title: Nitrate, Nitrite, and Ammonium Variability in Drinking Water Distribution Systems.
abstract: Accurate assessments of exposure to nitrate in drinking water is a crucial part of epidemiological studies investigating long-term adverse human health effects. However, since drinking water nitrate measurements are usually collected for regulatory purposes, assumptions on (1) the intra-distribution system variability and (2) short-term (seasonal) concentration variability have to be made. We assess concentration variability in the distribution system of nitrate, nitrite, and ammonium, and seasonal variability in all Danish public waterworks from 2007 to 2016. Nitrate concentrations at the exit of the waterworks are highly correlated with nitrate concentrations within the distribution net or at the consumers' taps, while nitrite and ammonium concentrations are generally lower within the net compared with the exit of the waterworks due to nitrification. However, nitrification of nitrite and ammonium in the distribution systems only results in a relatively small increase in nitrate concentrations. No seasonal variation for nitrate, nitrite, or ammonium was observed. We conclude that nitrate measurements taken at the exit of the waterworks are suitable to calculate exposures for all consumers connected to that waterworks and that sampling frequencies in the national monitoring programme are sufficient to describe temporal variations in longitudinal studies.
authors.affiliation: Geological Survey of Denmark and Greenland (GEUS), C.F. Møllers Allé 8, 8000 Aarhus C, Denmark. jsc@geus.dk.|National Centre for Register-Based Research, Department of Economics and Business Economics, School of Business and Social Sciences, Aarhus University, Fuglesangs Allé 4, 8210 Aarhus V, Denmark. jsc@geus.dk.
authors.forename: Jörg
authors.initials: J
authors.lastname: Schullehner
authors.affiliation: School of Public Health, Epidemiology and Biostatistics Division, University of Illinois at Chicago, 1603 W. Taylor Street, Chicago, IL 60612, USA. lstayner@uic.edu.
authors.forename: Leslie
authors.initials: L
authors.lastname: Stayner
authors.affiliation: Geological Survey of Denmark and Greenland (GEUS), C.F. Møllers Allé 8, 8000 Aarhus C, Denmark. bgh@geus.dk.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Hansen
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis*; D003718:Denmark; D060766:Drinking Water / Q000032:analysis*; D004784:Environmental Monitoring; D005843:Geography; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D012621:Seasons; D013997:Time Factors
chemical_list: D064751:Ammonium Compounds; D060766:Drinking Water; D009566:Nitrates; D009573:Nitrites
keywords: Denmark; ammonium; drinking water; exposure assessment; nitrate; nitrification; nitrite