saumel2012berlingardenproductscontamination

I. Säumel et al. / Environmental Pollution 165 (2012) 124e132 129
[Zn] in mg/kg DW [Pb] in mg/kg DW
40
30
20
10
0
400
300
200
100
Leafy
vegetables
A
a
D
a
a
a
b
a
15
10
5
0
100
80
60
40
20
B
a
E
a
Fruits
a
ab
b
b
15
10
5
0
100
80
60
40
20
Stem and Root
vegetables
b
C
a
F
a
a
a
a
0
0
0
[Ni] in mg/kg DW [Cr] in mg/kg DW
8
6
4
2
0
4
3
2
1
G
a
J
a
a
a
a
a
2
1
0
4
3
2
1
H
a
K
a
a
a
a
a
2
1
0
4
3
2
1
I
a
L
a
ab
ab
b
b
0
low medium high
0
low medium high
Overall traffic burden
0
low medium high
Fig. 3. Content of trace metals in the crop biomass in mg/kg biomass dry weight (DW) in relation to the overall traffic burden at each site. The boxplots indicate the 25th and 75th
percentiles of the distribution. Lower case letters associated with the boxplots indicate significant differences in overall traffic burden (low, medium and high). The significance level
is p < 0.05. For ANOVA results see Table 2.
in previous studies (e.g., Kloke et al., 1984; Finster et al., 2004; Peris
et al., 2007; UBA, 1995; Kachenko and Singh, 2006; Alexander et al.,
2006; Murray et al., 2009 and 2011). The majority of these studies
used controlled experimental approaches, which attempt to mimic
‘real’ garden situations (e.g., Alexander et al., 2006; Murray et al.,
2009, 2011) or took place on rural sites (Peris et al., 2007). Field
surveys in urban areas are scarce but crucial to determine health
risks of urban horticulture. The few existing studies did not focus
on inner city neighbourhoods (e.g., Kloke et al., 1984; Schönhard
and von Laar, 1992; UBA, 1995; Ge et al., 2002; Finster et al.,
2004; Kachenko and Singh, 2006), where urban horticulture is
currently booming (e.g., Meyer-Renschhausen and Holl, 2000;
Viljoen, 2005; Mougeout, 2006; van Veenhuizen, 2006). Traffic
related lead exposure has been reduced in recent years by the
introduction of unleaded gasoline (Mielke et al., 2011). To our
knowledge, our study is the first within the last two decades which
focused explicitly on crops grown in inner city neighbourhoods and
which related trace metal content of crop samples to traffic-related
parameters.
Surprisingly, vegetables planted in urban soil beds were less
likely to have lead values above the critical values than vegetables
planted in pots or beds that had been supplemented with
commercial garden soil. This might result from the use of compost,
which increases metal solubility (Murray et al., 2011), but more
research is needed to reveal underlying causes as we could not
analyse soil trace metal contents. Thus, the high variability of trace
metal content in the biomass across different sites might have
reflected the general heterogeneity of urban soils. Some of the
extreme levels of trace metals might indicate additional point
pollutant sources related to previous uses of the sites or from paint
particles (Alloway, 2004). In Berlin, the patchiness of trace metal
contamination is exacerbated by the haphazard distribution of
debris resulting from bombing in World War II (Mekiffer et al.,
2000; Alloway, 2004).
In contrast to other studies (e.g., Ge et al., 2000; Finster et al.,
2004; Alexander et al., 2006), we did not find that the vegetable
type, i.e. fruit, root, stem or leafy vegetable, significantly affected
the trace metal contents of the edible biomass. Some of the