Influence of fertilizing on the 137Cs so (1)
Journal of Environmental Radioactivity 100 (2009) 489–496
Contents lists available at ScienceDirect
Journal of Environmental Radioactivity
journal homepage: www.elsevier.com/locate/jenvrad
Influence of fertilizing on the
of Southern Germany
137
Cs soil–plant transfer in a spruce forest
G. Zibold a, *, E. Klemt a, I. Konopleva a, A. Konoplev b
a
b
Hochschule Ravensburg-Weingarten, University of Applied Sciences, 88250 Weingarten, Germany
Scientific Production Association ‘‘TYPHOON’’, Obninsk, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 August 2008
Received in revised form
4 March 2009
Accepted 12 March 2009
Available online 18 April 2009
Fertilization with 2.5 t/ha limestone: (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) reduces the 137Cs transfer
from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by
a factor of 2–5 during at least 11 years as measured by the aggregated transfer factor Tag. In 1997 and
2006 these results were confirmed by additional measurements of the 137Cs transfer factor TF, related to
the root zone (Oh horizon), which were explained by the selective sorption of 137Cs in the root zone by
measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP > 179 meq/kg) and nonfertilized soils (RIP < 74 meq/kg).
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
137
Cs root uptake
Fertilization
Forest soil
Selective sorption
1. Introduction
Forest liming has been used successfully in Europe for more
than 50 years to revitalize forests and reduce acid water runoff. In
Germany since 1984 about 3 million ha have been limed which is
nearly 1/3 of the total forest area (Bericht u¨ber den Zustand des
Waldes, 2006). Together with liming, improvement of the soil
nutrient quality by additions of potassium (K2O) and phosphate
(P2O5) fertilisers have been used as a standard practice in BadenWu¨rttemberg (Forstliche Versuchs- und Forschungsanstalt BW,
2000). In a radioactive fallout situation e.g. after the Chernobyl
accident 1986, it is of interest to investigate the effects of fertilization on the 137Cs activity concentration in forest plants and to
assess whether fertilization can be a possible countermeasure or
restoration technique (Fesenko et al., 2005). A one-time treatment
of a spruce forest site (Baden-Wu¨rttemberg, Germany) in 1984 with
fertiliser consisting mainly of CaCO3 has been found to reduce
substantially the 137Cs uptake. At this site the highest fraction of the
total caesium inventory was found in the Oh horizon, rich in organic
matter (Lindner et al., 1994). After the treatment the effect of liming
has been measured in the years between 1991 and 1996 (Drissner
* Corresponding author. Hochschule Ravensburg-Weingarten, P.O. Box 1261,
D-88241 Weingarten, Germany. Tel.: þ49 751 94011; fax: þ49 751 501 9876.
E-mail address: zibold@hs-weingarten.de (G. Zibold).
0265-931X/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jenvrad.2009.03.011
et al., 1996; Zibold et al., 1997, 2003). Konopleva et al. (1998)
showed that results of liming are morphological changes of litter
and changes of characteristics of the root soil layer, determining the
biological availability of 137Cs, the parameters of caesium selective
sorption, radiocaesium exchangeability and ion composition of
a soil solution. On the basis of a model of 137Cs transfer from soil to
plants the prediction of 137Cs transfer factors for forest plants has
been made.
In central Finland Levula et al. (2000) reported the decrease of
the 137Cs concentrations in lingonberry (Vaccinium vitis-idaea L.)
berries in a 100-year-old Scots pine (Pinus sylvestris L.) stand due to
ash fertilization and prescribed burning. Kaunisto et al. (2002)
discussed the effect of fertilization on the potassium and radiocaesium distribution in tree stands (P. sylvestris L.) and peat on
a pine mire; fertilization with potassium-containing fertilisers
decreased the caesium uptake by pine trees considerably. In
western Finland fertilization experiments using potassium fertiliser
on a scots pine stand were reported (Bre´chignac et al., 2006). The
137
Cs concentrations in bark, wood and needles of Scots pine, as
well as in many samples of branches of different ages, were found
to be lower in the fertilized plots than in the control plots, both on
mineral soil and on peat-land. On the mineral soil site, the 137Cs
concentration was lower in Deschampsia flexuosa and Vaccinium
myrtillus on the fertilized plots as compared to the control plots. In
herbs, grasses, dead vegetation, Dryopteris carthusiana, and V. vitisidaea the activity concentrations at fertilized plots were 38–68% of
490
G. Zibold et al. / Journal of Environmental Radioactivity 100 (2009) 489–496
temperature is about 8 C. At Bad Schussenried, close to Altdorfer Wald, the
following average values for the years 1980–2005 were recorded: maximum
temperature: 17.8 C in July, minimum temperature: 1.1 C in January, maximum
precipitation: 116 mm in July, minimum precipitation: 49 mm in February, and
a total precipitation of 916 mm on average per year. The annual precipitation varies
locally between 700 and 1400 mm. The main type of soil is Luvisol with a tendency
to podsolic Luvisol belonging to the soil family mottled loam. The geology of the
bedrock is mainly moraine. A schematic map of the area under study and the 32
sampling sites are presented in Fig. 1. In 1984 one part of the site was treated with
fertiliser consisting mainly of CaCO3 (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) with
a dose of 2.5 t/ha. In summer 2002, after soil and plant sampling at sites 15 and 32,
another fertilization was applied to the whole area shown with a dose of 3 t/ha (3%
CaO, 2% MgO, 53% CaCO3, 42% MgCO3).
those at control plots, although the differences were not statistically significant (Bre´chignac et al., 2006).
In agricultural soils the application of lime and fertilisers may
influence the concentration of major elements (such as K, Ca and Mg)
in the plant root exchange complex and in the soil solution, thus
changing equilibrium parameters affecting the interaction between
the soil matrix and radiocaesium (Lembrechts, 1993; Konoplev et al.,
1993; Rauret and Firsakova, 1996; Rauret et al., 1996). Camps et al.
(2004) found that ploughing plus reseeding plus applying K-fertiliser
led to a maximal decrease in radiocaesium transfer at most sites. At the
doses applied, lime did not affect the Ca2þ and Mg2þ concentrations in
the exchange complex and soil solution of the ploughed soils. With
respect to radiocaesium, an increase in the Kþ and NHþ
4 concentrations
in the exchange complex and soil solution was consistent with an
increase in soil–plant transfer.
The objective of this paper was to study the migration and
bioavailability of 137Cs in non-fertilized and fertilized soils of spruce
forest in the pre-alpine region in South-Western Germany in
connection with soil characteristics and soil solution composition.
Results from field measurements spread over 15 years are
summarized and compared with data from soil analysis. Special
attention was devoted to the uptake of 137Cs by the plants fern (D.
carthusiana) and blackberry (Rubus fruticosus) and its quantitative
assessment.
2.1.1. Soil and plant sampling
In the years 1991–2002 soil samples were taken at the sites N . 1–15 and N .
18–32 in Fig. 1, and the total material within a frame of 40 cm 40 cm was dug
and separated during sampling according to the different soil horizons, which
were identified in situ by their colour, texture, mean grain size and smell. The
thickness of the different horizons was measured and after removal of stones and
tree roots, the material of the horizons was air dried for two weeks. After sieving
(2 mm), the 137Cs inventories of the different horizons were measured by gamma
spectrometry using HPGe detectors. Activity concentrations of plant species
growing within the sampling frame were determined after drying at 105 C. The
sampled species were fern (D. carthusiana) and blackberry (R. fruticosus). The
137
Cs activity concentration was determined by gamma spectrometry using HPGe
detectors. Measuring times were chosen in order to achieve a statistical uncertainty smaller than 5%.
In 2006 soil material was taken as a monolith at sites N . 16 and 17. A volume of
dimension of about 30 cm 20 cm area, and depth of about 25 cm was dug and
divided according to the different horizons. Plant samples growing on the monolith
were harvested and the 137Cs activity concentration was determined as described
above.
Statistical evaluation of soil and plant data was made using the software STATISTICA 7 from StatSoft, Inc. USA. The frequency distributions of soil and plant data
could be classified as normal or lognormal according to the Kolmogorov–Smirnov
test. Because of simplicity the normal distribution was chosen. For correlation
analysis, the Pearson linear correlation coefficient r as well as the non-parametric
2. Materials and methods
2.1. Sampling sites, altitude, precipitation, soil type, geology
The spruce forest area Altdorfer Wald is located 30 km north of Lake Constance
in the south of Germany (sampling site Gauss–Krueger coordinates (PD) 3552; 5290,
see Fig. 1 and Konopleva et al., 2009, Fig. 2), altitude about 650 m. Mean annual
7
6
10
5
1
16
13,14 11,12
4
Germany
9
8 15
18
2
24
25
30, 19
31
20
23
3
28,29
21
22
27
17
32
Date
1984
Fertilisation of profile number
1-16
1991
1995
1997
26
2002
2002
2006
1-32
Nonfertilized profile studied
18-27
28,29
30,31
32
Fertilized profile studied
1-10
11,12
13,14
15
16, 17
Fig. 1. Contour map of Germany (left) and sampling sites (N . 1–32) in spruce forest Altdorfer Wald (right). The grid has a 100 m spacing. Gauss–Krueger (PD) coordinates of the
upper right grid point are x: 3,551,900, y: 5,290,200. The area surrounded by a thick black line was fertilized twice (1984 and 2002) the area shaded in grey outside the black line
was fertilized only once (2002). A survey about fertilization and study of profiles is given in the table.
491
G. Zibold et al. / Journal of Environmental Radioactivity 100 (2009) 489–496
a
137Cs,
0
0
200
L
400
Bq/(m²*cm)
600
800
1000
1200
1400
Of
Oh
Depth, cm
4
Ah
8
2.2. Radiocaesium interception potential (RIP)
B
The product of the distribution coefficient Kd (137Cs) and the potassium
concentration in the soil represents the value of the radiocaesium interception
potential RIP(Kþ) in relation to potassium, which will be written as ‘‘RIP’’ in this
work. RIP is a measure for the selective sorption of 137Csþ by soils.
12
16
b
137Cs,
0
0
1000
2000
Bq/(m²*cm)
3000
4000
5000
6000
L
Of
Oh
Depth, cm
4
Ah
B
8
12
16
c
137Cs,
0
0
500
1000
Bq/(m² * cm)
1500
2000
2500
3000
3500
L
Of
Ah
Depth, cm
of the air dried soil from the horizon, where most of the plant roots are located. For
fern and blackberry in spruce forest this is the Oh horizon. TF determination was
done for sites 13, 14, 16, 17 fertilized and 30 and 31 non-fertilized at the date of
sampling. Five more sites in non-fertilized spruce forest in the neighbourhood were
studied and the results are given in Konopleva et al. (2009). Those results are
considered in this discussion as well.
Oh
B
10
2.2.1. RIP determination (Wauters et al., 1996)
The air dried soil sample with organic matter being present (about 1 g) was
equilibrated with a mixed potassium–calcium solution (0.5 mM KCl þ 100 mM
CaCl2) to mask the regular exchange sites (RES) by Ca2þ and to saturate frayed edge
sites (FES) by Kþ. After pre-saturation (3 times 20 h) a phase separation was
implemented by centrifugation and the centrifuged soil sample was equilibrated
with the same K–Ca solution, now spiked with 137Cs. (The level of contamination of
the original soil was
Contents lists available at ScienceDirect
Journal of Environmental Radioactivity
journal homepage: www.elsevier.com/locate/jenvrad
Influence of fertilizing on the
of Southern Germany
137
Cs soil–plant transfer in a spruce forest
G. Zibold a, *, E. Klemt a, I. Konopleva a, A. Konoplev b
a
b
Hochschule Ravensburg-Weingarten, University of Applied Sciences, 88250 Weingarten, Germany
Scientific Production Association ‘‘TYPHOON’’, Obninsk, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 August 2008
Received in revised form
4 March 2009
Accepted 12 March 2009
Available online 18 April 2009
Fertilization with 2.5 t/ha limestone: (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) reduces the 137Cs transfer
from spruce forest soil into plants like fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus) by
a factor of 2–5 during at least 11 years as measured by the aggregated transfer factor Tag. In 1997 and
2006 these results were confirmed by additional measurements of the 137Cs transfer factor TF, related to
the root zone (Oh horizon), which were explained by the selective sorption of 137Cs in the root zone by
measurements of the Radiocaesium Interception Potential (RIP) in fertilized (RIP > 179 meq/kg) and nonfertilized soils (RIP < 74 meq/kg).
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
137
Cs root uptake
Fertilization
Forest soil
Selective sorption
1. Introduction
Forest liming has been used successfully in Europe for more
than 50 years to revitalize forests and reduce acid water runoff. In
Germany since 1984 about 3 million ha have been limed which is
nearly 1/3 of the total forest area (Bericht u¨ber den Zustand des
Waldes, 2006). Together with liming, improvement of the soil
nutrient quality by additions of potassium (K2O) and phosphate
(P2O5) fertilisers have been used as a standard practice in BadenWu¨rttemberg (Forstliche Versuchs- und Forschungsanstalt BW,
2000). In a radioactive fallout situation e.g. after the Chernobyl
accident 1986, it is of interest to investigate the effects of fertilization on the 137Cs activity concentration in forest plants and to
assess whether fertilization can be a possible countermeasure or
restoration technique (Fesenko et al., 2005). A one-time treatment
of a spruce forest site (Baden-Wu¨rttemberg, Germany) in 1984 with
fertiliser consisting mainly of CaCO3 has been found to reduce
substantially the 137Cs uptake. At this site the highest fraction of the
total caesium inventory was found in the Oh horizon, rich in organic
matter (Lindner et al., 1994). After the treatment the effect of liming
has been measured in the years between 1991 and 1996 (Drissner
* Corresponding author. Hochschule Ravensburg-Weingarten, P.O. Box 1261,
D-88241 Weingarten, Germany. Tel.: þ49 751 94011; fax: þ49 751 501 9876.
E-mail address: zibold@hs-weingarten.de (G. Zibold).
0265-931X/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jenvrad.2009.03.011
et al., 1996; Zibold et al., 1997, 2003). Konopleva et al. (1998)
showed that results of liming are morphological changes of litter
and changes of characteristics of the root soil layer, determining the
biological availability of 137Cs, the parameters of caesium selective
sorption, radiocaesium exchangeability and ion composition of
a soil solution. On the basis of a model of 137Cs transfer from soil to
plants the prediction of 137Cs transfer factors for forest plants has
been made.
In central Finland Levula et al. (2000) reported the decrease of
the 137Cs concentrations in lingonberry (Vaccinium vitis-idaea L.)
berries in a 100-year-old Scots pine (Pinus sylvestris L.) stand due to
ash fertilization and prescribed burning. Kaunisto et al. (2002)
discussed the effect of fertilization on the potassium and radiocaesium distribution in tree stands (P. sylvestris L.) and peat on
a pine mire; fertilization with potassium-containing fertilisers
decreased the caesium uptake by pine trees considerably. In
western Finland fertilization experiments using potassium fertiliser
on a scots pine stand were reported (Bre´chignac et al., 2006). The
137
Cs concentrations in bark, wood and needles of Scots pine, as
well as in many samples of branches of different ages, were found
to be lower in the fertilized plots than in the control plots, both on
mineral soil and on peat-land. On the mineral soil site, the 137Cs
concentration was lower in Deschampsia flexuosa and Vaccinium
myrtillus on the fertilized plots as compared to the control plots. In
herbs, grasses, dead vegetation, Dryopteris carthusiana, and V. vitisidaea the activity concentrations at fertilized plots were 38–68% of
490
G. Zibold et al. / Journal of Environmental Radioactivity 100 (2009) 489–496
temperature is about 8 C. At Bad Schussenried, close to Altdorfer Wald, the
following average values for the years 1980–2005 were recorded: maximum
temperature: 17.8 C in July, minimum temperature: 1.1 C in January, maximum
precipitation: 116 mm in July, minimum precipitation: 49 mm in February, and
a total precipitation of 916 mm on average per year. The annual precipitation varies
locally between 700 and 1400 mm. The main type of soil is Luvisol with a tendency
to podsolic Luvisol belonging to the soil family mottled loam. The geology of the
bedrock is mainly moraine. A schematic map of the area under study and the 32
sampling sites are presented in Fig. 1. In 1984 one part of the site was treated with
fertiliser consisting mainly of CaCO3 (83% CaCO3, 8% MgO, 6% K2O, 3% P2O5) with
a dose of 2.5 t/ha. In summer 2002, after soil and plant sampling at sites 15 and 32,
another fertilization was applied to the whole area shown with a dose of 3 t/ha (3%
CaO, 2% MgO, 53% CaCO3, 42% MgCO3).
those at control plots, although the differences were not statistically significant (Bre´chignac et al., 2006).
In agricultural soils the application of lime and fertilisers may
influence the concentration of major elements (such as K, Ca and Mg)
in the plant root exchange complex and in the soil solution, thus
changing equilibrium parameters affecting the interaction between
the soil matrix and radiocaesium (Lembrechts, 1993; Konoplev et al.,
1993; Rauret and Firsakova, 1996; Rauret et al., 1996). Camps et al.
(2004) found that ploughing plus reseeding plus applying K-fertiliser
led to a maximal decrease in radiocaesium transfer at most sites. At the
doses applied, lime did not affect the Ca2þ and Mg2þ concentrations in
the exchange complex and soil solution of the ploughed soils. With
respect to radiocaesium, an increase in the Kþ and NHþ
4 concentrations
in the exchange complex and soil solution was consistent with an
increase in soil–plant transfer.
The objective of this paper was to study the migration and
bioavailability of 137Cs in non-fertilized and fertilized soils of spruce
forest in the pre-alpine region in South-Western Germany in
connection with soil characteristics and soil solution composition.
Results from field measurements spread over 15 years are
summarized and compared with data from soil analysis. Special
attention was devoted to the uptake of 137Cs by the plants fern (D.
carthusiana) and blackberry (Rubus fruticosus) and its quantitative
assessment.
2.1.1. Soil and plant sampling
In the years 1991–2002 soil samples were taken at the sites N . 1–15 and N .
18–32 in Fig. 1, and the total material within a frame of 40 cm 40 cm was dug
and separated during sampling according to the different soil horizons, which
were identified in situ by their colour, texture, mean grain size and smell. The
thickness of the different horizons was measured and after removal of stones and
tree roots, the material of the horizons was air dried for two weeks. After sieving
(2 mm), the 137Cs inventories of the different horizons were measured by gamma
spectrometry using HPGe detectors. Activity concentrations of plant species
growing within the sampling frame were determined after drying at 105 C. The
sampled species were fern (D. carthusiana) and blackberry (R. fruticosus). The
137
Cs activity concentration was determined by gamma spectrometry using HPGe
detectors. Measuring times were chosen in order to achieve a statistical uncertainty smaller than 5%.
In 2006 soil material was taken as a monolith at sites N . 16 and 17. A volume of
dimension of about 30 cm 20 cm area, and depth of about 25 cm was dug and
divided according to the different horizons. Plant samples growing on the monolith
were harvested and the 137Cs activity concentration was determined as described
above.
Statistical evaluation of soil and plant data was made using the software STATISTICA 7 from StatSoft, Inc. USA. The frequency distributions of soil and plant data
could be classified as normal or lognormal according to the Kolmogorov–Smirnov
test. Because of simplicity the normal distribution was chosen. For correlation
analysis, the Pearson linear correlation coefficient r as well as the non-parametric
2. Materials and methods
2.1. Sampling sites, altitude, precipitation, soil type, geology
The spruce forest area Altdorfer Wald is located 30 km north of Lake Constance
in the south of Germany (sampling site Gauss–Krueger coordinates (PD) 3552; 5290,
see Fig. 1 and Konopleva et al., 2009, Fig. 2), altitude about 650 m. Mean annual
7
6
10
5
1
16
13,14 11,12
4
Germany
9
8 15
18
2
24
25
30, 19
31
20
23
3
28,29
21
22
27
17
32
Date
1984
Fertilisation of profile number
1-16
1991
1995
1997
26
2002
2002
2006
1-32
Nonfertilized profile studied
18-27
28,29
30,31
32
Fertilized profile studied
1-10
11,12
13,14
15
16, 17
Fig. 1. Contour map of Germany (left) and sampling sites (N . 1–32) in spruce forest Altdorfer Wald (right). The grid has a 100 m spacing. Gauss–Krueger (PD) coordinates of the
upper right grid point are x: 3,551,900, y: 5,290,200. The area surrounded by a thick black line was fertilized twice (1984 and 2002) the area shaded in grey outside the black line
was fertilized only once (2002). A survey about fertilization and study of profiles is given in the table.
491
G. Zibold et al. / Journal of Environmental Radioactivity 100 (2009) 489–496
a
137Cs,
0
0
200
L
400
Bq/(m²*cm)
600
800
1000
1200
1400
Of
Oh
Depth, cm
4
Ah
8
2.2. Radiocaesium interception potential (RIP)
B
The product of the distribution coefficient Kd (137Cs) and the potassium
concentration in the soil represents the value of the radiocaesium interception
potential RIP(Kþ) in relation to potassium, which will be written as ‘‘RIP’’ in this
work. RIP is a measure for the selective sorption of 137Csþ by soils.
12
16
b
137Cs,
0
0
1000
2000
Bq/(m²*cm)
3000
4000
5000
6000
L
Of
Oh
Depth, cm
4
Ah
B
8
12
16
c
137Cs,
0
0
500
1000
Bq/(m² * cm)
1500
2000
2500
3000
3500
L
Of
Ah
Depth, cm
of the air dried soil from the horizon, where most of the plant roots are located. For
fern and blackberry in spruce forest this is the Oh horizon. TF determination was
done for sites 13, 14, 16, 17 fertilized and 30 and 31 non-fertilized at the date of
sampling. Five more sites in non-fertilized spruce forest in the neighbourhood were
studied and the results are given in Konopleva et al. (2009). Those results are
considered in this discussion as well.
Oh
B
10
2.2.1. RIP determination (Wauters et al., 1996)
The air dried soil sample with organic matter being present (about 1 g) was
equilibrated with a mixed potassium–calcium solution (0.5 mM KCl þ 100 mM
CaCl2) to mask the regular exchange sites (RES) by Ca2þ and to saturate frayed edge
sites (FES) by Kþ. After pre-saturation (3 times 20 h) a phase separation was
implemented by centrifugation and the centrifuged soil sample was equilibrated
with the same K–Ca solution, now spiked with 137Cs. (The level of contamination of
the original soil was