Stable isotopes of atmospheric precipitation and its environmental drivers in the Eastern Chinese Loess Plateau, China

Abstract Based on 487 event-based precipitation samples collected at 4 stations in the Fenhe river basin on the Eastern Loess Plateau (ECLP) during 2016-2017, we analyzed the influences of meteorological parameters, geographical parameters, sub-cloud evaporation and recycled moisture on precipitation and its isotopic compositions. A strong seasonal variation was observed in δ18O, δ2H, d-excess of precipitation. Although there are no obviously correlations between precipitation δ18O and meteorological parameters for all precipitation data in the ECLP, stable isotopic signature on precipitation displayed variability in different temperature or precipitation amount gradient. The local meteoric water line was calculated to be δ2H=7.7δ18O+7.0 indicating raindrops have undergone partial evaporation. The sub-cloud evaporation and the recycled moisture from evapotranspiration have been proven to have strong influence on the isotopic composition precipitation of ECLP. Results show that 12.1±4.7% of precipitation are evaporated before reaching the ground in the ECLP during March-October. The moisture recycling fraction accounted for 28±14 % to local precipitation. The significant seasonal variation of the remaining fraction (f) of raindrop mass can be seen in the Linfen station, and the more significantly seasonal fluctuation of the f can be observed in 2017. The remaining fraction of rainfall is always larger under a lower air temperature, larger precipitation amount and higher relative humidity. This study will improve the understanding of regional water cycling and have implications for water resource management during water shortages.