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  • Journal article
    Sephton MA, 2010,

    Drilling in Extreme Environments: Penetration and Sampling on Earth and other Planets, Yoseph Bar-Cohen, Kris Zacny (Eds.), Wiley-VCH, 2010. (Book Review)

    , International Journal of Rock Mechanics and Mining Science, Vol: 47, Pages: 1405-1405, ISSN: 1365-1609
  • Journal article
    Grant J, Westall F, Beaty D, Cady S, Carr M, Ciarletti V, Coradini A, Elfving A, Glavin D, Goesmann F, Hurowitz J, Ori JG, Phillips R, Salvo C, Sephton MA, Syvertson M, Vargo Jet al., 2010,

    Two Rovers to the Same Site on Mars, 2010: Possibilities for Cooperative Science

    , Astrobiology, Vol: 10, Pages: 663-685, ISSN: 1531-1074
  • Journal article
    Jolley D, Gilmour I, Gurov E, Kelley S, Watson Jet al., 2010,

    Two large meteorite impacts at the Cretaceous-Paleogene boundary

    , Geology, Vol: 38, Pages: 835-838

    The end-Cretaceous mass extinction has been attributed by most to a single asteroid impact at Chicxulub on the Yucatán Peninsula, Mexico. The discovery of a second smaller crater with a similar age at Boltysh in the Ukraine has raised the possibility that a shower of asteroids or comets impacted Earth close to the Cretaceous-Paleogene (K-Pg) boundary. Here we present palynological and δ13C evidence from crater-fi ll sediments in the Boltysh impact crater. Our analyses demonstrate that a post-impact fl ora, formed on the ejecta layer, was in turn devastated by the K-Pg event. The sequence of fl oral recovery from the K-Pg event is directly comparable with that in middle North America. We conclude that the Boltysh crater predated Chicxulub by ~2–5 k.y., a time scale that constrains the likely origin of the bodies that formed the two known K-Pg craters.

  • Journal article
    Blyth AJ, Watson JS, Woodhead J, Hellstrom Jet al., 2010,

    Organic compounds preserved in a 2.9 million year old stalagmite from the Nullarbor Plain, Australia

    , Chemical Geology, Vol: 279, Pages: 101-105
  • Journal article
    Cockell CS, Osinski GR, Banerjee NR, Howard T, Gilmour I, Watson JSet al., 2010,

    Microbe–mineral environment and gypsum neogenesis in a weathered polar evaporite

    , Geobiology, Vol: 8, Pages: 293-308

    Evaporitic deposits are a globally widespread habitat for micro-organisms. The microbe–mineral environment in weathered and remobilized gypsum from exposed mid-Ordovician marine evaporite beds in the polar desert of Devon Island, Nunavut, Canadian High Arctic was examined. The gypsum is characterized by internal green zones of cyanobacterial colonization (dominated by Gloeocapsa/Aphanothece and Chroococcidiopsis spp. morphotypes) and abundant black zones, visible from the surface, that contain pigmented cyanobacteria and fungi. Bioessential elements in the gypsum are primarily provided by allochthonous material from the present-day polar desert. The disruption, uplift and rotation of the evaporite beds by the Haughton meteorite impact 39 Ma have facilitated gypsum weathering and its accessibility as a habitat. No cultured cyanobacteria, bacteria and fungi were halophilic consistent with the expectation that halophily is not required to persist in gypsum habitats. Heterotrophic bacteria from the evaporite were slightly or moderately halotolerant, as were heterotrophs isolated from soil near the gypsum outcrop showing that halotolerance is common in arctic bacteria in this location. Psychrotolerant Arthrobacter species were isolated. No psychrophilic organisms were isolated. Two Arthrobacter isolates from the evaporite were used to mediate gypsum neogenesis in the laboratory, demonstrating a potential role for microbial biomineralization processes in polar environments.

  • Journal article
    Gomes RL, Meredith W, Snape CE, Sephton MAet al., 2009,

    Conjugated steroids: analytical approaches and applications

    , ANAL BIOANAL CHEM, Vol: 393, Pages: 453-458, ISSN: 1618-2642

    An introduction to conjugated steroids and the justification for their analysis is provided covering both environmental and biological samples. Determining conjugated steroids or indeed any organic chemical which is conjugated upon excretion from the body has relevance in diagnostic monitoring, forensic screening and environmental analysis (from the endocrine disrupter perspective). The various analytical approaches and the accompanying issues are application-dependent. There are numerous options at each stage of analysis, from extraction, hydrolysis, derivatisation, and detection, and advances can be confined to the specific application for which it was developed. Emphasis is placed on the choice of separation and how gas or liquid chromatography necessitates different preparative stages to enable conjugated steroid determination. Possible future directions and research for conjugated steroid analysis are discussed.

  • Journal article
    Sephton MA, Visscher H, Looy CV, Verchovsky AB, Watson JSet al., 2009,

    Chemical constitution of a Permian-Triassic disaster species

    , GEOLOGY, Vol: 37, Pages: 875-878, ISSN: 0091-7613

    One of the most controversial biological proxies of environmental crisis at the close of the Permian is the organic microfossil Reduviasporonites. The proliferation of this disaster species coincides with the mass extinction and numerous geochemical disturbances. Originally Reduviasporonites was assigned to fungi, opportunistically exploiting dying end-Permian forests, but subsequentgeochemical data have been used to suggest an algal origin. We have used high-sensitivity equipment, partly designed to detect interstellar grains in meteorites, to reexamine the geochemical signature of Reduviasporonites. Organic chemistry, carbon and nitrogen isotopes, and carbon/nitrogen ratios are consistent with a fungal origin. The use of this microfossil as a marker of terrestrial ecosystem collapse should not be merely discounted. Unequivocally diagnostic data, however, may have been precluded by post-burial replacement of its organic constituents.

  • Journal article
    Gomes RL, Meredith W, Snape CE, Sephton MAet al., 2009,

    Analysis of conjugated steroid androgens: Deconjugation, derivatisation and associated issues

    , Journal of Pharmaceutical and Biomedical Analysis, Vol: 49, Pages: 1133-1140, ISSN: 0731-7085

    Gas chromatography/mass spectrometry (GC/MS) is the preferred technique for the detection of urinary steroid androgens for drug testing in athletics. Excreted in either the glucuronide or sulfated conjugated form, steroids must first undergo deconjugation followed by derivatisation to render them suitable for GC analysis. Discussed herein are the deconjugation and the derivatisation preparative options. The analytical challenges surrounding these preparatory approaches, in particular the inability to cleave the sulfate moiety have led to a focus on testing protocols that reply on glucuronide conjugates. Other approaches which alleviate the need for deconjugation and derivatisation are also highlighted.

  • Journal article
    Blyth AJ, Watson JS, 2009,

    Thermochemolysis of organic matter preserved in stalagmites: a preliminary study

    , Organic Geochemistry, Vol: 40, Pages: 1029-1031

    The analysis of organic matter (OM) preserved in stalagmites is a growing field, but there have been few studies of biomarker compounds such as lignin phenols that are widely used in other palaeoenvironmental contexts. Here we present a preliminary qualitative study of the OM in six stalagmite samples from contrasting environments, using thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH). The results indicate that a wide variety of products is preserved, including several potential lignin-derived compounds, but also that further research is needed to maximise compound recovery and allow the analysis of dissolved OM preserved in stalagmites to reach its full potential.

  • Journal article
    Nicoara S, Tonidandel L, Traldi P, Watson J, Morgan G, Popa Oet al., 2009,

    Determining the levels of volatile organic pollutants in urban air using a gas chromatography-mass spectrometry method

    , Journal of Environmental and Public Health

    The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7–60 μg/m3 (B), 13–90 μg/m3 (T), 7–50 μg/m3 (E), 10–70 μg/m3 (X-m,p), and 20–130 μg/m3 (X-o). The limits of quantitation/detection of the method LOQ/LOD are of 10/5 μg/m3 (Xo), 5/3 μg/m3 (B, E, X-m,p), and of 3/1 μg/m3 (T), respectively.

  • Journal article
    Court RW, Sephton MA, 2009,

    Quantitative flash pyrolysis Fourier transform infrared spectroscopy of organic materials

    , Analytica Chimica Acta, Vol: 639, Pages: 62-66, ISSN: 0003-2670

    Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)–FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are known to vary depending on the rate of heating, with lower heating rates of biomass associated with increased yields of solid char and decreased yields of volatiles, as well as a greater opportunity for secondary reactions between the residue and the pyrolysis products. Hence, it is difficult to relate the products of organic matter thermally degraded at <100 °C min−1 in TGA to the products of flash pyrolysis at up to 20,000 °C s−1. We have developed and applied a novel methodology for quantitative flash pyrolysis–FTIR analysis of the volatile pyrolysis products of organic-rich materials. Calibration curves of water, carbon dioxide and methane have been constructed and used to determine absolute volatile release from wood (ash, Lat. Fraxinus). This technique is quicker and simpler than comparable pyrolysis–gas chromatography–mass spectrometry techniques, and avoids errors associated with the lower rates of temperature increase associated with techniques such as thermogravimetric analysis.

  • Journal article
    Court RW, Sephton MA, 2009,

    Investigating the contribution of methane produced by ablating micrometeorites to the atmosphere of Mars

    , EARTH PLAN SCI LETT, Vol: 288, Pages: 382-385, ISSN: 0012-821X

    The presence of methane in the atmosphere of Mars has been suggested as evidence of life, as methane has a short lifetime in the atmosphere of Mars of just a few hundred years, requiring replacement by mechanisms, continuous or episodic, such as biology, volcanism, serpentinization of ultramafic crust or large cometary or asteroidal impacts. The potential of meteoritic infall to deliver significant quantities of methane is restricted by the low abundance of free methane in carbonaceous meteorites. However, the delivery of meteoritic material to the surface of a planet is an energetic process, and the ability of carbonaceous meteorites to generate methane upon ablation during atmospheric entry has not been previously considered. Here, we use analytical pyrolysis to simulate the ablation and pyrolysis of carbonaceous micrometeorites upon atmospheric entry, and Fourier-transform infrared spectroscopy to quantify the subsequent yield of methane. We show that ablation produces a yield of methane that is approximately two orders of magnitude greater than the measured free methane present in the CM2 carbonaceous chondrite, Murchison, but that this previously overlooked source of methane can only account for less than 10 kg of methane annually, a mass far below that required to maintain the abundance of methane observed in the atmosphere of Mars. Our data support attempts to search for life and explore subsurface chemical processes on the Red Planet.

  • Journal article
    Peeters Z, Quinn R, Martins Z, Sephton MA, Becker L, van Loosdrecht MCM, Brucato J, Grunthaner F, Ehrenfreund Pet al., 2009,

    Habitability on planetary surfaces: interdisciplinary preparation phase for future Mars missions

    , INT J ASTROBIOL, Vol: 8, Pages: 301-315, ISSN: 1473-5504

    Life on Earth is one of the outcomes of the formation and evolution of our solar system and has adapted to every explored environment on planet Earth. Recent discoveries have shown that life can exist in extreme environments, such as hydrothermal vents, in deserts and in ice lakes in Antarctica. These findings challenge the definition of the ‘planetary habitable zone’. The objective of future international planetary exploration programmes is to implement a long-term plan for the robotic and human exploration of solar system bodies. Mars has been a central object of interest in the context of extraterrestrial life. The search for extinct or extant life on Mars is one of the main goals of space missions to the Red Planet during the next decade. In this paper we describe the investigation of the physical and chemical properties of Mars soil analogues collected in arid deserts. We measure the pH, redox potential and ion concentrations, as well as carbon and amino acid abundances of soils collected from the Atacama desert (Chile and Peru) and the Salten Skov sediment from Denmark. The samples show large differences in their measured properties, even when taken only several meters apart. A desert sample and the Salten Skov sediment were exposed to a simulated Mars environment to test the stability of amino acids in the soils. The presented laboratory and field studies provide limits to exobiological models, evidence on the effects of subsurface mineral matrices, support current and planned space missions and address planetary protection issues.

  • Journal article
    Perry RS, Sephton MA, 2009,

    Reply to comments on defining biominerals and organominerals: Direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157-179]

    , SED GEOL, Vol: 213, Pages: 156-156, ISSN: 0037-0738
  • Book chapter
    Martins Z, Sephton MA, 2009,

    Extraterrestrial amino acids

    , Origins and Synthesis of Amino Acids., Editors: Hughes, Hughes, Weinheim, Publisher: Wiley-VCH, Pages: 3-42, ISBN: 9789783527324
  • Journal article
    Court RW, Sephton MA, 2009,

    Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR

    , GEOCHIM COSMOCHIM AC, Vol: 73, Pages: 3512-3521, ISSN: 0016-7037
  • Book chapter
    Bougeard CMM, Janmohamed IHS, Goslan EH, Jefferson B, Watson JS, Morgan GH, Parsons SAet al., 2008,

    Parameters affecting haloacetic acid and trihalomethane concentrations in treated UK drinking waters

    , Occurrence, Formation, Health Effects, and Control of Disinfection By-Products in Drinking Water, Editors: Karanfil, Krasner, Westerhoff, Xie, Publisher: Oxford University Press, USA, Pages: 95-108, ISBN: 9780841269507
  • Journal article
    Montgomery W, Crowhurst JC, Zaug JM, Jeanloz Ret al., 2008,

    The chemistry of cyanuric acid (H(3)C(3)N(3)O(3)) under high pressure and high temperature

    , JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 112, Pages: 2644-2648, ISSN: 1520-6106
  • Journal article
    Lomax BH, Fraser WT, Sephton MA, Callaghan TV, Self S, Harfoot M, Pyle JA, Wellman CH, Beerling DJet al., 2008,

    Plant spore walls as a record of long-term changes in ultraviolet-B radiation

    , Nature Geoscience, Vol: 1, Pages: 592-596, ISSN: 1752-0894

    Stratospheric ozone screens the Earth's surface from harmful ultraviolet-B radiation. Concentrations of stratospheric ozone are governed by a variety of natural and anthropogenic factors, including solar cycles1, volcanic aerosols2, ozone-depleting substances3 and climate change4. However, assessing this variability before instrumental records has proved difficult owing to the lack of a well-constrained proxy5. Here, we use microspectroscopy to analyse the chemical composition of herbarium samples of clubmoss (Lycophyta) spores originating from high- and low-latitude localities, where they were exposed to different ultraviolet-B histories. We show that the concentration of two ultraviolet-B-absorbing compounds in the walls of high-northern- and southern-latitude spores is strongly regulated by historical variations in ultraviolet-B radiation. Conversely, we find little change in the concentration of these compounds in spores originating from tropical Ecuador, where ultraviolet levels have remained relatively stable. Using spores from Greenland, we reconstruct past (1907–1993) changes in ozone concentration and ultraviolet-B flux; we reveal strong similarities between spore-wall reconstructions, and independent instrumental records6 and model results7. Our findings suggest that ultraviolet-B-absorbing compounds in plant spore walls have the potential to act as a proxy for past changes in terrestrial ultraviolet-B radiation and stratospheric ozone. The chemical signature of plant spore walls in herbaria, and possibly also in sedimentary and ice-core archives, may therefore prove valuable for reconstructing past variations in stratospheric ozone and their connections with changes in solar radiation and climate.

  • Journal article
    Martins Z, Botta O, Fogel ML, Sephton MA, Glavin DP, Watson JS, Dworkin JP, Schwartz AW, Ehrenfreund Pet al., 2008,

    Extraterrestrial nucleobases in the Murchison meteorite

    , EARTH PLAN SCI LETT, Vol: 270, Pages: 130-136, ISSN: 0012-821X

    Carbon-rich meteorites, carbonaceous chondrites, contain many biologically relevant organic molecules and delivered prebiotic material to the young Earth. We present compound-specific carbon isotope data indicating that measured purine and pyrimidine compounds are indigenous components of the Murchison meteorite. Carbon isotope ratios for uracil and xanthine of δ13C=+44.5‰ and +37.7‰, respectively, indicate a non-terrestrial origin for these compounds. These new results demonstrate that organic compounds, which are components of the genetic code in modern biochemistry, were already present in the early solar system and may have played a key role in life's origin.

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