title: A dual-isotope approach to allow conclusive partitioning between three sources.
abstract: Stable isotopes have proved to be a transformative tool; their application to distinguish between two sources in a mixture has been a cornerstone of biogeochemical research. However, quantitatively partitioning systems using two stable isotopes (for example, (13)C and (12)C) has been largely limited to only two sources, and systems of interest often have more than two components, with interactive effects. Here we introduce a dual-isotope approach to allow conclusive partitioning between three sources, using only two stable isotopes. We demonstrate this approach by partitioning soil CO2 emissions derived from microbial mineralization of soil organic carbon (SOC), added pyrogenic organic matter (PyOM) and root respiration. We find that SOC mineralization in the presence of roots is 23% higher (P<0.05) when PyOM is also present. Being able to discern three sources with two isotopes will be of great value not only in biogeochemical research, but may also expand hitherto untapped methodologies in diverse fields.
authors.affiliation: Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Thea
authors.initials: T
authors.lastname: Whitman
authors.affiliation: Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, New York 14853, USA.|Atkinson Center for a Sustainable Future, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lehmann
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry* / Q000378:metabolism; D002247:Carbon Isotopes / Q000737:chemistry* / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D045868:Sorghum / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D012987:Soil; D002245:Carbon Dioxide