EGU2020-6734
https://doi.org/10.5194/egusphere-egu2020-6734
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Triple oxygen isotope variations in precipitation from southeast China and its hydrological significance

Pengzhen Duan1, Sasadhar Mahata1, Lijuan Sha1, and Hai Cheng1,2
Pengzhen Duan et al.
  • 1School of human settlements and civil engineering, Xi'an Jiaotong University, Xi'an, China (duan2008qq@stu.xjtu.edu.cn)
  • 2Department of Earth Sciences, University of Minnesota, Minneapolis, USA

    High precision triple oxygen isotope measurement of meteoric water is a newly added tracer in hydrological and paleoclimate research. However, it is prerequisite to study the controls on precipitation 17O-excess for proper application of it. Here we report two years highly precise precipitation data from Nanjing, a southeast China station dominated by Asian monsoon. All the water isotopes (δ17O, δ18O and δD) reported here are based on mass spectrometer measurements and optical measurements (cavity ring-down spectroscopy). Nanjing receives moisture from different vapor sources and experiences different rainout mechanisms during various monsoonal sessions. Combined use of above parameters can help us to delineate processes occurring during evaporation, transport, condensation and re-evaporation. Year to year 17O-excess variability is observed in the obtained dataset and no notable seasonal variation is observed. However, the 17O-excess seasonal amplitude is little larger in the first year than the subsequent year. So far, it is known that the precipitation 17O-excess depends on three values: 17O-excess of the source water bodies, amount of 17O-excess gain during evaporation and 17O-excess loss during raindrops evaporation. During dry months 17O-excess gain is balanced by 17O-excess loss, which might lead to the near absence of seasonal cycle at Nanjing. From the comparison of observed data and model simulation, the amount of re-evaporation on falling raindrop is estimated to be about 10% at Nanjing. In addition, correlation with available meteorological parameters has been discussed. Except temperature no significant correlation has been found with other metrological variables (relative humidity and rainfall amount). This study will serve as a baseline to understand some of issues in paleoclimate that have puzzled the scientific community for years.

How to cite: Duan, P., Mahata, S., Sha, L., and Cheng, H.: Triple oxygen isotope variations in precipitation from southeast China and its hydrological significance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6734, https://doi.org/10.5194/egusphere-egu2020-6734, 2020