Journal
of Chemical
Technology
and Metallurgy,
52, 3,52,
2017,
602-612
Journal
of Chemical
Technology
and Metallurgy,
3, 2017
QUALITY ASSESSMENT OF THE WATER RESOURCES INTENDED
FOR WATER SUPPLY OF VARNA REGION, BULGARIA
Anna Simeonova1, Rozalina Chuturkova1, Dora Slavcheva2, Sofiya Kiryakova2
Department of Ecology and Environmental Protection
Technical University - Varna, 1 Studentska str.
9010 Varna, Bulgaria
E - mail: [email protected]
2
Water Supply and Drainage Sytems Co. Ltd, 33,
Prilep str., 9000 Varna, Bulgaria
1
Received 13 September 2016
Accepted 20 December 2016
ABSTRACT
Quality of the main water resources intended for water supply to Varna region was assessed for the period 2011 - 2014.
Kamchiya dam, Devnya and Batovo underground water bodies were subjected to investigation. Key physico-chemical and
bacteriological indices were analyzed following the EU and national standards. Some abnormalities like ammonium concentrations above the guide value were registered for the Kamchiya dam - the highest value of 0,508 mg dm-3 was registered
in 2013. Nitrates contamination above the standards was established for the Batovo water body, probably from nonpoint
sources of pollution. The highest nitrate value of 56,85 mg dm-3, 1,49 times above the threshold value, was measured at
one of the monitoring points during 2011. Most of the values obtained were below the threshold limits through the whole
period and the water was classified as suitable for drinking purposes and household needs.
Keywords: water resources, drinking water quality, physico-chemical indices, pollution, Varna, Bulgaria.
INTRODUCTION
The challenges faced by all countries in their struggle for economic and social development are largely
related to water. Fresh water resources are essential
for every human activity and must always be of quality appropriate to their intended use. The problems of
fresh water referring to pollution, over-exploitation,
shortages, improper treatment are identical worldwide.
Fresh water resources are not inexhaustible and they
must be conserved, controlled and, if possible, increased
or sustainably used [1 - 7].
The water resources on the territory of Bulgaria
(110912 sq. km.) depend on numerous factors: climate,
topography, geology and geomorphology, hydrographical characteristics of the river basins and anthropogenic
impacts. The geographical position of the country, the
specific atmospheric circulation and diverse landscape
structure are the main reason for unfavorable water. The
602
latter refers to the water resources balance. It is worth
noting that the water sources are scarce - 20 billion m3/y,
excluding Danube river, and besides they are unevenly
distributed throughout the country. The average annual
amount of water per capita is about 2300 m3/y - 2500
m3/y which ranks the country among the five poorest
countries in Europe, i.e. Poland, Czech Republic, Belgium and Cyprus (the average annual amount of water
per capita for Europe is 5300 m3/y) [8]. On the other
hand, almost all water resources are formed on the territory of Bulgaria providing the country’s independence
in this respect.
The water resources within the territory of Republic of Bulgaria are exclusive state property and their
management is carried out on a national and basin level
regulated by the Water Act [9] and many national regulations, fully harmonized with EU directives [10 - 16].
The Ministry of Environment and Waters (MOEW) is
the responsible authority for the quality of the water
Anna Simeonova, Rozalina Chuturkova, Dora Slavcheva, Sofiya Kiryakova
resources on a national level, while the four River Basin
Directorates are engaged on river basin level. Six-year
river basin management plans (RBMPs) are the main tool
for ensuring the required amount and quality of water without any to human health and no environmental damages.
The Ministry of Health and its regional structures
(28 regional health inspectorates, RHI) are the competent
authority in the field of drinking water. The water supply
and sewerage companies (WSSC), in their capacity as
entities, are responsible for implementing the requirements of drinking water legislation. They are active in
complete drinking water quality monitoring.
Following the UN proposed global goals concerning
water and the EU Water Framework Directive goal [17]
of reaching “sustainable water use based on a long-term
protection of available water resources” for all Community waters by 2015, Bulgaria needs to make great efforts
in fulfilling a number of objectives such as preventing
and reducing pollution, promoting sustainable water
use, timely and adequate provision of clean water and
sanitation services, preventing, controlling and reducing
water-related diseases, etc. [18].
The present study aims to investigate the quality of
the available water resources intended for human consumption and household needs in Varna region as well as
the quality of the drinking water for 2011 - 2014 period.
dm3/per capita/day), Blagoevgrad (105 dm3/per capita/
day - 110 dm3/per capita/day), Pernik (102 dm3/per
capita/day-111 dm3/per capita/day), Plovdiv (94 dm3/
per capita/day - 101 dm3/per capita/day). Some of these
districts are less populated than Varna. However there are
many Bulgarian districts of water consumption similar
to that of Varna or even lower (Fig. 1b).
Characterization of water resources intended for
water supply of Varna region
The water supply of Varna region is carried out by two
types of water resources - surface and underground water.
The region is water provided by three different in size and
origin water supplying systems situated outside the territorial boundaries of the municipality: the Kamchiya dam,
the Devnya Springs group and the Batovo Springs group.
The Kamchiya dam is the main surface water source
used for water supply of the central Black Sea coast
(Burgas - Varna) and the only one which supplies Varna
EXPERIMENTAL
Study area
Varna is the third largest city in Bulgaria with
population of 335,949 and the largest seaside resort on
the Bulgarian Black Sea coast, often referred to as the
marine (or summer) capital of Bulgaria (Fig. 1a). The
hydrogeological conditions of Varna municipality are a
prerequisite of the insufficient water resources to meet its
needs for drinking water supply. The water consumption
varies through the seasons and strongly increases during
the summer period due to the large number of tourist and
recreational users visiting the resort areas. The drinking water from the public water supply to Varna district
varied from 90 dm3/per capita/day to 95 dm3/per capita/
day (2011 - 2014) [19], which is considerably lower
than that of several Bulgarian districts such as Sofia, the
capital of the country (128 dm3/per capita/day-136 dm3/
per capita/day), Burgas (108 dm3/per capita/day - 112
dm3/per capita/day), Ruse (99 dm3/per capita/day - 113
Fig. 1. Map of Bulgaria (a) and drinking water consumption of the Bulgarian population by districts, average per
capita (b).
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Journal of Chemical Technology and Metallurgy, 52, 3, 2017
region. The dam is built on the Luda Kamchiya river,
about 120 km south-west of Varna city with capacity of
228 million m3. It collects mostly surface water from
snowmelt and rainfall. The water is fed to Varna with a
flow rate of 1800 dm3 s-1 through “Kitka-Varna” derivation. Bearing in mind that the dam is an open reservoir,
there is a potential risk for direct and indirect water
contamination caused by anthropogenic activities and
unfavorable weather conditions [20].
The Devnya Springs are located in Devnya river valley, about 28 km to the west of Varna. They are the biggest karst springs in Bulgaria. They are approximately
30 in number and are combined in seven spring groups.
The geological horizon is exclusively represented by
the karst limestone rocks of Malm-Valanginian aquifer
forming a water-bearing layer. The underground water
body is directly fed by rain and surface streams’ infiltration. The Devnya Springs are the only place where the
underground water comes out naturally to the surface.
The average delivery rate of the springs is about 3400
dm3 s-1, while 1600 dm3 s-1 are used for Varna water
supply. A lot of potential sources of contamination are
situated in the area of the Devnya Springs but the MalmValanginian aquifer (powerful coated waterproof marl)
provides good natural protection of the springs from
deterioration [21]. The Batovo springs group is located
about 10 km north of Varna city along the terrace of
Batovo river. The underground water body is accumulated in Sarmatian deposits - organogenic limestone,
sand and diversity of clays. The water is karst but is also
precipitation influenced. The total number of catchments
of Batovo water supplying system amounts to 40. The
average flow rate of the water supplying system is 95
dm3 s-1 - 100 dm3 s-1. The potential sources of contamination refer to agricultural activities, wastewater, landfills,
manure and livestock farms, as well as settlements of no
sanitation located in the catchment area. The periodical
water pollution is caused by torrential rains and heavy
snowmelt due to the shallow underground water and the
weak waterproof clay coating of the aquifer [21].
Quality assessment of the water resources intended for water supply of Varna region
The quality of the surface water intended for water
supply and their categorization is determined in compliance with the national requirements of Ordinance
No1/2011 and Ordinance No 12/2002 [15, 12] on the
604
basis of monitoring programs approved by the MOEW.
The Black Sea Basin Directorate (BSBD) and RHI Varna are the responsible authorities for the quality of
the surface water intended for drinking on the territory
of Varna region. On yearly based monitoring programs
BSBD and RHI organize the sampling of the surface
water. The water quality is analyzed by selected key
indices as dissolved oxygen (DO), biochemical oxygen
demand (BOD5), ammonium (NH4 - N) and nitrate (NO3
- N) nitrogen, phosphate (PO4 - P), heavy metals, total
coliforms, streptococci, etc. The project category of
the surface water intended for drinking (A1, A2 and A3
category) is determined on the basis of average annual
values of physico-chemical and bacteriological indices
compared with guide (GV) and mandatory values (MV).
A1 category is given to water of best quality which could
be used for water supply after preliminary treatment and
disinfection only. A2 water category requires preliminary
treatment as well as physico-chemical treatment and disinfection. Water determined as A3 category needs more
precise treatment including several stages of preliminary
and physico-chemical treatment and disinfection [12].
The quality of the underground water in Varna is
determined in compliance with the requirements of
Directive 98/83/ЕО and Ordinance No1/2007 [10, 14]
under the responsibility of BSBD and WSSC-Varna.
The water quality is assessed at different monitoring
points and levels (aquifers) on the basis of the average
annual values of the following key indices: рН, electroconductivity, total hardness, permanganate, ammonium,
nitrate, sulfates, chlorides, Na, Mg, K, heavy metals,
etc. The monitored indices are compared with the quality standards (QS) of Ordinance 1/2007 and Directive
98/83/ЕО and threshold values (TV).
Quality assessment of Varna region drinking
water
The water intended for drinking is supplied to Varna
region on the basis of special permits issued by the BSBD
following the Water Act requirements. The permanent
sanitary control is carried out by the WSSC-Varna and
RHI-Varna in accordance with the monitoring programs
and the water quality is evaluated according to the results
of the following indices: organoleptic - colour, odour,
taste and turbidity; physico-chemical - temperature, pH,
total hardness, calcium and magnesium, conductivity,
manganese, fluoride, permanganate oxidizability (PO),
Anna Simeonova, Rozalina Chuturkova, Dora Slavcheva, Sofiya Kiryakova
nutrients, heavy metals, and bacteriological indices Escherichia coli (E. coli) and enterococci, following
the requirements of Ordinance 9/2001 and EU Directive
98/93/EC [10, 11].
RESULTS AND DISCUSSION
Quality of the water resources intended for water
supply of Varna region
The results referring to the surface water (the Kamchiya dam) for 2011-2014 period (Table 1) showed that
most of the values are in compliance with the MV and
GV for A1 category [20, 22 - 24]. The values of pH varied from 7,39 to 8,32 (GV for A1 category pH is in the
range of 6,5 - 8,5); nitrates varied from 1,20 mg dm-3 to
2,27 mg dm-3 (GV for A1 category NO3 is 25 mg dm-3);
phosphates were within the range from 0,01 mg dm-3
to 0,032 mg dm-3 (GV for A1 category PO4 is 0,4 mg
dm-3); BOD5 was below 3 mg dm-3 (GV for A1 category
BOD5 is less than 3 mg dm-3) and DO was within 71,87
% to 81,4 % (GV for A1 category DO is greater than
70 %). The heavy metals’ concentrations were considerably below the GV for A1 category. The results of the
microbiological indices showed compliance with GV for
A1 category varying from 8,88 total coliform/100cm3 to
45 total coliform/100cm3 (the corresponding GV value
is equal to 50 total coliforms/100 cm3).
The ammonium concentrations values were above
those of GV for A1 category through the whole monitoring period: 0,209 mg dm-3 in 2011 year; 0,324 mg dm-3 in
2012; 0,508 mg dm-3 in 2013 and 0,48 mg dm-3 in 2014
(GV for A1 category NH4 is equal to 0,05 mg dm-3). The
annual average values were within the GV and MV range
regarding A2 category (P > 0.05, Table 1). The Kamchiya
dam water is found A2 category in correspondence with the
quality requirements in respect to surface water intended
for water supply.
The monitoring results of the Devnya ground water
body (obtained at two monitoring points) showed good
water quality for the whole period. Most of the indices
were in compliance with the TV and QS. Regarding
the results of the Batovo underground water body for
the same period (obtained at two points) - most of the
indices except nitrates showed compliance with the
national requirements. Considerable deviations of the
values of most indices and changes of the Batovo and
Devnya water bodies’ status were not registered during
the monitoring period. That is why the annual average
values of the physico-chemical characteristics of the water
bodies for 2014 year only [25] are listed in Table 2. Both
water bodies showed high total hardness, high conductivity, high Ca and Mg ions concentrations, which could
be explained with the origin of the underground water.
The latter comes from a limestone rock - Sarmatian
limestone (Batovo springs) and Karst limestone (Devnya
springs). The sulphate and chloride concentrations were
considerably lower than those of TV and QS, typical for
the fresh waters.
The following results were recorded in 2014 (Table 2)
with reference to Devnya springs physico-chemical
characteristics: the water pH was stable, equal to 7,46;
the oxidisability value was 0,70 mg dm-3 (5 mg dm-3
QS for oxidisability); the nitrates highest concentration was 5,78 mg dm-3 (50 mg dm-3 QS for NO3); the
ammonium concentration was equal to 0,05 mg dm-3
(50 mg dm-3 QS for NH4). The average annual values
did not show significant differences (P > 0.05). Casual
ammonium concentrations above those of QS and TV
were registered. For example, ammonium concentrations
of 0,78 ± 0.044 mg dm-3 were recorded at monitoring
point 2. This value is 1,56 times higher than that of QS
and 1,85 times higher than that of TV (0,4213 mg dm-3
TV for NH4). The good quality of the water body of the
Devnya springs is determined by the perfect protection
is provided by the Malm - Valanginian aquifer.
Regarding the Batovo springs the following results were
recorded in 2014 for both monitoring points (Table 2): the
water pH value was in the range of 7,50 - 7,61; that of
oxidisability was in the range of 0,50 mg dm-3 - 0,70 mg
dm-3; the ammonium concentration value was equal to
Fig. 2. Nitrate concentrations in Batovo underground
water body for the period 2011 - 2014.
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Journal of Chemical Technology and Metallurgy, 52, 3, 2017
Table 1. Annual average values of the physico - chemical characteristics of the Kamchiya dam, used for water
supply to Varna region, 2011 - 2014.
pH
-
Conductivity μS cm-1
MV
A2 - category
GV
MV
2011
2012
2013
2014
GV
7,39
7,95
8,32
8,03
6,5 - 8,5 -
14,11
8,17
9,77
10
20
50
100
3,36
1,65
1,5
25
-
-
-
9,68
11,49
11,92
22
25
22
25
309,19
228,33
316
1000
-
1000
-
mg dm-3 11,06
Color, Pt
Non
mg dm-3 2,28
dissolved
substances
8,5
Temperature °С
335,37
5,5, -9,0 -
Odor
intensity 0
0
0
0
3
-
10
0
NO3
mg dm-3 1,20
2,08
2,27
1,7
25
50
0
50
F
mg dm-3 0,16
1,30
0,05
11,15
0,7 – 1,0 1,5
0,7 -1,7
-
Fe
mg dm
0,032
0,05
0,038
0,1
0,3
1
2
Mn
mg dm-3 0,0053
0,0051
0,0033
0,0183
0,05
-
0,1
-
Cu
mg dm-3 0,00238
0,00138
0,00195
0,00278 0,03
0,05
0,05
-
Zn
mg dm-3 0,00245
0,0228
0,0044
0,02150 0,5
3
1
5
Ni
mg dm-3 0,00229
<0,0001
0,02
-
-
-
Cd
mg dm
<0,0001
0,00005
0,0001
0,001
0,005
0,001
0,005
Cr total
mg dm-3 0,00054
0,00023
0,00003
0,02710 -
0,05
-
0,05
Pb
mg dm-3 <0,0001
<0,0001
0,00005
0,00005 -
0,05
-
0,05
Hg
mg dm-3 <0,0003
<0,0003
0,000015
0,00005 0,0005
0,001
0,0005
0,001
CN
mg dm-3 <0,006
<0,006
-
-
-
0,05
-
0,05
SO4
mg dm-3 30,3
24,48
30,22
20,56
150
250
150
250
Cl
mg dm-3 6,69
4,383
4,85
11,15
200
-
200
-
Surface
active
substances
mg dm-3 <0,0375
<0,05
-
1
0,2
-
0,2
-
PO4
mg dm-3 0,032
0,043
0,01
0,017
0,4
-
0,7
-
Аs
mg dm
<0,00042
<0,0001
0, 000753 0,0005
0,01
0,05
-
0,05
81,4
71,87
77,15
73,18
>70
-
>50
-
-3
-3
-3
Dissolved О2 %
606
A1 - category
Year
Indices
0,047
<0,00005
BOD5
mg dm-3 <3
<3
1,5
1,5
<3
-
<5
-
N - Keldal
mg dm-3 <0,7
<0,7
0,35
1,1
1
-
2
-
NH4
mg dm-3 0,209
0,324
0,508
0,48
0,05
-
1
1,5
Total
coliforms
37°C
/100cm3 45
10
8,88
37,52
50
-
5000
-
Anna Simeonova, Rozalina Chuturkova, Dora Slavcheva, Sofiya Kiryakova
Table 2. Annual average values of the physico - chemical characteristics of the Devnya and Batovo underground water bodies, used for water supply to Varna region - 2014.
Indices
Devnya undergroung
water body, ID
BG2G000J3К1041
Batova underground
water body, ID
BG2000000N018
QS
TV
Point 1
Point 2
Point 1
Point 2
7,46
7,48
7,61
7,50
6,5 - 9,5
-
0,05
0,78
0,05
0,05
0,5
0,4213
Temperature °С
16,60
-
12,25
12,70
-
-
Conductivity μS cm-1
740,33
708,50
661,50
793,00
2000
1682,0000
K
mg dm-3
3,84
-
3,76
3,86
-
-
Ca
mg dm-3
70,67
-
90,67
66,33
150
-
mg dm-3
16,52
-
16,52
16,52
-
-
Mg
mg dm-3
45,00
-
29,33
34,67
80
-
NO3
mg dm-3
1,65
5,78
18,45
43,03
50
38,2500
mg dm-3
458,33
-
445,00
397,67
-
-
mgeq dm-3
7,23
-
6,93
6,17
12
-
Oxidisability mg dm-3
0,70
-
0,50
0,70
5
-
Dissolved
oxygen
mg dm-3
2,80
7,20
6,61
2,44
-
-
SO4
mg dm-3
53,70
-
65,77
35,30
250
197,4875
Cl
mg dm-3
22,20
-
8,33
28,27
250
191,8125
Hydro
carbonate
ions
mg dm-3
405,00
-
311,00
358,00
-
-
pH
NH4
H2CO3
Total dry
residue
Total
Hardness
mg dm-3
0,05 mg dm-3 (P > 0.05), i.e. it was in compliance with
the standards.
Nitrate concentrations above TV were recorded at
both monitoring points of the Batovo springs (Fig. 2)
during the monitoring period of 2011 - 2014. The highest
value of 56,85 mg dm-3 was measured at point 1 in 2011.
It was 1,49 times greater than that of TV (TV for NO3
is 38,25 mg dm-3) and even higher than GS value (GS
for NO3 is 50 mg dm-3). Decrease of the nitrates values
(below the TV) was registered during the following
three years – the values found referred to 28,05 mg dm-3
in 2012, 16,73 mg dm-3 in 2013 and 18,45 mg dm-3 in
2014. Nitrates concentrations above the standards were
obtained at point 2 almost throughout the whole period.
The values were equal to 44,7 mg dm-3 in 2011, 42,03 mg
dm-3 in 2013 and 43,03 mg dm-3 in 2014 [26]. For that
reason Batovo spring was identified as a water body at
risk from the point of view of fulfilling the main goals
of environmental protection. The high nitrate concentrations resulted most probably from nonpoint sources of
pollution (land runoff, precipitation, agricultural activities) favored by the geomorphology of the water body.
Quality of Varna region drinking water
The water intended for drinking is supplied to Varna
region from three water supplying systems – the Devnya
and Batovo springs network and the Kamchiya dam
derivation. The results of the monitoring carried out
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Journal of Chemical Technology and Metallurgy, 52, 3, 2017
Table 3. Physico - chemical and bacteriological indices of the drinking water in Varna, 2011 - 2014.
Indices according to
Ordinance 9/2001
Maximum
permissible
values
Kamchiya
derivation
Devnya
supplying
system
Batovo supplying
system
6,5 - 9,5
0,50
5-7
7,5 - 7,8
<0,01
16 - 16,5
7,3 - 7,4
<0,01
12 - 13
7,1 - 7,3
<0,01
0,50
<0,01
<0,01
<0,01
0,3 - 0,4
0,3 - 0,4
0,3 - 0,4
0,3 - 0,4
250
25 - 30
60 - 65
30 - 40
Phosphate, mg dm
0,5
<0,03
<0,03
<0,03
Chloride, mg dm-3
250
9 - 12
18 - 20
20 - 25
200
10 - 15
<5
<5
Manganese, mg dm
50
<10
<10
<10
Zink, mg dm
5,0
<0,05
<0,05
<0,05
Copper, mg dm-3
2,0
<0,02
<0,02
<0,02
Cyanide, mg dm
50
<2
<2
<2
Nickel, mg dm
20
<2
<2
<2
Chromium, mg dm-3
50
<10
<10
<10
Fluoride, mg dm-3
1,5
<0,10
<0,10
0,10 - 0,13
-3
Cadmium, mg dm
5
<2
<2
<2
-3
Selenium, mg dm
10
<4
<4
<4
Lead, mg dm-3
10
<10
<10
<10
Sodium, mg dm-3
200
<10
12 - 15
<10
Arsenic, mg dm
10
<5
<5
<5
Total coliforms and Е.coli ,
number/100cm3
Enterococci,
number/100
cm3
0
0
0
0
0
0
0
0
Temperature °C
pH
Ammonium, mg dm-3
Nitrite, mg dm-3
Free residual chlorine,
mg dm-3
Sulphate, mg dm-3
-3
Iron, mg dm
-3
-3
-3
-3
-3
-3
during 2011 - 2014 period showed a very good quality of
Varna region drinking water supplied by all water supplying groups. Most of the values were in compliance with the
national standards without significant variations (P > 0.05).
The minimum and maximum concentrations of the key
indices are presented in Table 3.
The organoleptic indices - colour, odour, taste and
turbidity were in compliance with the Ordinance 9/2001
requirements [11]. The water was colourless, odourless,
without an unpleasant taste, acceptable to consumers
with no abnormal changes. The water temperature of
608
Varna
the Devnya supplying system was 16°C - 16,5°C, that
of Batovo was 12°C - 13°C, while that of Kamchiya
dam was 5°C - 7°C. The active reaction of the water of
the three supplying systems was neutral (pH range of
7,1 - 7,8). It was not aggressive.
The total hardness (TH) of the drinking water varied
considerably depending mostly on its origin (Fig. 3a,
3b). The value of TH was higher for the water coming
from Devnya and Batovo supplying systems due to the
origin of the underground water - Karst limestone and
Sarmatian limestone, respectively. The TH varied from
Anna Simeonova, Rozalina Chuturkova, Dora Slavcheva, Sofiya Kiryakova
Batovo supplying system, 2,80 mgeq dm-3 - 3,45 mgeq
dm-3 for Devnya and 0,33 mgeq dm-3 - 0,66 mgeq dm-3
for Kamchiya derivation (Fig. 3a, 3b). The different
Ca to Mg ratio for both Devnya and Batovo supplying
systems is due to the way the underground water reaches
the surface (pressure outflow through the neck orifice of
the Devnya springs and slow outflow of Batovo water)
and the chemical composition of the limestone rocks of
both water bodies.
Water conductivity is an important electrochemical
index presenting the anion and cation concentrations of
the dissolved substances in the water. The lowest (see
Fig. 4) was the water conductivity of Kamchiya dam
(325 mS cm-1 - 345 mS cm-1), while the highest was that
of Devnya supplying system (730 mS cm-1 - 750 mS cm-1).
The high conductivity of Devnya and Batovo (670 mS
cm-1 - 680 mS cm-1) supplying systems is determined by
the high mineralization of both ground water bodies.
The most common problem regarding the physicochemical properties of the drinking water is the content
Fig. 3. Total hardness, calcium and magnesium ions of
the drinking water in Varna for the period 2011 - 2014, (a)
min. concentrations, (b) max. concentrations.
7,1 mgeq dm-3 to 7,6 mgeq dm-3 for Devnya supplying
system and from 6,2 mgeq dm-3 to 6,8 mgeq dm-3 for
Batovo. These values are closely related to those of TH
of the underground water bodies. The water was classified as hard regarding both supplying systems. Soft was
the water coming from Kamchiya dam with TH varying
from 3,0 mgeq dm-3 to 3,3 mgeq dm-3.
The water TH depends mostly on the calcium
and magnesium concentrations. The highest were the
calcium concentrations of Batovo supplying system
ranging from 4,99 mgeq/dm3 to 5,99 mgeq dm-3, followed by those of Devnya, which varied within 3,74
mgeq/dm3 - 3,99 mgeq dm-3 and those of Kamchiya dam,
whose values were in the range of 2,50 mgeq dm-3 2,79 mgeq dm-3. The magnesium concentrations ranges
were as follows: 0,82 mgeq dm-3 - 1,23 mgeq dm-3 for
Fig. 4. Conductivity of the drinking water in Varna for
the period 2011 - 2014.
Fig. 5. Nitrates of the drinking water in Varna for the
period 2011 - 2014.
609
Journal of Chemical Technology and Metallurgy, 52, 3, 2017
Fig. 6. Permanganate oxidisability of the drinking water
in Varna for the period 2011 - 2014.
of ions from the nitrogen group. Nitrate concentrations
greater than 50 mg/dm3 could cause serious health
problems as methemoglobinemia in infants and young
children [27]. Very low levels of nitrates ranging from
3 mg dm-3 to 5 mg dm-3 were registered in Devnya and
Kamchiya water supplying systems (Fig. 5). Different
was the case with Batovo supplying system, where
nitrate concentrations of 35 mg dm-3 - 40 mg dm-3 were
registered (NO3 permissible value is 50 mg dm-3). The
main reason refers to the high values of nitrates content
of Batovo underground water body - they are well above
the guide value. Ammonium and nitrites were not found
in all water supplying systems. The phosphates concentrations were also considerably below the permissible
values (Table 3).
The PO is a very important indicator of the organic
and mineral contamination of water. The results from
the monitoring showed values ranging from 0,4 mg
dm-3 to 0,6 mg dm-3 for Batovo supplying system and
from 0,5 mg dm-3 to 1,2 mg dm-3 for Devnya supplying
system (PO permissible value is equal to 5 mg dm-3).
Higher values were found for the drinking water from
Kamchiya dam derivation (ranging from 2,0 mg dm-3 to
2,3 mg dm-3). In fact the latter tendency is expected in
case of surface water bodies that are easily influenced
by different natural and anthropogenic impacts and
meteorological conditions (Fig. 6).
The content of the heavy metals Pb, Cd, As, Cr, Se,
Ni was below the permissible values (Table 3). Fluoride
concentrations lower than 0,10 mg dm-3 were recorded
for all water supplying systems. They are in compliance with the national and WHO guideline maximum
610
values (the fluoride permissible value is 1,5 mg dm-3).
The manganese concentrations were below 10 mg dm-3
(Mn permissible values refer to 50 mg dm-3).
The microbiological quality of drinking water is
assessed by the parameters Escherichia coli (E. coli)
and enterococci which are of paramount importance.
E. coli has been used for many years as an indicator
of contamination by faecal matter. The enterococci
parameter comprises another group of faecal indicator
organisms and its determination supplements that of E.
coli. Regarding the microbiology of the drinking water
supplied to Varna region from Kamchiya dam, Batovo
and Devnya springs E. coli and enterococci were not
found during the whole monitoring period.
CONCLUSIONS
The quality of the water resources intended for water supply to Varna region was in compliance with the
national standards and safe for human health. Most of
the physico-chemical and microbiological indices were
below the threshold values, which made the water investigated suitable for drinking purposes and household
needs. Problems were identified with some of the water
resources intended for water supply - Kamchiya dam and
Batovo springs. Kamchiya dam provides surface water
easily influenced by natural and anthropogenic impacts
leading to some abnormalities of the water quality like
ammonium concentrations above the guide value for
A1 category. Batovo is a shallow ground water source
contaminated by nitrates – the latter content is above the
threshold values and which is why the water body is at
risk. The highest nitrate concentrations found could be
referred to nonpoint sources of pollution generally from
land runoff, precipitation and agricultural activities.
It was found that the drinking water supplied to
Varna region from Kamchiya dam, Devnya and Batovo
springs was of a good quality. The values of the key
indices were in compliance with the national standards
without significant variations.
The water quality of the water sources in Varna
region can be further improved in case:
• The sanitary protection zones around Kamchiya
dam are revalidated according to Ordinance No 3/2000;
• Analytical methodologies referring some specific
chemical elements are introduced to provide data accu-
Anna Simeonova, Rozalina Chuturkova, Dora Slavcheva, Sofiya Kiryakova
racy in compliance with the standard set in Ordinance
12/2001 and Water Act;
• Good agricultural practices and serious control of
the fertilizers and pesticide usage in the area of Batovo
ground water body are applied.
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