pb-210 and fly ash particles as indicators of industrial impact in peatlands taavi vaasma, helen...
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Pb-210 and fly ash particles as indicators of industrial impact in peatlandsTaavi Vaasma, Helen Karu, Madis Kiisk, Margus Pensa, Alan Henry Tkaczyk
University of Tartu, Institute of Physics andInstitute of Ecology and Earth SciencesTallinn University, Institute of Ecology INCO-PoPb-201511-14.10.2015 Kusadası, Turkey
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Research at the University of Tartu
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TARTU
Institute of Physics
3
Where can we find oil shale?
The oil shale industry
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Estonian oil shale
What is oil shale?
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The oil shale-fired power plants
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~20% Pb-210Around 60 GBq Pb-210 emitted yearly
0.77 1.12 3 3.85 4.2
Pb-210 enrichment factor
Pulverized fuel technology
?% Po-210
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Emissions to the environment
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Few available research on the distribution of natural
(U-238 and Th-232 series) radioactive isotopes in
soils near thermal power plants.
Average Pb-210 and Ra-226 values around Ra-rich
soils remain between 90-95 Bq/kg.
Fly ash deposition from PP’s.
Location Kg m-2 a-1
Narva-Jõesuu 0.21
Narva 0.24
Eesti PP 0.14
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Selisoo mireLocated in the northeast of Estonia
Ombrotrophic and Sphagnum-dominated bog with sparse pine cover
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~ 50 km
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Pb-210 activity concentrations
Approximately 30 cm long peat cores were taken.
These cores were sliced into 1 cm thick samples.
Samples were packaged, sealed and measured gammaspectrometrically.
Maximum values remain between 6-8 cm.
Results indicate to an additional influx of Pb-210.
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0-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9
9-10 10-11 11-12 12-1313-1414-1515-1616-1717-1920-2121-2222-2323-2424-2525-2626-27
0 100 200 300 400 500 600
367.7282.7
310.6384.7386.3
487.3498.1
431.0405.7
399.2386.2
370.6328.1
271.7216.2193.9
186.199.695.1107.3
78.272.066.3
28.2
Pb-210 activity concentration (Bq/kg)
Dep
th (
cm)
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Ash particles
Spherical ash particles are created by oil shale combustion (PF boilers).
Temperatures in the combustion boiler are up to 1400 °C.
Dominating are particles, which consist mainly of aluminosilicate glassy material.
Samples were pretreated and homogenized.
Known amount of Lycopodium clavatum marker-spores were added.
Spores and ash particles were counted and the number of spherical ash particles
were calculated from the known concentration of the exotic spores (Alliksaar,
2000).
The concentration of the spherical particles were up to 20 000 per gramm of peat
and were predominantly of glassy type.
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Ash particles in the moss
Results follow similar trend with Pb-210
values.
Majority of ash particles remain fixed to the
moss layer where they are precipitated.
Under 1% of fly ash particles placed on the
surface of a 6–10 cm thick Sphagnum layer
were washed out with water during a 241 days
of lab experience (Punning and Alliksaar,
1997).
Low mobility of ash particles and Pb-210
within the moss is expected.
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0-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9
9-10 10-11 11-12 12-1313-1414-1515-1616-1717-1920-2121-2222-2323-2424-2525-2626-27
0 500 1000 1500 2000
186.477439695516
194.116757056936446.7328766988
92 1541.993526499141098.895669759
21143.88126982211078.432862430
051416.94190425365595.9289994647
74605.282503878439
380.741003032911423.23028996743881.00186557256
8563.7938967697762
14.3574859342811
7.30453442638719
08.081165671156
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Ash particles per cm3 of peat
Dep
th (c
m)
0-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9
9-10 10-11 11-12 12-1313-1414-1515-1616-1717-1920-2121-2222-2323-2424-2525-2626-27
0 100 200 300 400 500 600
367.7282.7
310.6384.7386.3
487.3498.1
431.0405.7
399.2386.2
370.6328.1
271.7216.2193.9
186.199.695.1107.3
78.272.066.3
28.2
Pb-210 activity concentration (Bq/kg)
Dep
th (c
m)
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Emissions from the power plants
Similar trends between oil shale consumption and fly ash
emissions.
Impact of the emissions on peatlands:
• Increased deposition of airborne nutrients and alkaline dust in
surrounding environment;
• Increase in the bog tree diameter and elevated forestation of the
bog area;
• Increase in pH values in nearby peatlands;
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1960
1965
1970
1975
1980
1988
1990
1992
1995
1999
2000
2001
2002
2003
0 10000 20000 30000 40000
6955
14721
20488
28144
30818
25853
25699
20501
15420
12662
13254
13250
13077
15474
Consumption of oil shale (thousands of tonnes/year)
Yea
r
1960
1965
1970
1975
1980
1988
1990
1992
1995
1999
2000
2001
2002
2003
0 100000 200000 300000
122150
193750
256100
263700
232180
194800
182200
132278
69600
61030
48270
46520
25410
21920
Fly ash from oil shale-fired power plants (tonnes/year)
Yea
r
18081821183418471860187318861899191219251938195119641977199020030
0.5
1
1.5
2
2.5
Incr
ease
in d
iam
eter
(m
m)
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Anthropogenic radionuclides
Measurements of anthropogenic radionuclides
(Cs-137 and Am-241) to specify the time of
radionuclide and fly ash deposition.
Maximum Cs-137 values are between 12-13 cm.
This indicates to a period around 1960’s (nuclear
weapons testing).
Due to Cs-137 migration potential, errors in
estimations can occur.
Am-241 measurements give ground to similar
assumptions.
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0-2 2-3
3-4
4-5
5-6
6-7
7-8
8-9
9-10
10-11
11-12
12-13
13-14
14-15
15-16
16-17
17-19
20-21
21-22
22-23
23-24
24-25
25-26
26-27
0
50
100
150
200
250
300
350
400
450
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
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Depth (cm)
Am-2
41 a
ctivi
ty co
ncen
trati
on (B
q/kg
)
Cs-
137
acti
vity
con
cent
rati
on (B
q/kg
)
1960’s
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To conclude Pb-210 activity concentration and number of spherical fly ash particles
possess similar trend with the maximum values at the depth of 7-8 cm.
This data coincides well with the consumption of oil shale and the amount of fly ash released from the power plants.
Cs-137 and Am-241 measurements help to improve the determination of the deposition period.
Combining radionuclide measurements and ash particle data we aim assess the magnitude of the radiological impact from industrial activity during different time periods.
Peatlands have the potential to be used as archives to estimate pollution from industrial installations.
The next steps:
• Additional cores have been gathered for further measurements;
• Test if a correlation between spherical particles and Pb-210 can be found
in fly ash.
• Use the collected data and parameters to try and date the peat cores.
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Acknowledgement
COST Action TU1301. www.norm4building.org
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And the work goes on…