@article {2764,
	title = {Mineral protection regulates long-term global preservation of natural organic carbon},
	journal = {Nature},
	volume = {570},
	year = {2019},
	month = {Jan-06-2019},
	pages = {228 - 231},
	abstract = {The balance between photosynthetic organic carbon production and respiration controls atmospheric composition and climate1,2. The majority of organic carbon is respired back to carbon dioxide in the biosphere, but a small fraction escapes remineralization and is preserved over geological timescales3. By removing reduced carbon from Earth{\textquoteright}s surface, this sequestration process promotes atmospheric oxygen accumulation2 and carbon dioxide removal1. Two major mechanisms have been proposed to explain organic carbon preservation: selective preservation of biochemically unreactive compounds4,5 and protection resulting from interactions with a mineral matrix6,7. Although both mechanisms can operate across a range of environments and timescales, their global relative importance on 1,000-year to 100,000-year timescales remains uncertain4. Here we present a global dataset of the distributions of organic carbon activation energy and corresponding radiocarbon ages in soils, sediments and dissolved organic carbon. We find that activation energy distributions broaden over time in all mineral-containing samples. This result requires increasing bond-strength diversity, consistent with the formation of organo-mineral bonds8 but inconsistent with selective preservation. Radiocarbon ages further reveal that high-energy, mineral-bound organic carbon persists for millennia relative to low-energy, unbound organic carbon. Our results provide globally coherent evidence for the proposed7 importance of mineral protection in promoting organic carbon preservation. We suggest that similar studies of bond-strength diversity in ancient sediments may reveal how and why organic carbon preservation{\textemdash}and thus atmospheric composition and climate{\textemdash}has varied over geological time.},
	issn = {0028-0836},
	doi = {10.1038/s41586-019-1280-6},
	url = {http://www.nature.com/articles/s41586-019-1280-6},
	author = {Hemingway, Jordon D. and Rothman, Daniel H. and Grant, Katherine E. and Rosengard, Sarah Z. and Eglinton, Timothy I. and Derry, Louis A. and Galy, Valier V.}
}
@article {2608,
	title = {Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation},
	journal = {Biogeosciences},
	volume = {14},
	year = {2017},
	month = {Jan-01-2017},
	pages = {5099 - 5114},
	doi = {10.5194/bg-14-5099-201710.5194/bg-14-5099-2017-supplement},
	url = {https://www.biogeosciences.net/14/5099/2017/https://www.biogeosciences.net/14/5099/2017/bg-14-5099-2017.pdfhttps://www.biogeosciences.net/14/5099/2017/bg-14-5099-2017-supplement.zip},
	author = {Hemingway, Jordon D. and Rothman, Daniel H. and Rosengard, Sarah Z. and Galy, Valier V.}
}
@article {2638,
	title = {Hidden cycle of dissolved organic carbon in the deep ocean},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {111},
	year = {2014},
	month = {Jan-11-2016},
	pages = {16706 - 16711},
	abstract = {Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via [Formula: see text]C and age via [Formula: see text]C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30\% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle.},
	keywords = {Carbon cycle, carbon isotopes, dissolved organic carbon, Oceanography, radiocarbon},
	issn = {0027-8424},
	doi = {10.1073/pnas.1407445111},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1407445111https://syndication.highwire.org/content/doi/10.1073/pnas.1407445111},
	author = {Follett, Christopher L. and Repeta, Daniel J. and Rothman, Daniel H. and Xu, Li and Santinelli, Chiara}
}
