Dr Gunnar Mallon

University Teaching Assistant

Gunnar Mallon

Room number: A9b
Telephone (internal): 27954
Telephone (UK): 0114 222 7954
Telephone (International): +44 114 222 7954
Email: G.Mallon@Sheffield.ac.uk

Gunnar Mallon received a BSc (First Class Honours) in Environmental Science from the University of Stirling in 2007 and a PhD in Palaeoecology (entitled: Patterns of mid-Holocene climate change – evidence from the peat archive) from the University of Southampton in 2012. From 2010 to 2013, Gunnar worked as PDRA on the NERC-funded PRECIP project at the University of Southampton, investigating Holocene climate change in Atlantic Canada and Maine.

He started his post at Sheffield in February 2013.

Research interests

    Impacts of changes in permafrost on ocean fertilisation.

    The biogeochemistry and ecological evolution of Arctic wetlands with regards to changes in the depth of the active layer are key research priorities, as many cascading system are influenced by these changes. The ocean is a large driver in global climate and its contribution to greenhouse gas emissions is often neglected in large-scale climate models. My work focuses on understanding biogeochemical and hydrological changes on a landscape-scale of Arctic permafrost regions and their link to ocean fertilisation.

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                                                                                     Wetland in Adventdalen, Svalbard (Photo: G. Mallon)

    Reconstruction of natural climate variability (palaeoclimatology)

    In order to make sense of our current climate and to gauge the influence that we, as a species, are having on the system, we need to understand natural climate variability. Reconstructing natural climate change and climate cycles allows us to establish relatively short-term trends in the climate system. I use testate amoebae, plant macrofossils, pollen, radiocarbon dating, tephrochronology, and stable isotopes (O, H, and C) in order to build up a model of what we would expect the climate to do without any anthropogenic disturbance.

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                                Extraction of a peat core from Kortlandamossen, Sweden (left) using a Russian Corer (right) (Photos: M. Amesbury, G. Mallon)

    Testate amoebae ecology

    Testate amoebae are single cell organisms that live on the water film, which forms on the leaves of bog mosses (Sphagnum). With over 20 generations per year, testate amoebae respond very quickly to changes in their environment. Understanding their modern ecological preferences, allows us to use them in a palaeo setting in order to reconstruct past climates and environments. However, there are still many questions regarding the ecological niches occupied by different testate amoebae species. My research focuses on a handful of species (e.g. Difflugia pulex) in order to understand their habitat preferences.

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                                                                       Nebela carinata (left) and Drosera intermedia (right) (Photos: G. Mallon)

    The Viking settlement at L’Anse Aux Meadows, Newfoundland

    According to Viking Saga, Leif Erikson, son of Eric the Red, discovered Vinland (Newfoundland) when his boat was blown off-course during his travels from Iceland to Greenland. He consequently established an encampment at L’Anse Aux Meadows on the Northern Peninsula of Newfoundland, which served as a maintenance and restocking settlement. Iron ore was smelted at L’Anse Aux Meadows and transported back to Greenland along with charcoal. However, the settlement was only occupied for a brief period and my research aims to answer the questions if climatic factors were responsible for the abandonment of L’Anse Aux Meadows.

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                                                                    Remains of layout of Viking settlement at L’Anse Aux Meadows (Photo: G. Mallon)

Current research

    Biogeochemistry and hydrology of Arctic lowland permafrost regions - LowPerm

    With changes in the depth of the active layer and geochemical processes, there is large uncertainty as to the concentration of nutrients flowing into the Arctic Ocean. The international LowPerm project, led by Prof. Andy Hodson (Geography), brings together partners from the UK, Norway, Denmark, and Russia in order to quantify biogeochemical fluxes on a landscape scale and to determine effects on ocean productivity.

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                                                Open pingo landform in Adventdalen with drainage (and reindeer) in the background (Photo: G. Mallon)

    New Zoo – NOAH initiative

    Part of a cross-faculty working group, led by Prof. Steve Banwart (Kroto Research Institute), we aim to set up an Environmental Observatory at a wetland owned by the Yorkshire Wildlife Park (YWP) in Doncaster. The Observatory will be the only depositional wetland in a global network of Critical Earth Observatories supported by the American, Chinese, French, German, and UK research councils. The observatory will provide a great teaching and research environment as well as providing invaluable outreach information for YWP.

    Image Source: YWP

    Environmental history of Adventdalen, Svalbard

    Previous work in Adventdalen, Svalbard, has shown peat formation to date back 3.5k years. Given the large-scale environmental changes experienced in the Arctic during the Holocene, the peat deposits in Adventdalen are an ideal proxy source of palaeoenvironmental and palaeoclimatic information. A combination of pollen, testate amoebae, and plant macrofossil analysis will provide clues into the environmental history of Spitsbergen.

    Ecology of testate amoebae - the link between wetland geochemistry and testate amoebae

    Testate amoebae are a very useful indicator of past bog surface wetness, as these respond very quickly to changes in the depth of the water table. However, their usefulness as indicators of geochemical parameters, in addition to hydrological parameters, still remains largely unexplored. Focussing on a number of key species, I aim to establish a link between physical and chemical parameters of a range of peatlands (minerotrophic and ombrotrophic) and the ecological preferences of testate amoebae living on them.

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                                     Collaborator Dr. Matt Amesbury (Exeter) holding up a 15 cm-long monolith tin of Sphagnum. (Photo: G. Mallon).

    Holocene palaeoclimatic changes in the Atlantic provinces of Canada and Maine, USA

    The climate of eastern Canada is closely linked to the balance between the Gulf Stream and the Labrador Current, producing a strong north-south climatic gradient. The PRECIP project aims to reconstruct this climatic gradient in order to make inferences about the strength of the respective ocean current throughout the Holocene. A combination of palaeoecological, chronological, and geochemical techniques are being employed to untangle the unique climatic and environmental history of the region.

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                              PRECIP Project partners on Petite Bog, Nova Scotia. Left to right: Prof. Dan Charman (Exeter), Dr. Paul Hughes (PI, Southampton),

                                                                Dr. MattAmesbury (Exeter), Dr. Tim Daley (Plymouth). (Photo: G. Mallon)

Teaching

Gunnar convenes and lectures on a range of practical and theoretical undergraduate and postgraduate modules from the Geography and Environmental Science curricula as well as the PAC and ID masters programmes.

Geography & Environmental Science:

  • GEO108 Earth’s Changing Surface
  • GEO150 Practical Methods for Physical Geography
  • GEO152 Statistical Data Analysis in Geography
  • GEO154 Geoenvironmental Fieldwork Skills
  • GEO163 Information & Communication Skills for Geographers
  • GEO232 Dryland Geomorphology
  • GEO244 Earth and Ecosystem Dynamics
  • GEO266 Research Skills for Physical Geography
  • GEO302 Extended Geographical Essay
  • GEO356 Geographical Research Project
  • GEO377 Western Ireland Fieldclass
  • APS255 Environmental Interpretation Field Course
  • APS332 Issues in Environmental Science

Polar and Alpine Change MSc:

  • GEO6030 Research Design in Physical Geography
  • GEO6604 Geochemical Techniques in Environmental Analysis
  • GEO6611 Polar and Alpine Environments

International Development MA:

  • GEO6807 Understanding Environmental Change

Recent publications

  • Loader, N.J., Street-Perrott, F.A., Daley, T.J., Hughes, P.D.M., Kimak, A., Levanic, Mallon, G., T., Mauquoy, D., Robertson, I., Roland, T.P., Van Bellen, S., Ziehmer, M.M., Leuenberger, M. (in review). Simultaneous determination of stable carbon, oxygen and hydrogen isotopes in cellulose. For: Technical Chemistry.
  • Jensen, B.J.L., Pyne-O’Donnell, S., Plunkett, G., Froese, D.G., Hughes, P.D.M., Sigl, M., McConnell, J.R., Amesbury, M.J., Blackwell, P.G., v.d.Bogaard, C., Buck, C.E., Charman, D.J., Clague, J.J., Hall, V.A., Koch, J., MacKay, H., Mallon, G., McColl, L., Pilcher, J.R. (2014). An American Ash in Europe: the intercontinental correlation of the Alaskan White River Ash. Geology, 42, 875-878 (link: http://geology.gsapubs.org/content/42/10/875.full)
  • Loisel, J., 60 co-authors including Mallon, G. (2014). A circum-Arctic database of synthesis of peatland soil properties and Holocene carbon and nitrogen accumulation. The Holocene, 24, 1028-1042
  • Mallon, G., Amesbury, M.J., Charman, D., Hughes, P.D.M., Loader, N.J., Mauquoy, D., Street-Perrott, F.A., Daley, T.J., (2013). Talk: Multi-proxy evidence of a mid-Holocene shift in the climate system of Maritime Canada at ca. 6.8 ka BP. AGU Fall Meeting 2013, San Francisco
  • Daley, T., Street-Perrott, F.A., Loader, N., Hughes, P.D.M., Charman, D., Mauquoy, D., Amesbury, M.J., Mallon, G., (2013). Poster: Providing a challenge for isotope-enabled models: stable isotopic analysis of Sphagnum alpha-cellulose from raised peat bogs. AGU Fall Meeting 2013, San Francisco
  • Hughes, P.D.M., Mallon, G., Brown, A., Essex, H.J., Stanford, J.D., Hotes, S., (2013). The impact of high tephra loading on late‐Holocene carbon accumulation and vegetation succession in peatland communities. Quaternary Science Reviews, 67, 160-175
  • Amesbury, M.J., Mallon, G., Charman, D.J., Hughes, P.D.M., Booth, R.K., Daley, T.J., Garneau, M. (2012). Statistical validation of a new testate amoebae based transfer function for water- table depth reconstruction on ombrotrophic peatlands in north-eastern Canada and Maine, United States. Journal of Quaternary Science, 28, 27-39
  • Hughes, P.D.M., Mallon, G., Essex, H.J., Amesbury, M.J., Charman, D.J., Blundell, A., Chambers, F.M., Daley, T.J., Mauquoy, D., (2012). The use of k-values to examine plant ‘species signals’ in a peat humification record from Newfoundland. Quaternary International, 268, 155-165
  • Pyne-O’Donnel, S., Hughes, P.D.M., Froese, D.G., Jensen, B.J.L., Kuehn, S.C., Mallon, G., Amesbury, M.J., Charman, D.J., Daley, T.J., Loader, N.J., Mauquoy, D., Street-Perrott, F.A., Woodman-Ralph, J., (2012). High-precision ultra-distal Holocene tephrochronology in North America. Quaternary Science Reviews, 52 (2), 6-11.
  • Mallon, G., Amesbury, M.J., Hughes, P.D.M., Charman, D.J., Street‐Perrott, A., Loader, N., Mauquoy, D., Daley, T., (2011). Poster: Comparison of instrumental and reconstructed climate data from Maritime Canada. EGU General Assembly 2011, Vienna.
  • Pyne-O'Donnell, S., Hughes, P., Amesbury, M., Booth, R., Charman, D., Daley, T., Loader, N., Mallon, G., Mauquoy, D., Street-Perrott, A., Woodman-Ralph, J., (2011). Poster: North American ultra‐ distal tephrochronology. AGU Fall Meeting 2011, San Francisco
  • Amesbury, M., Hughes, P.D.M., Booth, R., Charman, D., Daley, T., Loader, N., Mallon, G., Mauquoy, D., Pyne-O'Donnell, S., Street-Perrott, A., Woodman-Ralph, J., (2011). Poster: Holocene land-ocean-atmosphere interactions on the eastern seaboard of North America. INQUA XVIII, Bern, Switzerland.
  • Pyne‐O'Donnell, S., Hughes, P., Amesbury, M., Booth, R., Charman, D., Daley, T., Loader, N., Mallon, G., Mauquoy, D., Street-Perrott, A., Woodman-Ralph, J., (2011). Poster: Towards a Holocene distal tephrochronology for north‐eastern North America. INQUA XVIII, Bern Switzerland.
  • Hughes, P.D.M., Amesbury, M., Mallon, G., Charman, D., Street‐Perrott, A., Loader, N., Woodman-Ralph, J., Mauquoy, D., Daley, T., Pyne‐O'Donnell, S., Booth, R., (2011). Poster: Land-Ocean-Atmosphere interactions on the Eastern Seaboard of North America: Evidence from the Peat Archive. EGU General Assembly 2011, Vienna.
  • Mallon, G. (2011). Palaeoecological evidence of mid-Holocene climate change in south-central Sweden. Quaternary Newsletter, 124, 59-61
  • Mallon, G., Hughes, P.D.M., Barber, K.E., (2010). Poster: Palaeoecological records of Holocene climate change ‐ evidence from the peat archive. British Ecological Society Annual Discussion Meeting, Leeds University.
  • Amesbury, M.J., Mallon, G., Hughes, P.D.M., Charman, D.J., Street‐Perrott, A., Loader, N., Mauquoy, D., Daley, T., (2010). Poster: Reconstructions of ocean-atmosphere coupling from the peat archive (PRECIP). British Ecological Society Annual Discussion Meeting, Leeds University.
  • Mallon, G., Cole, J., (2009). The Quaternary of the Solent Basin and West Sussex raised beaches. Quaternary Newsletter, 118, 19-27