Steingruber, S. Swiss Federal Institute for Environmental Science and Techmology (EAWAG), Limnological Research Center, firstname.lastname@example.org
Wehrli, B. Swiss Federal Institute for Environmental Science and Techmology (EAWAG), Limnological Research Center, email@example.com
Gächter, R. Swiss Federal Institute for Environmental Science and Techmology (EAWAG), Limnological Research Center, firstname.lastname@example.org
NITROGEN REMOVAL IN A WETLAND POND
A water- and nitrogen-mass balance was used to investigate the nitrogen removal capacity of a wetland pond in Lucerne, Switzerland. Inflows, outflow and water table variation were measured continuously. Precipitation was measured weekly. Evaporation data could be obtained from a meteorologic station close to the study area. Groundwater influence was estimated with a mass balance, a tracer experiment, piezometric network and soil permeability data. Nitrogen compounds were measured every two to four weeks. Atmospheric nitrogen input was estimated by collecting rain and dry deposition.
Nitrate in the inflows (agricultural drainage water) was almost constant during the entire year and measured between 3 and 3.5 mg N/l. In the pond, however, nitrate reached maximum concentratios in the winter (0.8-1.5 mg N/l) and minimum concentrations in the summer (0.06 mg N/l). Total dissolved organic nitrogen (TDON) varied between 0.5 and 0.8 mg N/l while total particulate nitrogen (TPN) levels ranged from 0.2 to 0.5 mg N/l. Concentrations of TDON and TPN were slithly smaller in winter than in summer time.
In spring and summer time total nitrogen elimination rates were about 20 tN/(km2.yr), Nitrate elimination rates were 30 tN/(km2.yr) and organic nitrogen production rates were 10 tN/(km2.yr).
Day: Tuesday, Feb. 2
Location: Sweeney Center