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Research projects

A selection of current and recent QEG research projects are outlined below.

The unsaturated zone as a novel archive for Quaternary environmental change (2015-)

Staff member: Abi Stone

The unsaturated zone (or part of the hydrogeological cycle below the surface, but above the water table) is an archive from which we can obtain signals about environmental conditions in the past. However, it remains underutilised and the potential of this archive has yet to be fully realised.

This research focuses on the natural chemical tracers contained within moisture in the sediments of the USZ and examines how the tracer signals establish and are transmitted vertically in order to provide hydrostratigraphies.

Hydrostratigraphies provide a record of variations in palaeomoisture availability though time. The signals are established in the near-surface recycling zone, and this inherited signal is then transmitted vertically in the moisture that is infiltrating through the sediment, so that a depth-based profile of samples represents a temporal record. The establishment of that signal is the product of what arrives as in input in rainfall and the subsequent modification in the near-surface zone by evapotranspiration, which removes water enriching the tracer concentration.

This research began with the late Professor Mike Edmunds. 

Nitrate beneath the surface in drylands (2016-)

Can we connect the gap between high groundwater nitrate and near-surface sources?

Staff member: Abi Stone

There is a pressing need to better understand the sustainability and quality of groundwater in dryland regions, where it is the vital source of freshwater. High groundwater nitrate is a serious global environmental issue owing to deleterious implications for health.

In drylands the discovery of significant areas of high nitrate in the subsoil has highlighted significant concerns surrounding its future re-mobilisation. In the Stampriet Artesian Basin (SAB) in the Kalahari, southern Africa, groundwater nitrate concentrations exceed 20 times the WHO guidelines. Whilst there are detailed studies of nitrogen cycling in the surface soil-plant system, there is a significant gap in understanding how exactly this links to deep groundwater.

This research provides detailed analysis of nitrate across more than 10m depth of the unsaturated zone (USZ) to fill this gap. Stone and Edmunds (2014) uncovered spatially heterogeneous, high nitrate concentrations in USZ of the SAB, which is moving towards the water table via the diffuse pathway at rates of 5 to 27 mm/y as ascertained by chloride mass balance (Stone and Edmunds, 2012). The stable isotope analysis that is key to this project is crucial to identify the source(s) of nitrate in this USZ pore moisture and investigate potential nitrate transformation processes.

This research is funded by the University of Manchester and the NERC Stable Isotope Facility. 

Investigating the 3D spectral behaviour of quartz grains with diverse luminescence behaviours (2015-)

Staff member: Abi Stone (with Martina Demuro, Donald Creighton and Nigel Spooner, University of Adelaide)

Optically stimulated luminescence (OSL) dating is a key geochronological method for quartz-rich sediments over Quaternary timescales. Analysis of individual grains of quartz is now commonly applied and this offers additional insights into the depositional history of samples. However, there is significant grain-to-grain signal variability and a range of quartz OSL behaviours.

Not all of these behaviours are understood, particularly those that have been termed non-intersecting (Arnold et al., 2012) or ‘over-saturating’ (Stone and Bailey, 2012). These grains types can be described as ‘badly-behaving’ as we cannot use them to obtain an estimate of the sample’s equivalent dose (needed in the age equation).

The 3D TL spectrometer at the University of Adelaide provides an opportunity to study the emission spectra of these badly-behaving grains. We have been trying to discover whether there are observable differences in the luminescence trapping or recombination properties of these badly-behaving grains as compared to well-behaved grains. 

Rapid age assessment of dune sediments using a portable luminescence reader (2014-)

Staff member: Abi Stone (Phase 1 with Mark Bateman, University of Sheffield and Dave Thomas, University of Oxford)

This research applies the portable luminescence reader to sand dune samples. During the first phase of research with Bateman and Thomas, the focus was on the Namib Sand Sea on the west coast of Namibia. Fieldwork at sites in the south was funded by the British Society for Geomorphology, and the research also used previously collected further north as part of a NERC-funded PhD project.

The portable luminescence reader has the potential to allow us to make a rapid assessment of the burial age of sedimentary materials at the stage of fieldwork. This aids in-situ interpretation of sites and sequences during fieldwork and can guide more detailed targeted field-sampling for full dating back in the laboratory. However, the information from the portable luminescence reader had until this point only been used to make broad inferences about the relative age of samples and pick out differences in sediment sources in the field. 

The first stage of the research produced a simple calibration curve between the portable luminescence reader signal from bulk material collected in the field and the ages of those same samples (as obtained using full laboratory optically stimulated luminescence dating protocols on the quartz fraction). Results show that portable luminescence reader signals of late Holocene and Last Interglacial age samples differ by two orders of magnitude. Using the calibration curve, approximate ages of bulk samples measured by the portable luminescence reader can be obtained rapidly (within minutes in the field).

From the summer of 2016, Abi has been extending this approach to samples from the southern Kalahari linear dunefield.

Compiling a tephrostratigraphic record of Holocene volcanic activity for the Virunga Volcanic Province (2016)

Staff member: Christine Lane

Funded by the Quaternary Research Association, Quaternary Research Fund: £760.  PI. February 2016.

Integrating ice, marine and terrestrial records (INTIMATE): ensuring continued research excellence (2015-16)

Staff member: Christine Lane

Funded by the University of Manchester Faculty of Humanities Strategic Investment Fund.

Total value: £6,150 (£3,527.08 from Humanities Faculty, matched by £2,623 from School of Environment, Education and Development).

January 2015 – January 2016.

Deep CHALLA - International Continental Scientific Drilling Project (2014-)

Two glacial-interglacial cycles (>250,000 years) of climate and ecosystem dynamics on the East African equator

Staff member: Christine Lane 

Collaborator on Chronology Team (PI: Verschuren, Ghent).

June 2014 on-going. Award: $700,000. 

A 500,000 year environmental record from Chew Bahir, south Ethiopia (2014-)

Testing hypotheses of climate-driven human evolution, innovation, and dispersal

Staff member: Christine Lane

NERC standard grant: £1,192,177 (£87,001 to Oxford for radiocarbon and tephra work). Researcher Co-Investigator, leading tephrochronological investigations.

In collaboration with Prof Christopher Ramsey, Henry Lamb (lead PI) and others at University of Aberystwyth, NIGL/BGS, University of St Andrews.

36 months, beginning November 2014.

An INTIMATE Example (2013)

Staff member: Christine Lane (Co-PI with Dr Stefan Engels, University of Amsterdam)

€12,500 to run a training school research initiative for Early Stage Researchers, within EU-COST action ES0907.

July 2013.

Exploring the environmental context for Late Pleistocene hominin occupation using tephrostratigraphy (2012-13)

North Africa, the Near East and into Europe

Staff member: Christine Lane

Small grant £4,200, John Fell OUP Research Fund.

August 2012-July 2013.

Using glacier-climate proxies to model the Younger Dryas climate in Europe (2013-16)

Staff members: Philip Hughes and Roger Braithwaite

Leverhulme Trust International Network Grant with Brice Rea, Matteo Spagnolo, Ramon Pellitero (Aberdeen), Jostein Bakke (Bergen), Susan Ivy Ochs (ETH Zurich), Hans Renssen (Amsterdam), Sven Lukas (Queen Mary, London), Adriano Ribolini (Pisa). 2013-2016. 

This project will instigate a research network across seven institutions and five European nations to investigate glacier-climate relationships and atmospheric circulation during the Younger Dryas (~12,000 years ago). It will develop a state-of-the-art methodology for palaeo-glacier-climate reconstructions and apply this to previously studied sites. These reconstructions will be placed within a coherent and newly-calibrated chronology to provide a temporally constrained spatial record of palaeoclimate. These data will then be used to locate the polar front, track of mid latitude depressions and to calibrate numerical modelling experiments of the regional climate during the Younger Dryas.