Environmental Engineering Reference
In-Depth Information
Table 2
Intensity of lime leaf necrosis (%) in Riga, summer 2005, 2007
Range (mean ± SE
)
June 2005
Site
August 2005
June 2007
August 2007
1 (n = 3)
0 (0.0)
0 (0.0)
0 (0.0)
0 (0.0)
2 (n = 3)
5 (5.0 ± 0.0)
45-65 (56.7 ± 6.0)
5 (5.0 ± 0.0)
20-70 (36.7 ± 16.7)
3 (n = 3)
0-5 (3.3 ± 1.7)
10-30 (18.3 ± 6.0)
0-3 (1.0 ± 1.0)
10-15 (11.7 ± 1.7)
4 (n = 5;
n = 4)
0-30 (7.0 ± 5.8)
0-85 (33.0 ± 14.7)
0-5 (3.3 ± 1.81)
0-70 (29.3 ± 16.1)
5 (n = 3)
0 (0.0)
10-60 (36.7 ± 14.5)
0-3 (1.0 ± 1.0)
0-5 (1.7 ± 1.7)
6 (n = 3)
5 (5.0 ± 0.0)
15-50 (28.3 ± 10.9)
3 (3.0 ± 0.0)
5-90 (43.3 ± 24.9)
7 (n = 4)
0-5 (3.6 ± 1.3)
5-65 (38.8 ± 12.5)
0-5 (2.8 ± 1.0)
0-90 (30.0 ± 20.7)
8 (n = 3)
0 (0.0)
0 (0.0)
0 (0.0)
0 (0.0)
9 (n = 3)
5 (5.0 ± 0.0)
70-85 (78.3 ± 4.4)
5-10 (6.8 ± 1.7)
15-25 (18.3 ± 3.3)
10-15
(n = 15)
0 (0.0)
0 (0.0)
0 (0.0)
-
The occurrence of the first toxic symptoms in the form of leaf necrosis caused
by Na toxicity was detected when the Na content in most of the cases ranged from
0.14% to 0.26%. The obtained relationships between the Na content in the leaf
samples and visual injury symptoms of the leaves are in good agreement with those
reported by
[7, 21]
.
Conclusions
The results revealed that the ecological status of street trees in Riga could be char-
acterized as seriously injured due to high concentrations of Na and Cl
−
in soil
(maxNa 1,568.1 mg/kg; maxCl 744.9 mg/kg) and lime leaves (maxNa 1.93%;
maxCl 3.00%). The concentrations exceeding 2.0% Cl
−
in lime leaves were revealed
as extremely toxic for
Tilia
×
vulgaris
, leading to tree decay. The concentrations of
Na and Cl
−
in lime leaves demonstrated a marked tendency to increase during sum-
mer, while the concentrations of K in leaves decreased (minimum 0.15%). The high
variability in Na and K concentrations resulted in a wide range of K/Na ratios in
Riga's greenery. Close correlations were found between the concentration of Na and
Cl
−
in lime leaves and the extent of leaf necrosis, although unfavorable K/Na ratio
has additive negative impact.
Acknowledgement
This work was supported by the European Social Fund.
References
1. Anonymous (2005) Riga Development Program 2006-2012 (in Latvian). Council of Riga, Riga
2. Marschner H (1995) Mineral Nutrition of Higher Plants. 2nd edn. Academic Press, London
