Uptake of PAH compounds by specialty crops grown in biochar amended soils
description
Transcript of Uptake of PAH compounds by specialty crops grown in biochar amended soils
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
BC
0 10 20 30 40 50 60 70 80 90 100
Tot
al P
AH
Con
cent
ratio
n (
g g-
1 )
0
20
40
60
80
100
Tradit
ional K
iln/S
oil
Mou
nd
Slo
w P
yro
lysi
s
Fast
Pyro
lysi
s
Unknow
n
Hyd
roth
erm
al
Microwave
Ass
iste
d Pyrolysis
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
) py
rene
Ben
zo(b
) flu
oran
then
e
Ben
zo(g
,h,i)
pery
lene
Ben
zo(k
)flu
oran
then
e
Chr
ysen
e
Dib
enz(
a,h)
anth
race
ne
Flu
rant
hren
e
Flu
oren
e
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
) py
rene
Ben
zo(b
) flu
oran
then
e
Ben
zo(g
,h,i)
pery
lene
Ben
zo(k
)flu
oran
then
e
Chr
ysen
e
Dib
enz(
a,h)
anth
race
ne
Flu
rant
hren
e
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
)flu
oran
thre
ne
Flu
oran
then
e
Nap
thal
ene
Phe
nant
hren
e
Pyr
ene
Ben
zo(k
)flu
oran
thre
ne
Chy
rsen
e
PA
H C
once
ntra
tion
(g
kg-1
)
0
10
20
30
40
Soil+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
rag
e H
eig
ht (c
m)
02468
101214161820
Potting Soil ControlUnground BiocharGround Biochar
0 10 20 30 40 50 60
Ave
rag
e H
eig
ht (c
m)
0
5
10
15
20
25
30
Elapsed Days from Planting
0 10 20 30 40 50 60
Ave
rag
e H
eig
ht (c
m)
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