RESEARCH - PHASE II
During the second phase of the Hg study, we will conduct detailed laboratory studies examining effects of redox state on Hg interactions with soil and organic matters as well as its effects on the soil microbial community and its potential for Hg transformations. The overall objective of this phase of the study is:
Objective 2: To determine conditions controlling the complexation, immobilization and net methylation of Hg.
Microbial transformations play a key role in the geochemical cycling of Hg by methylating Hg, degrading MeHg and other organomercury compounds, and reducing Hg2+ to volatile Hg0. Hence, determining environmental factors controlling the microbial transformations of Hg, such as factors that control availability of substrates or the redox environment, is critical to understanding the ultimate fate of Hg. Since the accumulation of MeHg is the net result of MeHg formation and destruction, an understanding of MeHg dynamics requires an assessment of the role of terminal electron acceptors and their effect on rates and pathways of Hg transformations.
In this study phase we are quantifying the effect of redox conditions
on Hg interactions with dissolved organic matter and wetland soil collected
from the Sunday Lake. In addition, we are characterizing the microbial
community at several locations of Sunday Lake with respect to its potential
to methylate and demethylate Hg. As part of this characterization we will
be measuring methylation and demethylation kinetics using a range of electron
donors and terminal electron acceptors. Molecular biology tools will be
employed to describe microbial community structure and to determine the
predominant demethylation pathways in the Sunday Lake wetland as a function
of redox conditions.
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