沙漠研究 24-1, 105-108 (2014)
Ἃ₍◊✲ 24-1, 105 - 108 (2014)
Journal of Arid Land Studies
Journal of Arid Land Studies－ DT11 Refereed Paper －㸫DT11 Refereed Paper㸫

Water Quality in the Lake Issyk-Kul and the River Flowing into It
Yoshiko KAWABATA*1), Tomoko KURITA1), Masahiro NAGAI2), Vyacheslav APARIN3),
Siaw ONWONA-AGYEMAN1), Masaaki YAMADA1), Yoshikazu FUJII2) and Yukio KATAYAMA2)
Abstract: Lake Issyk-kul is an inland and saline lake in the northern Tian Shan Mountains in eastern Kyrgyzstan. Vertical profile
components in the lake water showed that major components and alkalinity were conservative type, concentrations of which werealmost homogenized vertically, and nutrients were of the middle type between conservative and nutrient, concentrations of which werea little higher in deep water than in surface water. Concentrations of major components and alkalinity were compared to those in
1986. Both Na+ and alkalinity increased by only 12 meq/L for two decades, but the others remained almost unchanged inconcentration. Concentrations of nutrients in the rivers through lands were not related to the land-use types.
Key Words: CIS, Kyrgyz Republic, Lake Issyk-kul, Water quality

1. Introduction
Brackish Lake Issyk-kul is located in the northeastern partof the Kyrgyz Republic and is a high altitude lake in Central
Asia (Fig. 1). With a maximum depth of 665m it is theworld’s fifth deepest lake (Lyons et al., 2000).
There are concerns that the water quality of Lake Issyk-kul,in whose catchment area agriculture, grazing and tourism havebeen developed since the Soviet era, is worsening. As thedevelopment of industries increases water withdrawal from therivers discharge (flowing) into the lake year by year, there arefears that salinity of the lake water may be increasing.
Development of agriculture and grazing are also likely toincrease concentrations of nutrients in the lake water.
The lake is in a semiarid setting with precipitation highest
in spring and summer whereas winters are relatively dry(Lyons et al., 2000). Open Lake water never freezes and thewinter mixed layer temperatures are greater than 4°C(Romanovsky et al., 2002). The lake does not overturn fully
during the summer season and the deep water is ventilated by
local convection in addition to vertical turbulent mixing(Martin et al., 2002). Past climate changes have caused shifts
in the lake’s hydrological budget, which have led to lake level
fluctuations with occasional basin closures (Rasmussen et al.,2000). Due to its basin closure during such a shift about 6900
yrs to 4900 yrs ago, the lake has evolved from a freshwater
body to a saline one (Ricketts et al., 2001).
Kadyrov (1986) researched water quality in Lake Issyk-kul
from 1958 to 1980. Savvaitova and Petr (1992) revealed thatthe major components of the Lake were Na൅ + K൅> Mg2+ >Fig. 1. Map showing the location of Lake Issyk-kul.

Ca2+, ClǦ SO42- >> HCO3-and salinity was ~ 6 g / L. Lyon
et al. (2000) reported that the ion major components of theLake Issyk-kul were similar to the composition of the CaspianSea and the Aral Sea in Central Asia. In this paper, wediscuss the water quality of Lake Issyk-kul, in August 2007,
and twenty seven rivers flowing into the lake in order tounderstand the present water quality of the lake and its
catchment area and to compare to the previous years.

2. Materials and Methods
The sampling sites are shown in Figure 2. Water samples
from Lake Issyk-kul were collected in August 2007, whilesamples from river water were collected in August 2006 andAugust 2007. The position of each sampling spot wasdetermined by using an eTrex Legend portable Global
Positioning System. Water temperature, pH, EC, DO and㸦Received, September 9th, 2013; Accepted, December 30th, 2013㸧

* Corresponding Author: yoshikok@cc.tuat.ac.jp
2-24-16, Nakacho, Koganei, Tokyo, 184-8588, Japan1) Tokyo University of Agriculture and Technology
2) University of Human Environments

3) State Committee of Geology and mineral resources of Uzbekistan

106CoCon
centncratio

entn ofrat

Na+ioandnofMg2

K++Fig. 2. Sampling Sites in Lake Issyk-kul, Kyrgyzstan.

Turbidity were all determined in the field.
Water samples were filtered through a 0.45 ȝm Membranefilter (DISMIC 25AS020AS, ADVANTEC Corporation) andcollected in polypropylene bottles. Concentrations of major
components (K+, Mg2+, Ca2+, Cl-, SO42-, Alkalinity) weredeterminedusingion
chromatographic
analyzer.
+Concentrations of Na were determined using an atomic
absorption spectrophotometer. Alkalinity was calculated
from concentrations of major components (Alkalinity = Na++K+ + Mg2+ + Ca2+ - Cl- - SO42-). Nutrient concentrations(PO4-P, NO3-N, NO2-N, NH4-N) were determined by an
Auto-analyzer (Buran Luebee Corporation), while those ofSi(OH)4-Si were determined by a visible-ultraviolet
spectrophotometer. Finally, accuracy and precision of theanalytical methods were shown to be satisfactory with 2-5%
error.

3. Results and Discussion3.1. Water quality of Lake Issyk-kul
Horizontal distribution of Na+, K+, Mg2+, Ca2+
concentrations are shown in Figure 3 while Vertical
distribution of concentrations of Na+, K+, Mg2+, Ca2+ are
shown in Figure 4. Horizontal distribution of concentrationsof Si(OH)4-Si, NO3-N, PO4-P can be seen in Figure 5 while
Figure 6 shows the vertical distribution of Si(OH)4-Si, NO3-N,PO4-P concentrations.
In summer 2007, cation concentrations of distribution inboth the vertical and horizontal directions were substantially
uniform. From these results, in the range of measuring depth,
the lake was found to be stirred.
The same trend in the horizontal distribution of nutrients inthe lake water was observed from the shore to the center ofsampling site on the lake. With the vertical distribution, nochanges in the concentrations of NO2-N and NH4-N wereobserved from the bottom of the lake to near surface.
However, concentrations of PO4-P, and NO3-N had increasedin the 20 - 40 m depth. This trend is considered to be theinfluence of biological activities.

mmanol/Ld)

Fig. 3. Horizontal distribution of concentrations of Na+, K+, Mg2+, Ca2+
in Lake Issyk-kul (‫ی‬: Na+, ‫ە‬: K+, : Mg2+, ‫ڸ‬: Ca2+).
Concentration of Na+ and Mg2+ mmol/L)

Concentration of K+ and Ca2+ (mmol/L)

Fig. 4. Vertical Distribution of Concentrations of Na+, K+, Mg2+, Ca2+
in Lake Issyk-kul (‫ی‬: Na+, ‫ە‬: K+, : Mg2+, ‫ڸ‬: Ca2+).

Fig. 5. Horizontal Distribution of Nutrient Concentrations in LakeIssyk-kul (‫ە‬:Si(OH)4-Si, +:NO3-N, ‫ڦ‬:PO4-P).

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Concentration of Si(OH)4-Si and NO3-N(µmol/L)
Concentration of Si(OH)4-Si and NO3-N(µmol/L)

Fig. 8. Comparing the Nutrient Component of River Water
Fig. 8. Comparing the Nutrient Component of River Water(No.1-27) and Lake Waters.
(No.1-27) and Lake Waters.

Concentration of PO4-P (µmol/L)
Concentration of PO4-P (µmol/L)

Fig. 6. Vertical Distribution of Nutrient Concentrations in Lake
Fig. 6. Vertical Distribution of Nutrient Concentrations in Lake
Issyk-kul (‫ە‬:Si(OH)4-Si, +:NO3-N, ‫ڦ‬:PO4-P).
Issyk-kul (‫ە‬:Si(OH)4-Si, +:NO3-N, ‫ڦ‬:PO4-P).

Fig. 9. Comparing the Cation Component with Our Results andFig. 9. Comparing the Cation Component with Our Results andPast Research.
Past Research.

Fig. 7. Comparing the Cation Component of River Water (No.1-27)
Fig. 7. Comparing the Cation Component of River Water (No.1-27)
and Lake Waters.
and Lake Waters.

3.2. Comparison of river water and lake
3.2. Comparison of river water and lake
The results of comparing the major ion component of river
The results of comparing the major ion component of riverand lake waters are shown in Figure 7. Major cationand lake waters are shown in Figure 7. Major cation
concentrations in the lake water were higher than the riverconcentrations in the lake water were higher than the riverwater. Trends of major anion concentrations were similar towater. Trends of major anion concentrations were similar tothe cations. Compared with river water, Na+ concentration
the cations. Comparedwith river water, Na+ concentration+
was 450 times, Mg2+2+ concentration was 150 times, K+
was 450 times, Mg concentration
was 150 times, K
concentration was 50 times, Ca2+2+ concentration was 10 times
concentration was 50 times, Ca concentration was 10 times
higher in the lake water. Trends of anion concentrations (Cl--,higherin the lake water. Trends of anion concentrations (Cl ,SO422-, alkalinity) were similar to the cation concentrations. InSO4 , alkalinity)
were similar to the cation concentrations. In
particular, Cl-- ions were 950-fold concentrated in the lakeparticular, Cl ions were 950-fold concentrated in the lakewater.
water.
The results obtained by comparing the nutrients component
The results obtained by comparing the nutrients componentof river and lake waters are shown in Figure 8. There was noof river and lake waters are shown in Figure 8. There was nosignificant difference in concentration when the lake and riversignificant difference in concentration when the lake and riverwaters were compared. The concentration ratios ofwaters were compared. The concentration ratios ofSi(OH)4-Si, NH4-N, NO2-N were reduced in the lake
Si(OH)4-Si, NH4-N, NO2-N were reduced in the lakecompared to river water. However, there were observed
compared to river water. However, there were observed

Fig. 10. Comparing the Anion Component with Our Results andFig. 10. Comparing the Anion Component with Our Results andPast Research.
Past Research.

increments in PO4-P and NO3-N.
increments in PO4-P and NO3-N.
3.3. Comparison with past data
3.3. Comparison with past data
A vast collection of data on major ions has been reported
A vast collection of data on major ions has been reported
by Kadyrov (1986), and more recently by Vollmer et al. (2002)
by Kadyrov (1986), and more recently by Vollmer et al. (2002)

108

as well as Karmanchuk (2002). Results of major ion
concentrations obtained in our investigations comparedreasonably well with those in these studies (Figs. 9 and 10).
Concentrations of cation components (K+, Ma2+, Ca2+) andalso those of anion components (Cl-, SO42-, alkalinity) are
increasing every year. From these results, it is clear that thebuildup of salt concentration is in progress in the Issyk-kul
Lake. Due to the increasing alkalinity and Na+, thecomposition of the main component has changed.

4. Conclusion
The horizontal distribution of PO4-P, and NO3-N in theLake Issyk-kul increased in the 20 - 40 m depth. This trend isconsidered to be the influence of biological activities. The
results indicate that major ion concentrations of the lake water
were higher than river water and that there is an annual
increase in the concentrations of major components. Due tothe increasing alkalinity and Na+, the composition of the main
component has changed. However the others remained
almost unchanged in terms of concentration. Concentrationsof nutrient components in river waters were compared, but thereason why concentrations of only two components increased
could not be ascertained.
Acknowledgments
This work was supported Grant-in-Aid for Science
Research, by Ministry of Education, Culture, Sports, Scienceand Technology of Japan, 2004-2007 and 2008-2011(Monbusho International Scientific Research Program,represented by KAWABATA Y.).

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