Fluoride Vol. 32 No. 2 67-70 1999
Research Report
67
SOME OBSERVATIONS ON FLUORIDE PROBLEMS
IN THE MOLDOVA REPUBLIC
S Toma,a J Kreidman,a O Vedina,b and S Veliksara
Chishinau, Moldova, and Logan, Utah USA
SUMMARY: Fluoride content was determined in different soil types of Moldova. The total fluoride concentrations varied in soils depending on their
granular composition. Flood sodic soils are characterized by the highest
content of fluoride - up to 1120 ppm. The level of water-soluble fluoride
ranged from 0.2 to 14.6 ppm. Long-term phosphoric fertilizer application and
irrigation with fluoride-containing water have led to fluoride accumulation in
soil and plants.
Keywords: Anthropogenic impact, Fertilizers, Fluoride pollution, Fluoride content, Moldova.
INTRODUCTION
Fluoride (F) is of special interest as a pollutant of the environment. Insufficient knowledge about the nature and magnitude of environmental fluoride
pollution has led to underestimation of its damaging effects on plants, animals
and humans. It is possible there is a connection between environmental fluoride pollution, certain ecological changes and manifestation of some diseases
(Siberian ulcer, cancer etc.). 1-3
The purpose of this study was to investigate changes in fluoride content in
soils, water, and plants of Moldova, and to examine the influence of different
doses of phosphoric fertilizers and irrigation with water containing fluoride.
MATERIALS AND METHODS
The content of fluoride was investigated in ground-litter rocks of different
geological age,4 in subsurface waters, and in the main soil types and subtypes
of Moldova.5-7 The samples were collected from 72 sections and 14 drill holes
in the 4 soil provinces. Fluoride content in soils was determined in different
genetical horizons at a depth of 230 cm. For some samples, the content of fluoride was determined theoretically using special equations of regression. 7-8
The influence of long-term (23 years) phosphate fertilizer application and
irrigation on the fluoride content of soils and plants was also examined. Fluoride determinations were conducted with alizarin complexing without preliminary distillation.9
RESULTS AND DISCUSSION
Moldova Republic is situated in Eastern Europe. It borders Romania on the
west and the Ukraine on the northeast and south. In terms of the geological
structure, the territory belongs completely to the southwestern slope of the
Russian platform, and only its southern portion is part of the Scythian plate.
The majority of the sedimentary rocks are submerged in the southwest and
make Pre-Dobrudja deep glades in the south. 4
———————————————
aFor correspondence: Dr. J. Kreidman, Institute of Plant Physiology, Padurii 22, Chisinau
2002, Moldova. bBAICOR Inc., P.O. Box 725, Logan, Utah 84321, USA.
68
Toma, Kreidman, Vedina, Veliksar
In the foundation of the Upper Cretaceous layer a basal conglomerate is
observed, which consists of slightly worn fragments of underlying rocks with
phosphorite accumulations up to 34,000 mg/kg.
The range of the total fluoride in the soils depends on their granular composition (Table 1). Thus the super-sandy soils contain 64 to 269 ppm of fluoride, and sodic soils 542 to 794 ppm. Flood soils are characterized by a high
content of fluoride - 500 to 1120 ppm. The concentrations of water-soluble
fluoride range from 0.2 to 14.6 ppm, or less than 1% of total fluoride content.
Table 1. Total and water-soluble fluoride in soils of Moldova (depth 0-50 cm).
Soil
types
Granular
composition
Total F (ppm)
min
max
super sandy
heavy loam
super sandy
light and
medium loam
super sandy
light and
medium loam
heavy loam
64
260
90
247
509
220
0.6
0.8
0.8
2.3
2.9
1.8
161
558
0.2
5.8
68
185
269
859
0.2
0.2
3.5
4.1
87
648
0.3
4.1
123
761
0.7
14.6
127
750
0.8
3.8
250
652
1.0
3.9
542
500
285
794
1120
1050
0.3
0.6
0.4
6.7
4.3
4.3
Water soluble F (ppm)
min
max
Forest soils
Burozem (steppe
brown soil)
Light grey
forest
Grey forest
Dark grey forest
Chernozems (Steppe soils)
Podzolic
heavy loam light
and medium clay
Leached
light and
medium loam
Calcareous
light-medium and
heavy loam
Sodic soils
heavy clay
River valley
light clay
soils
heavy loam
Subsurface waters are used in Moldova as a water source. The Cretaceous
water-bearing horizon is saturated with fluoride. High fluoride concentrations
are found in mixed waters containing chalk and torton; the water of lower
Sarmatian deposits has lower concentrations of fluoride (up to 0.5 mg/L) and
constitutes a major part of the territory.
The anthropogenic contribution of fluoride to total soil content was also
studied. The reaction of soils and plants to different doses of phosphoric fertilizers and irrigation with water containing fluoride was investigated. The content of fluoride in the above-ground part of wheat at the growth stage of 5-7
Fluoride 32 (1) 1999
Fluoride problems in Moldova
69
leaves was 6.13 (without fertilizers) and 10.38 mg/kg dry weight (after 23
years of superphosphate application). The concentration of fluoride in grain
and roots was much lower than in leaves. Long-term superphosphate application leads to retarded growth, chlorosis, and yield reduction of wheat because
of fluoride toxicity.
The water used for irrigation in the southern part of Moldova contains relatively high levels of fluoride. The effect of this water on the fluoride content
in wheat was studied during a 5-year period (Table 2). The irrigation of wheat
with fluoride-containing water increased the content of fluoride in plants, especially at the stage of tillering and in stems at the stage of booting. High levels of fluoride in soil were observed after irrigation with fluoride-containing
water.
Table 2. Change in fluoride content of wheat grown on calcareous light
chernozem (steppe soil) after irrigation with fluoride-containing water.
Stage of growth
Part of plant
Tillering
Booting
Whole plants
Stems
Leaves
Fluoride content (mg/kg, dry wt)
no irrigation
after irrigation
12.2
4.7
10.7
28.2
13.8
10.0
Fluoride research on stockbreeding was also carried out. Fluorosis in animals can occur subsequent to absorption of fluoride from potable water (8591% of fluoride is assimilated from it) and from ingested materials (forages
and fodder mineral additions), especially from grass grown on the soil after
long-term treatment with phosphoric fertilizers (40-50% fluoride assimilation
from ingested materials).
The degree of animal fluorosis has also been investigated, especially in
spotted, cretaceous-pigmented, speckled, and deformed teeth. Fluoride likewise accumulates in animal organisms, mainly in bone tissue. A high content
of fluoride impedes some metabolic processes and also disturbs the function
of the liver and the thyroid gland. 3,9
CONCLUSION
There are many problems connected with fluoride in the environment in
the territory of Moldova. Regions exist with high and low levels of fluoride in
potable water. Some have high accumulation of fluoride in soils and plants
after long-term application of phosphate fertilizers, and the animals suffer
from elevated fluoride intake. Under conditions of high fluoride pollution it is
important to minimize exposure and to investigate its environmental and ecological consequences.
Fluoride 32 (1) 1999
70
Toma, Kreidman, Vedina, Veliksar
REFERENCES
1
2
3
4
5
6
7
8
9
10
Shliahov E, Prisacaru V. Epidemiological supervision of Siberian ulcer.
Chisinau (Kishinev): Stiinza, 1989 (in Russian).
Gaponiyk E. Degree and ecological consequences of fluoride contamination.
Obninsk: Hydrometheorology, 1983 (in Russian).
Toma S, Kreidman J. Fluoride problems in Moldova: Review. Chisinau (Kishinev): MoldNIITI, 1997 (in Russian).
Dziadevich G. Fluoride determination in soils and waters using alizarin
complexing without preliminary distillation. Moscow: MSU, 1974 (in Russian).
Drumia A. Ecological structure. Atlas of Moldova Republic. Moscow: GUGiK, 1978 (in Russian).
Feldman E. Medical-geographical investigation of the territory of Moldova.
Chisinau (Kishinev): Stiinza, 1977 (in Russian).
Petrasov E. Geochemistry of fluoride in water of Moldavian artesian basin.
Leningrad: Nauka, 1973 (in Russian).
Kreidman J. Fluoride in soils of Moldova. Chisinau (Kishinev): Stiinza, 1992
(in Russian).
Kreidman J. Formulae for fluoride content calculation in chernozems, forest
and river valley soils. In: Anthropogenic volution, evaluation and methods of
soil study. Chisinau (Kishinev): Stiinza, 1992: 95-107 (in Russian).
Mandric F, Iacubovscaja I. Prophylactic and measures of control of fluorosis
in Moldova: review. Chisinau (Kishinev): MoldNIITI, 1981 (in Russian).
——————————————————————
Published by the International Society for Fluoride Research
Editorial Office: 17 Pioneer Crescent, Dunedin 9001, New Zealand
Fluoride 32 (1) 1999