Sulfur, oxygen, and hydrogen isotope compositions of ...svr4.terrapub.co.jp/journals/GJ/pdf/4605/46050443.pdf · The H and O isotope values in the summer are plotted near the global

443

Geochemical Journal, Vol. 46, pp. 443 to 457, 2012

*Corresponding author (e-mail: [email protected])

Copyright © 2012 by The Geochemical Society of Japan.

fuel combustion in industrialized and heavily populatedregions. Potential sources of sulfur oxides include: oil-refinery operations, oil- or coal-based power generation,automobile combustion, and other oil- or coal-reliant fa-cilities. On the other hand, major ion distributions in pre-cipitation are primarily controlled by contributions frommarine (sea-salt aerosols), terrestrial (soil dust, biologicemissions) and anthropogenic (industrial, biomass burn-ing, vehicle emissions, and others) sources (Junge, 1963;Nakai and Takeuchi, 1975).

SO2, which is mainly produced by anthropogenic ac-tivities, undergoes oxidation to form SO4

2– and the reac-tion is enhanced by metallic ions in urban atmospheres(Newman et al., 1991). However, substantial amounts ofatmospheric SO4

2– arise from sea spray in coastal areasas well (Nielsen, 1978). The abundance of 34S/32S ratiosin snow and rainwater derived from SO4

2– bearing pre-cipitation may be used to delineate anthropogenic S inthe atmosphere, provided that the isotopic compositionof pollutant S is distinct from S originating from naturalsources. Sulfur isotopes have been widely used to inter-pret substances’ origins, forming conditions, and envi-

Sulfur, oxygen, and hydrogen isotope compositions of precipitation in Seoul,South Korea

CHUNGWAN LIM,1 INSUNG LEE,1* SANG-MOOK LEE,1 JAE-YOUNG YU2 and ALAN J. KAUFMAN3

1School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea2Department of Geology, Kangwon National University, Chuncheon 200-701, Korea

3Department of Geology, University of Maryland, College Park, MD 20742-4211, U.S.A.

(Received December 28, 2011; Accepted August 2, 2012)

To evaluate the source of sulfur and the extent of seasonal and local characteristics in Seoul’s precipitation chemistry,we measured sulfur, oxygen, and hydrogen isotopic ratios of precipitation. The pH of precipitation ranges from 4.6 to 7.0in Seoul. Precipitation shows positive correlations between ions in the Ca2+–Mg2+–SO4

2––NO3– system, indicating that

the dissolution of Ca and Mg particles by H2SO4 and HNO3 from the combustion of fossil fuels is a major process control-ling the chemical composition of snow and rain. The values of oxygen and hydrogen isotope composition of rain range–15.7~–3.2‰ and –114.7~–18.0‰, respectively. The H and O isotope values in the summer are plotted near the globalmeteoric water line by Craig (1961). The d-excess values in winter are higher than 10, which indicate that the source ofrain during winter is a dry air mass from continental China. The sulfur isotope ratio of precipitation in Seoul ranges from+3.0 to +7.3‰, which is similar to typical metropolitan air pollution levels. The data suggests that the main source ofsulfur is SO2 produced by the combustion of fossil fuels. The pollutant SO4 is estimated to have a δ34Snss range from +1.0to +6.2‰ in the Seoul area. The δ34S values of precipitation range from +5.1 to +7.3‰ (mean +6.4‰) in winter and from+3.0 to 4.8‰ (mean +4.0‰) in summer. The higher δ34S values in winter (December and February) seem to be correlatedto the air mass from northern China, of which the δ34S values of oil or coal is higher than that of southern China. The lowersulfur isotopic values in summer (June to August) are correlated to the air mass moving from southern China. Isotopiccomposition and chemical concentrations of SO4 depend on wind provenance, thus supporting the idea that a seasonallytransported source for the pollutant sulfur is from China.

Keywords: sulfur isotope, oxygen, hydrogen, pollution, precipitation, sulfate, Korea, East Asia

INTRODUCTION

The chemistry of acidic precipitation worldwide hasbeen intensively studied for the past several decades. Acidrain is known to cause serious environmental damage insensitive environments (Ayers and Yeung, 1996;Kulshrestha et al., 2003; Lee et al., 2000; Das et al., 2005;Cape and Leith, 2002; Andronache, 2004; Zunckel et al.,2003; Yamaguchi et al., 1991). The increase of fossil fuelburning in east Asian countries has likely intensified acidrain in east Asian countries including Korea, China, Ja-pan, and Russia (Lee et al., 2000; Park et al., 2000; Chunet al., 2000; Park and Cho, 1998), while there are consid-erable contributions of sulfur from Yellow sand (Asiandust) from the inland of the continent.

Sulfur oxides mainly as SO2 are among the major pre-cursors of acid rain, and they are released through fossil

444 C. Lim et al.

ronmental alterations (Mizutani and Rafter, 1969; Nakaiand Takeuchi, 1975; Nissenbaum, 1978; Nriagu et al.,1987; Ohizumi et al., 1991; Yu and Park, 2004). Also,there is a distinct difference in the sulfur isotope ratios offossil fuels such as coal and petroleum. Sulfur isotopefractionation is also demonstrated by Hong et al. (1992)and Maruyama et al. (2000) through their combustionexperiments. Sulfur exists in small amounts in the atmos-phere, but when anthropogenic sources of sulfur that causeair pollution are introduced, the atmospheric sulfur iso-topic chemistry changes in a very subtle manner. Becauseof this phenomenon, a study on the sulfur isotope ratio ofsulfate ions in precipitation is considered a useful methodin tracking the source and distribution cycle of air pollut-ants.

Thus the sulfur isotopic and major element composi-tion of rainwater along with meteorological informationcan be used to trace the sources of sulfur in precipitation,and to evaluate contributions from different sources(Krouse, 1980; Krouse and Case, 1981; Na et al., 1995;Yu and Park, 2004). In this case variation among sourcesmust be isotopically significant and changes in isotopiccomposition during transport and transformation must betrivial. Additional information on both sources and mix-ing phenomena can be obtained by combining concentra-tion and isotopic composition data with meteorologicalparameters (e.g., wind direction, temperature etc.). Iso-topic studies on water samples in Korea have been madefor oxygen and hydrogen isotopic compositions of pre-cipitation in Taejeon and Seoul (Lee and Chang, 1994)and Cheju Island (Lee et al., 1997); studies have also beenmade for isotopic compositions in ground water (Na etal., 1995) for sulfur, oxygen, and hydrogen isotopes ofacid mine drainage (Yu and Coleman, 2000). Data onsulfur isotope compositions of precipitation in Korea arevery rare.

The oxygen and hydrogen isotopic compositions ofprecipitation in natural waters are governed by tempera-ture, evaporation, and condensation. Deuterium excess (d)is a second order parameter derived from δD and δ18Ovalues. Deuterium excess reflects the different sensitivi-ties of these isotopes to kinetic effects in the hydrologiccycle. Theory predicts that deuterium excess respondsprimarily to changes in sea surface temperature (SST),humidity, and wind speed at the moisture source(Dansgaard, 1964). The value of deuterium excess is de-termined from the equation as d = δD – 8δ18O. The val-ues of deuterium excess of any sample can be interpretedas the intercept with the δD axis (for δ18O = 0) of the linewith slope ∆δD/∆δ18O = 8 which passes through thatpoint; such a line presumably would be the locus of allprecipitation samples which are derived from that par-ticular air mass by rainout; as will be discussed, the “d-parameter” according to this view relates to the vapor-

forming process whereas the position of any point on theslope = 8 line is determined by the rainout process(Dansgaard, 1964). These measurements could potentiallyprovide a means for determining the relative importanceof different air masses for summer and winter precipita-tion (Epstein and Mayeda, 1953; Craig, 1961; Dansgaard,1964; Lee and Lee, 1999). In this study the isotopic ra-tios of sulfur, hydrogen and oxygen of wet depositions inSeoul, Korea are determined through the analyses of snowand rainwater to distinguish between different precipita-tion events and their associated meteorological conditions.

The purpose of this research is to characterize the pre-cipitation chemistry of the Seoul area, namely for sulfur,oxygen, and hydrogen isotope compositions, and to evalu-ate the source of sulfur and the extent of seasonal andlocal characteristics of snow and rain. This data will pro-vide a context for potential solutions to environmentalproblems in East Asia. The present work deals with ur-ban atmospheric conditions in Seoul, a very densely popu-lated city in Korea, surrounded by a wide and crowdedindustrial belt. Consequently air pollution poses a poten-tial problem to environment. For this reason, a system-atic chemical and isotopic study was undertaken to quan-

Fig. 1. Map of the sampling location of study area (black cir-cle; in Seoul) and reference area (open triangle; Chuncheonby Yu and Park, 2004 and open rectangular; Chonju by Na etal., 1995).

Stable isotope compositions of precipitation in Seoul 445

tify the chemistry and S isotopic composition of aqueousSO4

2– in a variety of precipitation events at Seoul Na-tional University in Gwanak-gu, Seoul, during the periodof December 2000 to October 2001.

STUDY AREA

Seoul is the capital city of South Korea, which ac-commodates about ten million people with more than threemillion motor vehicles, as well as numerous industrialplants within the metropolitan area.

The referenced location is Chuncheon, which occu-pies the eastern part of the Korean peninsula. This area issurrounded by developed and developing mining indus-tries and forested areas. The emissions of atmosphericpollutants from Chuncheon are relatively insignificant toemissions from domestic fossil fuel consumption (Yu andPark, 2004). The last referenced area is Chonju (Na etal., 1995), which has a few industrialized areas surroundedby agricultural fields (Fig. 1).

The climate of Seoul and Chuncheon is temperate andshows distinct seasonality. In winter, winds commonlyoriginate from the north-northwest or north-northeast re-sulting in a wide range of temperatures typical of north-ern continents. Winters are bitterly cold and are influ-enced primarily by Siberian air masses. In the summer,prevailing winds commonly come from the south-south-east, bringing in the maritime Pacific air mass into theregion which results in high temperature and humidity.Temperatures recorded over a 30-year period show typi-cal cyclic variation between –7.0 and +30.0°C with a sea-sonal mean temperature of about –2.0°C in winter and+25.0°C in summer (Table 1). The average annual pre-cipitation is about 1330 mm (data from Korea Meteoro-logical Administration) with more than half of the totalrainfall concentrated in the summer monsoon. Winter pre-cipitation takes up less than 10% of the annual total. Hightemperature and humidity are caused by the northern Pa-cific air mass usually in the monsoonal rainy season fromJune to September in Korea.

Date (dd-mm-yy) Precipitation type (season) Direction Velocity (m/s) Precipitation (mm) T (°C) pH EC (µS/cm) Condition

16-Dec-00 Snow (Wt) NW 1.5 5.4 −0.6 4.92 16.3

24-Dec-00 Snow (Wt) NW 2.2 13.9 −2.2 4.87 7.53

1-Jan-01 Snow (Wt) NW 3.7 21.7 0.4 5.07 5.92 Heavy snowfall27-Jan-01 Snow (Wt) NW 3.6 1.9 0.0 4.95 72.2 Yellow sand9-Feb-01 Snow (Wt) W 2.6 0.2 −0.9 5.87 6.79

15-Feb-01 Snow (Wt) NE 3.2 23.4 3.4 6.17 18.127-Feb-01 Rain/Snow (Wt) N 1.7 7.7 3.0 5.81 9.484-Mar-01 Snow (Wt) NW 4.9 11.2 1.0 6.55 96.2 Yellow sand28-Mar-01 Rain/Snow (Wt) NW 1.8 2.7 2.9 6.77 11.411-Apr-01 Rain (Sp) WNW 3.0 6.5 9.3 6.99 55.3 Yellow sand7-May-01 Rain (Sp) SW 1.5 5.4 18.3 6.86 14.3 Dry Season22-May-01 Rain (Sp) ENE 1.3 7.9 22.3 6.69 12.418-Jun-01 Rain (Sm) SW 0.8 36.2 20.2 6.58 36.725-Jun-01 Rain (Sm) SW 2.0 7.8 22.6 6.20 16.8 Typhoon5-Jul-01 Rain (Sm) SW 4.5 21.1 24.6 6.47 52.710-Jul-01 Rain (Sm) W 1.0 14.2 21.8 6.01 66.1 Rainly season15-Jul-01 Rain (Sm) SW 1.0 273 23.2 5.51 6.53 Heavy rainfall7-Aug-01 Rain (Sm) ENE 0.5 17.7 26.7 5.45 50.715-Aug-01 Rain (Sm) S 0.7 162 25.2 4.60 25.66-Sep-01 Rain (At) SSW 1.2 43.4 22.7 5.20 64.230-Sep-01 Rain (At) ENE 1.6 5.4 15.7 5.10 46310-Oct-01 Rain (At) SW 2.6 46.3 13.8 4.80 14.8

13-Feb-01 Stream water 5.2 6.72 125

19-May-01 Stream water 16.3 7.03 87.4

1-Jul-01 Stream water 23.5 6.55 130

8-Oct-01 Stream water 12.4 7.36 78.7

13-Feb-01 Ground water 7.4 6.57 201

19-May-01 Ground water 11.8 7.19 165

1-Jul-01 Ground water 15.4 8.22 157

8-Oct-01 Ground water 9.5 7.63 216

Table 1. The general weather conditions of precipitation in Seoul

Wt, winter; Sp, spring; Sm, summer; At, autumn.

446 C. Lim et al.

METHODOLOGY

Samples of snow and rainwater were collected foroxygen, hydrogen, and sulfur isotope measurements fromDecember, 2000 to October, 2001, including both dry andrainy seasons. Stream and ground waters from nearby areaGwanak were collected and analyzed for reference. Thesampling site is located within the Gwanaksan granite,just south of the Seoul granitic batholith (Fig. 1). Themeteoric water (rain and snow) samples in Seoul wereacquired on the roof of a five-story building at the Schoolof Earth and Environmental Sciences in the Seoul Na-tional University Campus. The referenced Chuncheonsamples of meteoric water were collected at each precipi-tation event of Kangwon National University inChuncheon from October, 2000 to July, 2001 (Yu andPark, 2004).

Precipitation samples were collected using contain-ers with large funnels directly from the atmosphere. Sam-ples of snow and rainwater were acquired manually us-ing a bulk deposition sampler equipped with a stainlesssteel funnel (65 cm in top diameter), a Teflon bottle set(500 ml) and plastic boxes (60 cm × 40 cm × 15 cm) onthe roof of the building (location: E 126°57′18″, N37°27′14″, 171 m above sea level). The lid of the sam-pler was manually removed to collect samples. After aprecipitation event, the sample was immediately trans-ported to the laboratory. The pH of the snow or rainfallwas measured immediately after sample collection. Snowsamples were collected in the plastic boxes and were al-lowed to melt at laboratory temperature. More than 10liters of sample were collected for the S isotope analy-ses. The collected sample was passed through a 0.45 µmMillipore filter and each aliquot (500 ml) of filtered sam-ple was acidified with HNO3 for cation analyses (EANET,2000).

General weather information related to precipitationwas obtained from the weather station of the Korea Me-teorological Administration located about 5 km NW ofthe sampling site.

Major chemical compositions of water samples wereanalyzed using the Inductively Coupled Plasma—AtomicEmission Spectrometer (SHIMADZU/ICPS-1000IV) atthe National Center for Inter-University Research Facili-ties (NCIRF), Seoul National University for Na, Mg, K,and Ca. Ion Chromatography (at the Center for MineralResources Research, Korea University: DIONEX-120Automated Dual Column I.C.) was used for the analysesof Cl–, SO4

2–, NO3–, and NH4

+. The external precision, orreproducibility, is defined as two standard deviations (2σ)of the average values of major chemical ions of repeatedanalyses of the same sample during various data acquisi-tions (WMO Manual; Allan, 2004).

Oxygen and hydrogen isotope sample preparations

were carried out separately. Samples for oxygen isotopicanalysis were prepared through H2O–CO2 equilibration(Epstein and Mayeda, 1953). About 2 ml of each watersample was equilibrated with CO2 of known isotopic com-position at 25°C. The CO2 gas was then extracted,cryogenically purified, and analyzed using the massspectrometer. For deuterium analysis, metallic zinc wasused to produce hydrogen gas (Coleman et al., 1982). Theoxygen and hydrogen isotopic compositions of the sam-ples were determined using the VG Isotech Prism II massspectrometer at Korea Basic Science Institute (KBSI). Theanalytical reproducibility was ±0.1‰ for δ18O vs. SMOWand ±1‰ for δD vs. SMOW.

When measuring the amount of sulfur isotope of asample that has such a small amount of sulfur, it is neces-sary to concentrate and extract the sulfur. Precipitationcontains an infinitesimal amount of sulfur in the SO4

2–

form so in order to measure sulfur isotopes, the easily-performed Barium sulfate precipitation method was usedin this study. The dissolved SO4 in the samples was pre-cipitated as BaSO4. For sulfur isotopic analysis, about 3mg of BaSO4 powder was suitable. The following methodwas used in concentrating and extracting sulfur.

The collected sample was immediately filtered througha 0.45 µm Millipore filter and after weighing it with amass cylinder, it was filled into a beaker. 1~2 ml of 1NHCl was added to the sample to acidify it and after cov-ering the beaker with a watch glass, it was heated up toits boiling point on a hot plate. After the heating was con-tinued for one day, the system was cooled down at roomtemperature. The precipitated BaSO4 was rinsed with dis-tilled water, dried, powdered and treated with HCl acidin order to remove oxygen-bearing compounds other thanBaSO4. Then BaCl2 was added in order to concentratethe formed crystals for convenient collection. Next, theywere filtered with glass wool filters. BaSO4 was concen-trated on the filter and after drying it below 100°C, it wasweighted. BaSO4 was then packed and stored with thefilter.

Barium sulfate powders were recovered and the sam-ples were placed in quartz tubes then decomposed by heat-ing to at least 950°C (Yanagisawa and Sakai, 1983). Be-fore heating, the sulfur isotope ratio analyzing SO2 gaswas produced using Rob’s method which is mixing Cuand Mg wool by 1:2 in a vacuum line for oxidation. Theresulting SO2 was separated from trace contaminants bycryogenic distillation using three cold baths: liquid ni-trogen (–196°C), liquid nitrogen-pentane slush (–131°C)and dry ice-ethanol (–86°C). In the vacuum line, gas pu-rification was carried out by getting rid of H2O using dryice temperature and collecting pure SO2 gas at the freez-ing point. All the sulfur contained in the SO4

2– ions wasconverted to pure SO2 gases. The prepared SO2 wasanalyzed for its δ34S composition using the Isoprime gas


source mass spectrometer at KBSI. The δ34S values aregiven in per mil [‰] units, with reference to CDT.

RESULTS AND DISCUSSION

Chemistry of precipitationTable 1 summarizes the pH and temperature of rain-

water, stream, and ground water samples collected dur-ing this study along with prevailing wind direction, windvelocity, and rainfall amounts from December 2000 toOctober 2001 in Seoul. The pH of the precipitation sam-ples range from 4.6 to 7.0, averaging 5.80 in Seoul (Fig.2). Similar mean pH values in Seoul and Chuncheon wereobtained by Yu and Park (2004). However, the averagevalues of pH are higher than the value reported in 2000(4.7 ± 1.4 by Lee et al. (2000)). The reason for this isperhaps due to the widespread deposition of Yellow sand(Asian dust) from central Asia in early spring, 2001.

The winter rain collected on December 24, 2000 wasa bit more acidic (pH 4.9) compared to samples from thespring season which had pH values of about 7.0 (Table

1). This variation in pH values is attributed to the inten-sity of rainfall received and the spring time Yellow sandphenomenon (Table 2).

The Yellow sand phenomenon was observed acrossthe entire Korean peninsula in the January 1st, March 4th,and April 11th of 2001. A trajectory analysis showed thatthe Yellow sand could reach Seoul within two days fromthe Gobi Desert (Chun et al., 2000, 2001). The pH risesand alkali ion concentration abruptly increases abovemean values during the Yellow sand event as shown inthe EC values (Table. 1). Subsequently heavy snow andrainfall in Seoul and Chuncheon diluted the atmosphericflux so that the aerosol collected during that time had K2O,Na2O, CaO, and Al2O3 abundances near long-term re-ported values (Chun et al., 2000; Fujita et al., 2000).

Data collected on March 4th had the highest concen-trations of cations. Abundances of Ca2+ and Mg2+ were269.0 µeq/L and 107.3 µeq/L, respectively. Inspection ofthis figure indicates that the present values are higher rela-tive to those reported in northeastern North America andcentral Europe (Galloway, 1995). The arithmetic means

0

50

250

300

Pre

cipi

tatio

n(m

m)

–10

0

10

20

30

Tem

pera

ture

(C

)4

5

6

7

pH

1

10

100

1000

Con

duct

ivity

(s/

cm)

Dec/0

0

Dec/0

0

Jan/

01

Jan/

01

Feb/0

1

Feb/0

1

Feb/0

1

Mar

/01

Mar

/01

Apr/0

1

May

/01

May

/01

Jun/

01

Jun/

01

Jul/0

1

Jul/0

1

Jul/0

1

Aug/0

1

Aug/0

1

Sep/0

1

Sep/0

1

Oct/01

(mm

/yy)

Precipitation (mm)

Temperature ( C)

pH

Conductivity ( s/ cm)

Fig. 2. Seasonal variations of precipitation, air temperature, pH and conductivity in Seoul.

448 C. Lim et al.

Tabl

e 2.

C

hem

ical

and

iso

topi

c co

mpo

siti

ons

from

met

eori

c w

ater

in

Seou

l

AM

, ar

t hi m

eti c

mea

n; S

TD

, st

anda

rd d

evi a

t ion

; W

t , w

i nt e

r; S

p, s

pri n

g; S

m,

sum

mer

; A

t , a

utum

n.

Dat

eP

reci

pita

tion

type

Che

mic

al d

ata

(uni

t: µ

eq/L

)Is

otop

ic d

ata

(dd-

mm

-yy)

(sea

son)

Na+

Mg2+

K+

NH

4+C

a2+

Cl−

NO

3−S

O42−

nssS

O42−

δ18δ

d-ex

cess

δ34 obse

rved

δ34 pollu

tion

16-D

ec-0

0S

now

(W

t)18

.213

.48.

9634

.291

.939

.721

.950

.648

.4−1

5.7

−114

.710

.65.

14.

4

24-D

ec-0

0Sn

ow (

Wt)

7.21

4.62

7.21

15.8

21.5

13.1

11.8

5.41

4.54

−14.

7−1

01.8

15.8

6.7

4.2

1-Ja

n-01

Snow

(W

t)8.

781.

676.

3321

.413

.64.

2824

.312

.311

.2−1

2.6

−79.

821

.17.

36.

1

27-J

an-0

1S

now

(W

t)98

.345

.336

.647

.928

717

613

811

810

6−1

5.0

−100

.120

.06.

55.

0

9-F

eb-0

1S

now

(W

t)7.

092.

619.

0425

.632

.512

.015

.011

.010

.1−7

.8−3

1.5

31.4

15-F

eb-0

1S

now

(W

t)4.

985.

8616

.520

.251

.214

.925

.229

.829

.2−1

0.1

−60.

819

.66.

56.

2

27-F

eb-0

1R

ain/

Sno

w (

Wt)

16.7

4.92

18.2

29.5

24.5

3.88

27.6

11.3

9.30

−10.

1−6

5.4

16.1

4.4

1.0

4-M

ar-0

1S

now

(W

t)94

.610

75.

2124

.126

939

.411

423

222

1−8

.2−5

9.2

6.9

3.6

2.8

28-M

a r-0

1R

a in/

Snow

(W

t)20

.84.

246.

1842

.141

.814

.422

.913

.210

.7−1

2.2

−79.

717

.3

11

-Apr

-01

Rai

n (S

p)92

.263

.28.

9215

.512

285

.577

.511

210

1−6

.2−3

3.1

16.3

4.4

2.7

7-M

a y-0

1R

ain

(Sp)

20.9

3.27

23.0

64.6

20.5

12.1

17.1

28.8

26.3

−3.2

−18.

07.

53.

01.

4

22-M

ay-0

1R

ain

(Sp)

14.3

1.73

1.93

38.9

41.5

19.7

11.4

19.8

18.1

−8.6

−70.

2−7

.94.

32.

8

18-J

un-0

1R

ain

(Sm

)12

.219

.114

.77.

8414

122

.648

.181

.780

.2−7

.4−6

0.4

7.0

25-J

un-0

1R

ain

(Sm

)7.

139.

229.

5220

.756

.59.

5323

.233

.132

.2−1

4.2

−107

.65.

63.

73.

2

5-Ju

l-01

Rai

n (S

m)

37.3

38.7

24.8

17.9

157

60.0

73.0

104

99.5

−5.1

−36.

24.

53.

32.

5

10-J

ul-0

1R

ain

(Sm

)26

.826

.913

.123

.422

148

.525

.910

910

6−8

.1−5

7.8

6.4

4.2

3.7

15-J

ul-0

1R

ain

(Sm

)14

.84.

1813

.840

.527

.118

.912

.412

.710

.9−6

.5−4

4.6

8.0

4.8

2.3

7-A

ug-0

1R

ain

(Sm

)49

.838

.355

.233

.513

232

.260

.216

616

0−3

.9−2

8.6

2.6

4.7

4.1

15-A

ug-0

1R

ain

(Sm

)21

.714

.12.

4924

.964

.527

.328

.536

.533

.9−5

.2−3

3.0

8.6

3.2

1.9

6-S

ep-0

1R

ain

(At)

98.3

68.9

10.0

35.8

107

86.2

34.7

142

130

−7.9

−40.

322

.95.

34.

0

30-S

ep-0

1R

ain

(At)

34.8

10.3

41.2

11.9

164

57.8

103

45.6

41.4

−12.

6−7

8.3

22.5

6.1

4.7

10-O

ct-0

1R

ain

(At)

27.8

8.33

3.82

33.4

26.5

23.2

17.7

18.1

14.8

−15.

8−1

05.2

21.2

5.8

2.6

AM

33.4

22.6

15.3

28.6

96.8

37.3

42.4

63.3

Σ− /Σ+ =

0.7

3−7

.1−6

3.9

12.9

4.9

3.2

STD

32.1

27.6

13.5

12.9

81.5

39.1

36.4

61.6

7.7

29.1

8.9

1.3

0.9

13-F

eb-0

1S

trea

m w

ate r

130

73.2

39.4

64.1

482

88.7

205

263

247

−10.

6−7

1.6

13.8

2.6

1.5

19-M

ay-0

1S

trea

m w

a ter

133

86.1

15.6

73.7

172

146

65.2

204

188

−10.

3−7

5.7

6.4

3.3

1.9

1-Ju

l-01

Str

eam

wa t

er13

511

325

.619

131

412

210

524

322

6−1

0.4

−74.

39.

24.

83.

7

8-O

c t-0

1S

trea

m w

a ter

114

46.2

5.72

49.6

317

274

90.3

81.8

68.1

−9.6

−62.

314

.54.

71.

6

AM

128

79.6

21.6

94.8

321

158

117

199

Σ− /Σ+ =

0.7

3−1

0.2

−71.

011

.03.

92.

2

STD

9.63

27.8

14.4

56.6

127

80.9

61.5

82.6

0.4

6.0

3.9

1.1

1.0

13-F

eb-0

1G

roun

d w

ater

295

206

15.1

75.3

512

58.2

254

454

418

−8.9

−62.

09.

23.

42.

0

19-M

ay-0

1G

roun

d w

ater

199

226

16.8

38.1

303

49.6

287

237

213

−13.

3−9

2.6

13.8

2.8

0.9

1-Ju

l-01

Gro

und

wat

er14

412

934

.079

.843

127

219

916

614

9−9

.1−6

2.8

10.2

3.7

1.8

8-O

ct-0

1G

roun

d w

ater

312

373

37.8

63.9

228

78.8

455

229

191

−9.5

−68.

17.

94.

10.

9

AM

238

234

25.9

64.2

384

115

299

271

Σ− /Σ+ =

0.7

2−1

0.2

−71.

410

.33.

51.

4

STD

80.0

98.2

11.7

16.2

151

106

110

126

2.1

14.4

2.5

0.5

0.6


and standard deviation of major ion concentrations areshown in Table 2.

Na+ and Cl– can be considered to be components ofsea salt. Non-sea salt ion (nss) can be expressed as theratio of dissolved elements of rainwater, and its referenceis either dissolved Na+ or Cl–. These references can bechosen depending on the observation site. Generally, Na+

is better choice in polluted sites such as urban areas, be-cause Cl– can be produced from polluted HCl in indus-trial areas (Keene et al., 1986). In this study, Na+ wasalso used as a reference for nss ion value (Table 2). Thenss value of rainwater can be used to compare rainfallcomposition with sea salt composition. Using known so-dium and chlorine weight ratio in sea water and assum-ing no fractionation during aerosol formation from seawater, the contribution from sea salt can be determined(Berner and Berner, 1996). The concentration of an ionwhich is larger than the sea water proportion is referredto as the non-sea salt ion or excess ion (Millero, 1996).The relation between the concentrations of Na and Cl– inSeoul is shown in Fig. 3. The regression line betweenNa+ and Cl– are indicated by the solid line. The regres-sion broken line shows the ratio of the concentrations ofNa+ and Cl– in sea water (Fig. 3), respectively (Nozaki,1992). The plot shows a linear relation to the ratio in seasalt in Seoul, indicating that most of Na+ and Cl– in wetdepositions originated from the sea salt. However, the plotof 1st January and 4th March in 2001 shift to sodium el-ements occurred with heavy snowfall and yellow sand,

respectively.The isotopic composition of non-sea salt sulfate

(δ34Snss) was calculated from the isotopic composition ofthe sample’s total sulfate (δ34Smeasured). The (Na+)measuredand (SO4

2–)measured stand for the measured concentrationof Na+ and SO4

2– of samples and (SO42–/Na+)nss indicate

the seawater SO42–/Na+ ratio of 0.120 (Weast et al., 1987).

The calculated sulfur isotope composition of the sulfatewhich is derived from non-sea salt (pollution) sources isshown in Table 2. The concentration of SO4

2– is the mostabundant with an average of 63.3 µeq/L and correspond-ing non-sea salt SO4

2– (nssSO42–) of 56.7 µeq/L, which is

over 90% of the total SO42– (Table 2). The values of non-

sea salt SO42– are very similar to those from precipitation

measurements in Kangwha, Korea (Fujita et al., 2000).The other most abundant anion is Cl– with a mean

concentration of 37.3 µeq/L, and NO3– amounts to 42.4

µeq/L. Comparison of rain waters collected at differenttimes of the year shows that concentrations of SO4

2– weredominated by much higher values in winter than those ofNO3

– in summer. Average concentrations of SO42– and

NO3– in summer are 53.8 µeq/L and 44.5 µeq/L, respec-

tively. Average concentrations of SO42– and NO3

– in win-ter are 77.6 µeq/L and 38.8 µeq/L, respectively. The datashows that SO4

2– concentration in winter is about 1.7 timeshigher than that of summer (77.6 µeq/L vs. 53.8 µeq/L).On the other hand, the concentrations of NO3

– in the win-ter are much lower than those in the summer (38.8 µeq/Lvs. 44.5 µeq/L) (Table 2). The average NO3

– concentra-tion was found to be higher than SO4

2– in summer. It isknown that there are farming activities such as swine pro-duction and dairy production that result in animal waste

1 10 100 1000+

1

10

100

1000

Cl–

(eq

/L)

Wet depoisiton in Seoul

–

+

Chemical weatheringCation exchange

Air pollutantOrganic waste

Heavy snowfall

Yellow Sand

Y=1.05XR2=0.63

0 0.2 0.4 0.6 0.8 1

1

0.8

0.6

0.4

0.2

01

0.8

0.6

0.4

0.2

0Sampling of Seoul

Winter precipitation

Spring Precipitation

Summer precipitation

Fall precipitation

2–

2–

–

Summ

er

Winter

Fig. 3. The relationship between Cl– vs. Na+ of rain and snowwater in Seoul. The solid line indicates the Cl–/Na+ = 1.16(Millero, 1996).

Fig. 4. SO42––NO3

––Cl– ternary diagrams for precipitation andsurface and ground water in Seoul area (unit: µeq/L).

450 C. Lim et al.

including NH3. On the other hand, the average SO42– con-

centration was found to be higher than NO3– in winter

due to evolve from the long rang transport contributingfrom the local industrial combustion sources (Fig. 4)(Ohizumi et al., 1991). However, stream and ground wa-ters did not show the seasonal variation in cations andanions (Table 2).

Atmospheric dispersion in winter tends to be strongercompared to that in summer, and consequently pollutantsemitted in the winter are easily dispersed and transportedover large areas. Additionally, as more intense solar ra-diation, higher temperatures and greater concentrationsof water vapor in summer favor faster photochemicalconversions of SO2 and NO2 to sulfate and nitrate. Thesealkaline ions (Ca2+ and Mg2+) act as buffers, neutralizingthe acidity of precipitation. Furthermore there are greateremissions of air pollutants in cold seasons relative to warmseasons (So et al., 1996).

The rain and snow waters in summer precipitationcontain greater concentrations of SO4

2– and these phasescarry higher levels of neutralizing cations (Table 2). Theconcentration ratio of alkaline ions to acidic ions in sum-mer is greater than that in winter (Table 2). This result

indicates that sulfuric acid is the main cause of acidifica-tion of precipitation in winter months and nitric acid isthe main cause of acidification in summer months (Fig.4).

Oxygen and hydrogen isotopesThe O and H isotopic composition of precipitation in

this study is quite variable, with δ18O values ranging from–15.8 to –3.2‰ and δD from –114.7 to –18‰ (Fig. 5).Seasonal variation is reflected in this data. The values ofdeuterium excess (d-values) for winter precipitation (d>10‰) are clearly distinct from those for summer pre-cipitation (d < 10‰) (Fig. 5). The deuterium excess (d-values) for winter precipitation significantly deviates fromd-excess value obtained from the global meteoric waterline, more or less reflecting the effects of various degreesof evaporation (Fig. 5). The slope and intercept of theregression line for precipitation were virtually identicalto the global meteoric water line (GMWL) defined byCraig (1961). Here, the mean meteoric water line of Seoul(δD = 7.3δ18O + 5.0), Chuncheon meteoric water line (δD= 7.2δ18O + 2.7; Yu and Park, 2004), and Chunju mete-oric water line (δD = 6.8δ18O + 7.7; Na et al., 1995) were

–10

0

10

20

30

40

dex

cese

–20

–16

–12

–8

–4

0

–120

–100

–80

–60

–40

–20

0

Dec/0

0

Dec/0

0

Jan/

01

Jan/

01

Feb/0

1

Feb/0

1

Feb/0

1

Mar

/01

Mar

/01

Apr/0

1

May

/01

May

/01

Jun/

01

Jun/

01

Jul/0

1

Jul/0

1

Jul/0

1

Aug/0

1

Aug/0

1

Sep/0

1

Sep/0

1

Oct/01

(mm

/yy)

18O

(,S

MO

W)

D(

,SM

OW

)

Fig. 5. Seasonal variations of relationship between d-excess and Oxygen and Hydrogen isotopic values in the precipitation fromSeoul. The value of d-excess is determined from the equation as d = δD – 8δ18O (Dansgaard, 1964).


comparable to the Global meteoric water line (δD = 8δ18O+ 10). These data indicate the nature of the coupled oxy-gen and hydrogen isotopic variation for different seasons,which follow the relationship: δD = 9.3δ18O + 8.3 forsummer (rainy season precipitation) and δD = 8.8δ18O +28.0 for winter (dry season precipitation) in Seoul (Fig.6). Seasonal isotopic differences could also result fromthe effect of different air masses; cold and dry continen-tal Siberian air masses predominate in winter while hotand humid maritime North Pacific air masses predomi-nate in summer (Lee et al., 1999).

Oxygen and hydrogen isotope measurements revealsimilarities to the global meteoric water line. However,despite the limited number of samples examined and therelatively short sampling period, it is noteworthy that ourdata are very similar to those reported by Lee and Chang(1994). The deviation of the isotopic composition of thisgroup of samples above the summer season GMWL canbe determined from the d-values listed in Table 2. Theannual mean d-value of these precipitation samples is+12.9, as shown in Table 2, slightly displaced below+10.0. The average d-value for winter precipitation (for

December, 2000 and March, 2001) is +17.6 and for sum-mer precipitation (from June to August, 2001) is +6.1.

The δ18O and δD values of the meteoric waters inChuncheon align fairly well along the global meteoricwater line (GMWL: Craig, 1961) (Fig. 6). The δ18O andδD values of the surface waters have a similar range thoseof the meteoric waters in Seoul. The referenced Chonjuvalues are very close to the long-term weighted average(δ18O = –3.0~–13.4‰ and δD = –13~–92‰) for rainfallin the global meteoric water (Na et al., 1995). The iso-topic compositional range of the Chonju meteoric watermay be due to an insignificant amount of samples col-lected for the seasonal variation, the attenuation of thetemporal variation.

Sulfur isotope chemistryThe sulfur isotopic composition of sulfate (δ34SSO4)

ranges between +3.0 and +7.3‰ in snow and rain watersamples in this study (Table 2 and Fig. 7). Major sulfurion distributions in precipitation are mostly controlled bythe diverse contributions from seawater sulfate, biogenicemissions, volcanic gases, and anthropogenic S (Thode

–20 –15 –10 –5 0

–150

–120

–90

–60

–30

0

Seoul winterSeoul springSeoul summerSeoul fallChuncheon during 2000–2001(Yu and Park, 2004)Chunju during 1994–1995(Na et al., 1995)

Global meteoric water

Seoul meteoric water

Chuncheon meteoric water

Chunju meteoric water

Ave. cool season(Winter)

Ave. warm season(Summer)

Fig. 6. Plot of δD versus δ18O in precipitation, surface and ground water. Global meteoric water line (GMWL) of Craig (1961)is also shown.

452 C. Lim et al.

et al., 1961; Ohizumi et al., 1991; Mandeville et al., 2009).The isotopic composition of S in modern marine sulfateis constant within narrow limits and is represented by aδ34S value of about +20.1‰. A number of sulfur isotopicstudies have been carried out on sulfate ions in rainfall(Mizutani and Rafter, 1969; Holt et al., 1972; Jamiesonand Wadleigh, 2000). These studies show that rainwatersulfate is depleted in 34S with respect to seawater sulfate,the effect being more pronounced in sulfate from othersources. The isotopic composition from biogenic emis-sions (H2S and DMS from seawater) is difficult to estab-lish, but it may have δ34S values ranging between –10and 0‰ (Herut et al., 1995, Nielsen, 1978). The δ34S val-ues of volcanic gas sulfur are known to range widelyaround 0‰ (Mizutani et al., 1986), but there is no activelocal volcano near the study area.

Chloride concentrations have been utilized to deline-ate the seawater spray sulfate component in precipitation.Mizutani and Rafter (1969) utilize the parameter:

A = {[SO42–]seawater/[SO4

2–]observed }

= {[Na+]observed/[SO42–/Na+]seawater }/[SO4

2–]observed.

This relationship assumes that all sodium comes fromthe sea and the sulfate/sodium ratio in the marine compo-nent of precipitation is the same as that of seawater, i.e.,[SO4

2–/Na+]seawater = 0.120 by weight (SO4 seawater: sulfateions from the seawater, Na+

seawater: sodium ions from theseawater, SO4 observed: sulfate ions of chemical analysis).The equation using A and sodium content to establishseawater spray sulfate concentrations is a general equa-tion of sulfate isotopic values (δ34Snss) from the contami-nated atmosphere.

δ34Snss = [δ34Sobserved – Aδ34Sseawater][1 – A]

Table 2 shows the calculated sulfur isotopic composi-tion of the sulfate derived from the sources that experi-ence the pollution (combustion of fossil fuels such as coalor petroleum). The present research reveals that δ34Snssvalues ranging from +1.0 to +6.2‰ are found in Seoul.These observations support a major anthropogenic sourceof SO4 in precipitation in the study area. The major an-thropogenic S source in East Asia is known to be coalcombustion. China is the largest source of SO2 emissionsin East Asia and its total emissions are estimated to be

0001001011

–10

–5

0

5

10

15

20

25

Locations of precipitationSeoul winterSeoul springSeoul summerSeoul fallChuncheon during 2000–2001(Yu and Park, 2004)Chunju during 1994–1995(Na et al., 1995)

Sulfate concentrations

(Thode et al., 1961; Ohizumi et al., 1991)

(Thode et al., 1961; Ohizumi et al., 1991)

(Maruyama et al., 2000)

(Hong et al., 1992; Maruyama et al., 2000)

(Yu and Park, 2004)

(Maruyama et al., 2000)

Ave. summer(This research)

Ave. winter(This research)

Fig. 7. Plot of δ34S against the concentration of the SO42– in wet precipitation.


more than 10 times that of Japan and Korea (Fig. 8;EAGrid, 2000). The proportion of coal combustion as partof the total energy demands in China is as high as 70%;therefore, coal combustion is the major source of anthro-pogenic SO2 production. The δ34S values of S in coal werereported as 9.7 ± 11.4‰ in northern China and 5.5 ± 4.8‰in Russia (Maruyama et al., 2000) and the δ34S values ofS in aerosol sulfate and sulfur dioxide were reported as4.2 ± 0.7‰, 6.4 ± 0.5‰, and 6.1 ± 1.2‰ in winter atHarbin, Changchun, Dalian, and Waliquan in northernChina (Maruyama et al., 2000), respectively. These δ34Svalues are higher than that of coals from southern China(4.5 ± 6.2‰) (Hong et al., 1992; Maruyama et al., 2000;Yanagisawa et al., 2001) and the δ34S values of S in aero-sol sulfate and sulfur dioxide were reported as 2.1 ± 1.4‰,and –4.0 ± 3.6‰ in summer at Nanjing and Guiyang insouthern China (Maruyama et al., 2000), respectively. Al-most all of the coal and petroleum used in Korea are im-ported from foreign countries. The δ34S values of organicS in coal from Gangwon province, Korea is known tocontain less than 1 percent total sulfur with a value of–2.4‰ , which falls within the general range(–10.0~+1.6‰) of pyrite from coal mines in Korea (Yu

0.03 0.1 0.3 1 3 10 g/m2/y

SO2

Fig. 8. Distribution of annual emissions of SO2 in the East Asian to EAGrid (2000).

and Coleman, 2000), which is much lower than that ofcoal in neighboring countries. The δ34S values of sulfatein precipitation in the southern part of Korea were re-ported in the range of 0.0 to 1.8‰ (Na et al., 1995), whichis lower than the sulfur isotope values in this study.

The δ34S values of atmospheric samples are higher inwinter (from +5.1 to +7.3‰) and lower in summer (from+3.0 to +4.8‰) (Fig. 7). In neighboring Japan, Maruyamaet al. (2000) reported on seasonal variations of sulfur iso-tope ratios of rain and aerosol on the west coast, in whichsulfur during winter is mainly derived from space heat-ing and industrial sources; but in summer the large emis-sions of 34S-depleted biogenic sulfur come from soil, veg-etation, marshes, and wetlands, which results in the de-crease of δ34S values of airborne sulfur.

Plots of δ34S values versus SO42– concentrations can

be used in identifying sources and fates of sulfur-bearingcompounds. The dominant δ34S values appear to have anarrow range near +6.4‰ in winter and +4.0‰ in sum-mer showing distinct correlation between the seasonalvariations and the sources of sulfur in the neighboringcountries (Fig. 7). However, the δ34S values had no cor-relation with SO4

2– concentrations (Fig. 7).

454 C. Lim et al.

Origin and migration of sulfur sources in East AsiaThe sulfur isotopic signatures of rainwater sulfate may

be used to delineate anthropogenic sulfur in the atmos-phere, provided the isotopic composition of pollutantsulfur is distinct from that of sulfur from natural sources(Krouse, 1980; Na et al., 1995). Identification of atmos-pheric sulfur sources in rainwater has been conductedmainly in the acid rain regions through sulfur isotopeanalysis (Krouse and Case, 1981; So et al., 1996). Usu-ally the sulfur isotopic values of rainwater sulfate are al-tered by oxidation of SO2 and different contribution ofsulfur sources (e.g., coal burning, biogenic sulfur, etc.).The minor sources are sea spray and biological activityas sea spray has a δ34S value of about + 20.1‰ and thebiogenic component shows a δ34S value ranging from–10‰ to –2‰ (Mizutani and Rafter, 1969; Holt et al.,1972; Ohizumi et al., 1991; Jamieson and Wadleigh,2000). Because more samples having low sulfate con-centrations and low δ34S values were found at Chonju(Na et al., 1995) rather than at Seoul and Chuncheon ar-eas (Fig. 7), the significantly more negative rainwater δ34Svalues at the rural site in Chonju (δ34S = –3.2‰) com-pared to the urban site Seoul and Chuncheon areas maybe also due to higher contribution of biogenic sulfur. Theδ34S values for rainwater and sea spray are sufficientlydistinct to be able to conclude that seawater contributionsare negligible due to the calculation of δ34Snss values.

The relationship between S isotope values and winddirection reflects the marked seasonal variations of sulfurisotopic values during winter and summer (Fig. 9). The

variations are more pronounced for the origin of sulfursources than for the concentrations of sulfur component.On average, the sulfur isotopic values for Seoul in winterand summer are +6.4 and +4.0‰, respectively. The pe-riod of higher sulfur isotopic values in winter (Decemberand February) seems to be related to the wind direction(northeast-northwest) prevailing in northern China, whoseδ34S values of oil (+22.5‰) and coal (+9.7‰) is knownto be higher than oil (+7.2‰) and coal (+4.5‰) of south-ern China (Hong et al., 1992; Na et al., 1995; Maruyamaet al., 2000). The lower sulfur isotopic values in summer(June to August) may be related to the summer wind di-rection (west-southwest) blowing from southern China,whose δ34S value is lower than that of northern China.

Sulfur isotopic composition of sulfate (δ34SSO4) showsvalues ranging from +2.6 to +4.8‰ in the streams of thestudy area. Sulfate isotopic values from the southern partof the Han River reported during spring and summer re-veal δ34SSO4 values of +3.5 ± 1‰ (Ryu et al., 2007). Thesulfur in streams and shallow groundwater may be de-rived from the oxidation of sulfide minerals as well asdeposition of atmospheric sulfates through precipitation.The δ34S values of sulfide minerals collected from hy-drothermal deposits in Korea range from +2.0 to +7.0‰representing high homogeneity in sulfur isotopic compo-sition of the acidic crustal magma (Kim and Nakai, 1980).This suggests that dissolved SO4

2– in the streams and shal-low groundwater in the study area might be coming fromthe oxidation of sulfide minerals in the granitic basementrocks distributed upstream as well as from depositions ofatmospheric sulfates and rainfall.

In order to develop a consistent and effective method,it is necessary to carry out a long term study accumulat-ing data on the isotope compositions of contaminants andother environmental materials, not only from Korea butalso from neighboring countries: China, Japan, Russia,etc.

SUMMARY

In the Seoul metropolitan area and Chuncheon min-ing area, we carried out a study on sulfur, oxygen, andhydrogen isotope compositions to discover the source ofsulfur and the extent of seasonal and local chemical char-acteristics in snow and rain. Our findings are:

1) The pH of the rainwater collected in the Seoul areais in the range of 4.6–7.0. The variation pattern has a goodcorrelation among the amount of rainfall, seasonal varia-tion, pH, EC, cations, and anions of rainwater. The re-sulting data are similar to those of adjacent countries in-cluding China, Japan, and Russia.

2) Precipitation shows positive correlations betweenions in the Ca2+–Mg2+–SO4

2––NO3– system, indicating

that dissolution of Ca and Mg particles by H2SO4 and

Fig. 9. Relationship between the δ34S(‰) signature in SO42– of

precipitation and the prevailing wind direction in East Asia.


HNO3 from the combustion of fossil fuels is a major proc-ess controlling the chemical composition of snow and rain.Based on weighted means in precipitation, enrichmentfactors relative to seawater are 69.9 for Ca2+, 13.1 forMg2+, 2.2 for SO4

2–, and 1.8 for NO3– assuming that Na+

comes only from seawater.3) During the survey period, airborne particles (Yel-

low sand) appeared to be the dominant source of higherconcentrations of Ca2+ and Mg2+ (alkaline ion) in pre-cipitation. The concentrations of nss SO4

2– and NO3– are

the same as those in typical acid rain regions. However,most of them are neutralized forms of base cations, Ca2+

and Mg2+. As a result the average pH of precipitation isaround 6.2.

4) The value of oxygen and hydrogen isotope compo-sition of the rain is in the range of –15.7~–7.8‰ and–115~–31‰, respectively. The H and O isotope values insummer are plotted near the global meteoric water lineby Craig (1961). The d-excess values in winter are higherthan 10, which indicate that the source of rain during win-ter is a dry air mass from continental China.

5) The sulfur isotope ratio of precipitation ranges from+3.0 to +7.5‰ similar to typical metropolitan air pollu-tion. It is suggested that the main source is SO2 producedby the combustion of fossil fuels. Pollutant SO4 is esti-mated to have δ34Snss ranging from +1.0 to +6.2‰ in theSeoul area.

6) The sulfur isotope composition of precipitationshows an overlapping range with those of the adjoiningstream and shallow groundwater. In the study area theδ34S values of SO4 in streams and shallow groundwaterare not only directly affected by the deposition of atmos-pheric sulfates through the addition of meteoric water tothe system but also are affected by the oxidation of sulfideminerals in the granitic basement rocks.

7) The δ34S values of precipitation range from +5.1 to+7.3‰ (mean +6.4‰) in winter and from +3.0 to 4.8‰(mean +4.0‰) in summer. The higher δ34S values in win-ter (December and February) seem to be correlated to theair mass (northwest in main wind direction) from north-ern China, whose δ34S value of oil or coal is higher thanthat of southern China. The lower sulfur isotopic valuesin summer (June to August) are correlated with the airmass (west-southwest is the main wind direction) mov-ing from southern China, whose δ34S value of fossil fuelis lower than that of northern China.

Acknowledgments—This study was partly supported by grantNo. 2000-2-13200-001-1 from the Basic Research Program ofthe Korean Science and Engineering Foundation. This studywas also supported by the BK21 program of the School of Earthand Environmental Sciences, Seoul National University. Theauthors would like to thank Dr. K.-S. Lee and his staff in theKorean Basic Science Institute for the S, H, O isotopic analy-sis of water samples and Ms. Seonyoung Kim in the National

Center for Inter-University Research facilities, Seoul NationalUniversity for the chemical composition data. Review of thismanuscript by Michael J. Lee for English edits is greatly ap-preciated.

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