As reducing conditions are reached during bioremediation, common polyanionic species like nitrate and sulfate are reduced to their less oxidized states (in this case, nitrogen gas and sulfide). These changes in nitrate and sulfate concentrations often indicate that oxidation-reduction reactions are occurring within an aquifer due to actions of microorganisms which is consistent with the onset of anerobic bioremediation.
SiREM’s anion analysis measures anions to assess the concentrations of redox-sensitive anionic species, including nitrate and sulfate, which can confirm that suitable reducing conditions have been achieved so that reductive dehalogenation can occur. Chloride measurement can also be used as another line of evidence for dechlorination at contaminated sites with very high chlorinated solvent concentrations.
In addition, stable anionic tracers, such as bromide, can be used to trace groundwater velocity and flow paths.