The Effects of Mercury Contamination on Tree, Fungal, and Soil Composition along East Fork Poplar Creek, Anderson and Roane Counties, Tennessee

The Oak Ridge Reservation established under The Atomic Energy Commission was the site for uranium enrichment and the construction of the atomic bomb during the early 1950’s and 60’s. Unfortunately, large quantities of “heavy metals” such as mercury, uranium, technetium, plutonium and fission products that were produced were dumped into unlined landfills, settling ponds and surface streams. One such creek affected was East Fork Poplar Creek, whose head water begins at the Y-12 Facilities located on the Oak Ridge Reservation, and was once used as an industrial drainage ditch for runoff, which included mercury and other heavy metals.

The release of mercury, in particular, into East Fork Poplar Creek was probably lethal to established seed banks, vegetation, and soil microbial and fungal communities. The soil microbial communities play an important role in ecological processes, and the fungal communities are important, in particular, due to the mutualistic associations shared with more than 85% of plant species. This study evaluating the long term effects of mercury on plant and fungal presence and abundance indicated that soil mercury concentration was not significantly correlated with these factors. In order to better understand the effects of mercury compounds on plant and fungal interaction, a greenhouse study was conducted. Survival of seedlings in mercury-contaminated media was more dependent on mercury compound applied than on the presence of fungal inoculates tested. The ability of four tree species to germinate in different mercury compounds was also investigated. The germination of seedlings in mercury solution was dependent on tree species, mercury compound and concentration.

The detection of mercury in environmental samples was based on conventional methods such as cold vapor atomic absorption spectroscopy (CVAAS), and inductively coupled plasma emission mass spectrometer (ICP-MS). Analysis of mercury and other metals by non-destructive techniques such as infrared spectroscopy, specifically near-infrared (NIR) and mid-infrared (MIR) spectroscopy was investigated. Quantitative analysis of plant foliar tissue exposed to mercury was investigated by NIR, and mercury- contaminated soil was investigated by MIR. Due to mercury’s volatility, the ability to differentiate NIR spectra of control versus treated seedlings could not be confirmed through statistical analysis, however MIR spectra obtained from mercury-contaminated soil was used to develop significant calibration models for mercury and several other metals correlated to mercury.