Additional Funding Sources
The project described was supported by a student grant from the UI Office of Undergraduate Research and the Research Experience for Undergraduates Program Site: Molecular and organismal evolution at the University of Idaho under Award No. 1757826.
Abstract
Pristine forests are nitrogen limited with conservative nutrient cycles, although anthropogenic nitrogen (N) inputs cause many ecosystems to saturate and lose N to the surrounding environment, causing an increased risk of leaching and eutrophication in freshwater ecosystems. The effects of nutrient additions are being studied in a time-series of five forest water reclamation facilities operating in Northern Idaho with treatment durations ranging from 9 to 44 years. This time-series presents an opportunity to compare microbially controlled nitrification processes. Insight into sustainable forest wastewater application has the potential to allow greater rates of carbon sequestration and increase water quality in surrounding freshwater systems. Nitrifying bacteria and archaea oxidize ammonium from wastewater to nitrate, which is highly mobile in soils. The rate-limiting step of nitrification is catalyzed by ammonia monooxygenase (AMO). Ammonia monooxygenase is encoded by the amoA gene, which can be used to detect presence and abundance of nitrifiers. Using qPCR amplification of amoA, the abundance of nitrifiers across the time series of forest water reclamation facilities were compared to adjacent non-treated control plots. Comparing the respective nitrification rates and amoA abundance between treated and control plots can help determine critical nitrogen saturation and subsequent leaching risk. Treatment effects were highly significant (P < 0.01) in amoA concentration when controlling for establishment. Establishment dates non-significant. Establishment effects have a high interaction significance depending on treatment. For nitrification, there is high interaction effects in treatments. Establishment date is only a significant interaction effect for nitrate flux. Treatment and establishment interaction effects only significant (P < 0.05) for initial ammonium and nitrate flux. Establishment years 1978, 1989, and 2000 showed highly significant differences for all variables between treatments, indicating that they have undergone greater changes to nitrogen cycling than younger facilities that yielded non-significant differences, 2010 and 2013.
Nitrification and Ammonia-Oxidizing Bacteria Abundance in a Time-Series of Forest Reclaimed Water Applications
Pristine forests are nitrogen limited with conservative nutrient cycles, although anthropogenic nitrogen (N) inputs cause many ecosystems to saturate and lose N to the surrounding environment, causing an increased risk of leaching and eutrophication in freshwater ecosystems. The effects of nutrient additions are being studied in a time-series of five forest water reclamation facilities operating in Northern Idaho with treatment durations ranging from 9 to 44 years. This time-series presents an opportunity to compare microbially controlled nitrification processes. Insight into sustainable forest wastewater application has the potential to allow greater rates of carbon sequestration and increase water quality in surrounding freshwater systems. Nitrifying bacteria and archaea oxidize ammonium from wastewater to nitrate, which is highly mobile in soils. The rate-limiting step of nitrification is catalyzed by ammonia monooxygenase (AMO). Ammonia monooxygenase is encoded by the amoA gene, which can be used to detect presence and abundance of nitrifiers. Using qPCR amplification of amoA, the abundance of nitrifiers across the time series of forest water reclamation facilities were compared to adjacent non-treated control plots. Comparing the respective nitrification rates and amoA abundance between treated and control plots can help determine critical nitrogen saturation and subsequent leaching risk. Treatment effects were highly significant (P < 0.01) in amoA concentration when controlling for establishment. Establishment dates non-significant. Establishment effects have a high interaction significance depending on treatment. For nitrification, there is high interaction effects in treatments. Establishment date is only a significant interaction effect for nitrate flux. Treatment and establishment interaction effects only significant (P < 0.05) for initial ammonium and nitrate flux. Establishment years 1978, 1989, and 2000 showed highly significant differences for all variables between treatments, indicating that they have undergone greater changes to nitrogen cycling than younger facilities that yielded non-significant differences, 2010 and 2013.