Sveriges lantbruksuniversitet Klas Rosén Department of Soil and Environment SLU – Uppsala Sweden E-mail: [email protected]@slu.se.

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


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


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


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


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


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


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


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)


Lactarius rufus, Pepparriska

Suillus variegatus, Sandsop

Rozites caperata, Rynkad tofsskivling

Cortinarius semisanguineus, Rödskivig kanelspindelskivling


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:


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


137Cs (Bq/kg d.w.) activity concen-trations in vaccinium vitis-idaea,

lingonberry Vaccinium vitis-idaea

Lingonris

*

**

***

*****

***

*

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


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


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


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


, 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


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


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


137Cs (Bq/kg d.w.) activity concentra-tions in Cortinarius semisanguineus, 1992-2009


137Cs (Bq/kg d.w.) activity concentrationsin Suillus variegatus, Sand Soup 1992-2009

Suillus variegatus, Sandsopp

****

**

*

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



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


TACK END

Sveriges lantbruksuniversitet Klas Rosén Department of Soil and Environment SLU – Uppsala Sweden E-mail: [email protected]@slu.se.

Documents

sveriges lantbruksuniversitet

heather slide

lingonberry slide

cs bqkg

cs activity bqkg

johanson slide

year slide

mgkg slide