The stable isotope composition of hoarfrost

Atmospherically deposited hoarfrost is probably the least important quantitative component of the hydrosphere, yet in places acts as an important source of water. Although countless studies have investigated the stable isotope composition of virtually all other components of the global hydrosphere, little is known on its stable isotope composition. We addressed this gap in knowledge by investigating the stable isotope composition of hoarfrost and precipitation in the Southern Carpathian Mountains (East-Central Europe) in relation with the local and regional meteorological parameters and hoarfrost characteristics. Hoarfrost and precipitation were collected at the Țarcu Peak Weather Station (2180 m a.s.l.) between December 2018 and February 2019. The main sources of moisture (as indicated by high deuterium excess values) were the Black (and possibly Caspian) Sea as well as the terrestrial sources in Eastern Europe and Western Asia. Hoarfrost was deposited during periods of intense wind, with δ18O and δ2H being strongly correlated with air temperature. No correlation has been found between the intensity of hoarfrost deposition and its stable isotope characteristics. Our data indicates that the δ18O values of hoarfrost deposits faithfully record air temperature variability during deposition, while the d-excess parameter records conditions at the moisture sources.

大气沉积白霜或许是水圈中定量占比最低的组成部分，但在部分区域却是重要的水资源补给源。尽管已有大量研究对全球水圈中几乎所有其他组分的稳定同位素组成展开了探讨，但针对大气沉积白霜的稳定同位素组成，目前仍所知甚少。本研究以南喀尔巴阡山脉（中东欧）的白霜与降水为研究对象，结合局地与区域气象参数及白霜自身特征，对二者的稳定同位素组成展开分析以填补这一认知空白。研究样本（白霜与降水）采集于2018年12月至2019年2月期间的塔尔库峰气象站（海拔2180米，a.s.l.）。高氘过量（deuterium excess）值表明，本次研究的主要水汽来源为黑海（可能还有里海）以及东欧与西亚的陆面水汽源。白霜形成于强风时段，其δ18O与δ2H值与气温呈显著相关关系。未发现白霜沉积强度与其稳定同位素特征存在相关性。本研究数据显示，白霜沉积的δ18O值可精准记录沉积过程中的气温变化，而d-excess参数则能够反映水汽源区的环境条件。