Geochemistry ~ Environmental Forensics ~ Mineralogy
 

Upcoming Events - Presentations---TBA

Forensic Isotope Geochemistry Text

In collaboration with Elsevier Publishers, Dr. Hurst is continuing to write and revise a volume dedicated to forensic geochemistry with applications to timing environmental releases and discriminating among sources of contamination in the environment.  Unlike other volumes that often focus on light stable isotopes, this volume will focus on isotopes of strontium and lead, explaining how these stable isotopes can be integrated with other geochemical data.  The expected date of completion is Fall, 2010.

The cover photo for the volume entitled "Pricnciples and Application of Forensic Isotope Geochemistry:  Strontium and Lead" is shown above.  The photo was taken by Dr. Hurst's Son, Chris, at the home of Mr. Charles Kovacic who has set up a room in his home that accurately depicts the study of a well-known forensic detective, Sherlock Holmes.

For those interested, Mr. Kovacic's site can be reached at www.221bbakerstreetla.com.

Hydrocarbon Releases:  Approaches to Age Dating

The application of stable lead isotopes and the ALAS Model, Anthropogenic Lead ArchaeoStratigraphy (Hurst, 2000, Jour. Environ. Foren. and  Environ. Geosci., 2002) continues to be refined to estimate the age of gasoline releases dating back to the 1920s when tetraethyllead was first introduced.  This research has now added another dimension  to petroleum hydrocarbon-source correlations and provides a foundation for modeling degradation rates of carcinogenic gasoline constituents, such as benzene, in groundwater; the latter application can be used to evaluate, on a case-by-case basis, the time scale of natural attenuation at a site. 

As a result of the release of data pertaining to crude oil geochemistry into the public domain, Gene Schmidt (GW/S Environmental) and Richard W. Hurst (Hurst & Associates, Inc.) have revised and re-evaluated the use of the nC₁₇ to pristane ratio as a means of age dating middle distillate fuel releases (Environ. Geosci, 2005, v. 12, 177-192).  The rate of change in this ratio was evaluated as a function of environmental conditions (aerobic versus anaerobic); additionally, the initial nC₁₇/Pr ratio of nearly 4000 crude oils and 100 refined middle distillate fuels was calculated to assess the expected variability in this ratio.  The paper also addresses regional variations in the ratio as well as the limitations of the use of the so-called Middle Distillate Degradation Model in age dating releases. 

 Advances in  Forensic Investigations Concerning Lead in Paint

Collaborations between Hurst & Associates, Inc. and the Isotope Geochemistry Laboratory at the Massachusetts Institute of Technology (Prof. S. A. Bowring and Dr. F.O. Dudas) have resulted in new, more rigorous approaches to evaluating the potential contribution of lead derived from lead-based paint to the urban lead budget.   The approach integrates high precision lead isotope ratio analyses with electron microprobe/microscopic techniques to more effectively assess the distribution of lead in multiple paint layers on walls and exteriors of older homes.

Southeastern U.S. Gasoline Lead Releases

Dr. Hurst (right) and his Son Chris in North Carolina prior to investigating leaded gasoline releases in the area.

American Chemical Society Award

On October 10th, the California Los Padres Section of the American Chemical Society (ACS) presented Dr. Hurst the Sandra Lamb Award for 2009.  He was honored for his significant contributions to the section in 2001, when he served as both the Meeting and Program Chair of the Western Regional Meeting of the ACS.  He was also honored for his contributions to the field of Environmental Geochemistry, notably his work on applications of naturally-occurring to problems encountered in environmental investigations.  The award is named for Sandra Lamb who, in 1994, began seeking ACS members in the Ventura-Santa Barbara-San Luis Obispo region with an interest in developing a new section---Dr. Hurst is also one of the co-founders of the section which was chartered by ACS National in 1996.

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Last modified: 10/25/2009