SS4.06 Speciation, Bioavailability, and Impacts of Atmospheric Trace Metals in Aquatic Systems
Date: Wednesday, June 12, 2002
Time: 4:00:00 PM
Location: Esquimalt
HudsonRJ, Dept. of Nat. Resour. & Environ. Sci., Univ. of Illinois, Urbana-Champaign, IL, USA,
Rue, E, L, Inst. of Marine Sci. University of California, Santa Cruz, CA, USA,
Bruland, K, W, Dept. of Ocean Sciences, Univ. of California, Santa Cruz, CA, USA,
The use of voltammetric competitive ligand equilibration techniques (ACSV/CLE) for measuring the organic complexation of Cu and Fe in freshwater and marine ecosystems has grown in recent years. Among the most ecologically interesting applications of ACSV/CLE is the quantification of microbially-produced chelators (L1), which are secreted in order to sequester either essential or toxic elements, in field samples. However, recent studies have questioned the validity of some methods used to analyze the CLE data and stressed the adoption of proper methods of calibration and objective methods of detecting strong microbial complexes (L1) as important priorities. Artifacts due to surfactants and slow coordination kinetics also need to be considered. We present recent work aimed at addressing these issues. Our findings indicate that non-linear regression methods can be effectively applied to multiple detection window data sets to clearly identify strong chelators and the presence of disequilibria due to kinetic effects.