All Issue

2025 Vol.30, Issue 1

Article

Tracing the Origin of Low-Salinity Surface Waters in the East China Sea and Korea Strait During Summer 2020 Using Seawater Oxygen Isotopes

해수 산소동위원소를 이용한 2020년 여름철 동중국해와 대한해협 표층 저염수의 기원 추적

YESEUL KIM1
,
INHEE LEE2
,
DOSHIK HAHM3
,
DONG-JIN KANG45*
김 예슬1
,
이 인희2
,
함 도식3
,
강 동진45*
1Senior Research Specialist, Advanced Infrastructure Operations Center, Korea Institute of Ocean Science and Technology, Busan 49111, Korea
2Graduate Student, Department of Oceanography, Pusan National University, Busan 46241, Korea
3Associate Professor, Department of Oceanography and Marine Research Institute, Pusan National University, Busan 46241, Korea
4Principal Research Scientist, Office of the Vice President, Korea Institute of Ocean Science and Technology, Busan 49111, Korea
5Professor, Department of Ocean Science, University of Science and Technology, Daejeon 34113, Korea
1한국해양과학기술원 첨단인프라운영센터 선임기술원
2부산대학교 해양학과 대학원생
3부산대학교 해양학과 및 해양연구소 부교수
4한국해양과학기술원 부원장실 책임연구원
5과학기술연합대학원대학교 한국해양과학기술원스쿨 해양과학전공 교수
*Corresponding Author
28 February 2025. pp. 1-10
PDF XML Citation
Abstract

In this study, we identified the origin of low-salinity surface waters observed around the Korean Peninsula in August 2020, based on stable oxygen isotopes in seawater (δ18OH2O). During the observation period, surface waters with significantly lower salinity of 26.78 and 25.59 with δ18OH2O values of -1.54‰ and -2.46‰ were detected in the East China Sea and Korea Strait, respectively. By analyzing the relationship between salinity and δ18OH2O, it was found that the origins and characteristics of the two observed low-salinity waters differed based on the differences in endmember mixing. The low-salinity surface water in the East China Sea exhibited a mixing characteristic of δ18OH2O = 0.221 × S – 7.47, indicating that it originated from the Changjiang River discharge, which was supported by the δ18OH2O value of -7.47‰. Meanwhile, the low-salinity surface waters in the Korea Strait showed a mixing characteristic of δ18OH2O = 0.297 × S – 9.85, suggesting it originated from freshwater inflow from the Nakdong River estuary due to the heavy rainfall (downpours) from the prolonged summer monsoon and typhoons in 2020. The low δ18OH2O value of -9.85‰ reflects the characteristics of rainwater-derived freshwater. These results demonstrate that seawater oxygen stable isotopes can be effectively used as a tool to understand the origins and mixing characteristics of low-salinity surface waters.

Keywords
Low-salinity surface waters
Seawater oxygen isotopes
River discharge
East China Sea
Korea Strait

이 연구에서는 해수 산소 안정동위원소(δ18OH2O)를 활용하여 2020년 8월 한반도 주변 해역에서 관측된 표층 저염수의 기원을 구명하고자 하였다. 조사 기간동안 동중국해와 대한해협에서 주변 해역보다 현저히 낮은 염분(26.78과 25.59)을 보이는 표층 해수가 관측되었으며 δ18OH2O 역시 각각 -1.54‰과 -2.46‰의 작은 값을 나타냈다. 염분과 δ18OH2O 간의 상관관계를 이용하여 저염수의 기원과 특성을 추적한 결과, 끝 성분 혼합(endmember mixing)의 차이를 통해 동중국해와 대한해협에서 관찰된 두 표층 저염수의 기원이 다름을 확인하였다. 동중국해의 표층 저염수는 δ18OH2O = 0.221 × S – 7.47의 혼합 특성을 가지며 장강 희석수에서 기원한 것으로 나타났고 δ18OH2O 값(-7.47‰)이 이를 뒷받침하였다. 대한해협의 표층 저염수는 δ18OH2O = 0.297 × S – 9.85의 혼합 특성을 보였으며, 2020년 여름의 장마와 태풍에 의한 집중호우 영향으로 낙동강 하구로 유입된 담수에서 기원한 것으로 나타났고 -9.85‰의 낮은 δ18OH2O 값은 집중호우 기원의 담수 특성을 잘 반영한다. 이 결과는 해수 산소동위원소가 표층 저염수의 기원과 혼합 특성을 이해하는 데 효과적인 도구로 활용될 수 있음을 보여준다.

References
1

김병국, 이창래, 이문옥, 김종규, 2016. 군집분석을 이용한 통영· 거제 연안역의 수온· 염분 계절 변동 특성. 한국해양환경･ 에너지학회지, 19(3): 173-184.

10.7846/JKOSMEE.2016.19.3.173
2

이문옥, 이수화, 김평주, 김병국, 2018. 하계 한국 남해연안에 출현하는 수괴의 변동 특성. 한국해양환경･ 에너지학회지, 21(2): 76-96.

10.7846/JKOSMEE.2018.21.2.76
3

이종섭, 윤은찬, 백승우, 이재철, 2003. 홍수기 낙동강 하천플륨의 3차원 거동해석. 한국수산과학회지, 36(5): 549-561.

10.5657/kfas.2003.36.5.549
4

이준호, 2014. 제주도 주변해역의 양자강 저염수 분석과 예측, Doctoral dissertation, 제주대학교 대학원.

5

현경훈, 방익찬, 1998. 제주도 주변해역의 여름철 이상저염수에 관한 연구, 해양과학연구소 연구논문집, 22: 69-78.

6

Belkin, I.M., 2009. Rapid warming of large marine ecosystems. Progress in Oceanography, 81: 207e213.

10.1016/j.pocean.2009.04.011
7

Benway, H.M. and A.C. Mix, 2004. Oxygen isotopes, upper-ocean salinity, and precipitation sources in the eastern tropical Pacific. Earth and Planetary Science Letters, 224: 493-507.

10.1016/j.epsl.2004.05.014
8

Clark, I.D. and P. Fritz, 1997. Environmental isotopes in Hydrogeology. Lewis Publishers.

9

Craig, H., 1961. Isotopic variations in meteoric waters. Science, 133(80): 1702-1703.

10.1126/science.133.3465.170217814749
10

Dagg, M., R. Benner, S. Lohrenz and D. Lawrence, 2004. Transformation of dissolved and particulate materials on continental shelves influenced by large rivers: plume processes. Continental Shelf Research, 24: 833e858.

10.1016/j.csr.2004.02.003
11

Dansgaard, W., 1964. Stable isotopes in precipitation. tellus, 16(4): 436-468.

10.1111/j.2153-3490.1964.tb00181.x
12

Epstein, S. and T. Mayeda, 1953. Variation of O18 content of waters from natural sources. Geochimica et Cosmochimica Acta, 4: 213-224.

10.1016/0016-7037(53)90051-9
13

Frew, R.D., P.F. Dennis, K.J. Heywood, M.P. Meredith and S.M. Boswell, 2000. The oxygen isotope composition of water masses in the northern North Atlantic. Deep Sea Research Part I: Oceanographic Research Papers, 47(12): 2265-2286.

10.1016/S0967-0637(00)00023-6
14

Han, X., Y. Lang, T. Wang, C.Q. Liu, F. Li, F. Wang, Q. Guo, S. Li, M. Liu, Y. Wang and A. Xu, 2021. Temporal and spatial variations in stable isotopic compositions of precipitation during the typhoon Lekima (2019), China. Science of The Total Environment, 762: 143143.

10.1016/j.scitotenv.2020.14314333121782
15

Helm, K.P., N.L. Bindoff and J.A. Church, 2010. Changes in the global hydrological-cycle inferred from ocean salinity. Geophysical Research Letters, 37: 18.

10.1029/2010GL044222
16

Keum, G., Y. Kim, K.S. Lee and J. Jeong, 2022. The geochemistry and isotopic compositions of the Nakdong River, Korea: weathering and anthropogenic effects. Environmental Monitoring and Assessment, 194(7), 487.

10.1007/s10661-022-10143-335674833
17

Kim, D., J.G. Choi, J. Park, J.I. Kwon, M.H. Kim and Y.H. Jo, 2023. Upwelling processes driven by contributions from wind and current in the Southwest East Sea (Japan Sea). Frontiers in Marine Science, 10: 1165366.

10.3389/fmars.2023.1165366
18

Kim, Y., T. Rho and D.-J. Kang, 2021. Oxygen isotope composition of seawater and salinity in the western Indian Ocean: Implications for water mass mixing. Marine Chemistry, 237: 104035.

10.1016/j.marchem.2021.104035
19

Lee, K.S. and B.U. Chang, 1994. Oxygen and hydrogen isotopic composition of precipitation in Taejeon and Seoul, Korea. Journal of the Geological Society of Korea, 30: 475-481.

20

Lee, K.S., A.J. Grundstein, D.B. Wenner, M.S. Choi, N.C. Woo and D.H. Lee, 2003. Climate controls on the stable isotopic composition of precipitation in Northeast Asia. Climate Research, 23: 137-148.

10.3354/cr023137
21

Li, C., E. Lian, C. Yang, K. Deng, P. Qian, S. Xiao, Z. Liu and S. Yang, 2020. Seasonal variability of stable isotopes in the Changjiang (Yangtze) river water and its implications for natural climate and anthropogenic impacts. Environmental Sciences Europe, 32: 1-13.

10.1186/s12302-020-00359-w
22

McKinney, C.R., J.M. McCrea, S. Epstein, H.A. Allen and H.C. Urey, 1950. Improvements in mass spectrometers for the measurement of small differences in isotope abundance ratios. Review of Scientific Instruments, 21(8): 724-730.

10.1063/1.174569814781446
23

Muller-Karger, F.E., R. Varela, R. Thunell, R. Luerssen, C. Hu and J.J. Walsh, 2005. The important of continental margins in the global carbon cycle. Geophysical Research Letters, 32: L01602.

10.1029/2004GL021346
24

Park, K.A. and K.R. Kim, 2010. Unprecedented coastal upwelling in the East/Japan Sea and linkage to long‐term large‐scale variations. Geophysical research letters, 37(9): L09603.

10.1029/2009GL042231
25

Park, K.-A., J.-E. Park, B.-J. Choi, S.-H. Lee, H.-R. Shin, S.-R. Lee, D.-S. Byun, B. Kang and E. Lee, 2017. Schematic maps of ocean currents in the Yellow Sea and the East China Sea for science textbooks based on scientific knowledge from oceanic measurements. Journal of the Korean Society Oceanography, 22(4): 151-171.

26

Rohling, E.J. and G.R. Bigg, 1998. Paleosalinity and δ18O: a critical assessment. Journal of Geophysical Research: Ocean, 103: 1307-1318.

10.1029/97JC01047
27

Senjyu, T., H. Enomoto, T. Matsuno and S. Matsui, 2006. Interannual salinity variations in the Tsushima Strait and its relation to the Changjiang discharge. Journal of Oceanography, 62: 681-692.

10.1007/s10872-006-0086-y
28

Tak, Y.-J., Y.-K. Cho, H. Song, S.-H. Chae and Y.-Y. Kim, 2023. Spatial similarity between the Changjiang diluted water and marine heatwaves in the East China Sea during summer, The Sea Journal of the Korean Society of Oceanography, 28(4): 121-132.

29

Takaya, Y., I. Ishikawa, C. Kobayashi, H. Endo and T. Ose, 2020. Enhanced Meiyu‐Baiu rainfall in early summer 2020: Aftermath of the 2019 super IOD event. Geophysical Research Letters, 47(22): e2020GL090671.

10.1029/2020GL090671
30

Ye, F., W. Deng, L. Xie, G. Wei and G. Jia, 2014. Surface water δ18O in the marginal China seas and its hydrological implications. Estuarine, Coastal and Shelf Science, 147: 25-31.

10.1016/j.ecss.2014.05.033
31

Zhang, J., R. Letolle, J.M. Martin, C. Jusserand and J.M. Mouchel, 1990. Stable oxygen isotope distribution in the Huanghe (Yellow River) and the Changjiang (Yangtze River) estuarine systems. Continental Shelf Research, 10(4): 369-384.

10.1016/0278-4343(90)90057-S
32

Zhou, Z.Q., S.P. Xie and R. Zhang, 2021. Historic Yangtze flooding of 2020 tied to extreme Indian Ocean conditions. Proceedings of the National Academy of Sciences, 118(12): e2022255118.

10.1073/pnas.202225511833798097PMC8006176
Information
  • Publisher :The Korean Society of Oceanography
  • Publisher(Ko) :한국해양학회
  • Journal Title :The Sea Journal of the Korean Society of Oceanography
  • Journal Title(Ko) :한국해양학회지 바다
  • Volume : 30
  • No :1
  • Pages :1-10
  • Received Date : 2024-12-05
  • Revised Date : 2025-02-06
  • Accepted Date : 2025-02-13
  • DOI :https://doi.org/10.7850/jkso.2025.30.1.001
Journal Informaiton The Sea Journal of the Korean Society of Oceanography The Sea Journal of the Korean Society of Oceanography
  • NRF
  • KOFST
  • KISTI Current Status
  • KISTI Cited-by
  • crosscheck
  • orcid
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close