New paper on the covariation between hydrogen and oxygen stable isotopes in organic compounds in eudicot plants


Jochem Baan led the work as a part of his PhD, with co-authors Meisha Holloway-Phillips, Daniel B. Nelson, and Ansgar Kahmen, which was recently published in Geochimica et Cosmochimica Acta. The study explores the extent to which large variation in the hydrogen and oxygen isotopic compositions of organic compounds from plants growing in a single location vary in similar ways. Although previous work has demonstrated large isotopic variation among species at a single site for individual compound classes, this study is unique in comparing among compound classes and isotope systems. The study confirms that biochemical isotope fractionation is a major driver for variation in organic compound hydrogen and oxygen isotopic compositions among species grown in a single location, but it also shows that this is not consistent between elements and compounds. Furthermore, the species-pattern in n-alkane hydrogen isotope values was found to be highly consistent between different years, but this was not the case for cellulose hydrogen and oxygen isotope values. The study concludes that, among species, biochemical isotope fractionation is: (1) not constant, (2) not the same between O and H and between different compounds, suggesting independent biochemical isotope fractionation mechanisms, and (3) the mechanisms driving species-variation in organic compound hydrogen and oxygen isotope values are differently sensitive to environmental forcing. Ultimately, these results contribute to the continued development of proxies aimed at extracting both metabolic and climatic information from organic compounds in archived plant material.

(Figure: Distribution of variation across species relative to mean of hydrogen (A) and oxygen (B) isotope values among different organic compounds and leaf water.)

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