We report a new method for measurement of the isotopic composition of nitrate (NO3-) at the natural-abundance level in both seawater and freshwater. The method is based on the isotopic analysis of nitrous oxide (N20) generated from nitrate by denitrifying bacteria that lack N2O-reductase activity. The isotopic composition of both nitrogen and oxygen from nitrate are accessible in this way. In t...

Solar energetic particles (SEPs), like the solar wind, provide a direct sample of the Sun. Although SEP abundances show a variable amount of mass fractionation, it is possible to develop methods of correcting for it in order to deduce the composition of the corona. Using high-resolution measurements from the Solar Isotope Spectrometer on the Advanced Composition Explorer, we have studied the is...

We assessed the utility of stable isotope analysis as a tool for understanding community ecological structure in a species-rich clade of scincid lizards from one of the world's most diverse lizard communities. Using a phylogenetic comparative framework, we tested whether δ15N and δ13C isotopic composition from individual lizards was correlated with species-specific estimates of diet and habitat...

The isotopic composition of an element records information about its history. Given a fossil, it is possible to analyse the isotopic composition of the elements in the fossil and to use this to reconstruct the diet that the animal consumed. The process of dietary reconstruction, however, is far from simple. Biological systems are quite complex and can themselves introduce isotopic fractionation...

Introduction: Noble gases in Martian meteorites are an important source of our knowledge of composition and evolution of the volatile inventory of Mars [1]. Ancient (ALH 84001), fractionated (nakhlites), and recent atmosphere (shock-produced glass in shergottite EETA 79001) as well as at least one component originating from the interior (Chassigny) have been identified based on analyses of the ...