Dr Timothy Knowles

Research Associate in Accelerator Mass Spectrometry

  • Office Number: Bristol Radiocarbon Accelerator Mass Spectrometry Facility
  • Telephone: +44 (0)117 3317211
  • Fax: +44 (0)117 925 1295
  • Email: tim.knowles@bristol.ac.uk


I graduated from the University of Bristol with a BSc (Hons) in Chemistry in 2003. For my final year project, I conducted a preliminary investigation into the fate of oestrogens of agricultural origin in the environment. This involved the detection and quantification of oestrogens from farm wastes and soils by SIR-GC/MS.

My doctoral research centred on investigating the fate of organic nitrogen in soil.  My thesis was entitled “Following the fate of proteinaceous material in soil using a compound-specific 13C- and 15N- labelled tracer approach” and involved compound-specific 15N and 13C stable-isotope ratio determinations of soil amino acids, δ13C determinations of respired CO2 and bulk 15N and 13C analysis of whole soils to trace and quantify N and C fluxes from dual-13C,15N-labelled proteinaceous material within soils at a molecular level. I was awarded my PhD in 2008

Following my PhD, I worked as a Postdoctoral Research Associate developing analytical techniques for the determination of the δ13C and δ2H values of organochlorinated compounds in soils and groundwaters.  These isotope ratio determinations ratios can be used to infer the source of, or the extent of natural biodegradation of these pollutants within the environment.

I then worked for two years in a private forensic science company in the field of stable isotope forensics as a reporting forensic scientist and the Head of IRMS. During this time I worked on many projects and cases involving packaging, drugs and explosives; and conducted research into developing new methods for the stable isotope analysis of alcoholic beverages for food authenticity purposes.

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I am a Research Associate in Accelerator Mass Spectrometry, managing the new Bristol Radiocarbon Accelerator Mass Spectrometry Facility (BRAMS).  The facility, is located within the Department of Archaeology and Anthropology, but spans the faculties of Arts and Science will house a state-of-the-art MICADAS (Mini radioCarbon Dating System) accelerator mass spectrometer with an ion source capable of accepting solid (graphite) or gaseous (CO2) samples. This will be supported by a fully automated graphitization system and will be able to directly accept CO2 generated by an elemental analyser and a carbonate handling system.  One of the aims of the facility is to push the boundaries of the sample preparation and introduction techniques and the types of scientific questions which can be addressed by AMS, and as such there is a strong emphasis on the development of compound- and compound class-specific methodologies for radiocarbon analyses.

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Further details of publications can be found in the University of Bristol publications system

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