#	Pagina
attuale pagina	/open-h2020/projects/193529/results.html

Report

Teaser, summary, work performed and final results

Periodic Reporting for period 3 - ALKENoNE (Algal Lipids: the Key to Earth Now and aNcient Earth)

Teaser

Summary

The first part of the ALKENoNE project focused on developing algal (alkenone, long-chain diols) and bacterial/archaeal (tetra ethers) as proxies for temperature and/or other environmental parameters in the Canadian Prairies. Through the work of one post-doctoral research associate and two PhD students, we have successfully related alkenones and diols to temperature change in the prairies and GDGTs to salinity and anoxia changes. In the final phase of the project we will reconstruct past temperatures and hydrological changes over the last several thousand years using lake sediments as archives of change. We have collected eight sediment cores across the Saskatchewan prairies from which we are now developing accurate, high-resolution age models, validating our proxy calibrations and generating long-term data. These data will provide the first long-term (2,000 to 8,000 year long) records of change from this region where traditional proxies do not work due to high evaporative regime that prevents tree growth (no tree-ring records) and creates unusual lake chemistries (high concentrations of evaporite minerals) that stress organisms and/or overprints other environmental signals.

This work will be the first to show quantitative temperature and salinity records dating back before human instrumental records. We will determine the response and resilience of lake and catchment ecosystems to these environmental change through periods of known extremes, such as the Dust Bowl Drought (1930\'s) and the Little Ice Age. This work will inform land managers about the potential severity of future droughts and temperature extremes and the ecosystem\'s ability to adapt to and/or survive these changes.

The overall objective is to fill in the knowledge gap of what temperature extremes the Northern Great Plains region experienced over the past 8,000 years, and assess how common rapid rates of change associated with modern climate change were in the past.

Work performed

Since the beginning of the project, we have established a framework of environmental statistical analysis that can be applied not only to testing the correlation of alkenones, but any biomarkers, with the large, environmental meta-dataset that is a unique asset to this project (Plancq et al. 2018). We have for the first time, shown through generalised linear models which environmental parameters affect the presence and absence of the haptophyte algae that produce alkenones, creating a testable hypothesis that can now be applied more globally (Plancq et al. 2018). This analysis also shows which environmental parameters lead to the highest production of alkenones and may have algal biofuel implications that can be followed up in future work. We have genetically identified the haptophyte species present in the Northern Great Plains lakes, namely two Group II haptophytes and one Group I haptophyte, and identified appropriate existing calibrations that can be applied to downcore records. With our Japanese colleagues and Steering Group member, Professor Shiraiwa, we have isolated 6 new haptophyte algal strains, grown them in cultures and performed temperature experiments to develop bespoke temperature calibrations for not just known indices, but have also created new indices that are temperature sensitive using the full suite of alkenone homologues and associated molecules (Ariae et al. 2018). For the final period we are now applying these and the tetraether and diol proxies to reconstruct long-term changes. We have presented our work at a number of international conferences, including AGU 2017, Goldschmidt 2017, 2018, and AGU 2018. We also had the opportunity this year to give an invited seminar at the US-Japan Research Institute in Washington DC (Dec. 2018) that was aimed at using the networks that USJI has in DC to reach and facilitate discussions on timely research with politicians, government bodies and companies.

Final results

There are several aspects of the work underway that are beyond state of the art, including: (1) having in isolated cultures 6 strains of haptophyte algae that will be used for further culture studies for environmental and biofuel work in the final stage of funding and beyond; (2) in the final stage of the project, accurate and high-resolution chronologies are needed to constraint the timing of extreme and abrupt events, so we are developing the BECS laboratory as a site of compound-specific radiocarbon sample preparation in concert with the Scottish Universities Environmental Research Centre, which has the capability to measure these rare, small samples and has developed a new positive ion mass spectrometer that revolutionises the introduction (via gas instead of graphite target) and size of sample needed for radiocarbon measurement. We expect samples from our project to be the first environmental (non-pharmaceutical) samples to be analysed on this instrument. (3) The first environmental calibration of lacustrine long-chain diols with temperature and a novel GDGT-based salinity calibration with potential for global application. (4) Our work points to the feasibility of a universal calibration for Group II haptophytes that would allow for a more global application of alkenones in terrestrial lake records â€“ on par with the marine system (Theroux et al., in review at EPSL & Plancq et al., in review Biogeosciences). (5) Our laminated, likely annually resolved, time series of environmental change from Lake Success takes advantage of MALDI-FTIR/TOF-MS biomarker analysis through collaboration with Professor Kai-Uwe Hinrichs at Bremen University to decipher biogeochemical and ecological responses to past extreme and abrupt warm events during the mid-Holocene.