Water Resources Research Act Program

Details for Project ID 2018CT315B

Fe-OM Coprecipitation and its Effects on Bioavailability of Cu and OM to Denitrifiers

Institute: Connecticut
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $8,000 Total Non-Federal Funds: $16,000

Principal Investigators: Timothy Vadas

Abstract: Wetlands undergo changes in water that result in fluctuations of anoxic and oxic conditions. During these changes in redox potential, wetlands experience fluctuations in Fe and N cycles, organic matter (OM) turnover, and trace metal retention. These shifts can impact denitrification, resulting in variable nitrogen gas (N2) concentrations and nitrous oxide (N2O) yields, [N2O/(N2O +N2)]. The Fe cycle combined with Cu and OM precipitation dictate the partitioning of OM and Cu between dissolved, colloidal, and bulk solid phases which are used to infer bioavailability. Water, oxygen, OM and Cu availability, and pH are all factor influencing N2O yields. However, studies investigating constant water, oxygen, or carbon concentrations demonstrated variability in N2O yields across wetlands; suggesting that there may be other factors controlling yields. Carbon is used as an electron donor and it promotes their metabolism and consumption of O2. Cu is used as an enzyme cofactor which facilitates the reduction of N2O to N2. Therefore, when Cu is not available in the environment N2O yields should increase and as C is limited in the environment, yields should decrease in the system as well as net denitrification should decrease. Slurries will be amended to set different exposures of Cu and OM for the denitrifying population. Anaerobic mesocosms of soil slurries will be conducted in triplicate. Each exposure condition will have a pair of samples, one will be designated for N2O analysis and the other for N2 analysis. The N2O yields will be determined to compute a trend across exposure conditions.