Quantitative estimates of past UV-B irradiance from fossil pollen

QUEST-UV is a new project funded by the Research Council of Norway beginning in Autumn 2021.

Project overview

Large variations in ozone and surface UV-B radiation are also thought to have occurred in the past, with potentially major implications for climate, human societies and ecosystems. Although UV-B radiation is an important variable for understand process influencing life on Earth, at present it remains challenging to reconstruct changes in UV-B radiation at the Earth’s surface beyond the instrumental measurements since the 20th century.

QUEST-UV will attempt to solve this challenge through the chemical analysis of fossil-pollen grains. Since the 2000s researchers have suggested that chemical sunscreens produced by plants, and which are also found in the walls of pollen grains and subsequently buried in lakes and bogs over thousands of years, may be used to reconstruct UV-B radiation received at the Earth’s surface. However, although the evidence base for a chemical response of UV-B absorbing compounds spans a variety of species under a range of experimental settings, a quantitative understanding of the dose-response relationship of UV-B absorbing compounds in pollen to UV-B radiation does not currently exist. This makes it difficult to generate precise reconstructions that can be be used in Earth system models and studies of the effects of UV-B radiation on the biosphere in the past.

In this project, funded by the Research Council of Norway, QUEST-UV will continue our research on Pinus sylvestris. We will use greenhouse and field experiments to quantitatively determine the response of Pinus sylvestris pollen to different wavelengths of light. We will also experiment with different extraction techniques to isolate UV-B absorbing compounds in modern pollen grains and then use this understanding to provide the first quantitative reconstruction of UV-B radiation based on sediments representing up to the last 10,000 years.

Overview of QUEST-UV. WP1 uses controlled greenhouse experiments to measure the response of Pinus sylvestris to UV-B wavelengths. WP2 extends field validation studies in the modern environment to validate the quantitative dose-response relationship estimated under controlled conditions. We will also develop new workflows for extraction and analysis of bound and unbound modern components (WP3) and quantify the abundance of polyphenolic compounds using a combined py-GC-MS/ vibrational spectroscopy approach in field and fossil settings (WP4-6). Process-based radiation models will be used to simulate past changes in polyphenolic compounds in fossil pollen, which are then validated against sediment data (WP7).

We are hiring!

A 3.5 year postdoctoral position has been announced for the project. Application deadline is 25th October and the link to the advert is here.

The Team

Alistair Seddon (UiB, Project PI). Global Change Ecologist and Palaeoecologist.  Leads the PalaeoChem Research Group at the Department of Biological Sciences, University of Bergen, and will supervise the analysis of UV-B absorbing compounds in pollen grains using pyrolysis Gas Chromatography Mass Spectrometry

Postdoctoral Research Fellow (UiB) Will work on refining extraction protocols of UV-B absorbing compounds in modern pollen grains, and conduct greenhouse and field experiments to assess UV-B responses. Look out for the advertisement coming soon!

Prof. Richard Bindler (Umeå University) Over 20 years in palaeoclimate research. Worked specifically on varved Lake Karssjön and will collaborate on sediment coring and collection to enable reconstructions of UV-B radiation through the Holocene.

Professor Børge Hamre (UiB)     Physicist based at then Department of Physics, University of Bergen. Has worked on studies to determine biological response functions of marine organisms to UV-B. Measures radiation doses in greenhouse (WP1) and in field sites (WP2) and conducts radiation modelling for fossil sites

Associate Professor Monica Jordheim (UiB). Organic chemist based at the Department of Chemistry, University of Bergen. Experience in the isolation and structural elucidation of natural products, and particular polyphenols and pigments, using a range of analytical and preparative chromatographic techniques and spectroscopic instrumentation.

Dr Matthew Robson (University of Helsinki): Photobiologist with experience in using field, greenhouse and attenuation experiments, and radiative transfer modelling & measurement of UV-B; quantitative analysis of UV-induced plant phenolic compounds, UV-B/climate-stress interactions.

Dr Boris Zimmerman (NMBU) 17 years’ experience in developing spectroscopy approaches for physical and organic chemistry. Involved in nine previous projects related to vibrational spectroscopy of pollen.


Related papers from the research team

Seddon, A.W.R., Festi, D., Nieuwkerk, M., Gya, R., Krüger, L.C., Östman, S.A.H., Robson, T.M. (2021). Pollen-chemistry variations along elevation gradients and their implications for a proxy for UV-B radiation in the plant-fossil record. Journal of Ecology DOI: 10.1111/1365-2745.13720

Seddon, A.W.R., Festi, D., Robson, T.M. and Zimmermann, B. (2019) Fossil pollen and spores as a tool for reconstructing ancient solar-ultraviolet irradiance received by plants: an assessment of prospects and challenges using proxy-system modelling. Photochemical and Photobiological Sciences DOI: 10.1039/C8PP00490K

Seddon, A.W.R., Jokerud, M., Barth, T., Birks, H.J.B., Krüger, L., Vandvik, V. and Willis, K.J. (2017). Improved quantification of UV-B absorbing compounds in Pinus sylvestris L. pollen grains using an internal standard methodologyReview of Palaeobotany and Palynology 247: 97-104