Sequestration of Subsurface Elemental Mercury (Hg0)EPA Grant Number: GR832212
Title: Sequestration of Subsurface Elemental Mercury (Hg0)
Investigators: Barnett, Mark , Harper, Willie F. , Hamilton, William P. , Savage, Kaye S.
Institution: Auburn University Main Campus , Vanderbilt University
EPA Project Officer: Hahn, Intaek
Project Period: March 1, 2005 through March 31, 2008 (Extended to March 31, 2009)
Project Amount: $324,342
RFA: Greater Research Opportunities: Persistent, Bioaccumulative Chemicals (2004) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Safer Chemicals , Hazardous Waste/Remediation , Human Health
The primary goal of this proposal is to develop an improved understanding and predictive capability for the in situ abiotic immobilization of subsurface elemental mercury (Hg0) using sulfide minerals. Specific objectives are to 1) elucidate the fundamental thermodynamic and kinetic parameters that control the partitioning (uptake and release) of Hg to these materials; 2) investigate the behavior of these materials under more complex hydrodynamic (i.e., flow-through) and environmental conditions, including the long-term stability of the products; 3) probe the immobilized Hg with state-of-the-art environmental spectroscopic techniques to determine the mechanism(s) responsible for immobilization; and 4) validate our results with materials from contaminated sites. These objectives are based on our hypotheses that: 1) sustained Hg immobilization can be achieved using sulfide minerals; 2) the product will be kinetically stable over long time periods under a range of environmental conditions; 3) the molecular mechanism responsible for the removal of the Hg, which will govern its removal efficiency and long-term stability, can be elucidated through the use of state-of-the-art spectroscopic techniques; and 4) the dynamic behavior of Hg in such systems can be quantified to provide a clearer understanding and long-term predictive capability for Hg immobilization.
The research will proceed through a series of interconnected, hypothesis-driven tasks performed at Auburn University and at the Stanford Synchrotron Radiation Laboratory (SSRL) by researchers from Vanderbilt University. A combination of static batch and dynamic column studies will be used, with initial experiments focused on simple, well-controlled laboratory systems to develop an improved understanding of the kinetics, thermodynamics, and mechanisms of the reactions. Subsequently, the understanding developed in these simpler systems will be tested and validated using contaminated groundwater and sediments from field sites.
This proposal addresses a critical risk assessment/characterization research need for persistent and bioaccumulative chemicals, developing sequestration technologies for elemental mercury. While the proposed methodology is novel in its ability to immobilize Hg in soils and sediments, the fundamental approach to construction and implementation of immobilization strategies such as permeable reactive barriers to treat other metals and organics has been well developed, which should lead to accelerated implementation. Finally, this proposal reflects a commitment to increasing minority student enrollment, as Auburn University is one of the nation’s top producers of African-American engineers.