Environmental Engineering Reference
In-Depth Information
Influence of De-Icing Salt on K Supply
and Street Trees Ecological Status
in Riga, Latvia
Gunta Cekstere, Anita Osvalde, and Olgerts Nikodemus
Introduction
The street greenery as a very significant landscape's design element with important
ecological value in Riga's central part is subjected to a multiple stresses, e.g.
chemical injury. In urban area, safe driving conditions during winter season are of
primary concern. The most common de-icing material used in Riga is sodium chloride
(NaCl). The total area of streets and roads in Riga is 24.64 km
2
[1]
and the average
rate of NaCl application is about 10,000 t/year which leads to ca. 4.06 kg spread
salt per m
2
.
While Na
+
and Cl
−
in small amounts are thought to be beneficial for some plants
or even essential for halophytes
[2-4]
, in general these ions are toxic for plants.
It was shown that high concentrations of Na
+
and Cl
−
in cells can inhibit membrane
functions, induce ion deficiency, decrease chlorophyll concentration and the activity
of several enzymes, producing disturbance of various metabolic processes, such
as gas exchange and photosynthesis
[5-10]
. Plant injury can also be caused by salt-
induced water stress
[2]
. One of the physiological mechanisms of salt toxicity in
plants is closely related to unfavorable K/Na ratio. K as plant macronutrient has
important functions as osmoregulation, maintenance of electrochemical equilibria,
effects on protein conformation, regulation of enzyme activity etc.
[3]
. The most
widespread tree species in the street greenery of Riga is
Tilia × vulgaris H
. In deciduous
trees visual symptoms of Na
+
and Cl
−
damage usually appear as post-flushing
dieback and foliage discoloration
[5]
, burning of leaves
[7]
, as well as chlorosis and
necrosis of leaves
[9, 11]
.
The first studies in Riga to assess the impact of chloride on Riga street trees were
carried out in 1966/1967 by
[12]
. Our previous work on chestnut and lime in Riga
G. Cekstere and O. Nikodemus
Faculty of Geography and Earth Sciences, University of Latvia
G. Cekstere and A. Osvalde
Laboratory of Plant Mineral Nutrition, Institute of Biology University of Latvia
