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This article was downloaded by: [New York University]On: 18 September 2013, At: 01:51Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number:1072954 Registered office: Mortimer House, 37-41 Mortimer Street,London W1T 3JH, UK
Journal of EnvironmentalScience and Health .Part A: EnvironmentalScience and Engineeringand Toxicology: Toxic/Hazardous Substances andEnvironmental EngineeringPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/lesa19
Seasonal variation of highdam lake waterR.M. Awadallah a & S.M.N. Moalla aa Chemistry Department, Faculty of Science,Aswan, EgyptPublished online: 15 Dec 2008.
To cite this article: R.M. Awadallah & S.M.N. Moalla (1996) Seasonal variationof high dam lake water, Journal of Environmental Science and Health . PartA: Environmental Science and Engineering and Toxicology: Toxic/HazardousSubstances and Environmental Engineering, 31:4, 731-746
To link to this article: http://dx.doi.org/10.1080/10934529609376384
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J..ENVIRON. SCI. HEALTH, A31(4), 731-746 (1996)
Seasonal Variation of High Dam Lake Water
R.M.Awadallah and S.M.N.MoallaChemistry Department, Faculty of Science, Aswan, Egypt
Abstract
Seasonal vertical and horizontal variations in water level, temperature, con-
ductivity, transparency, pH, dissolved oxygen, free carbon dioxide, calcium,
magnesium, total hardness, sulphates, soluble silicates, inorganic ortho-
phosphates, chlorides, bicarbonates, nitrates and nitrites were determined
during the period January to December 1983 (winter, spring, summer and
autumn). The samples were taken from surface, at 25, 50, 65 and 80% depth
between Abu Simbel and the High Dam wall (Abu Simbel, Tushki, Tomas,
Korosko, El Madig, Allaqi, Wadi Abyad, Kalabsha and El Ramla). The
results showed that the water depth in the Lake was in range 171.79 to
169.42 m a.m.s.l; temperature, 15.0 to 30.4 °C; conductivity, 18.7 to 30.0
mSm-1; transparency, 50 to 450 cm; dissolved oxygen, 0.2 to 12.0 mg/L; free
C O 2 , 0.88 to 5.88 mg/L; CO32-, 4 to 24 mg/L; HCOJ ,78 to 108 mg/L;
NO2-, 0.256 mg/L; NO3
-, 0.05 to 3.76 mg/L; PO43-, 0.002 to 0.156 mg/L ;
S iO 2 , 4.8 to 10.7 mg/L; Ca2+ , 17.9 to 39.6 mg/L; Mg2+, 4.2 to 14.8 mg/L;
TH, 74.0 to 121.2 mg/L; Cl - , 5.8 to 11.0 and SO, 7.3 to 28.0 mg/L. SD and
SE were in the range, 0.049 to 18.91 and 0.069 to 18.6, respectively.
Statistical analysis of the database showed positive, significant and interesting
correlation coefficient values ( r =0.44 to 0.89) between the physical and
chemical components existing in the water of the High Dam Lake.
* To whom correspondence should be addressed.
731
Copyright © 1996 by Marcel Dekker, Inc.
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732 AWADALLAH AND MOALLA
IntroductionThe irregular distribution of water supply in Africa, both geographically, and seasonally,
has led, in recent years, to the construction of dams on many rivers in an effort to full
advantage of natural water resource (agriculture, hydroeiectricity,.., etc.).
As a result of the construction of dams, many lakes have been created such as the High
Dam (Egypt-Sudan), Kariba (Zimbabwe-Zambia), Volta (Ghana), Chad (Chad),..etc.
The presence of large numbers of metals, organic compounds, weeds, micro-organisms
and parasites in the water, many of which are known to be toxic or pathogenic, has caused
considerable and widespread concern. There is mounting evidence that longterm exposure
to low concentration of certain substances can be a significant factor in the development
and manifestation of Bilharzia and other parasites, kidney diseases, Alzheimer's disease,
cancer,....etc. The distribution of certain chemical components may provide information
about charge and discharge of water, fertility of water masses for the growth of micro-
organisms, aquatic plants and fish; and sedimentation of heavy metals.
Geographical Morphology
The High Dam reservoir is about 500 km, 350 km of which are in Egypt and 150 km ino o
the Sudan, and extends approximately within latitudes 21 N in the Sudan and 24 N in
Egypt. The reservoir started filling up in 1964. It is bounded in the west by the Great
Western Desert and in the east by Eastern Desert, which extends as far as the Red Sea.
During the period January-December 1983, the water level of the High Dam Lake was
171.79 to 169.42 m above mean sea level.
Sampling and MethodsWater samples were collected from different localities (Abu Simbel, Tushki, Tomas,
Korosko, El Madig, Allaqi, Wadi Abyad, Kalabsha and El Ramla) at various depths
(surface, 25, 50, 65 and 80% depth) by means of a stainless steel water sampler, Nansen
bottle [1]. Water samples were filtered through Whatman number 42 filter paper and the
filtrate was analysed for free CO2, HCO J and CO2" in situ by titration with HCI[2], Ca2+
and Mg2+ by EDTA,[3], PO*~, NOJ, SiO2 [4], CI" by Hg(NO3)2 method[5], SO2" iasitu
[6&7], NOT [8], dissolved oxygen iasiülby Winkler method, whereas temperature was
immediately measured in situ by thermometer, pH immediately by Orion Research Model
211 /digital pH meter, electrical conductivity in situ by conductivity bridge YST Model 33
S-C-T Meter and transparency was immediately measured in situ using Sechhi disc. The
samples were collected during the period January to December 1983. Samples' locations
are shown on the attached map (Fig. 1).
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 733
N
36 Km.
High Dam Wall
WadiAbyad
Fig. (1) Lake Nasser - Lake Nubia.
Preparation of Solutions
All the chemicals used were purchased from BDH, Aldrich, Sigma, E, Merck, Riedel de
Haen of AnalaR quality (99.9%). The standard, reagent, solvent, indicator [3&4] and
buffer [9] solutions were prepared following recommended methods.
Results and Discussion
The data obtained are represented graphically in Figs.2-8. The figures show vertical and
horizontal changes in temperature, conductivity, pH, dissolved oxygen, free CO2, CO^~,
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734 AWADALLAH AND MOALLA
-Winter j Spring j Summer; _ ,_Autumn
33
29
25
21
17
13
33
29
£ 2573«-*Saï 21a.E_0; 17
13
33
29
25
21
17
13
On surface
At 50°/. depth
- - " \
,-V-/^/
At 807. depth
A
\ /
n in iv v vi vu vra ix
300
260
E 2 2 0
u
SI
£r 3oo
On surface
o 260•a§ 220
alo 180
At 50V. depth
U300
260
220
180
At SO'/, depth
i H m iv v vi vn vin ix
Fig. (2) Seasonal distribution of temperature and electrical conductivityvalues of the High Dam Lake water during Winter-Autumn 1983.
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SEASONAL VARIATION OF HIGH DAM LAKE WATER
Winter* Sprfng; Summer,- *—.*—*-«Autumn
735
On s u r f a c e
At 50 •/. depth
I II III IV V VI VIIVIII IX I II III IV V VI VII VIII IX
Fig. (3) Seasonal distribution of dissolved oxygen and free CO2
concentrations of the High Dam Lake water during Winter-Autumn 1983.
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736 AWADALLAH AND MOALLA
-Winter; •Spring: Summer * .—.—.-.-. Autumn
25
20
15
10
• On surface
/
/
/ . , ,
/f
\\
m
\
V \ '.
i'\rrIïI
\\X
\
r/7\ fi%
/ •
\
, \
At 80°/. depth
. . / .
I II III IV V VI VII VIIIIX
70
\ / , - \
130
110
100
90
80
At 80°/. depth
/ '
1 U 111 IV V VI VII VIIIIX
Fig. (4) Seasonal distribution of [COf] and [HCO^] of the High DamLake Water during Winter-Autumn 1983.
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 737
On surface
s P r i n 9 ; . _ . Summer; ,_ ,___Autumn
IGOi
7.6
7.2
6.8
8-4
8.0
7.6
7.2i ii m iv v vi vnvin ix
120
2 0
80
«0
0
At 80s/. depth
At 50"/. depth
AI II HI IV V VI VII VIII IX
500
400
. A *
Mv
Ut8O*/.
X\\depth 300
w 2002
% 100
0.0
1 II III IV V VI VII VIII IX
Fig. (5) Seasonal distribution of pH, Secchi disc tronsparency and [NO'2]Values of the High Dam Lake Water during Winter-Autumn 1983.
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738 AWADALLAH AND MOALLA
-Winter ;
80 On surface
20
00
80
60.
4 0
rO 2 0
D_
J / Wyy
1ii
X
At 50*/. depth
3.00
a 120
100
80
60
40
20
00
I Ati1iiLiI
• M1
1
80°/.
h. I
VI
depth
A
II"
Spring Summer,- «-«-«-«Autumn
i n m iv v vi vu vin \x
1.6
1-2
0.8
0.4
0.0
. At eo'i.
A
depth
i
i n HI iv v vi vu vin ix
Fig. (6) Seasonal distribution of [Pc£] and [NO"3] of the High Dam Lakewater during Winter-Autumn 1983.
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 739
-Winter »Spring ; Summer »*-*-*—»-Autumn
29
25
21
17
30
On surface
ÀO22
18
30
28
26
24
22
20i ii in iv v vi vu vin ix i ii m iv v vi vii vra ix
Fig. (7) Seasonal distribution of [Ca2+] and [Mg2+] of the High Dam Lakewater during Winter-Autumn 1983.
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-Winter Spring ; — . - - — S u m m e n . »Autumn
\u
12
10
8
6
At eO'/o depthxAt 80
• A :
1 \
•/o depth
:-'vy— \
I II III IV V VIVII VIIIIX I II III IV V VI VII VIII IX
Fig. (8) Seasonal distribution of [SO4"] , [CF] and [soluble silicate] of theHigh Dam Lake water during Winter-Autumn 1983.
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 741
HCO3, Ca2+, Mg2+, NO", NO", PO^ , SiO2, SO2," , and Cl~ between Abu Simble and
El Ramla. Variations of Or1 were exhibited between 18.7 (winter, 1983) and 30 (summer,
1983) mSm"1. There was a good correlation between conductivity^ tempera-ture and
soluble salts. The relative decrease of electrical conductivities during winter and spring
was consistent with the low temperature and high pH values, and with the lower Ca and
Mg data. This might be attributed principally to the uptake of dissolved salts (Ca2+, Mg2+,
HCO", SO2", SiO2) by fish (breeding duration), to a lack of soluble salts in the region as
a result of sedimentation [as CaCO3, MgCO3, Ca(OH)2,...etc.], adsorption of these salts
on the suspended matter or on silt [10]. The relative increase of electrical conductivity
during summer and autumn (high temperature and low pH values) may be ascribed to the
hydrolyses and redissolution of insoluble salts, and desorption of these salts into the water
of the lake.
Seasonal vertical and horizontal variations of dissolved oxygen values showed a relative
increase in winter and spring and a relative decrease in summer and autumn. However,
dissolved oxygen values decreased from the south (Abu Simbel) to the north (El Ramla)
and from surface to bottom. The variations in dissolved oxygen values may be related to
the water temperature, penetration of light and photosynthesis [11], concurrent changes of
the formation and decomposition of organic compounds, and the uptake of inorganic
carbon and release of nutrient elements, i.e., N, P,....etc.[12]. Increase of dissolved oxygen
amounts may be attributed to the high rate of biosynthesis of oxygen; penetration of light
energy [11] accompanied by the uptake of inorganic carbon; photosynthetic production of
hydrocarbons, humic acids and carbohydrates by utilisation of CO2 (CO2 + H2O -> CH2O
+ O2) and nutrient ions[12]. Decreased dissolved oxygen levels in summer and autumn
may be ascribed to the raise of water temperature which led to a release of dissolved
oxygen. In addition, the isolation of the tropholytic zone from the upper waters, the
decrease of penetration of light energy from the surface to the bottom, the consumption of
dissolved oxygen by respiration of phyotoplankton and fish; and the decay of the aerobic
bacteria l'3l were also factors having decreasing effects.
Seasonal vertical and horizontal variations of CO2 were low in winter and spring, and
relatively high in summer and autumn. High CO2 values may be related to anaerobic
decomposition of organic matter present in the bottom sediments and the respirations of
biological bodies which led to the release of CO2 gas. Lower free CO2 values may be
related to its consumption as a result of the reaction between free CO2 product within the
water body and CaCO3 in the sediments, dissolving as Ca(HCO3 )2 [CO2 + H2O + CaCO3
-> Ca(HCO3 )2] and its consumption in the photosynthesis process (CO2 + H2O -> CH2O
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742 AWADALLAH AND MOALLA
+ O2). Carbonates showed seasonal horizontal increase and seasonal vertical decrease
from Abu Simbel to El Ramla while bicarbonates increased horizontally and vertically.
Decrease of carbonate concentrations and increase of bicarbonate concentrations may be
the result of turbulence promoting CO2[14], dissociation of CO*" into HC07 and H+ and
reaction between CO2 and OH" (CO2 + OH" -> HCOJ )[15], and between CO2 and
CO*" [CO2 + CO*" + H2O - • 2HCOJ ].
The relative decrease of HCOJ concentration may be attributed to the dissociation of
HCOj (2HC0 J -» H2O+COj"+CO2) and the uptake of combined CO2 in bicarbonate by
population and CO2-H2O interaction during the photosynthetic process [16], and
adsorption of dissolved bicarbonates on the surface of suspended particles[17]. There was
a slight horizontal increase and a slight vertical decrease of pH values from Abu Simbel to
El Ramla. The increase of pH may be as a result of high temperature effect, the buffer
action attributed to the dissolved CO2, CO^ and HCOJ ions, photosynthesis and growth
of aquatic plants such as fungi, algae and phytoplank-ton[18&19], while relative decrease
of pH may be attributed to the relative decrease in the production of phytoplankton
bloom and the decomposition of organic matter, bacteria and descending plankton
providing a release of CO2 gas, producing a decrease in pH values from the surface to
the bottom[20&21].
Nitrite appeared in some localities in 1983 and increased with depth. Nitrite was
produced and increased as a result of nitrate reduction by enzyme reductase, increase of
nitrification of free ammonia into nitrite, and denitrification of nitrate into nitrite by
bacteria existing in the Lake. The decrease of nitrite content may be principally due to the
increase of its oxidation to nitrate and reduction of nitrate to ammonia as well as its
uptake by plankton. Nitrate concentration decreased horizontally and vertically from the
south (Abu Simbel) to the north (El Ramla). Surface and bottom waters of the Lake
showed a slight decrease in nitrate concentration in spring and summer, and a high
concentration in winter and autumn.
The slight increase of nitrate concentration may be ascribed to nitrification of NH3, and
NO7 produced by biochemical decomposition of descending dead planktons into nitrate by
bacteria, and transformation of organic nitrogen to ammonia and nitrifying ammonia to
nitrate. The decrease of nitrate concentrations may be attributed to biological uptake in
spring and summer in the photic zone and recycling from the hypolimnion zone[22].
Seasonal vertical and horizontal distribution of phosphate showed a smaller decrease in
winter, spring and summer than in autumn. The increase of [PO4~] may be attributed to
the higher rate of decay of phytoplankton, release of the adsorbed phosphate on the
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 743
sediments of the Lake and excretion of large amounts of phosphate by Zooplankton and
fish[23]. On the other hand, the increase of phosphate was consistent with low pH and
dissolved oxygen. The decrease and depletion of phosphate may be related to its
adsorption on hydrous iron or aluminium oxides, its consumption by algae, bacteria or
aquatic plants[24&25].
Soluble silicates decreased in winter and spring, and increased slightly in summer and
autumn. The pronounced decrease of soluble silicate amounts during the winter-spring
period may be ascribed to its uptake by diatoms, fungi, algae, phytoplankton, zoo-
plankton (flowering season), and fish (breeding season)[26]. High soluble silicate contents
during the summer-autumn period may be related to the decay of diatoms, fish, and
animals[27], the effect of water flood loaded with large quantities of silicates, the
redissolution of hydrous silica or silicates adsorbed on clay deposited on the bottom of the
lake, and the effect of soluble silicates released from the surrounding feldspars. Silicon is
an essential element for the growth of diatoms, the rigidity of plant and fish tissues, for
backbones, skeletons fins and scales of fish[28], for the growth of planktonic
chrysophcean and algae silicon cells[22]. The chloride content in surface and bottom
waters of the High Dam Lake decreased in autumn and winter, and increased in spring
and summer. High chloride concentrations in summer time may be ascribed to the high
rate of water evaporation caused by high air temperature [29], while in spring, the
increase of chloride concentration may be related to the effect of NaCl used by
fishermen for salting fish in combination with the excretion of gastric fluids of fish [30],
where the maximal fish breeding season and fishering was stoped. The relative decrease
of chloride content in autumn may be attributed to the dilution effect of water by flood in
addition to its utilisation by algae, phytoplankton and aquatic plants. Seasonal vertical and
horizontal changes of sulphate during the study period showed a remarkable vertical
decrease and horizontal increase from the south to the north. The relative decrease of
sulphate in bottom waters may be attributed to its reduction into sulphide as a result of
the great effect of reducing bacteria, protein synthesis and subsequent precipitation of
detrital organic matter and its decomposition into hydrogen sulphate and insoluble
sulphides[31]. Sulphur is very important for protein structure, for stabilisation of enzyme
geometry and for cell division[22].
Calcium and magnesium showed seasonal vertical and horizontal variations. Ca and Mg
increased vertically and decreased horizontally from the south to the north. The relative
increase of Ca during winter and autumn may be attributed to the increase of CaCO3
solubility with the decrease of water temperature in winter, and the upwelling of bottom
water containing high Ca concentration to the overlaying water layers by the influence of
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744 AWADALLAH AND MOALLA
the stirring winds and induced current in autumn. The relative decrease of calcium and
magnesium contents in surface water in spring may be ascribed to the photosynthetic
precipitation of Ca as CaCO3 and Mg as Mg(OH)2 in alkaline waters, the utilisation of Ca
and Mg in chlorophyll synthesis during the day light, decrease of CaCO3 solubility and
adsorption of Ca on Mg(OH)2. In summer, the relative decrease of [Ca+2] and Mg(OH)2
may be attributed to decreasing CaCO3 and MgCO3 solubility as a result of temperature
increase and loss of CO2 [Ca(HCO3)2 o CaCO3 + H20 + CO2 and Mg(HCO3)2<=>
MgCO3 + H 2 0 +CO2] or may be due to their uptake by micro-organisms and fish living
in the Lake, photosynthesis, carbohydrate metabolism, fatty acids and chlorophyll
syntheses.
Magnesium is needed for phosphate transfer (ATP •» ATP + Energy) and serves as the
transition metal at the heart of the reactive centre of the chlorophyll molecule of plants.
From the statistical analysis of the database of the chemical analysis of the water samples
of the High Dam Lake. There are positive, significant and interesting correlation
coefficient values in spring (r = 0.401-0.928), summer (r = 0.414-0.892), autumn (r =
0.404-0.855) and in winter (r = 0.440-0.892). High correlations between chemical
components mean proportional relationships i.e., as one component increases the other
increases and exist as soluble salts while negative correlations reflect interlocking and
counteraction between the analysed items which exhibit negative correlations due to
environmental conditions.
ConclusionsFrom the results, it can be concluded that there is a marked thermal and nutrients
stratification, and there are also pronounced ecological and environmental changes in the
physical and chemical composition of water of the Lake due to regional and environmental
variations, physical circumstances (water masses movement, turbulence, eddies,...etc.),
hydrological, biological, biochemical, geochemical and biogeochemical variations. These
processes have great influence on the distribution of physical and chemical (nutrient)
components, on the populations (bacteria, algae, fungi, fish,...etc.) living in the Lake, and
on sedimentation of trace elements, on the distribution of trace elements between water
and mud sediments, on the water quality (the chemical components are within the desired
safety baseline levels for domestic, and irrigation uses of water), on the fertility (NOj ,
NO" ,PO?~,humâtes,...etc.) of irrigation water and soil, and on the productivity of crops.
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SEASONAL VARIATION OF HIGH DAM LAKE WATER 745
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Date Received: October 1, 1995Date Accepted: January 8, 1996
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