sveriges lantbruksuniversitet klas rosén department of soil and environment slu – uppsala sweden...
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Sveriges lantbruksuniversitetwww.slu.se
Klas Rosén Klas Rosén
Department of Department of Soil and Soil and EnvironmentEnvironment
SLU – Uppsala SLU – Uppsala SwedenSweden
E-mail: [email protected]
Long-term effect of single potas-sium fertilization on 137Cs levels in plants and fungi in a boreal forest in Sweden
K. Rosén, M. Vinichuk I. Nikolova
K-J. Johanson
Sveriges lantbruksuniversitetwww.slu.se
Radioecology activities at SLU
• Agricultural ecosystems- important food chains, long-term transfer of Cs- countermeasures• Forest ecosystems- nutrient-poor systems, long-term transfer of Cs- mushrooms, moose, deer, wild boar, fish• Natural Radionuclides
- in soil - water - plant - animal – systems- in agricultural and mining areas
• Reindeer
• Dynamic models
• Monitoring – experiments - modelling
• Radiation protection & national preparedness (in case of nuclear accidents)
Sveriges lantbruksuniversitetwww.slu.seed. Dahlgaard, 1994
137Cs deposited by the Chernobyl fallout in 1986 in the Nordic countries
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The study area were located in Heby commune, 40 km northwest of Uppsala in Sweden.
study area was on a rocky boreal forest;dominated by- Scots pine - Norway spruce - shrub species
Sveriges lantbruksuniversitetwww.slu.se
Aim of study:
Was to investigate the long-term effects of a single potassium (K) fertilizer in boreal forest ecosystems on 137Cs uptake by heather and fungi 1992 – 2009, 17 year
Sveriges lantbruksuniversitetwww.slu.se
Pools and processes in soil where Caesium is involved
Mycelium
Migration
Weathering Ion-exchange
Fixation
Particles
Frayed edge sites”
Soil solution
Interlayer sites
Organic material
Ion exch. sites
Non-labile fraction Labile fraction
Plant uptake
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Soil: The soil type was
a Haplic Podzol on sandy glacial till with mor humus type
organic matter content in upper layer about 70% pH 3.4 - 3.7 extractable K 480 – 35 mg/kg
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Treatment in field:
K+, fertilized area - about 1.0 ha100 kg K/ha, 1992, once as a single dose
K-, control area - about 1.0 ha K = potassium
The ground deposition of 137Cs 1986 was 35 - 40 kBq m2
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Sampling 1992-2009Auguste-September
Lingonberry, Bilberryand and Heather - the green parts were cut above ground
The sporocarps of fungi: Lactarius rufus (Pepparriska), Suillus variegatus (Sandsop), Rozites caperata (Rödskivig kanelspindelskivling)
Cortinarius semisanguineus (Rynkad tofsskivling)
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Lactarius rufus, Pepparriska
Suillus variegatus, Sandsop
Rozites caperata, Rynkad tofsskivling
Cortinarius semisanguineus, Rödskivig kanelspindelskivling
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Herbs plant was dried at 80-90 oC, milled and sieved (2 mm)
Sporocarps of fungi was dried at 55 oC milled and sieved (2 mm)
The 137Cs activity (Bq/kg, d.w.) were determined with HPGe detectors and decay corrected to sampling date
All statistical analyses were carried out using Minitab software
Samples preparation:
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Results: Mean 137Cs activity concentration (Bq/kg d.w.) 1992-2009
The effect of K+ and K-
K+ area showed a highly significant decrease in 137Cs activity (40-60%) compared with plants grown on K- area
Plant species K+ SE n K- SE n %
Lingonberry 1 295 ±83 90 2 162 ±111 59 40
Bilberry 1 409 ±114 86 2 691 ±160 62 47
Heather 4 563 ±314 89 11 584 ±587 64 60
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137Cs (Bq/kg d.w.) activity concen-trations in vaccinium vitis-idaea,
lingonberry Vaccinium vitis-idaea
Lingonris
*
**
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*****
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*
0
500
1 000
1 500
2 000
2 500
3 000
3 500
4 000
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2005 2009
137 C
s, B
q kg
-1
K-fertilized
Non-fertilized
n = 12 - 3
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137Cs (Bq/kg d.w.) activity concen-trations in Vaccinium myrtillus, Bilberry 1992-2009
Vaccinium myrtillusBlåbärsris
**
*****
*****
*
0
1 000
2 000
3 000
4 000
5 000
6 000
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2005 2009
137 C
s, B
q k
g-1
K-fertilized
Non-fertilized
n = 11 - 3
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137Cs (Bq/kg d.w.) activity concen-trations in Calluna vulgaris, Heather 1992-2009
Calluna vulgarisLjung
*
*
***
***
**
***
**
*****
0
2 000
4 000
6 000
8 000
10 000
12 000
14 000
16 000
18 000
20 000
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2005 2009
137 C
s, B
q kg
-1
K-fertilized
Non-fertilized
n = 13 - 3
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137Cs activity concentration before and up to 15 months after the K fertilizer application (expressed as % of 137Cs activity concentration in plants grown on control area).
K-f
ertil
izat
ion,
1992
-06-
01
40.0
50.0
60.0
70.0
80.0
90.0
100.0
1992
-05-
01
1992
-08-
01
1992
-11
-01
1993
-02-
01
1993
-05-
01
1993
-08-
01
13
7 Cs,
%
Calluna vulgaris
Vaccinium myrtillus
Vaccinium vitis-idaea
= Heather= Bilberry= Lingonberry
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, Teff (years), effective ecological half-life
The ecological half-life of radiocaesium (time taken for a given activity to decrease to half of the original value)
Control area: 11y for lingonberry & bilberry 9y for heather
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Effect of K-fertilization in plants
the effect was very clear for about 7 years, 1993 -2000
137Cs activity concentration in K-fertilized are compared with the control areashow a reduction with: 53% for lingonberry63% for bilberry69% for heather
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Schematic view of fungi in forest soil and its connection through the mycelia with roots
≈ 10%
Mycorrhizal fungi play a fundamental role in forest ecosystems and they are involved in nutrient cycling
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137Cs (Bq/kg d.w.) activity concentra-tions in Cortinarius semisanguineus, 1992-2009
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137Cs (Bq/kg d.w.) activity concentrationsin Suillus variegatus, Sand Soup 1992-2009
Suillus variegatus, Sandsopp
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**
*
0
25 000
50 000
75 000
100 000
125 000
150 000
175 000
200 000
225 000
250 000
275 000
300 000
1992 1993 1994 1995 1997 1998 1999 2000 2001 2002 2009
137 C
s, B
q kg
-1
K-fertilized
Non-fertilized
n = 33 - 1
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Conclusion
The results show that a single application of K- fertilizer (100 kg K/ha) to boreal forest plants is an effective way to decrease 137Cs activity concen-trations in plants over a period 17 yare
K-fertilizer decreased 137Cs in heather, lingonberry and bilberry even the first year
The most pronounced and significant reduction occurred over the first 7-8 years
The reduction on 137Cs in fungi after K fertilization was less pronounced, but still statistically significant
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