School of Natural and Environmental Sciences

Staff Profile

Dr Darci Rush

Visiting Researcher

Background

Research Interests

The fate of molecular biomarkers in marine and terrestrial systems.

I am an organic geochemist with a particular interest in microbial biogeochemistry. Microscopic organisms have been shaping their environment since the beginning of life on Earth. Lipids are resistant molecules, and are preserved over long periods of time in the geologic record, acting as chemical fossils to these microbes. Using lipids to extract information about the environmental conditions in which these organisms once lived, I develop biomarkers for specific microbial processes within biogeochemical cycles (Rush et al., 2011; 2014a; 2014b; 2016; Kool et al., 2014; Osborne et al., 2017). I specialise in the development of analytical methods (Rush et al., 2014b; Talbot et al., 2016) in order to apply novel organic proxies to paleoenvironments (Rush et al., 2012a; 2012b; 2014a; 2016; Hu et al., 2011; Wakeham et al., 2012; Zindorf, et al., in preparation). I also use a combination of genetic, isotopic, and lipid work to understand modern microbial processes (Rush et al, 2011; 2016; Osborne et al., 2017). By collaborating with biogeochemical modellers, I hope to improve our knowledge of past climate in order to better predict future changes in our ever dynamic Earth system, e.g., my ongoing RCUK NERC grant ANAMMARKS at Newcastle University (NU) collaborates with co-Investigator Dr F. Monteiro’s biogeochemical modelling group at the University of Bristol. Lipid biomarkers can trace back microbes through extreme climatic events, and ultimately help us to understand the influence of microorganisms on global biogeochemistry. My role developing and applying lipid biomarkers is essential to this ultimate goal.

I was Principal Investigator on NERC project ANAMMARKS awarded in 2016 until my Tenure Track position started at Royal NIOZ in the Netherlands (NIOZ). I maintain a consultant role on ANAMMARKS, which is now being led by Dr. Martin Jones

I am currently employed at NIOZ working to understand the organic geochemistry of marine anaerobic systems, and to reconstruct past marine methane release.

Previously, I was employed on the AMOProx project, led by Dr. Helen Talbot. The main objective of AMOProx was to investigate the the processes and environmental feedback of Aerobic Methane Oxidation (AMO). My specific role in this project was to develop and calibrate new proxies using baceriohopanepolyol lipids (BHPs) for AMO in the modern marine environment, as well as delving into the past by applying these new proxies to the marine sedimentary record. For more information about this project and other projects we work on at Newcastle, please visit our group webpage.

During my work on AMOProx, a potential avenue for the exploration for past anaerobic ammonium oxidation (anammox) was discovered.  While studying the bacteriohopanepolyol (BHP) lipid distributions in an oxic-to-anoxic fjord in Costa Rica, we noticed that the distribution of a relatively uncommon BHP, bacteriohopanetetrol isomer (BHT isomer) followed the distribution of ladderane lipids, well established, yet highly degradable, biomarkers of anammox. This led us to investigate the BHP lipid content of anammox bacteria, as the biological source of BHT isomer in marine settings was unknown. Indeed, we found that the marine species of anammox bacteria synthesise BHT isomer in very high abundance. As BHPs are more stable in the sedimentary record than ladderanes, BHT isomer may be a more appropriate biomarker to identify anammox in the geological past. These initial findings were published in Geochimica Cosmochimica Acta (Rush et al., 2014) and were used as the basis for the NERC project (ANAMMARKS), which started in 2017.

Current Projects

Start Jan 2017

Newcastle University · School of  Natural and Environmental Sciences

  • Tenure Track Researcher Position NIOZ Royal Netherlands Institute for Sea Research

Start April 2018

Soehngen Institute of Anaerobic Microbiology (SIAM) 

 

Past Projects

  • PostDoc Position at NIOZ 
March 2016 - March 2018 

Towards reconstructing past atmospheric methane concentrations using organic biomarkers. NESSC project

Aug 2012 – Feb 2016

ERC AMOProx Project: investigate the the processes and environmental feedback of Aerobic Methane Oxidation (AMO).

Newcastle University · School of Civil Engineering and Geosciences

 

  • PhD Thesis: "Ladderanes as tracers for present and past anaerobic ammonium oxidation"

Aug 2008 – Jul 2012

NIOZ Royal Netherlands Institute for Sea Research · Department of Marine Organic Biogeochemistry (BGC)


Background

I completed my PhD at the Royal Netherlands Institute for Sea Research (Royal NIOZ; Texel, Netherlands) under the supervision of Jaap Sinninghe Damsté and Stefan Schouten. My thesis was entitled Ladderanes as tracers for present and past anaerobic ammonium oxidation. This work at NIOZ focused on the fate of thermally labile ladderane lipids in the sedimentary record. I investigated the effects of biodegradation and thermal maturation on these biomarkers. I also applied ladderane biomarker lipids to novel modern environmental settings. 

I obtained my B.Sc. and Master's degrees in Biogeochemical Oceanography at l'Université de la Méditerranée (Marseille, France).

Membership

Member of the European Association of Organic Geochemists (EAOG)

Publications