Geochemistry

       Lake sediments and sedimenting material provides basic evidence of biogenic productivity and diagenetic reactions that may occur post deposition.   

      We extract and analyze pore waters on both the mm and cm scale.  Measurements include TCO2, oxygen, methane, nutrients and sulfur compounds. 

     We will analyze total C, organic C, total N, leachable P, total S, biogenic Si and carbonate content as a means of studying general sedimentation patterns and the forcing of biogenic particle formation.  We also use naturally occurring radioisotopes (Pb-210 and Cs-137) to establish sedimentation rates.

    Specific questions about lake sediment fabric may be addressed by use of a Hitachi-1000 SEM with Oxford-EDS attachment.

  Hydrocasts establish the time-course of lake chemistry evolution and the establishment of interesting redox gradients and   boundaries.  Our interest in these gradients involves both lake biology and the interesting microbial communities that live near these horizons but also in how they impact lake chemistry and biogenic sedimentation.

Walker Lake carbonate budgets

     –Use of stromatolites as paleolake-level and paleoenvironmental indicators
     –Fundamental questions about stromatolite formation

 Zaca Lake carbonate and chemical evolution

     – Study of carbonate and biogenic sedimentation in Zaca
     – Study of lake stratification and chemical evolution