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Uptake of PAH compounds by specialty crops grown in biochar amended soils. Eric Nooker Department of Soil, Water, and Climate University of Minnesota 6 /14/13. Specialty Crops & Biochar. Fruits , vegetables, tree nuts, and nursery crops Half of the value of U.S. crop production - PowerPoint PPT Presentation
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Uptake of PAH compounds by specialty crops grown in biochar amended soils
Eric Nooker
Department of Soil, Water, and ClimateUniversity of Minnesota
6/14/13
Specialty Crops & Biochar
• Fruits, vegetables, tree nuts, and nursery crops• Half of the value of U.S. crop production• Safety issue with PAHs sorbed on biochar
• Composed solely of carbon and hydrogen atoms• Have two or more fused aromatic carbon rings in
the structure • Simplest PAH is naphthalene• Compose a large group of compounds (200+)
PAH – Polycyclic aromatic hydrocarbon
NaphthaleneBenzo(g,h,i)perylene
• PAHs are among the most common organic pollutants
• Ease of atmospheric transport• Universal environmental presence• US EPA lists 32 of these PAHs as priority
pollutants
PAH Occurrence
PAH Formation• Incomplete combustion
Burning of fossil fuels: coal, diesel, gasolineTransportation sector
Burning of biomass (e.g. wood, tobacco, brush fires)
Cooking for meal preparation
• PAH production has also been confirmed during:Production of charcoal by pyrolysis Present in bio-oil from biomass pyrolysis
Natural Sources of PAH• Present in:
Fossil fuelsCrude oilShale oilCoal
Coal tars
• Present in gases and ashes from:Forest firesGrassland firesVolcanoes
• Biological Routes:Microbial degradation of black carbonsMicrobial production during complex
organic matter formation (soil humic substances)
Primary sources: Anthropogenic• Largest stationary point source emissions:
• Paper mills• Consumer wood product factories• Petroleum refining
PAH Presence in Various Materials
PAH Sorbed to Black Carbon
• Observed biochar range: 0.01 to 45 µg g-1
Pyrolysis influence on PAH • PAH range from 0.01 to 83 µg g-1 • Naphthalene was present on all biochars• Possible influence of production technique
• Not statistically significant within this sample pool
BC0 10 20 30 40 50 60 70 80 90 100
Tota
l PA
H C
once
ntra
tion
(g
g-1 )
0
20
40
60
80
100
Trad
ition
al K
iln/S
oil M
ound
Slow
Pyr
olys
is
Fast
Pyr
olys
is
Unkn
own
Hydr
othe
rma
l
Microwav
e As
siste
d Py
rolysis
Materials and Methods• Field and Greenhouse Experiments
• Field: One rate & biochar type • Greenhouse: Multiple rates, types of biochar, and soils
PAH Extraction
Field ResultsRosemount, MN
• Specialty crops grown in biochar amended soils bio-accumulate PAH compounds
• Could be contaminated from rainwater splash of BC-soils
Lettuce - grown in 1% biochar amended field plots
2-m
ethy
lnap
thal
ene
1-m
ethy
lnap
thal
ene
acen
apht
hyle
ne
acen
aopt
hale
ne
anth
race
ne
Ben
z(a)
anth
race
ne
Ben
zo(a
) pyr
ene
Ben
zo(b
) flu
oran
then
e
Ben
zo(g
,h,i)
pery
lene
Ben
zo(k
)fluo
rant
hene
Chr
ysen
e
Dib
enz(
a,h)
anth
race
ne
Flur
anth
rene
Fluo
rene
Inde
no(1
,2,3
-cd)
pyre
ne
Nap
thal
ene
Phe
nant
hren
e
Pyr
ene
Con
cent
ratio
n (
g kg
-1)
0
50
100
150
200
Lettuce - grown in control field plots
Con
cent
ratio
n (
g kg
-1)
0.0
0.5
1.0
Potatoes - grown in 1% biochar in field plots2-
met
hyln
apth
alen
e
1-m
ethy
lnap
thal
ene
acen
apht
hyle
ne
acen
aopt
hale
ne
anth
race
ne
Ben
z(a)
anth
race
ne
Ben
zo(a
) pyr
ene
Ben
zo(b
) flu
oran
then
e
Ben
zo(g
,h,i)
pery
lene
Ben
zo(k
)fluo
rant
hene
Chr
ysen
e
Dib
enz(
a,h)
anth
race
ne
Flur
anth
rene
Con
cent
ratio
n (
g kg
-1)
0.0
0.5
1.0
Potatoes - grown in Rosemount, MN field plots
Con
cent
ratio
n (
g kg
-1)
0.0
0.5
1.0
Greenhouse TreatmentsSoil Types Biochars Evaluated Amendment
Amounts Specialty Crops
Potting Mix Macadamia Nut Shell Lettuce
Rosemount, MN Wood Pellet Radish
[Wauken silt loam] 1% Hayward, WI Waste Wood Biochar Sweet Corn
[Vials loamy sand] 5% Becker, MN Corn Cob Biochar Cabbage
[Hubbard loamy sand] 10% Morris, MN Wheat Mids Biochar Spinach
[Barnes-Aastad clay loam] 20% University Park, PA Pine Wood Biochar Broccoli
[Birdsboro silt loam] Basil
Greenhouse Results Plant Growth Facility,University of Minnesota
• Specialty crops grown in biochar amended soils bio-accumulate PAH compounds
• Levels are variable as a function of soil type and biochar
0
10
20
30
40
Soil
Compound
1-M
ethy
lnap
thal
ene
2-M
ethy
lnap
thel
ene
Ben
zo(a
)ant
hrac
ene
Ben
zo(a
)pyr
ene
Ben
zo(b
)fluo
rant
hren
e
Fluo
rant
hene
Nap
thal
ene
Phe
nant
hren
e
Pyr
ene
Ben
zo(k
)fluo
rant
hren
e
Chy
rsen
e
PA
H C
once
ntra
tion
(g
kg-1
)
0
10
20
30
40Soil+Biochar
Radish grown in Morris, MN soil (Barnes loam soil)
Radish grown inBiochar amended Morris soil (10% w/w)
0 10 20 30 40 50 60
Ave
rage
Hei
ght (
cm)
02468
101214161820
Potting Soil ControlUnground BiocharGround Biochar
0 10 20 30 40 50 60
Ave
rage
Hei
ght (
cm)
0
5
10
15
20
25
30
Elapsed Days from Planting
0 10 20 30 40 50 60
Ave
rage
Hei
ght (
cm)
0
5
10
15
20
25
30
(A)
(B)
(C)
Cont
rolBC
BC
Biochar Weathering
Research Data• Spectrum of specialty crop PAH uptake:
• Increases• Decreases• No changes
• PAH concentrations are influenced by: • Feedstock moisture levels• Presence of oxygen during pyrolysis, and post-cooling • Post-production handling and storage• Soil organic content• Rate PAH sorbed biochar is applied
Uncertainties• PAH contents of each biochar• Human health impacts
Conclusions• Plant PAH uptake depends on:
• Crop• PAH content of the biochar• PAH content of the original soil• Native soil organic content
• PAH sorbed on biochar may elevate specialty crop PAH levels, especially at higher biochar application rates
AcknowledgementsMinnesota Department of Agriculture
Kurt Spokas
Martin DuSaire
Students: Abby Anderson, Amanda Bidwell, Ed Colosky, Mike Ottman, Tara Phan,Tia Phan, Rena WeissKia Yang, and Vang Yang