SPATIAL AND TIME VARIATIONS OF THE GROUNDWATER
QUALITY OF TWO DIFFERENT LANDSCAPES
György Szabó – Szilárd Szabó – Andrea Szabó – Beáta Szemán
University of Debrecen, Department of Landscape Protection and Environmental Geography
4010 Debrecen, POB. 9., Hungary, e-mail: gyszabo555@gmail.com
Abstarct
Szabó Gy., Szabó Sz., Szabó A., Szemán B.: Spatial and time variations of the groundwater quality of two
different landscapes
The state of pollution in groundwater wells was investigated in two settlements having different conditions, in
Mikepércs situated on the SW edge of the Nyírség and in Bodrogkeresztúr lying in the SE part of the Zemplén
Mountains. The sewage network was established in 2001 in Bodrogkeresztúr with 85% of the households
connected, however, almost every households keep cattle thus the possibility of groundwater pollution has not
ceased. In Mikepércs the establishment of the sewage network has just started therefore the majority of the
sewage (more than 90% according to our estimations) is still emitted into the soil and it generally reaches the
groundwater. Deeper groundwater producing the drinking water is in hydraulic connection with the shallower
groundwater at both settlements therefore polluted shallow groundwater endangers the drinking water as well.
Our research concluded that the water quality of the groundwater wells in Bodrogkeresztúr that have better
conditions is far better than that of the wells in Mikepércs, however, some of the studied water quality
parameters showed limit exceeding even in the wells of Bodrogkeresztúr as well.
Key-words: groundwater, groundwater pollution, dug wells, sewage network, spatial and time variations
Introduction
Considering subsurface water bases the state of the groundwater bases is the worst. This is
primarily explained by that groundwater is extremely sensitive against pollution as pollutants
reach the groundwater situated near the surface rapidly (Bíró T. et al., 1998).
The primary aim of our research was to gain a general view on the pollution state of
the water of the groundwater wells in the two settlements having different landscape and
infrastructural conditions. We tried to find out whether there is any positive effect of the
establishment of the sewage network in Bodrogkeresztúr. As water network is established in
both settlements inhabitants are not forced to drink groundwater, however, there are cases, as
far as we know, when people drink groundwater because that tastes better than channeled
drinking water. Although human drinking of the groundwater is rare cattle drinks almost
exclusively the groundwater of the dug wells causing potential problems considering cattle
health. Besides comparing the groundwater quality of the two settlements our aim was to
identify pollution sources within the settlements and to study the time and spatial change of
the possible pollutions.
Material and method
In the course of the work groundwater samples taken from the dug wells in the settlements on
a monthly base between July of 2005 and January 2006. All together 15 wells were sampled
in Bodrogkeresztúr and 17 ones in Mikepércs (Figs. 1. and 2.). We tried to cover the area of
the settlements when marking the wells.
1
Sampling took place with a water sample taker having a vacuum pump and the
collected samples were transported into the geographical laboratory of the University of
Debrecen in air free closed flacons. Determination of conductivity and temperature was
determined in situ at the time of sampling by a Schott type electric conductivity measuring
device. The depth of the groundwater table was measured at each sampling. The measurement
of nitrite, nitrate, orthophosphate, ammonium, and organic material content together with pH
was carried out in the laboratory the day after sampling (Literáthy P. 1973).
Fig. 1. Groundwater sampling points at Bodrogkeresztúr
Results were recorded in an Excell database and diagrams were partly also made by
this software. In the course of statistic analyses normality testes were carried out by
Kolmogorov-Smirnov test and as the majority of the data proved to be non normal the
Spearmann correlation coefficient was used in the correlation analyses and the non parametric
Mann-Whitney test was applied in the course of comparisons. For statistic analyses and for
the construction of the further diagrams the software SPSS 8.0 was applied.
Outline of the study area
Bodrogkeresztúr is situated in Tokaj-Hegyalja in the eastern part of the Zemplén Mountains.
The sewage network was constructed in 2001 in the settlement having a population of 1400
inhabitants. The number of households connected to the network reached 85% by the year
2006. Hydrogeology is very variable in the settlement situated at the bottom of the mountain.
Precipitation in the higher areas of the settlement and the running water from the surrounding
higher places influence the groundwater conditions, however, its lower part is laid on the
coast of the river Bodrog therefore the effect of the river can also be felt in the variation and
2
the flow of the groundwater. Due to the surrounding felsic volcanic rhyolite flood tuff and
fallen rhyolite tuff rocks more acid groundwater could be expected but pH falls below 7 very
rarely. The dominant soils in the area are the clay in-washed brown forest soil, the slope
alluvial soil and the wash soil on the alluvium of the Bodrog (Pinczés Z. et al. 1978).
The total annual precipitation in Bodrogkeresztúr was only 524 mm, however, the
average of the last 50 years is higher 565 mm. The groundwater under the settlement may not
form a continuous table especially in the higher pediment surfaces. Here the average depth is
around 8-9 m while it is 3-4 m in the lower areas.
Mikepércs is situated at the boundary of the Hajdúság and the Nyírség 5 km to the
South from the city of Debrecen. The majority of the inhabited area belongs to the Nyírség. In
the settlement having 3000 inhabitants the establishment of the sewage network started in
2006 after the closing of the research and it is expected to be finished in 2008. The high
sensitivity of the drinking water bases under the settlement and their significant pollution
made the construction of the sewage network inevitable.
Fig. 2. Groundwater sampling wells in Mikepércs
Sensitivity for groundwater pollution is fundamentally determined by the mechanic
composition of the soil together with the organic material content and the buffer capacity of
the soil. Mikepércs lying on the boundary of two different landscapes show a varied picture
regarding soils. The loess areas of the Hajdúság reach into the western part of the settlement
where cernozem soils were formed. In the Nyírség areas sandy soils are found that are more
sensitive to pollutions. The most frequent soils are the cernozem type sandy soil and the
humus sand.
The groundwater table was at a higher level during the measurements as the year 2005
proved to be wetter than regular. All together 766.4 mm of precipitation was fallen onto the
3
area and the second part of year was especially wet as 428 mm of precipitation was fallen
from July until December (Fig. 3.). Groundwater table varied between depths of 150 and 250
cm in the majority of the studied wells. The flow of the groundwater is from NE towards SW
towards the Kondoros stream West of the settlement.
120
100
mm
80
60
40
20
Mikepércs
Au
gu
st
Se
pt
em
be
r
O
ct
ob
er
No
ve
m
be
De
r
ce
m
be
r
Ja
nu
ar
y
Ju
ly
Ju
ne
ay
M
Ap
ril
ar
ch
M
Ja
nu
a
ry
Fe
br
ua
ry
0
Bodrogkesztúr
Fig. 3. Monthly precipitation in Mikepércs and Bodrogkeresztúr between 1. January 2005.
and 31. January 2006. (Source: VITUKI Inc.)
Results and discussion
Comparative analysis of the water quality of the groundwater wells
Table 1 and 2 show clearly that the water quality of the wells in the two settlements
significantly differ from each other in several water chemical parameters due to on the one
hand the different physical geographical conditions and on the other hand to the differences
experienced in the state of the sewage network. However, it is characteristic for both
settlements that the water quality of the groundwater wells show significant spatial and time
variation within the settlement.
Table 1. Results of groundwater analyses in Bodrogkeresztúr based on the average of the
results measured in the 15 wells.
pH
2005.07.27.
2005.09.05.
2005.10.11.
2005.11.10.
2006.01.16.
7.08 ± 0.20
7.16 ± 0.17
7.21 ± 0.17
7.33 ± 0.25
7.30 ± 0.22
4
conductivity
(µS/cm)
1615 ± 680
1869 ± 997
1647 ± 647
1802 ± 841
1601 ± 815
NO3- (mg/l)
94.1 ± 97.9
44.0 ± 19.3
52.8 ± 15.2
50.2 ± 19.2
118.5 ± 98.2
NO2- (mg/l)
0.07 ± 0.06
0.09 ± 0.12
0.04 ± 0.04
0.08 ± 0.14
0.04 ± 0.04
NH4+ (mg/l)
0.42 ± 0.24
1.35 ± 0.43
0.64 ± 0.32
2.67 ± 8.9
0.83 ± 0.43
PO43-(mg/l)
0.82 ± 1.45
0.90 ± 1.85
0.72 ± 1.53
1.06 ± 2.18
0.85 ± 1.51
CODp s (mg/l)
1.63 ± 1.80
2.06 ± 2.39
1.06 ± 0.66
3.03 ± 3.38
2.48 ± 2.76
groundwater
depth (m)
5.67 ± 2.56
5.56 ± 2.57
6.07 ± 2.78
5.85 ± 2.57
5.51 ± 2.59
Table 2. Results of groundwater analyses in Mikepércs based on the average of the results
measured in the 17 wells.
pH
2005.07.13
2005.08.10
2005.09.21
2005.10.24
2005.12.07
2006.01.12
7.46 ± 0.27
7.62 ± 0.25
7.58 ± 0.36
7.66 ± 0.24
7.68 ± 0.28
7.70 ± 0.26
1713 ± 865
1888 ± 1047
2109 ± 1072
2302 ± 1261
2194 ± 1045
conductivity
(µS/cm)
NO3- (mg/l)
121.7 ± 41.1
120.1 ± 43.0
107.7 ± 53.0
209.1 ± 199.4
113.6 ± 42.4
122.5 ± 41.7
NO2- (mg/l)
0.31 ± 0.41
0.38 ± 0.47
0.13 ± 0.17
0.12 ± 0.25
0.09 ± 0.03
0.11 ± 0.22
NH4+ (mg/l)
3.24 ± 4.15
3.09 ± 3.72
6.18 ± 12.53
4.80 ± 11.74
12.06 ± 34.88
0.32 ± 0.46
PO43- (mg/l)
4.03 ± 1.91
4.41 ± 1.65
4.51 ± 2.18
4.30 ± 2.01
4.24 ± 1.95
4.65 ± 2.05
3.48 ± 1.50
1.86 ± 0.74
6.14 ± 1.62
5.92 ± 1.83
2.91 ± 1.68
3.62 ± 1.25
1.64 ± 1.04
1.83 ± 0.99
1.84 ± 0.71
2.09 ± 0.94
1.90 ± 1.09
1.82 ± 0.94
CODp s
(mg/l)
groundwater
depth (m)
Although in the case of most of the parameters differences dominated between the two
settlements significant differences were not showed in the variation of the conductivity. This
parameter had values of 1600-2200 S/cm in both settlements. These values are regarded as
general in the groundwater under settlements that are not (or had only recently) established
the sewage network. As conductivity shows the total ion content of the water positive
correlation with water depth in the case of Bodrogkeresztúr does not directly mean pollution
increase in the water as for example increase of the dissolved salt content may be the result of
interaction with the surrounding volcanic rocks or of mixing from deeper strata. On the
contrary in Mikepércs a weak but sharp negative correlation can be observed i.e. the total ion
load is less in the case of the deeper wells. Here due to the very high quartz content of the
sand – and the high resistivity of the quartz against weathering the increase of the natural ion
concentration in the groundwater is not probable thus higher conductivity values must be the
result of pollution from anthropogeneous sources.
5
In the case of the studied water chemical parameters significant (p<0.05) differences
were observed between the two settlements reflecting without exception the greater pollution
load of the wells in Mikepércs.
The difference in the nitrate content of the wells is also well observable (Fig. 4.).
While values are mainly between 40-60 mg/l in Bodrogkeresztúr much higher values are
measured in Mikepércs as concentrations were between 70-150 mg/l with even greater values
occasionally. A strong positive correlation (r>0.7) was observed between the nitrate content
and the conductivity in the two settlements. This suggests that nitrate is accumulated in those
wells where the rest of the ions – having important roles in the variation of the conductivity –
are also having higher concentrations.
200
150
NITRATE (mg/l)
100
50
0
N=
69
89
Bodrogkeres ztúr
Mikepércs
Settlements
Fig. 4. Nitrate content of the groundwater based on the samples taken in Bodrogkeresztúr and
Mikepércs between July 2005. and January 2006.
The difference is even more apparent when the orthophosphate content of the water of
the wells is compared. In 68% of the measurements in Bodrogkeresztúr the orthophosphate
content stays below the 0.5 mg/l limit determined by the Decree 10/2000 (B pollution
category) and only 8% of the measurements produced values ten times higher than the limit
(Fig. 5.). Considering the samples of Mikepércs values below 0.5 mg/l were very rare and
almost half of the measurements showed higher concentrations than 5 mg/l i.e. ten times
higher pollution than the limit. The great difference between the two settlements is explained
by that orthophosphate brought into the groundwater mainly by the household sewage and
while more than 90% of the sewage is released into the groundwater in Mikepércs only 1520% of the sewage is emitted into the groundwater in Bodrogkeresztúr and furthermore not
the total pollution reaches the groundwater in deeper strata. This assumption is supported by
the strong negative correlation (r=-0.691) between the orthophosphate content and the depth
of the groundwater.
6
8
6
orto-phosphate (mg/l)
4
2
0
N=
75
96
Bodrogkeres ztúr
Mikepércs
Settlements
Fig. 5. Orthophosphate content of the groundwater in Bodrogkeresztúr and Mikepércs based
on the samples taken between July 2005. and January 2006.
There are great differences in the ammonium content as well between the two
settlements. While more than 40% of the measurements revealed values lower than the
pollution limit (B) (0.5 mg/l) determined in the decree 10/2000 this ratio just exceeded 10% in
the case of Mikepércs (Fig. 6.). Significant limit exceeding is characteristic for the Mikepércs
samples. We have to notice that although the situation is much more beneficial in
Bodrogkeresztúr than in Mikepércs more than 50% of the samples revealed concentrations
higher than the limit and this can be explained by the non appropriate treatment of the
fertilisers originating from cattle raising.
%
50
45
40
35
30
25
20
15
10
5
0
határértéken belül
1-2x-es túllépés
2-5x-ös túllépés
Mikepércs
>5x-ös túllépés
Bodrogkeresztúr
Fig. 6. Measurement results compared to the pollution limit (B) (0.5 mg/l) determined by the
Decree 10/2000 based on the samples taken between July 2005. and January 2006.
Comparing the organic material content of the samples from the two settlements it can
be concluded that the wells in Mikepércs experience greater load (Fig. 7.). CODps values are
between 2-6 mg/l while in Bodrogkeresztúr values between 1-2 mg/l were characteristic.
However, values higher than 10 mg/l only occurred in Bodrogkeresztúr. In the case of the
samples from Bodrogkeresztúr the relationship with the depth of the groundwater is strongly
negative (r=-0.609, p<0.01) i.e. deeper groundwater wells are less loaded. This suggests that
higher CODps values are due to washed in organic material from the surface or from the
cesspool, although due to the very high CODps values the direct pollution of the wells cannot
be excluded either.
7
chemical oxygen demand (mg/l)
12
8
4
0
N=
74
96
Bodrogkeres ztúr
Mikepércs
Settlements
Fig. 7. CODps values of the groundwater in Bodrogkeresztúr and Mikepércs based on the
samples taken between July 2005. and January 2006.
The factors lying behind the differences between the pollution of the groundwater
wells of the two settlements are listed in the followings:



The most important difference is that Bodrogkeresztúr is situated at the bottom of a
mountain (larger slopes, faster groundwater flow) and the groundwater in its southern
part is influenced by the Bodrog river as well. In Mikepércs the lowland character
dominates reflecting in the velocity of the groundwater flow (due to the slower flow at
certain sites in impermeable depressions inland water can develop – i.e. the possibility
for water substitution is slower).
The depth of the groundwater in Bodrogkeresztúr is 5.7 ± 2.5 m. The same value in
Mikepércs is 1.8 ± 0.9 m. The difference is significant (p<0.05) which is reflected in
the correlation analysis as well: the groundwater table variation in Bodrogkeresztúr
having deeper groundwater table has a sharper connection to the change of the
concentrations of the pollutants than that of Mikepércs having a shallower
groundwater table. This is explained by that pollutants get into the deeper groundwater
more difficultly while they reach the groundwater easier in the case of shallower wells
(in the parts of Bodrogkeresztúr closer to the Bodrog and in Mikepércs). Significant
correlation (p<0.01) was found in Bodrogkeresztúr with CODps (r=-0.609),
orthophosphate (-0.691); conductivity (r=0.428) and nitrate (r=-0438). In Mikepércs
only conductivity (r=-0.419) and orthophosphate (r=0.330) showed significant
correlations with groundwater table. Due to less water depth and to the soils with
sandy texture and therefore higher permeability pollutants may reach groundwater
easier thus in the case of groundwater depth of 2 m groundwater table has no
differentiating effect measurable against that in Bodrogkeresztúr.
The sewage network in Bodrogkeresztúr was established in 2001 and the number of
connected households increased year-by-year. Today around 85% of the households
are connected to the sewage network. This means that there are numerous households
that are in no rush to connect to the network despite the potential fines mentioned in
the implementing Local Government Decree of the Government Decree 219/2004.
This problem will be solved by the first fines that will have an “enforcing” effect
among families with lower income. These households and the old cesspools of those
that were connected recently may contaminate presently the groundwater further
increased by the inappropriate treatment of the manures and its leakage produced by
8

cattle raising. This pollution together with the contamination originating from the
fertilizing and artificial fertilizing of the surrounding vineyards were shown in the
groundwater of Bodrogkeresztúr. The establishment of the sewage network in
Mikepércs was only initiated after the closure of the study. Less than 10% of the
sewage originating from the networked water usage is transported to the sewage
treatment plant in Debrecen meaning that more than 90% of the sewage is released
into the soil. As there are sandy soils around the settlement the sewage reaches the
groundwater rapidly. It is also frequent at times of high groundwater table level that
the non insulated or improperly insulated bottom of the cesspool reaches below the
groundwater table enabling the direct mixing of the pollutants into the groundwater.
Thus in Mikepércs the cesspools play the most important role in polluting the
groundwater, however pollution associated with cattle raising is also significant.
Bodrogkeresztúr is in a better state as the rapidly flowing waters from the
mountainous areas are fresher and may help to dilute the pollution of the groundwater
(or wells) and they also help in the chemical and biological decomposition and the self
cleaning due to their higher dissolved oxygen content. In Mikepércs the slow flowing
and frequently already polluted waters cannot serve similar functions. Here mainly the
diluting effect of the precipitation can be mentioned as a concentration reducing
factor.
Conclusion
Two settlements with different physical geographical conditions were compared on the basis
of the water quality of their groundwater wells. It was revealed that the water quality was
significantly better in Bodrogkeresztúr having more advantageous conditions than in
Mikepércs. There are several reasons for the differences in water quality. In the case of
Bodrogkeresztúr lying in a pediment area the relief conditions result in faster groundwater
flow that increases the dilution and cleaning of the groundwater. Besides this, the
groundwater table is found significantly deeper here than in Mikepércs that makes it more
difficult for the pollutants to reach the groundwater. Furthermore the soil is much finer
grained in Bodrogkeresztúr that also impedes pollutants to reach deep into the ground. Apart
from natural conditions, however, other factors also played important roles in that the water of
the wells in Mikepércs are much more polluted than those in Bodrogkeresztúr. The
construction of the sewage network in Mikepércs started only in the second half of 2006 thus
more than 90% of the sewage in the settlement is released into the soil from where it filtrates
into the groundwater presenting a large load onto it. In contrary, the sewage network operates
for five years in Bodrogkeresztúr and thanks to the 85% of connected households a
significantly smaller load reaches the groundwater base under the settlement. Due to the lack
of earlier measurements the magnitude of improvement of the quality of the groundwater
cannot be estimated after the construction of the sewage network in Bodrogkeresztúr,
however, it can be assumed as significant and hopefully such significant improvement will be
experienced in Mikepércs as well and the magnitude of that future improvement hopefully
will be documented on the basis of the present record of the present state.
Acknowledgement
The scientific work was supported by the T 042635 OTKA Fellowship.
9
References
Bíró, T., Thyll, Sz., Tamás, J., 1998: Risk assassment of nitrate pollution in lower watershed of the Berettyó
River. In: Filep, Gy. (ed.) Soil water environment relationships. Wageningen - Debrecen. pp. 239-247.
Kolozsváriné Pásztor, A., 1995: Spatial and time variation of the nitrate pollution of the groundwater on the
example of villages in the Bükkalja, KLTE, Department of Applied Landscape Geography, PhD theses,
103 p. (manuscript)
Literáthy, P., 1973: Common methods of water analysis I. Chemical methods, Volume 1., Scientific Research
Institute of Water Management IV. Department of Water Quality and Technology, 233 p.
Pekárová, P., Pekár, J., 1998: The chemical regime and interaction of surface- and groundwater in the Small
Carpathian region. Ekológia (Bratislava), 17, 4, p. 391-406.
Pinczés, Z., Kerényi, A., Martonné Erdős, K., 1978 : Deterioration of the soil cover in the half basin at
Bodrogkeresztúr. Földrajzi Közlemények (26) pp. 210-236.
Water Data Bank – VITUKI INC., www.vizadat.hu/
10/2000 (VI.2.) Joint Decree of the Ministry of the Environment – Ministry of Health – Ministry of Agriculture
– Ministry of Environmental Protection on the limits required by the quality conservation of the
subsurface water and the geology, www.kvvm.hu
201/2005. (X.25.) Governement Decree on the quality requirements of the drinking water and the order of the
control, www.kvvm.hu
219/2004. (VII.21.) Governement Decree on the protection of the subsurface waters, www.kvvm.hu
10