15
20
25
0
5
Added P (P: Pb)
15
20
25
Added P (P: Pb)
"Bioaccessible" Pb
100
Melhich 3/ 1 N HNO3 (%)
10
Mehlich 3
extractable Pb : 1
N HNO3
extractable Pb may
approximate
RBALP extractable
Pb : total Pb
digestion
80
60
40
20
EXAFS
0
0
5
10
15
20
25
Added P (P: Pb)
Summary
Summary
• Phosphorus amendments increasingly common
• Phosphorus amendments increasingly common
• Lack affordable, accessible soil tests that measure Pb
bioaccessibility
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Summary
Summary
• Phosphorus amendments increasingly common
• Phosphorus amendments increasingly common
• Lack affordable, accessible soil tests that measure Pb
• Lack affordable, accessible soil tests that measure Pb
bioaccessibility
• Common soil tests have a range of sensitivities to phosphate
bioaccessibility
• Common soil tests have a range of sensitivities to phosphate
amendment
amendment
• In vivo research needed to identify which test is most
representative of Pb bioavailability
Summary
• Phosphorus amendments increasingly common
• Lack affordable, accessible soil tests that measure Pb
Acknowledgements
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•
USDA- Hatch Grant
Committee:
• Dr. Douglas Soldat (advisor)†
• Dr. Philip Barak †
• Dr. Stephen Ventura †
Geoffrey Siemering, MS †
Elizabeth Tomaszewski, Environmental Chemistry and Technology Program,
•
Dr. Kirk Scheckel, US EPA- Land Remediation and Pollution Control Division
•
•
bioaccessibility
• Common soil tests have a range of sensitivities to phosphate
amendment
• In vivo research needed to identify which test is most
representative of Pb bioavailability
University of Wisconsin, Madison
• Mehlich 3 test offers conservative estimation of Pb bioaccessibility
† Dept. of
Soil Science, University of Wisconsin, Madison
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