A simple rain collector preventing water re-evaporation dedicated for delta O-18 and delta H-2 analysis of cumulative precipitation samples

Abstract : A simple rainwater collector has been developed that allows virtually evaporation-free rain sampling for subsequent water stable isotope analysis. It is designed for collecting composite monthly samples as required for global monitoring networks of the isotopic composition in precipitation. The new collector has the advantages to minimize necessary staff time for sampling by easy and fast changes of sample bottles, to avoid any need of oil for prevention of evaporation, to be cheap in construction, and to be easily installed and used in remote areas (unattended during 1 month). Tests performed at the IAEA have proven that water stored in the sampler for nearly 1 year did not suffer significantly from any evaporation effect. Further comparisons performed at sampling stations of the Global Network of Isotopes in Precipitation (GNIP) show excellent performance of the new collector with advantages over some conventional precipitation samplers. Slightly more negative delta-values observed in the new collector than in conventional sampler types could indicate lower evaporation effects.