Isotopic and isotopomeric analyses of dissolved nitrous oxide (N 2 O) can provide important information about the mechanisms of production and consumption of this climatically important trace gas. Increased spatial and temporal data coverage for N 2 O isotopic measurements are needed to improve our understanding of the production of N 2 O in a variety of aquatic environments, such as coastal and open ocean areas. A new method is presented for automated measurement of δ 15 N bulk , δ 18 O, and site preference of dissolved nitrous oxide in natural waters using a GC‐Pal autosampler and a Finnigan Delta Plus isotope ratio mass spectrometer and is capable of analyzing 30 samples in 22 h without user attention after the start of the run. The system was first tested with samples produced by injecting our N 2 O reference gas and/or N 2 O test mixtures, ranging in isotopic composition and concentration, into N 2 ‐sparged seawater. The method was then applied to samples containing a large range of N 2 O concentrations, δ 15 N bulk , δ 18 O, and site preference values from two high‐resolution depth profiles from the Arabian Sea. The results showed precise determination of isotopic values of N 2 O from 160 mL aqueous samples over the concentration range normally found in the oceans (5–80 nmol L −1 ). Sample standard deviation for triplicate 160 mL samples at 6 nmol L −1 N 2 O is better than 0.3‰ for δ 15 N bulk , 0.5‰for δ 18 O, and 1.0‰ for 15 N site preference. The automated technique described here requires relatively minor modifications of existing N 2 O purge and trap systems and can be implemented broadly for a variety of applications.
No takes yet. Share an insight, caveat, or question.
McIlvin et al. (2010) studied this question.