title: HydroCrowd: a citizen science snapshot to assess the spatial control of nitrogen solutes in surface waters.
abstract: We organized a crowdsourcing experiment in the form of a snapshot sampling campaign to assess the spatial distribution of nitrogen solutes, namely, nitrate, ammonium and dissolved organic nitrogen (DON), in German surface waters. In particular, we investigated (i) whether crowdsourcing is a reasonable sampling method in hydrology and (ii) what the effects of population density, soil humus content and arable land were on actual nitrogen solute concentrations and surface water quality. The statistical analyses revealed a significant correlation between nitrate and arable land (0.46), as well as soil humus content (0.37) but a weak correlation with population density (0.12). DON correlations were weak but significant with humus content (0.14) and arable land (0.13). The mean contribution of DON to total dissolved nitrogen was 22%. Samples were classified as water quality class II or above, following the European Water Framework Directive for nitrate and ammonium (53% and 82%, respectively). Crowdsourcing turned out to be a useful method to assess the spatial distribution of stream solutes, as considerable amounts of samples were collected with comparatively little effort.
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.|Centre for International Development and Environmental Research, Justus Liebig University Gießen, Senckenbergstraße 3, 35392 Gießen, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Breuer
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.
authors.forename: Noreen
authors.initials: N
authors.lastname: Hiery
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kraft
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bach
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.
authors.forename: Alice H
authors.initials: AH
authors.lastname: Aubert
authors.affiliation: Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35390 Gießen, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Frede