Predictability of bacterial activity and denitrification in aquatic sediments with continuous measurements of redox potential.

Redox potential has been adopted as a qualitative parameter for interpreting solubility changes of nutrients and contaminants and the biological activity within wetland systems for several decades. The majority of studies considering the redox geochemistry in sediments used measurements of bulked material and single point measurement of biogeochemical parameters for interpretation, yet it remains questionable whether this information is reliable for environments that are very dynamic, such as wetlands. In this study it is evaluated whether variations in redox potential reflect dynamics of denitrification and overall bacterial respiration using continuous measurements of redox potential in time-series experiments in laboratory microcosms, in which the biogeochemical variation was enhanced by bioturbation. The results presented here suggest that measurements of redox potential have predictive potential in approximating rates of denitrification and overall bacterial respiration in aquatic sediments. The data clearly suggest that sediment bulk measurements and measurements of single profiles of redox potential, denitrification and bacterial activity may fail to provide ecological relevant information in dynamic systems, while also suggest that if temporal and spatial variability of redox potential measurements is considered, redox potential may provide a useful parameter that reflects biogeochemical processes and functioning of sediments.