Professor of Biogeochemistry and Earth History, University of Leeds

I was originally trained as a geologist, and my research focuses on geochemical and biogeochemical processes in modern sediments and waters, with a view to applying this understanding to ancient environments.

My research can be divided into four main areas:

Chemical Evolution of the Earth's Biosphere. A major research interest concerns examining links between atmospheric chemistry, climate change, ocean chemistry and biological evolution throughout Earth's history. Recent focus has been on periods of major transition in terms of the redox chemistry of the Precambrian ocean and links to biological evolution and the evolution of biogeochemical cycles. I am also interested in developing and applying novel paleoredox indicators to understand controls on major periods of environmental change during the Phanerozoic.

Nutrient Availability Through Time. I am interested in techniques to quantify the availability of nutrients (e.g. P, N, Mo, Fe, Cu) through time, and evaluation of the impact of changes in nutrient availability on biogeochemical cycles, ocean chemistry and oxygen production. This work involves both chemical speciation and isotopic techniques.

Modern Redox Sensitive Environments. A significant proportion of my work focuses on biogeochemical processes and elemental cycling in modern environments in order to aid understanding of ancient environments. A particular focus has been on the operation of the global Fe cycle, with ongoing work aimed at evaluating mineralogical, elemental, isotopic and microbial processes in redox sensitive water bodies and sediments.

Experimental Reaction Kinetics and Mechanisms. Experimental determination of reaction kinetics and mechanisms can significantly aid understanding of geochemical and biogeochemical processes in the environment. A variety of techniques are being used, ranging from batch experiments to advanced synchrotron methods, in order to monitor and understand redox-driven reactions and adsorption related to metal oxides and sulfides.


  • –present
    Professor of Biogeochemistry and Earth History, University of Leeds