bernine khan university of miami arsenic speciation of new & weathered cca-treated wood
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Bernine KhanUniversity of Miami
Arsenic Speciation of New & WeatheredCCA-Treated Wood
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• Arsenic Leaching from Lysimeter Study
• Arsenic Leaching from CCA-Treated Deck
Arsenic Study Outline
Arsenic Study Outline
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• Arsenic Leaching from Lysimeter Study
• Arsenic Leaching from CCA-Treated Deck
Arsenic Study Outline
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• Arsenic Leaching from Lysimeter Study
• Arsenic Leaching from CCA-Treated Deck
Arsenic Study Outline
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• Arsenic Leaching from Lysimeter Study
• Arsenic Leaching from CCA-Treated Deck
Arsenic Study Outline
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• As Leaching - Lysimeter Study (Jenna - UF)
• Arsenic Leaching from CCA-Treated Deck
Arsenic Study Outline
• Purpose
• Basic Arsenic Chemistry
• Solvent-Extraction Leaching Expts
• Arsenic Analysis of GW at Florida C&D Landfills
• Arsenic Leaching from Lysimeter Study
• Arsenic Leaching from a constructed
CCA-Treated Deck
• Identify & quantify arsenic species leaching from CCA-treated wood
• Arsenic toxicity varies with each species
• To study the migration of arsenic species [As(III) & As(V)] in soils
• Estimate the impact of arsenic leaching from in-service & disposed CCA-treated wood on groundwater
Purpose of Study
• Identify & quantify arsenic species leaching from CCA-treated wood
• Arsenic toxicity varies with each species
• To study the migration of arsenic species [As(III) & As(V)] in soils
• Estimate the impact of arsenic leaching from in-service & disposed CCA-treated wood on groundwater
Purpose of Study
• Identify & quantify arsenic species leaching from CCA-treated wood
• Arsenic toxicity varies with each species
• To study the migration of arsenic species [As(III) & As(V)] in soils
• Estimate the impact of arsenic leaching from in-service & disposed CCA-treated wood on groundwater
Purpose of Study
• Identify & quantify arsenic species leaching from CCA-treated wood
• Arsenic toxicity varies with each species
• To study the migration of arsenic species [As(III) & As(V)] in soils
• Estimate the impact of arsenic leaching from in-service & disposed CCA-treated wood on groundwater
Purpose of Study
• The individual parts that make up the whole:
What is Speciation?
Element valence
Particle size
Molecular weight size
Inorganic & organic form
• The individual parts that make up the whole:
What is Speciation?
Element valence
Particle size
Molecular weight size
Inorganic & organic form
• The individual parts that make up the whole:
What is Speciation?
Element valence
Particle size
Molecular weight size
Inorganic & organic form
• The individual parts that make up the whole:
What is Speciation?
Element valence
Particle size
Molecular weight size (Sheena - FIU)
Inorganic & organic form
• The individual parts that make up the whole:
What is Speciation?
Element valence
Particle size
Molecular weight size
Inorganic & organic form
Speciation
Arsenic
As(III) As(V) MMAA DMAA
Various forms of an element that make up the total concentration of that element
Inorganic Organic
-3 0 +1 +3 +5Valence
InorganicArsine (g)
Arsenic
As(III) As(V) MMAA DMAA
Various forms of an element that make up the total concentration of that element
Inorganic Organic
-3 0 +1 +3 +5Valence
InorganicArsine (g)
Speciation
Arsenic
As(III) As(V) MMAA DMAA
Various forms of an element that make up the total concentration of that element
Inorganic Organic
-3 0 +1 +3 +5Valence
InorganicArsine (g)
Speciation
• In nature – arsenites (As(III)) & arsenates (As(V))
• Soluble arsenic compounds
• As(III) - more soluble in water & body fluids
• Toxicity
Interest in Speciation
• In nature – arsenites (As(III)) & arsenates (As(V))
• Soluble arsenic compounds (As(III)) are more toxic to humans than insoluble
• As(III) - more soluble in water & body fluids
• Toxicity
Interest in Speciation
• In nature – arsenites (As(III)) & arsenates (As(V))
• Soluble arsenic compounds are more toxic to humans than insoluble
• As(III) compounds are generally more soluble in water & body fluids
– not excreted readily– accumulates in body– toxic at low concentrations
• Toxicity
Interest in Speciation
• In nature – arsenites (As(III)) & arsenates (As(V))
• Soluble arsenic more toxic to humans
• As(III) - more soluble in water & body fluids
• Toxicity is dependent upon: -arsenic compound-magnitude of exposure (conc. accumulated over time)
- species
Interest in Speciation
Toxicity of Arsenic Species Dependent on chemical form
• AsH3 - arsine (gas) – most toxic (formed under reduced conditions)
• As(III) - arsenite
• As(V) - arsenate
• MMAA - monomethylarsonic acid
• DMAA - dimethylarsinic acid
• TMAO - trimethylarsine oxide
• AsB - arsenobetaine (marine) *
• AsC - arsenocholine (marine) *
Toxicity of Arsenic Species Dependent on chemical form
• AsH3 - arsine (gas)
• As(III) - arsenite – inorganic (more toxic)
• As(V) - arsenate – inorganic - CCA
• MMAA - monomethylarsonic acid
• DMAA - dimethylarsinic acid
• TMAO - trimethylarsine oxide
• AsB - arsenobetaine (marine) *
• AsC - arsenocholine (marine) *
Toxicity of Arsenic Species Dependent on chemical form
• AsH3 - arsine (gas)
• As(III) - arsenite – inorganic
• As(V) - arsenate – inorganic
• MMAA - monomethylarsonic acid
• DMAA - dimethylarsinic acid
• TMAO - trimethylarsine oxide
• AsB - arsenobetaine (marine) *
• AsC - arsenocholine (marine) *
bacteria
Toxicity of Arsenic Species Dependent on chemical form
• AsH3 - arsine (gas)
• As(III) - arsenite – inorganic
• As(V) - arsenate – inorganic
• MMAA - monomethylarsonic acid
• DMAA - dimethylarsinic acid
• TMAO - trimethylarsine oxide
• AsB - arsenobetaine (marine) *
• AsC - arsenocholine (marine) *
Arsenic Leaching FromCCA-Treated Wood
Solvent-Extraction Tests
• Toxicity Characteristic Leaching Procedure (TCLP) – EPA’s standardized leaching test to determine if treated wood waste is hazardous. CCA-treated wood carries an exemption.
• SPLP – EPA’s leaching test
• Other Solvents
• pH Stat – Leaching of As species under different pH conditions (similar to TCLP)
Arsenic Leaching FromCCA-Treated Wood
Solvent-Extraction Tests
• TCLP – EPA’s leaching test
• Synthetic Precipitation Leaching Procedure (SPLP) – EPA’s standardized leaching test to (simulate rainfall) determine if treated wood waste should be land applied
• Other Solvents
• pH Stat – Leaching of As species under different pH conditions (similar to TCLP)
Arsenic Leaching FromCCA-Treated Wood
Solvent-Extraction Tests
• TCLP – EPA’s leaching test
• SPLP – EPA’s leaching test
• Other Solvents – Deionized Water, Rainwater, & Seawater
• pH Stat – Leaching of As species under different pH conditions (similar to TCLP)
Arsenic Leaching FromCCA-Treated Wood
Solvent-Extraction Tests
• TCLP – EPA’s leaching test
• SPLP – EPA’s leaching test
• Other Solvents – Deionized Water, Rainwater, & Seawater
• pH Stat – Leaching of As species under different pH conditions (similar to TCLP)
CCA-treated wood subjected to leaching solvent, rotated for 18 2 hrs & filtered. Filtrate analyzed for arsenic species
New CCA-treated
wood
TCLP
SPLP
DI Water
Rainwater
Untreated0.25 pcf0.6 pcf2.5 pcf
WeatheredCCA-treated
wood
PlaygroundUtility pole
FenceC&D waste
Solvent-Extraction of CCA-Treated Wood
CCA-treated wood subjected to leaching solvent, rotated for 18 2 hrs & filtered. Filtrate analyzed for arsenic species
New CCA-treated
wood
TCLP
SPLP
DI Water
Rainwater
Untreated0.25 pcf0.6 pcf2.5 pcf
WeatheredCCA-treated
wood
Solvent-Extraction of CCA-Treated Wood
PlaygroundUtility pole
FenceC&D waste
TCLP ResultsNew & Weathered Wood
Is treated wood waste hazardous?(Acetic Acid)
0
2
4
6
8
10
A B G J M T V
Con
cent
ratio
n (m
g/L
)
As(III)As(V)Total As
TCLP 5 mg/L
New Weathered
T V
SPLP Results New & Weathered Wood
Should treated wood waste be land applied?(Sulphuric Acid/Nitric Acid)
SPLP 0.05 mg/L
As(III)As(V)Total As
0
2
4
6
8
10
12
A B C D E F G H I J K L M N O P Q R S T V
Co
nce
ntr
ati
on
(m
g/L
)
New Weathered
T V
Deionized Water New & Weathered Wood
As(III)As(V)Total As
TCLP 5 mg/L
0
1
2
3
4
5
6
A B G J M T U
Con
cen
trat
ion
(m
g/L
)
New Weathered
T U
Rainwater Results New & Weathered Wood
TCLP 5 mg/L
0
2
4
6
8
10
12
14
A B G J M N O P Q R S T U
Con
cent
rati
on (m
g/L
)
As(III)As(V)Total As
New Weathered
T U
Results of TCLP & SPLPNew & Weathered Wood Ash
0
50
100
150
200
250
300
350
A B G J M T V
Con
cent
ratio
n (m
g/L
)
TCLP 5 mg/L
As(III)As(V)
As(III)As(V)
TCLP
SPLP
New Weathered
T V
pH Stat
• CCA-treated wood subjected to leaching solvent (HNO3 or NaOH – to obtain desired pH)
New (0.4 pcf) CCA-treated woodmeasured at 0.214 pcf
pH 123456789
101112
Weathered CCA-treated woodmeasured at 0.386 pcf
Results of pH StatNew Wood
0
10
20
30
40
50
1 2 3 4 5 6 7 8 9 10 11 12 13
pH
Conce
ntr
atio
n (m
g/L)
• As(V) was the only specie detected• Highest concentration at extreme pH • Environmental pH range – As(V) ~ 5mg/L
TCLP 5 mg/L
Environmental pH
Results of pH StatWeathered Wood
• Both As(III) & As(V) detected • As(III) up to pH 8.5• Environmental pH range – Total As increase
Total As > 5 mg/L
TCLP 5 mg/L0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12
pH
Con
cen
trati
on
(mg/L
) As(III)As(V)TotalEnvironmental
pH
Results of pH Stat Total Arsenic
0
10
20
30
40
50
1 2 3 4 5 6 7 8 9 10 11 12 13pH
Tota
l ars
enic
conc.
(mg/L
)
New (0.214 pcf)Weathered (0.386 pcf) – 14 yrs
TCLP 5 mg/L
Environmental pH
Summary
•As(III) present in all wood – new & weathered.
• If CCA-treated wood did not carry the exemption – it would fail TCLP and be categorized as hazardous waste
•All new & weathered CCA-treated wood failed the SPLP
•Slightly more As leaching from rainwater than the SPLP (simulate rainwater)
Summary
•As(III) present in all wood – both new & weathered
• If CCA-treated wood did not carry the exemption – it would fail TCLP and be categorized as hazardous waste
•All new & weathered CCA-treated wood failed the SPLP
•Slightly more As leaching from rainwater than the SPLP (simulate rainwater)
Summary
•As(III) present in all wood – both new & weathered
• If CCA-treated wood did not carry the exemption – it would fail TCLP and be categorized as hazardous waste
•All new & weathered CCA-treated wood failed the SPLP
•Slightly more As leaching from rainwater than the SPLP (simulate rainwater)
Summary
•As(III) present in all wood – both new & weathered
• If CCA-treated wood did not carry the exemption – it would fail TCLP and be categorized as hazardous waste
•All new & weathered CCA-treated wood failed the SPLP
•Slightly more As leaching from rainwater than the SPLP (simulate rainwater)
•CCA-treated wood should not be incinerated and dispose to MSW and C&D landfills or land applied
•As leaching is pH dependent
•As species leaching pH dependent
•At environmental pH range (6-10) – As ~ 5mg/L
•More As leaching from weathered wood than new
Summary
•CCA-treated wood should not be incinerated and dispose to landfills or land applied
•Total As leaching is pH dependent
•As species leaching pH dependent
•At environmental pH range (6-10) – As ~ 5mg/L
•More As leaching from weathered wood than new
Summary
•CCA-treated wood should not be incinerated and dispose to landfills or land applied
•As leaching is pH dependent
•As species leaching pH dependent
•At environmental pH range (6-10) – As ~ 5mg/L
•More As leaching from weathered wood than new
Summary
•CCA-treated wood should not be incinerated and dispose to landfills or land applied
•As leaching is pH dependent
•As species leaching pH dependent
•At environmental pH range (6-10) – As ~ 5mg/L
•More As leaching from weathered wood than new
Summary
•CCA-treated wood should not be incinerated and dispose to landfills or land applied
•As leaching is pH dependent
•As species leaching pH dependent
•At environmental pH range (6-10) – As ~ 5mg/L
•Overall, more As leaching from weathered wood than new
Summary
??Questions?
Lysimeter StudyLysimeter 1 – Untreated Wood
0
0.005
0.01
0.015
0.02
Aug.6
Aug.21
Sept.6
Oct.14
Nov.18
Dec. 2
Con
cen
trat
ion
(m
g/L
)
As(III)As(V)DMAAMMAA
Lysimeter StudyLysimeter 2 – CCA-Treated Wood
(50% New & 50% Used
As(III)As(V)DMAAMMAA
• Predominantly As(III) & As(V)• Low organoarsenic species concentrations
05
1015202530354045
Jan. 2
8
Jun. 1
2
Jun. 2
5
Aug. 6
Sept.
6
Oct
. 14
Dec. 2
Con
cen
trat
ion
(m
g/L
)
Lysimeter StudyLysimeter 3 – Typical C&D Mix
As(III)As(V)DMAAMMAA
• All species detected
0
0.005
0.01
0.015
0.02
0.025
0.03
Jun.25
Aug. 6
Aug.21
Sept.6
Sept.25
Oct.14
Nov.18
Dec.2
Con
cen
trat
ion
(m
g/L
)
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