Stephens, T. L. University of Southern Mississippi,
Shiller, A. M. University of Southern Mississippi, alan.shiller@usm.edu

 
TEMPERATURE-DEPENDENT MICROBIAL CONTROL OF DISSOLVED MANGANESE IN THE LOWER MISSISSIPPI RIVER
 
Through a combination of laboratory experiments and modeling of field data, we have found that microbial Mn removal occurs in the lower Mississippi River and that the temperature dependence of this process substantially contributes to the observed seasonal variability in the river's dissolved Mn concentration. Microbial Mn removal is also shown to occur in the Pearl River (MS) suggesting that this is a common fluvial process. The microbial mechanism provides a means by which biological toxins could indirectly affect dissolved Mn concentrations even if the toxins themselves do not interact with the metal. Because the microbial process affects the dissolved/particulate partitioning of Mn and because particulate Mn-oxides are involved in the adsorption of other trace elements, the mechanism described here also provides a potential explanation for why dissolved Pb and Zn have a seasonal variability similar to Mn in the lower Mississippi River. That is, the microbial mechanism may be an important overlooked control on fluvial dissolved trace elements in general. Fast turnover of dissolved Mn also means that samples collected for analysis of this element may require rapid processing to avoid artefacts.
 
Day: Wednesday, Feb. 3
Time: 03:45 - 04:00pm
Location: Sweeney Center
 
Code: SS28WE0345S