All peer-reviewed: * denotes student author; # denotes post-doctoral author; % denotes senior lab member.
Awarded 2013: DOE Division of Geosciences (BES): “Fundamental Research on the Fractionation of Carbon Isotopes during Photosynthesis: New Interpretations of Terrestrial Organic Carbon within Geologic Substrates” 2013-2016 (Co-P.I. Brian A. Schubert, University of Louisiana) $405,000 to Jahren.
Renewal of Previous Grants:
DOE Division of Geosciences (BES): “Development of the Carbon Isotope Signature of Terrestrial n-Alkanes as a potential Proxy for Paleo-pCO2” 2010-2013 (no Co-P.I.) $491,910 to Jahren.
DOE Division of Geosciences (BES): “Development of New Biomarkers for Surficial Earth Processes” 2006-2010 (No Co-P.I.) $315,595 to Jahren.
We propose to interrogate the effect of increased pCO2 on plant lipogenesis (synthesis of lipids) towards the goal of using the carbon isotope composition of specific lipid compounds as a proxy for paleo-pCO2. We hypothesize that the δ13C of n-alkanes in Raphanus sativus L. (common radish) leaves allow for the determination of the pCO2 level under which the plant grew, as suggested from our preliminary growth experiments ranging from ambient to 4200 ppm pCO2. Because a systematic increase in pCO2 results in an increased production of a lipogenic compounds, we hypothesize that increased intracellular pCO2 might have a systematic effect on the production and isotopic composition of other compounds with similar biosynthetic origins, namely n-alkanes, due to re-allocation.
B.A. Schubert and A.H. Jahren. 2015. Global increase in plant carbon isotope fractionation following the last glacial maximum caused by increase in atmospheric pCO2. Geology, DOI: 10.1130/G36467.1. (view/download pdf)
W.M. Hagopian%, B.A. Schubert and A.H. Jahren. 2015. Large-scale plant growth chamber design for elevated pCO2 and δ13C studies. Rapid Communications in Mass Spectrometry, 29(5): 440-446. (view/download pdf)
B.A. Schubert and A.H. Jahren. 2013. Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels. Nature Communications, 4:1653, DOI: 10.1038/ncomms2659. (view/download pdf)
B.A. Schubert% and A.H. Jahren. 2012. The effect of atmospheric CO2 concentration on carbon isotope fractionation in C3 land plants. Geochimica et Cosmochimica Acta, 96: 29-43. (view/download pdf).
D.C. King*, B.A. Schubert% and A.H. Jahren. 2012. Practical considerations for the use of pollen δ13C value as a paleoclimate indicator. Rapid Communications in Mass Spectrometry, (accepted and in-press). (view/download pdf).
B.A. Schubert%, A.H. Jahren. 2011. Quantifying seasonal precipitation using high-resolution carbon isotope analyses in evergreen wood. Geochimica et Cosmochimica Acta, doi: 10.1016/j.gca. 2011.08.002. (view/download pdf; partially supported at 50%)
B.A. Schubert% and A.H. Jahren. 2011. Fertilization trajectory of the root crop Raphanus sativus across atmospheric pCO2 estimates of the next 300 years. Agriculture, Ecosystems, and Environment, 140(1-2) 174-181, doi: 10.1016/j.agee.2010.11.024. (view/download pdf)
A.H. Jahren and N.C. Arens. 2009. Prediction of atmospheric δ13CO2 using plant cuticle isolated from fluvial sediment: tests across a gradient in salt content. Palaios, 24, 394-401. doi: 10.2110/palo.2008.p08-069r. (view/download pdf)
A.H. Jahren, N.C. Arens and S.A. Harbeson*. 2008 (Invited). Prediction of atmospheric δ13CO2 using fossil plant tissues. Reviews of Geophysics, 46/2006RG0002. (view/download pdf)
S.P. Werts* and A.H. Jahren. 2007. Estimation of temperatures beneath archaeological campfires using carbon stable isotope composition of soil organic matter. Journal of Archaeological Sciences, 34(6), 850-857. doi:10.1016/j.jas.2006.05.007. (view/download pdf)
A.H. Jahren, K. Kelm#, B. Wendland, G. Petersen and O. Seberg. 2006. The carbon stable isotope composition of DNA isolated from an incipient paleosol: Geology, 34(5), 381-384. (view/download pdf)
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Paleoenvironmental Reconstruction of the Eocene and Miocene Arctic
Awarded 2013: NSF GEO/EAR Sedimentary Geology and Paleobiology: "Paleoclimate Analysis of a Miocene Arctic Forest from the Kolyma River Basin, Northeastern Russia" 2013-2015 (No Co-P.I.s; $63,306 subcontract to B.A. Schubert at University of Louisiana at Lafayette) $150,000 to Jahren.
Russian literature from the 1970s and 80s described the Miocene sediments of Siberia as temporally extensive and spectacularly rich in fossil forests, however, they have not yet been examined using stable isotope techniques. We plan to collect, archive, and analyze Pinaceae and Taxodiaceae fossils from the Baekovo and Nekkeiveem floras, located in the Kolyma River Basin of northeastern Siberia. The sediments we will sample are part of the Khapchan Formation which is late Miocene in age (11.6 to 5.3 Ma; Nikitin, 2007); we will perform one season of fieldwork as part of the Polaris Project II, a recently funded NSF research and education initiative under the direction of Woods Hole Research Center to study transport and transformation of carbon in rivers flowing into the Arctic Ocean.
Awarded 2008: NSF Division of Arctic Sciences: “Paleoenvironmental Reconstruction of the Eocene Arctic” 2008-2011 (Co-P.I.s J. Eberle, L. Sternberg and R. Summons) $350,677 to Jahren.
A continuation of the work supported by a previous grant:
NSF Division of Arctic Sciences: “Environmental Fluctuations during the Arctic Eocene Growing Season: Stable Isotope Analyses of Plant Fossils from Axel Heiberg Island” 2003-2006 (Co-P.I.s L. Sternberg and R. Summons) $154,257 to Jahren.
The Eocene (~56 to ~34 Ma) has been characterized as a period of uniquely warm polar environments (Moran et al., 2006). During the Eocene epoch, much of Earth’s terrestrial landmasses north of the Arctic Circle supported forest (Wolfe, 1985). Although we have considerable knowledge of Eocene climate in isolated lower-latitude regions (Carpenter et al., 2007; Dominici and Kowalke, 2007; Uhl et al., 2007), most quantitative paleoclimate estimates of Eocene terrestrial Arctic ecosystems come from Axel Heiberg Island (reviewed in Jahren, 2007). In order to fully understand the present and past Arctic, we need to increase our knowledge of Eocene climate gradients across wide geographical areas of high-latitude.
B.A. Schubert, A.H. Jahren, S.P. Davydov and S. Warny. 2017. The transitional climate of the late Miocene Arctic: Winter-dominated precipitation with high seasonal variability. Geology, DOI: 10.1130/G38746.1. (view/download pdf)
B.A. Schubert and A.H. Jahren. 2015. Seasonal temperature and precipitation recorded in the intra-annual oxygen isotope pattern of meteoric water and tree-ring cellulose. Quaternary Science Reviews, 125: 1-14. (view/download pdf)
B.A. Schubert%, A.H. Jahren, J.J. Eberle, L.S.L. Sternberg, and D.A. Eberth. 2012. A summertime rainy season in the Arctic forests of the Eocene. Geology, 40(6): 523–526, doi: 10.1130/G32856.1.(view/download pdf)
B.A. Schubert%, A.H. Jahren. 2011. Quantifying seasonal precipitation using high-resolution carbon isotope analyses in evergreen wood. Geochimica et Cosmochimica Acta, 75(22): 7291-7303. (view/download pdf; partially supported at 50%)
A.H. Jahren, M.C. Byrne*, H.V. Graham*, R.A. Summons and L.S.L. Sternberg. 2009. The environmental water of the Middle Eocene Arctic: Evidence from δD and δ18O within specific compounds. Palaeogeography, Palaeoclimatology, Palaeoecology, 271(1-2), 96-103. doi: 10.1016/j.palaeo.2008.09.016. (view/download pdf)
A.H. Jahren and L.S.L. Sternberg. 2008. Annual patterns within tree rings of the Arctic middle Eocene (~45 Ma): Isotopic signatures of precipitation, relative humidity and deciduousness. Geology, 36(2), 99-102.(view/download pdf)
L.S.L. Sternberg, M.C. Pinzon, P.F. Vendramini, W.T. Anderson, A.H. Jahren and K. Beuning. 2007. Oxygen isotope ratios of cellulose derived phenylglucosazone: An improved paleoclimate indicator of environmental water and relative humidity. Geochimica et Cosmochimica Acta, 71, 2463-2473. (view/download pdf)
A.H. Jahren. 2007 (Invited). The Arctic forest of the middle Eocene. Annual Review of Earth and Planetary Sciences, 35, 509-540. (view/download pdf)
L.S.L. Sternberg, M.C. Pinzon, W.T. Anderson and A.H. Jahren. 2006. Variation in oxygen isotope fractionation during cellulose synthesis: molecular and biosynthetic effects. Plant, Cell and Environment, 29, 1881-1889. (view/download pdf)
A.H. Jahren, B.A. LePage and S.P. Werts*. 2004. Methanogenesis in Eocene Arctic soils inferred from δ13C of tree fossil carbonates. Palaeogeography, Palaeoclimatology, Palaeoecology, 214, 347-358. (view/download pdf)
A.H. Jahren and L.S.L. Sternberg. 2003. Paleohumidity estimates for the Eocene arctic rainforest. Geology, 31(5), 463-466. (view/download pdf)
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Isotopes and Human Diet
Awarded 2014: NIH;: “δ13C Added Sugar Intake Biomarker: Determining Validity in Children” 2014-2016 ($204,921 to P.I. B.M. Davy, Virginia Polytechnic Institute) $61,750 subcontracted to Jahren.
Awarded 2011: NIH;: “SIPSMARTER: a Nutrition Literacy Approach to Reducing Sugar-Sweetened Beverages” 2011-2016 ($3.15M to P.I. J. Zoellner, Virginia Polytechnic Institute) $230,402 subcontracted to Jahren.
The long-term goals of this research are to improve nutrition literacy among health disparate populations, reduce SSB consumption and the associated adverse health consequences related to excessive caloric and added sugar consumption (i.e. obesity, type II diabetes, coronary heart disease, dental caries, and cancer), bridge the conceptual gap among concepts in health behavior theory and health literacy, expand the reach of simple and cost-effective interventions among hard-to- reach populations, and reduce the reliance on self-reported measures of dietary intake.
B.M. Davy and A.H. Jahren. 2016 (Invited Review). New markers of dietary added sugar intake. Current Opinion in Clinical Nutrition and Metabolic Care, 19(4): 282-288. (view/download pdf)
B.M. Davy, A.H. Jahren, V.E. Hedrick, W. You and J.M. Zoellner. 2016. Influence of an intervention targeting a reduction in sugary beverage intake on the δ13C sugar intake biomarker in a predominantly obese, health-disparate sample. Public Health Nutrition, DOI: http://dx.doi.org/10.1017/S1368980016001439.
V.E. Hedrick, B.M. Davy, G.A. Wilburn, A.H. Jahren and J.M. Zoellner. 2016. Evaluation of a novel biomarker of added sugar intake (δ13C) compared with self-reported added sugar intake and the Healthy Eating Index-2010 in a community-based, rural US sample. Public Health Nutrition, 19(3): 429-436. DOI: 10.1017/S136898001500107X. (view/download pdf)
V.E. Hedrick, J.M. Zoeller, A.H. Jahren, J.N. Bostic% and B.M. Davy. 2015. A dual-carbon-and-nitrogen stable isotope ratio model is not superior to a single-carbon stable isotope ratio model for predicting added sugar intake in Southwest Virginian adults. The Journal of Nutrition, DOI: 10.3945/jn.115.211011. (view/download pdf)
J.N. Bostic%, S.J. Palafox*, M.E. Rottmueller* and A.H. Jahren. 2015. Effect of baking and fermentation on the stable carbon and nitrogen isotope ratios of grain-based food. Rapid Communications in Mass Spectrometry, 29(10): 937-947. (view/download pdf)
A.H. Jahren, J.N. Bostic% and B.A. Davy. 2014 (Invited Review). The potential for a carbon stable isotope biomarker of dietary sugar intake. Journal of Analytical Atomic Spectrometry, 29(5): 795-816. DOI: 10.1039/C3JA50339A.(view/download pdf)
T.H.I. Fakhouri, A.H. Jahren, L.J. Appel, L. Chen, R. Alavi and C.A.M. Anderson. 2014. Change in serum carbon isotopes in response to change in sugar-sweetened beverage intake. Journal of Nutrition, 144(6): 902-905. (view/download pdf)
R.J. Panetta#, A.H. Jahren. 2011. Single-step transesterification with simultaneous concentration and stable isotope analysis of fatty acid methyl esters by gas chromatography-combustion-isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry, 25(10) 1372-1381. (view/download pdf)
B.M. Davy, A.H. Jahren, V.E. Hendrick*, D.L. Comber*. 2011. Association of δ13C in fingerstick blood with added-sugar and sugar-sweetened beverage Intake. Journal of the American Dietetic Association, 111(6) 874-878. (view/download pdf)
E.H. Yeung#, C.D. Saudek, A.H. Jahren, W.M.L. Kao, M. Islas*, R. Kraft*, J. Coresh, and C.A. Anderson. 2010.Evaluation of a novel isotope biomarker for dietary consuption of sweets. American Journal of Epidemiology; doi:10.1093/aje/kwq247. (view/download pdf)
A.H. Jahren, and Schubert, BA#. 2010. The corn content of French-fry oil from national chain vs. small business restaurants, Proceedings of the National Academy of Sciences USA, 107(5) 2099-2101. (view/download pdf)
A.H. Jahren, R.A. Kraft*. 2008. Carbon and nitrogen stable isotopes in fastfood: Signatures of corn and confinement. Proceedings of the NationalAcademy of Sciences, 105(46), 17855-17860. doi: 10.1073 pnas.0809870105. (view/download pdf)
R.A. Kraft*, A.H. Jahren and C.D. Saudek. 2008. Clinical-scale investigation of stable isotopes in human blood: δ13C and δ15N from 406 patients at the Johns Hopkins Medical Institutions. Rapid Communications in Mass Spectrometry, 22(22), 3683-369. (view/download pdf)
A.H. Jahren, C. Saudek, E. Yeung*, W.H. Kao, R. Kraft* and B. Caballero. 2006. An isotopic method for quantifying sweeteners derived from corn and sugar cane. American Journal of Clinical Nutrition, 84, 1380-1384. (view/download pdf)
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Development for Stable Isotope Characterization of High Explosives
Awarded 2007: NSF (EXE): “Method Development for Stable Isotope Characterization of High Explosives” 2007-2011 (no Co-P.I.) $397,198 to Jahren.
This work will create inter-laboratory standards and minimize sample size requirements in order to overcome two fundamental barriers in the stable isotope forensics of High Explosives. This work is needed in order to make δ18O, δ13C and δ15N measurements on confiscated and post-blast residues of High Explosives widely useful for linking materials, perpetrators and sites of assembly.
W.M. Hagopian%, and A.H. Jahren. 2012. Elimination of nitrogen interference during online oxygen isotope analysis of nitrogen-doped organics using the “NiCat” nickel reduction system. Rapid Communications in Mass Spectrometry, 26: 1776-1782 (view/download pdf).
G.B. Hunsinger#, W.M. Hagopian%, A.H. Jahren. 2010. Offline Oxygen Isotope Analysis of Organic Compounds with High N:O, Rapid Communications in Mass Spectrometry, 24, 3182-3186. (view/download pdf)
W.M. Hagopian%, and A.H. Jahren. 2010. Minimization of Sample Requirements for δ18O in Benzoic Acid, Rapid Communications in Mass Spectrometry, v. 24, p. 2542-2546; doi 10.1002/rcm.4669. (view/download pdf)
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NSF Major Instrumentation Grant
Awarded 2010: NSF Major Research Instrumentation (NSF-MRI-R2): "Acquisition of IRMS Instruments for Stable Isotope Analyses of New Geobiological Substrates" 2010-2013 (Co-P.I. B. Popp) $716,368 to Jahren.
We secured UH cost-sharing funds to support an NSF MRI proposal to obtain three stable isotope mass spectrometers. These instruments will comprise state-of-the-art new capabilities for analysis of geobiological substrates of direct interest to (at least) 9 P.I.s within SOEST. These instruments would make five new Broad Areas of interdisciplinary science possible at UH: 1. Specific biological compounds (i.e., n-alkanes from leaf waxes and microorganism cell walls, alkenones from marine organisms); 2. Geobiological tissues (i.e., modern and fossil pollen, DNA, leaves, soil organic matter); 3. Soluble organic matter (i.e., individual amino acids, blood glucose) 4. Environmental water (precipitation, groundwater, plant, soil water and seawater) and 5. Isotopically labeled substrates (i.e., rate quantification for nitrogen fixation, archaeal and bacterial ammonia oxidation, anaerobic ammonia oxidation, nitrate reduction). We have identified 9 researchers throughout UH (in addition to the P.I.s) who would have need for analyses on these instruments within the first year after installation; it is notable that these 11 (total) individuals represent research and academic professors at every career stage, from recent Ph.D.s to long-established scientists, thus creating a mentorship network that facilitates the success of new research programs at UH, as well as the innovation of existing programs.
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