HR: 16:30h
AN: B52F-03    [PDF]
TI: Thiols in a Connecticut Stratified Freshwater Lake
AU: * Hu, H
EM: Haiying.hu@yale.edu
AF: Yale Environment School, Yale University, 21 Sachem Street, ESC Room 308, New Haven, CT 06511 United States
AU: Mylon, S E
EM: steven.mylon@yale.edu
AF: Yale Environment School, Yale University, 21 Sachem Street, ESC Room 308, New Haven, CT 06511 United States
AU: Benoit, G
EM: gaboury.benoit@yale.edu
AF: Yale Environment School, Yale University, 21 Sachem Street, ESC Room 308, New Haven, CT 06511 United States
AB: Thiols are an important class of dissolved reduced sulfur (DRS) species in aquatic environments. They are generally formed from biological processes or during diagenesis of biogenic matter. Thiols can affect the biogeochemistry of B-type metals as they form strong complexes that influence trace metal speciation, bioavailability and toxicity. While current literature focuses on the biogeochemistry of thiols in marine systems, little is known about the biogeochemistry of thiols in oxic freshwaters. We chose to study thiols in Linsley Pond a stratified freshwater lake that has been extensively studied by Hutchinson. Our goals were to identify and quantify the range of thiols present throughout this small lake. Additionally, we hoped to discern the environmental factors that influence the production and distribution of thiols in the water column, and to evaluate importance of thiols in trace metal speciation. To identify and quantify various thiols in freshwaters, we adopted a sensitive and selective analytical method, which involves precolumn fluorometric labeling coupled to high performance liquid chromatography and sensitive fluorescence detection. Using this method, our analytical detection limit is below one nanomolar. Among others, two thiol species were observed in Linsley Pond: 3-mercaptopropionic acid (3-MPA) and glutathione (GSH). 3-MPA exists in both oxic and anoxic water layers at nanomolar levels, and increases from surface to bottom. GSH is only detected in subsurface layer and co-varies with Chl a, indicating possible biological sources of GSH in these layers. There is a third, unidentified thiol species which is currently under investigation. The unidentified thiol species appears only in anoxic lake waters, and tests indicate that it is not PC2 (phytochelatin with 2 glutamic acid-cysteine units). Throughout the water column, concentrations of all three thiols are greater in whole water samples than in the dissolved phase (0.45 um).
DE: 1094 Instruments and techniques
DE: 1806 Chemistry of fresh water
DE: 1845 Limnology
SC: Biogeosciences [B]
MN: 2003 Fall Meeting