JOURNAL OF WATER RESEARCH AND ENGINEERING Vol.1, No 1 ISSN: 3105-8973
19
DOI: 10.5281/zenodo.17528384
Recei ed: 13 Oc obe 2025; Accep ed: 1 No embe 2025
PRELIMINARY STUDY OF Δ²H AND Δ¹⁸O SIGNATURES IN THE SELBE
RIVER BASIN DURING EARLY SPRING FLOW
Pu ew-E dene E demja gal1 , Do jpalam Od, Chinzo ig Sukhbaa a *
1Ins i u e o Geog aphy and Geoecology, Mongolia Academy o Science, Ulaanabaa a ci y, Mongolia
E-mail: [email p o ec ed]1
Abs ac : This esea ch s udy aimed o de e mine he s able iso ope (²H, ¹⁸O) composi ion o su ace and g oundwa e in
he Selbe Ri e basin. A o al o 50 samples we e collec ed om su ace and g oundwa e sou ces in he basin on Ap il 27,
28, May 1, and 2, 2023, and analyzed. Addi ionally, on Ap il 27 and 28, sampling was conduc ed e e y 4 hou s o e a 24-
hou pe iod (6 sampling ounds in o al), collec ing 42 wa e samples om 7 loca ions along he Selbe Ri e , om he
Dambada jaa B idge o i s con luence wi h he Tuul Ri e . The samples we e analyzed using he LGR-45EP lase
spec oscopy ins umen a he Ins i u e o Geog aphy and Geoecology.
The s udy u ilized da a om he GNIP (Global Ne wo k o Iso opes in P ecipi a ion) s a ion in Ulaanbaa a as baseline
in o ma ion. Acco ding o GNIP da a, he iso opic composi ion o p ecipi a ion exhibi s signi ican seasonal a ia ion, wi h
he ligh es alues (δ¹⁸O: -27.5 o -28.9‰; δ²H: -209 o -224.8‰) obse ed in No embe , Decembe , and Feb ua y, while
ela i ely hea ie alues (δ¹⁸O: -23.7‰; δ²H: -176.8‰) we e eco ded in Janua y. The hea ies iso opic alues (δ¹⁸O: -7.9
o -9.0‰; δ²H: -57.8 o -69.2‰) we e egis e ed be ween June and Sep embe .
The iso opic analysis esul s o he Selbe Ri e su ace wa e samples collec ed du ing he s udy pe iod sugges ha he
wa e sou ce du ing ha ime was likely p ima ily de i ed om Ma ch–Ap il p ecipi a ion. Addi ionally, he iso opic
composi ion was ligh e in he uppe eaches o he i e bu became p og essi ely hea ie downs eam, indica ing an
in luence om ac o s such as ele a ion and g oundwa e con ibu ions.
Fo u he esea ch on he wa e cycle p ocesses in he Selbe Ri e basin, i is necessa y o conduc seasonal s able iso ope
and hyd ochemical sampling, as well as i ium analysis o de e mine he age, echa ge, and mo emen o g oundwa e .
Keywo ds: Ri e , GNIP(Global Ne wo k o Iso opes in P ecipi a ion), p ecipi a ion, Hea y iso ope, Ligh iso ope, Global
Me eo ic Wa e Line.
I. INTRODUCTION
An iso ope e e s o di e en o ms (a oms) o a
chemical elemen ha ha e he same numbe o p o ons
in he a omic nucleus bu di e in he numbe o neu ons.
They exhibi nea ly iden ical chemical p ope ies bu
di e in hei physical p ope ies. Iso opes a e classi ied
as s able iso opes o uns able ( adioac i e) iso opes.
S able iso opes do no decay (non- adioac i e) o ha e
ex emely long hal -li es, whe eas adioac i e iso opes
ha e uns able nuclei and elease ene gy h ough he
p ocess o decay [1].
Unde s anding he o ma ion o uno and i s
ci cula ion p ocesses is undamen al o wa e esou ce
managemen , while he iso opic a ios in wa e p o ide a
powe ul ool o s udying hese mechanisms on a
b oade scale. Na u al wa e molecules con ain iso opes
o hyd ogen and oxygen (HD16O, H218O, HD18O), as
well as adioac i e iso opes such as i ium (³H), ca bon-
14 (¹⁴C), chlo ine-36 (³⁶Cl), and k yp on-81 (⁸¹K ). These
iso opes ca y aluable in o ma ion abou he global
wa e cycle, g oundwa e o igins and echa ge sou ces,
g oundwa e age, enewal a es, low dynamics, and
sou ces o wa e con amina ion [2].
The s udy o wa e iso opes eme ged as a cu ing-edge
scien i ic echnology in global esea ch his o y s a ing in
1961. In Mongolia, he pionee ing wo k was conduc ed
by So ie ( o me USSR) esea che Romano V.V. and
his eam a ound he mid-1980s. They collec ed iso opic
samples om p ecipi a ion, su ace wa e , and
g oundwa e in he eas e n and cen al egions,
de e mining ha he age o g oundwa e nea he Khalkh
Ri e a ea was app oxima ely 1,000 yea s and
con i ming i s echa ge p ima ily om p ecipi a ion
[3,4].
In line wi h he In e na ional A omic Ene gy Agency
(IAEA) de eloping and implemen ing me hodologies o
s udy wa e iso ope composi ion as pa o i s e o s o
p omo e peace ul uses o nuclea echnology o
de elopmen , Mongolia’s eques o conduc esea ch in
a id and d ough -p one egions, build human capaci y,
p o ide aining, and apply iso ope echniques o
de e mine wa e mo emen , age, and echa ge was
accep ed in 1988. Since hen, he IAEA has been
collabo a ing o imp o e wa e esou ce managemen in
Mongolia. F om 1988 onwa d, i e IAEA Technical
Coope a ion p ojec s and ou RCA (Regional
Coope a i e Ag eemen o Asia and he Paci ic) p ojec s
ha e been implemen ed in Mongolia o enhance he
coun y's wa e esou ce managemen .
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Sus ainable wa e esou ce managemen is o c i ical
impo ance o main aining ecosys em balance and socio-
economic de elopmen . The Selbe Ri e se es as a
majo wa e sou ce o Ulaanbaa a Ci y, and s udying i s
hyd ological cha ac e is ics and iso opic composi ion
helps o unde s and he wa e cycle mechanisms and
echa ge sou ces. The objec i e o his esea ch is o
de e mine he s able iso ope (²H, ¹⁸O) signa u es o he
Selbe Ri e and analyze he dynamics o i s hyd ological
sys em.
II. RESEARCH METHODS
1. S udy a ea
The Selbe Ri e is loca ed in he sou he n pa o he
Khen ii Range and is loca ed a an al i ude o 1510-1620
me e s abo e sea le el. I co e s a o al a ea o 342.2
squa e kilome e s. The e a e 7 species o ees and sh ubs
in he plan kingdom and 183 species o plan s om 40
amilies in he i e basin. The auna includes hedgehogs,
ha es, squi els, oxes, and g ay wol es in small numbe s,
while wild boa s, oe dee , elk, ed dee , and lynx a e seen
in he s eam and li e empo a ily.
2. Da a and ma e ials
As pa o he esea ch, om Ap il 28 o May 2, 2023,
esea che s om he Ins i u e o Geog aphy and
Geoecology collec ed s able iso ope samples om 10
su ace wa e poin s and 40 g oundwa e poin s in he
uppe eaches o he Selbe Ri e basin (Figu e 1). A o al
o 42 iso ope samples we e also collec ed om 6 selec ed
poin s a 4-hou in e als o e a 24-hou pe iod a he
Selbe Res o a ion P ojec si e. These samples we e
analyzed and p ocessed as pa o he s udy.
The esea ch used da a om he Global Ne wo k o
Iso opes o P ecipi a ion (GNIP), an ini ia i e o he
IAEA and he Wo ld Me eo ological O ganiza ion
(WMO) in 1960. This ne wo k p o ides aluable
in o ma ion o wa e cycle, wa e esou ces
managemen , clima e change, and ecosys em s udies, as
well as o moni o ing and s udying he iso ope
composi ion o p ecipi a ion.
The s udy o su ace and g oundwa e iso opes (2H,
18O) in he Selbe Ri e Basin used p ecipi a ion iso ope
da a om he Ulaanbaa a Ci y P ecipi a ion Iso ope
Ne wo k o 1990-2001 and 2021-2022.
Figu e 1. Wa e s able iso ope sampling poin s
3. Iso ope sampling
The e a e no special equi emen s o samples o 2H-
Deu e ium and 18O-Oxygen de e mina ion, and samples
we e collec ed in high-densi y polye hylene plas ic
bo les wi h a capaci y o app oxima ely 50 ml and in
glass bo les wi h sc ew caps. In ield condi ions, he
sample bo les we e no insed o cleaned using any
chemical cleane s. A e sampling, he wa e sample was
placed 2/3 o he way up he bo le o p e en any
expansion o eezing du ing anspo a ion. The lid o
each sample bo le was sealed wi h a plas ic seal o
double-sealed. The samples we e s o ed a oom
empe a u e un il deli e y o he labo a o y, and he lid
was equi ed o be igh enough o p e en e apo a ion
and change in s able iso ope composi ion. A o al o 92
wa e samples we e collec ed om Ap il 28 o May 2,
2023.
4. Analyzing s able iso opes o wa e
A o al o 92 samples o su ace and g oundwa e
om he Selbe Ri e we e analyzed using he “LIMS o
lase spec oscopy” p og am ins alled on a compu e wi h
32MB o memo y, wi h he sample size, loca ion,
ins umen b and, and a b ie desc ip ion o he wo k
being pe o med (Figu e 4) en e ed in o he Los Ga os
45EP model lase spec oscope ins umen o ob ain he
esul s o he s able iso opes (2H, 18O) o he wa e .
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Figu e 2. P epa ing samples aken in he ield o placemen in
he ins umen 's au oma ic sample
Figu e 3. S able iso ope de e mina ion lase spec oscopy
5. S able iso ope p ocessing o wa e
S able iso opes o wa e (2H, 18O) a e non-
adioac i e and do no decay, so hey only change as a
esul o he p ocess o wa e changing om one s a e o
ano he (e apo a ion and mixing). These iso opes can be
used in a wide ange o hyd ological s udies, and we e
used in his s udy o de e mine he sou ce o wa e and
whe he i has been in ol ed in he e apo a ion p ocess.
The amoun o s able iso opes o oxygen, ca bon,
and hyd ogen is no exp essed in concen a ion, bu is
measu ed in pa s pe housand (‰) o ela i e iso ope
a ios, and is deno ed by del a (δ).
𝛿′𝐸 =[ 𝑅𝑠𝑖𝑚𝑝𝑙𝑒
𝑅𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 −1]∗1000‰ (1)
Whe e:
i – a omic mass o he hea y iso ope o he elemen (O
o H)
Rsample - a io o he numbe o a oms o he hea y iso ope
(¹⁸O, ²H) o he ligh iso ope (¹⁶O, ¹H) o elemen E in he
sample
R e e ence – a io o he numbe o a oms o he hea y
iso ope o he ligh iso ope o he elemen in he
e e ence ma e ial
The e e ence o oxygen and hyd ogen is he
Vienna S anda d Mean Ocean Wa e (VSMOW), whe e
he alues o δ¹⁸O and δ²H a e de ined as 0.00‰. The
hea y iso ope o hyd ogen is commonly e e ed o as
deu e ium, and δ²H is some imes deno ed as δD.
The iso opes (δ¹⁸O and δ²H) in a mosphe ic
p ecipi a ion exhibi a linea ela ionship globally,
known as he Global Me eo ic Wa e Line (GMWL),
which is exp essed by he ollowing o mula:
𝛿2𝐻 =8𝛿18𝑂+10 (2)
This co ela ion has been con i med by nume ous
s udies (Figu e 4).
Figu e 4. The Global Me eo ic Wa e Line (GMWL) - he
global linea ela ionship o oxygen and hyd ogen iso opes in wa e
- se es as an iso opic geoindica o o s udying wa e - ock
in e ac ion p ocesses.
Figu e cap ion: 1- Global Me eo ic Wa e Line
(GMWL), 2- Mois u e ecycling, 3- Iso opic exchange
wi h H₂S, 4- Iso opic exchange wi h CO₂, 5- Wa e - ock
in e ac ion in geo he mal sys ems, 6- Mixed wi h
andesi ic wa e , 7- Wa e a ec ed by e apo a ion, 8-
Wa e mixed wi h seawa e , 10- Mois u e condensa ion
p ocess, 11- Paleowa e .
Howe e , he egional p ecipi a ion iso ope
wa e shed is essen ial o in e p e ing s able iso ope da a
om su ace and g oundwa e in a gi en egion. This
s able iso ope wa e shed is essen ial o s udying he
hyd ological p ocesses and ci cula ion o he i e o lake
basin unde s udy, hei wa e sou ces, in e ac ions
be ween wa e and soil and ock, g oundwa e echa ge,
and he mixing o di e en ypes o wa e .
The amoun o s able iso opes in na u al wa e allows
us o gene ally de e mine he o igin o he wa e , based
on which ype o end is bes ep esen ed.
III. RESULT AND DISCUSSION
1. Iso ope ne wo k alues in global p ecipi a ion
The In e na ional A omic Ene gy Agency (IAEA)
and he Wo ld Me eo ological O ganiza ion (WMO) a e
join ly implemen ing he Global Ne wo k o P ecipi a ion
Iso opes (GNIP) wo ldwide. The ne wo k is based in
Ulaanbaa a and collec s mon hly p ecipi a ion samples.
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The samples a e sen o labo a o ies o analysis o s able
iso opes (²H, ¹⁸O) in he wa e . This esea ch p o ides
basic in o ma ion o clima e change, wa e cycle, and
hyd ological s udies.
Figu e 5. S able iso ope da a o p ecipi a ion in Ulaanbaa a
om he Global Ne wo k o Iso opes o P ecipi a ion (GNIP)
The p ecipi a ion iso ope da a o Ulaanbaa a ci y, as
shown in Figu e 5, clea ly show seasonal e ec s, wi h he
lowes o ela i ely ligh iso opes (18O -27.5 o -28.9‰,
2H -209 o -224.8‰) in No embe , Decembe , and
Feb ua y. Howe e , Janua y is ela i ely highe han
hese mon hs (18O -23.7‰, 2H -176.8‰). The hea ies
iso opes a e obse ed be ween June and Sep embe (18O
-7.9 o -9.0‰, 2H -57.8 o -69.2‰).
2. The ela ionship be ween su ace and
g oundwa e
As pa o he Selbe Ri e iso ope s udy, 8 iso ope
samples we e aken om he su ace wa e o he uppe
and middle pa s o he i e basin, and 2 samples om
he Belkh Ri e on Ap il 28, 2023. The esul s indica e
ha he sou ce o he Selbe Ri e wa e is likely o be
echa ged by p ecipi a ion in Ma ch and Ap il. While he
wa e iso opes we e he ligh es in he uppe pa o he
i e , he s able iso opes o he wa e become ela i ely
hea ie as i mo es down he leng h o he i e (Figu e
6). This can be explained, i s ly, by he e ec o land
ele a ion. The di e ence in ele a ion be ween he highes
poin (B-2) and he lowes poin (B-13) is 154 m (Figu e
1). Secondly, as he Selbe Ri e wa e mo es down he
leng h o he i e , i is mo e in e connec ed wi h
g oundwa e and may be echa ged o a ce ain ex en by
g oundwa e . This can be explained by he ac ha he
s able iso opes o he wa e become ela i ely hea ie as
i mo es down he leng h o he i e .
In conclusion, based on he iso ope analysis o Selbe
Ri e wa e aken on Ap il 28, 2023, and g oundwa e
aken on May 1-2, 2023, he Selbe Ri e wa e may be
ed by he yellow wa e o win e p ecipi a ion and he
g oundwa e ed by he ain in he wa m season.
The iso ope analysis o he Belkh Ri e shows ha he
wa e in he i e has a ela i ely hea y iso ope
composi ion ha is di e en om ha o he Selbe Ri e
(Figu e 6). In o he wo ds, he wa e sample aken on
Ap il 28, 2023, coincides wi h he iso ope composi ion o
he wa m season p ecipi a ion, which is due o he ac
ha he ainwa e ha ell in p e ious yea s is eeding he
i e h ough g oundwa e .
3. 24-hou s able iso ope measu emen s a he
p ojec si e
As pa o his s udy, 6 samples we e collec ed a 4-
hou in e als o e a 24-hou pe iod on Ap il 27 and 28,
2023, om a o al o 7 loca ions along he leng h o he
Selbe Ri e om he Dambada jaa B idge o he
con luence o he Selbe Ri e and he Tuul Ri e . A o al
o 42 iso ope samples we e collec ed and analyzed using
an LGR-45EP lase spec ome e o p oduce s able wa e
iso ope esul s.
The esul s o he wa e s able iso ope measu emen s
conduc ed a he Selbe Ri e Res o a ion P ojec si e
show ha he ligh es iso opes we e measu ed a poin 1
nea he Dambada jaa B idge and poin 2 nea he 6 h
s a ion (18O -15.05 o -15.64‰, 2H -112.5 o -116.88‰).
As he i e goes down, he wa e s able iso opes become
ela i ely hea ie , eaching 18O 13.26 o -13.55‰ and
2H -102.93 o -100.43‰ a he poin be o e he Selbe
Ri e lows in o he Tuul Ri e .
This can be explained by wo easons as shown in
Figu e 7. 1. The e ec o ele a ion; 2. I is mixed wi h
g oundwa e o iso opic co ela ion. As can be seen om
he igu e below, he Selbe Ri e wa e in he p ojec a ea
coincides wi h he p ecipi a ion iso opes o Ap il and
May, which may be due o he p ecipi a ion wa e o hese
mon hs. The ele a ion o poin 1 o he 24-hou
measu emen su ey is 1350 m and he ele a ion o poin
7 is 1271 m, o an ele a ion di e ence o abou 80 m.
This can be explained by he ac ha he p ecipi a ion
iso ope becomes ela i ely ligh e as he su ace ele a ion
inc eases.
Howe e , as shown in Figu e 7, he mos plausible
explana ion is ha he Selbe Ri e wa e is mo e likely o
in e ac and mix wi h g oundwa e as i descends along
i s leng h. Poin 1 is he ligh es iso ope measu ed nea he
Dambada jaa B idge and poin 2 is he ligh es iso ope
measu ed nea he 6 h s a ion, while he g oundwa e in
he Selbe Ri e alley is ela i ely hea ie han he
su ace wa e . This can be explained by he ac ha he
s able iso ope o wa e becomes ela i ely hea ie as i
descends along he leng h o he i e due o he
in e ac ion be ween su ace wa e and g oundwa e .
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Figu e 6. S able iso opes o p ecipi a ion in Ulaanbaa a ci y and su ace and g oundwa e in he Selbe Ri e basin
Figu e 7. Global wa e lines, Ulaanbaa a ci y's me eo ological wa e lines, g oundwa e and 24-hou iso ope esul s
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IV. CONCLUSION
As pa o he iso ope s udy being conduc ed as pa
o he Selbe Res o a ion P ojec , a o al o 92 samples
we e collec ed and analyzed om su ace and
g oundwa e in he Selbe Ri e basin om Ap il 28 o
May 2, 2023.
The wa e o he Selbe Ri e in he sp ing season may
be ed by he yellow wa e ed by he p ecipi a ion in he
win e and sp ing seasons and by he g oundwa e ed by
he ain all in he wa m season. As he Selbe Ri e wa e
descends leng hwise, he wa e iso ope shi s om ligh
o hea y, app oaching he iso ope alue o he
g oundwa e , which is ela ed o he inc easing
in e ac ion o su ace wa e wi h g oundwa e as i
descends leng hwise. Acco ding o he esul s o he
wa e samples aken om he Belkh Ri e , he wa e o
his i e coincides wi h he iso ope o he p ecipi a ion in
he wa m season, which is ela ed o he ac ha he
ain all in p e ious yea s eeds he i e wa e h ough he
g oundwa e . The esul ha he Belkh Ri e has mo e
g oundwa e ed may be ela ed o he ac ha he yellow
wa e low may no ha e occu ed (o has al eady
occu ed) a he ime o sampling.
In he u u e, his esea ch wo k can be ca ied ou in
de ail by aking s able iso ope and hyd ochemical
samples o wa e on a seasonal basis o unde s and he
hyd ological p ocesses o su ace and g oundwa e in he
Selbe Ri e basin, he wa e cycle in he basin, and hei
in e ela ionships, and by aking adioac i e i ium
samples o de e mine he age, mo emen , and nu i ion o
g oundwa e in he basin.
ACKNOWLEDGEMENTS
We would like o hank he scien is s om he
Depa men o Wa e Resou ces and Wa e Use a he
Ins i u e o Geog aphy and Geoecology o hei
in aluable assis ance in ca ying ou his esea ch.
REFERENCES
[1] Э. Пүрэв-Эрдэнэ ба С. Чинзориг, Хөвсгөл нуур, түүний
цутгал голын усны тогтвортой изотопын судалгаа,
Улаанбаатар, 2024, pp. 109-120.
[2] Л. Жанчивдорж , Б. Эрдэнэчимэг and Д. Оюунбаатар,
Цөмийн технологи усны судалгаанд, Улаанбаатар: Цөмийн
энергийн комисс, 2013, pp. 103-106.
[3] Л. Жанчивдорж, Ус хөгжлийн түлхүүр, Улаанбаатар, 2018,
pp. Бүлэг 7:157-184.
[4] С. Санждорж, Газрын доорх усыг изотопын аргаар судалсан
дүн, Улаанбаатар: Усны бодлогын хүрээлэнгийн ЭШ-ний
бичиг, 1996, p. тэргүүн дэвтэр.
