@article {2478, title = {Stability of peatland carbon to rising temperatures}, journal = {Nature Communications}, volume = {7}, year = {2016}, month = {Jan-12-2017}, pages = {13723}, abstract = {Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. We show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH4 emissions. However, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20{\textendash}30 cm of peat from experimental plots have higher CH4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH4 and CO2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. There are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. These results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.}, doi = {10.1038/ncomms13723}, url = {http://www.nature.com/doifinder/10.1038/ncomms13723}, author = {Wilson, R. M. and Hopple, A. M. and Tfaily, M. M. and Sebestyen, S. D. and Schadt, C. W. and Pfeifer-Meister, L. and Medvedeff, C. and McFarlane, K. J. and Kostka, J. E. and Kolton, M. and Kolka, R.K. and Kluber, L. A. and Keller, J. K. and Guilderson, T. P. and Griffiths, N. A. and Chanton, J. P. and Bridgham, S. D. and Hanson, P. J.} } @article {74, title = {Radiocarbon signatures and size{\textendash}age{\textendash}composition relationships of major organic matter pools within a unique California upwelling system}, journal = {Geochimica et Cosmochimica Acta}, volume = {126}, year = {2014}, pages = {1-17}, abstract = {Coastal upwelling zones are among the most productive regions in the world and play a major role in the global carbon cycle. Radiocarbon (as Δ14C) is a powerful tool for tracing the source and fate of suspended particulate and dissolved organic matter (POM, DOM), and has the potential to reconcile key carbon budgets within upwelling systems. However, the extent to which upwelling processes influence the Δ14C signature of surface DIC, or that of POM or DOM remains almost completely unknown. Here we present a time series of stable carbon (δ13C) and Δ14C isotopic data of major water column carbon pools, including dissolved inorganic carbon (DIC), large (0.7{\textendash}500 μm) and small (0.1{\textendash}100 μm) POM, and high molecular weight (HMW; \~{}1 nm{\textendash}0.1 μm) DOM from an upwelling center along the Big Sur coast. We show that DIC Δ14C values (ranging between +29{\textperthousand} and -14{\textperthousand}) are strongly correlated to coastal upwelling processes, and that this 14C-signal readily propagates into both the POM and HMW DOM pool. However, the presence of negative POM and HMW DOM Δ14C values (ranging between +46{\textperthousand} and -56{\textperthousand}, +6{\textperthousand} and -123{\textperthousand} and -1{\textperthousand} and -150{\textperthousand}, respectively) suggests contributions of {\textquotedblleft}pre-aged{\textquotedblright} OM, complicating the direct use of {\textquotedblleft}bulk{\textquotedblright} Δ14C for tracing upwelling-derived carbon production/export. Using a triple-isotope mixing model (δ13C, δ15N, Δ14C) we estimate that 50{\textendash}90\% and 45{\textendash}51\% of large and small POM is newly-produced OM, while between 6{\textendash}22\% and 12{\textendash}44\% of large and small POM are derived from {\textquotedblleft}pre-aged{\textquotedblright} re-suspended sediments. Finally, we observe quantitative relationships between OM size, composition (C:N ratio) and Δ14C within this upwelling system, possibly representing a new tool for modeling ocean C and N biogeochemical cycles.}, issn = {0016-7037}, doi = {10.1016/j.gca.2013.10.039}, url = {http://www.sciencedirect.com/science/article/pii/S001670371300611X}, author = {Walker, B. D. and Guilderson, T. P. and Okimura, K. M. and Peacock, M. B. and McCarthy, M. D.} } @article {256, title = {Bioturbation artifacts in zero-age sediments}, journal = {Paleoceanography}, volume = {24}, year = {2009}, note = {id: 1826; 535DQ Times Cited:0 Cited References Count:18; YY}, abstract = {Most seafloor sediments are dated with radiocarbon, and the sediment is assumed to be zero-age (modern) when the signal of atmospheric testing of nuclear weapons is present (Fraction modern (Fm) > 1). Using a simple mass balance, we show that even with Fm > 1, half of the planktonic foraminifera at the seafloor can be centuries old, because of bioturbation. This calculation, and data from four core sites in the western North Atlantic indicate that, first, during some part of the Little Ice Age (LIA) there may have been more Antarctic Bottom Water than today in the deep western North Atlantic. Alternatively, bioturbation may have introduced much older benthic foraminifera into surface sediments. Second, paleo-based warming of Sargasso Sea surface waters since the LIA must lag the actual warming because of bioturbation of older and colder foraminifera.}, issn = {0883-8305}, doi = {10.1029/2008pa001727}, author = {Keigwin, L. D. and Guilderson, T. P.} } @article {1846, title = {Intcal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years Cal Bp Rid F-4952-2011 Rid B-7298-2008}, journal = {Radiocarbon}, volume = {51}, year = {2009}, note = {id: 1983; PT: J; UT: WOS:000274407500002}, month = {2009}, pages = {1111-1150}, abstract = {The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the (14)C and calendar timescales as established in 2002. No change was made to the curves from 0-12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and; ire available in the Supplemental Material at www.radiocarbon.org.}, isbn = {0033-8222}, author = {Reimer, P. J. and Baillie, M. G. L. and Bard, E. and Bayliss, A. and Beck, J. W. and Blackwell, P. G. and Ramsey, C. Bronk and Buck, C. E. and Burr, G. S. and Edwards, R. L. and Friedrich, M. and Grootes, P. M. and Guilderson, T. P. and Hajdas, I. and Heaton, T. J. and Hogg, A. G. and Hughen, K. A. and Kaiser, K. F. and Kromer, B. and McCormac, F. G. and Manning, S. W. and Reimer, R. W. and Richards, D. A. and Southon, J. R. and Talamo, S. and Turney, C. S. M. and van der Plicht, J. and Weyhenmeye, C. E.} } @article {2014, title = {NotCal04-Comparison/Calibration 14 C records 26-50 cal kBP}, journal = {Radiocarbon}, volume = {46}, year = {2004}, note = {id: 399}, month = {2004}, pages = {1225{\textendash}1238}, author = {van der Plicht, J. and Beck, J. W. and Bard, E. and Baillie, M. G. L. and Blackwell, P. G. and Buck, C. E. and Friedrich, M. and Guilderson, T. P. and Hughen, K. A. and Kromer, B.} } @conference {1592, title = {COMPARE04-Comparison/calibration of 14C records 26-50 ka}, booktitle = {Abstracts, 18th International Radiocarbon Conf.}, year = {2003}, note = {id: 564}, month = {2003}, address = {Wellington, NZ}, author = {van der Plicht, J. and Hughen, K. A. and Guilderson, T. P. and Reimer, P.} } @article {2099, title = {Influence of Vegetation Change on Watershed Hydrology: Implications for Paleoclimatic Interpretation of Lacustrine d180 Records}, journal = {Journal of Paleolimnology}, volume = {27}, year = {2002}, note = {id: 1386}, month = {2002}, pages = {117-131}, author = {Rosenmeier, M. F. and Hodell, D. A. and Brenner, M. and Curtis, J. H. and Martin, J. B. and Anselmetti, F. S. and Ariztegui, D. and Guilderson, T. P.} }