No abstract

Ancient starch research illuminates aspects of human ecology and economic botany that drove human evolution and cultural complexity over time, with a special emphasis on past technology, diet, health, and adaptation to changing environments and socio-economic systems. However, lapses in prevailing starch research demonstrate the exaggerated expectations for the field that have been generated over the last few decades. This includes an absence of explanation for the millennial-scale survivability of a biochemically degradable polymer, and difficulties in establishing authenticity and taxonomic identification. This paper outlines new taphonomic and authenticity criteria to guide future work toward designing research programs that fully exploit the potential of ancient starch while considering growing demands from readers, editors, and reviewers that look for objective compositional identification of putatively ancient starch granules.

The dissolution of organic matter into water via oxidative processes, named oxycracking, has been practiced for a long time for the removal of organic pollutants, in which oxygen induces breakage and functionalization of organic molecules. Recently, oxycracking has been explored as an alternative approach to handling the increased amount of solid residues produced in oil sands upgrading activities that involve carbon rejection in solvent deasphalting units. This study uses an asphaltene-rich feedstock, operationally known as petroleum pitch, isolated from an Athabasca bitumen vacuum residue, which was submitted to oxycracking reactions at 200 and 220 °C. The feed and water-soluble fractions isolated at pH 1, termed acid-soluble oxidized asphaltenes (ASOA), were analyzed by ultrahigh-resolution mass spectrometry [Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS)] using electrospray and atmospheric pressure photoionization ion sources. FTICR-MS analysis revealed extensive oxidation of all compound classes originally present in the asphaltene-rich feed. Double bond equivalent (DBE) distribution plots show that sequential carboxylation (formation of a carboxyl group) occurs progressively with an increasing reaction temperature, leading to the incorporation of up to 15 oxygen atoms per molecule, whereas simultaneous decarboxylation reactions produce a CO2-rich gas phase. ASOA samples also show lower overall carbon number distributions than the asphaltene feed, which is direct evidence of C–C bond cleavage during the oxycracking process. In addition, molecular fragments detected in ASOA after carbon–carbon bond cleavages showed not only lower carbon numbers but also lower DBEs per molecule, consistent with a more dominant archipelago architecture for the parent asphaltene molecules.

The reported method enables rapid (12 min FTICR-MS analysis time) and simultaneous detection of a broad range of multi-heteroatom, polar organic species in whole sediment extracts. This allows for higher sample throughput, a more comprehensive investigation of sedimentary geochemistry, and potentially the discovery of new components and derivation of novel, multi-species proxies. Copyright © 2016 John Wiley & Sons, Ltd.

Sulfur incorporation into sedimentary organic matter has a key role in carbon preservation in the geosphere. Such processes can inform strategies for human timescale carbon storage to mitigate climate change impacts and thus more detailed knowledge of sulfur incorporation into biomass species is needed. Until recently, detailed chemical characterization of sulfurized organic matter was only possible by analyzing individual building blocks obtained after desulfurization reactions. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), with atmospheric pressure photoionization in positive ion mode, (+) APPI, was used to (CID-) FTICR-MS experiments suggest the occurrence of intermolecular sulfur incorporation reactions, but only as a mechanism that is secondary to intramolecular sulfur addition. The CID-FTICR-MS experiments indicated that steroid sulfurization typically yields S-bearing cyclic structures and that thiol/thioether groups may be present throughout the chemical matrix but only to a minor extent. In addition, CID-FTICR-MS also confirms the occurrence of sulfurized alkenones in low maturity oils. Knowledge of organic sulfur molecule formation informs routes for carbon dioxide removal technologies that could be used to sequester carbon in the geosphere and/or hydrosphere in the form of recalcitrant organic species.