High temporal resolution monitoring of inorganic nitrogen load in drainage waters.
Nitrate (NO3-), ammonium (NH4+) and pH were monitored with a novel flow cell equipped with ion-selective electrodes (ISEs) in a drainage pipe during one year. The high temporal resolution of the measurements (six measurements per hour) allowed the detection of diurnal oscillations in pH, NO3- and NH4+ concentrations, the relation of variations in concentrations to discharge rates changing during rain events, understanding of the processes resulting in such variations and tracing of unpredictable manure spills. Annual loads estimated from random samples collected every second day tended to underestimate the "true" loads calculated from quasi-continuous electrode measurements by 550% for NH4+ and 22% for NO3-.
Swiss Federal Institute of Environmental Science and Technology (EA WAG), Swiss Federal Institute of Technology (ETH), Limnological Research Center, CH-6047 Kastanienbaum, Switzerland. beat.mueller@eawag.ch
Beat
B
Müller
Miriam
M
Reinhardt
René
R
Gächter
D004784:Environmental Monitoring / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D010507:Periodicity; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D012680:Sensitivity and Specificity; D014881:Water Supply
D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen