This research, conducted by Song Wang, involved measuring the rates and product distribution of dinitroaromatic herbicides (shown below) reduced by mineral surfaces. Trifluralin and pendimethalin are extensively used throughout the Midwestern United States. Although nitroaromatic herbicides are known to be susceptible to reductive transformation, little information is available regarding their fate in reducing environments. Our research  has demonstrated that these compounds are rapidly reduced by ferrous iron (Fe²⁺) adsorbed to goethite, an iron oxide mineral, but much more slowly by ferrous iron sorbed to clay minerals or in aqueous solution. Results using bisulfide and juglone (a quinone-type electron transfer mediator) were  used to calculate reduction potentials for the herbicides. This information was used to develop quantitative-structure-activity relationships that could be used to predict the rates of herbicide transformation by a variety of reductants. The results of this work have also inspired us to investigate in more detail the processes occuring at the mineral surface.