Isotopes-based characterization of precipitation compositions and atmospheric water vapor sources over typical Eurasian steppes in south mongolian Plateau

•Stable isotopes were measured to determine vapor sources of inland precipitation.•Local meteoric water lines (MWLs) had a smaller slope and intercept than global MWL.•Isotopic fractionations were induced by strong evapotranspiration.•Hydro-chemical ions were originated mainly from the continent rather than oceans.•Precipitation-forming water vapor came from multiple sources.