Watching Bioremediation in Action
Indigenous microbial communities can be used to immobilize radioactive or toxic contaminants in subsurface sediments, thus reducing their spread and associated risk. This strategy relies on encouraging the growth of these communities by providing them with nutrients. The microbes reduce the normally present iron-Fe(III) to iron-Fe(II), which in turn converts many metallic contaminants, including uranium, chromium, and technetium, from soluble to insoluble forms. Being able to visualize the flow of water through the sediment as it delivers both the nutrients and the contaminants to the microbes, as well as the three-dimensional density of Fe(II), is critical for understanding the progressive biological processes that produce Fe(II) and the evolution of flow patterns through the sediment. Scientists at Lawrence Berkeley National Laboratory have validated the utility of two radiotracers, 99mTc-pertechnetate (which measures Fe(II) density) and 99mTc-DTPA (which is a flow tracer) in bioreduced sediment. This work, recently published in Environmental Science and Technology, shows that these technetium radiotracers can be used to examine and guide the development of new bioremediation processes in environmental systems.
Vandehey, N. T., J. P. O’Neil, A. J. Slowey, R. Boutchko, J. Druhan, W. W. Moses, and P. S. Nico. 2012. “Monitoring Tc Dynamics in a Bioreduced Sediment: An Investigation with Gamma Camera Imaging of 99mTc-Pertechnetate and 99mTc-DTPA,” Environmental Science and Technology, DOI: 10.1021/es302313h.