Extensive uranium groundwater contamination at DOE’s legacy ore processing sites has resisted extensive remediation attempts. One of these sites lies within the upper Colorado River Basin. The sediments here are referred to as naturally reduced zones (NRZs) because they are generally nutrient-poor and have abundant iron sulfide minerals. There is concern that NRZs are acting as slow-release sources of uranium to the aquifer that could persist for hundreds of years. Microbial nitrogen cycling has the capability to “unlock” the biogeochemical nutrient supply stored within NRZs, drive carbon cycling, and cause uranium to be released to the aquifers. However, very little is currently known regarding the nitrogen-cycling communities within these sediments. The proposed study is one component of a DOE Office of Biological and Environmental Research Scientific Focus Area program.
Proposer’s Name: Christopher Francis, Stanford University