IAP-24-028

Reconstructing past volcanism using trace metals in ice cores

This PhD project aims to develop a continuous record of past volcanic activity through trace metal analysis of a newly obtained Antarctic ice core. Volcanic eruptions release gases, particulates, and chemical compounds into the atmosphere, which eventually settle onto ice sheets. These compounds, trapped in annual ice layers, offer an invaluable archive of past volcanism. While sulfur compounds have traditionally been used to identify volcanic events, the available Antarctic sulfur records are limited (Thomas et al., 2023), and not all eruptions emit sulfur. In some cases, biogenic sulfur contributions may even obscure volcanic signals.
Recent advancements in analytical techniques provide an exciting opportunity to extend beyond traditional proxies. Elevated concentrations of rare earth elements and low-boiling point heavy metals have been observed in Antarctic ice cores during past volcanic eruptions. For example, the Mount Takahe (Antarctica) volcanic eruption of 17.7 ka is characterised by high concentrations of lead, cerium, lanthanum, and thallium in the WAIS divide ice core (McConnel et al., 2017; Mason et al., 2022). Thallium peaks in ice cores have also been associated with large tropical eruptions, where the plume reached the stratosphere, such as the Tambora eruption (1815 C.E) (Kellerhals et al., 2010), and they have recently been used to show a decadal to centennial increase in Icelandic volcanism (Gabriel et al., 2024)

This project will focus on the development of a method to continuously measure volatile trace metals (such as cadmium, lead, bismuth, and thallium) using inductively coupled plasma mass spectrometry (ICP-MS). These records will be compared with sulfur, halogens (chlorine, bromine) and dust to explore the condensation, transport, and deposition pathways. By constructing these new records, the project will significantly enhance our understanding of volcanic activity from centennial to millennial timescales, offering a crucial framework to investigate the relationship between volcanism and climate since the last glacial maximum.

This PhD project offers a unique opportunity to analyse trace metals in Antarctic ice cores using inductively coupled plasma mass spectrometry (ICP-MS) as part of an innovative continuous flow analysis (CFA) method. This bespoke CFA system, used in the state-of-the-art labs at the British Antarctic Survey, allows for the continuous melting and analysis of ice cores, incorporating measurements of stable water isotopes, particulate material, major ion chemistry, and methane. The project will leverage a wealth of existing Antarctic ice core records spanning the Holocene, providing a rich data set for comparative analysis.
Although the project is not reliant on new data, there will be an exciting opportunity to work with a new ice core, the REWIND core, to be drilled on the Antarctic Peninsula during 2024-2026. Spanning the past 20,000 years, the REWIND core will allow the student to play a key role in developing the age scale using trace metal analysis. This PhD will involve method development, optimizing both ICP-MS and CFA techniques for volatile trace metals. Additionally, the student will actively participate in large-scale international ice core drilling initiatives, including the EU-funded Beyond EPICA project, which seeks to extract the oldest ice core ever drilled. This project combines technical innovation and collaboration with leading global research teams to advance our understanding of Earth’s climate history.

Year 1

Training in ice core analysis and sample preparation, including working in a -25°C cold laboratory and a class-100 cleanroom. The first year will incorporate instrument specific training, with the opportunity to work with industry partners (Agilent) to gain added insight into the ICP-MS analysis. By the end of year 1, the student will be a competent ICP-MS user capable of optimising the analysis of trace metals both as discrete samples and as part of the CFA.

Year 2

During year 2, the student will begin the sample analysis using existing Antarctic ice cores. By targeting past periods of known volcanic activity, the aim is to validate the trace metal approach through comparison with traditional proxies (e.g. sulfur compounds and targeted intervals for sulfur isotope analyses in St Andrews). The student will be encouraged to write up the method development and validation studies during this time.

Year 3

The student will support the CFA on the REWIND ice core (during year 2 & 3) leading the continuous analysis, quality control and interpretation of volcanic trace metals (lead, cadmium, thallium). In the event of unforeseen delays to the REWIND drilling, the student will have the option to work on one of the many existing Antarctic ice cores in the BAS archive. The research direction can also incorporate spatial deposition of trace metals, by analysing multiple Antarctic ice cores. During year 3, the student will develop a good understanding of the other climate proxies (e.g. stable water isotopes) to explore the relationship between past volcanism and climate.

Year 3.5

The final 6-months will be dedicated to summarising the results and writing up the final thesis (or publications).

In-house training for ice core specific sampling and analysis.
Instrument specific training for ICP-MS, together with our industry partners (Agilent).
Training in data processing using instrument specific software.
Training in Matlab to support data processing (if required).
Opportunities to participate in international ice core analysis campaigns, including the Beyond EPICA Oldest Ice project.
Opportunities to undertake lab visits and exchanges with UK and international collaborators.