A Soil Water Extraction Method Using Accelerated Solvent Extraction Technique for Stable Isotope Analysis / 分析化学

ABSTRACT

Soil water is one of the most important components in hydrological cycle. The stable hydrogen and oxygen isotopes in soil water have been increasingly used in the ecological, environment and hydrological research. In view of different techniques for extracting soil water, there is significant difference in theδD andδ18 O composition. This paper presents a method for analyzing hydrogen and oxygen isotopes in soil water by using elemental analyzer and isotope ratio mass spectrometry with accelerated solvent extraction for sample pretreatment. The conditions are extraction solvent dichloromethane, temperature 100 ℃, pressure of 10. 3 MPa, static time10 min. The samples were extracted three times, and with cycle values of four, four and three, respectively. Comparing with the added water, the deuterium and oxygen isotope values in the extracted soil water enrich 2. 12‰-4. 58‰ and 0. 17‰-0. 93‰, respectively. The reproducibility of replicate extractions of soil water is around ±0. 89‰ for δD and ±0. 37‰ for δ18 O.