“…Streams and rivers included in our data set range in size from small first-order headwaters to some of the major waterways on the Earth's surface including the Mississippi, Congo, and the Yukon and Ob Rivers. Data sets were obtained from multiple sources including the NSF-sponsored Long-Term Ecological Research (LTER) program and the Andrews, Bonanza Creek, Hubbard Brook (Campbell et al, 2021), Luquillo (McDowell et al, 2021, Niwot Ridge, and Plum-Island LTERs; the NSF-sponsored Arctic GRO and PARTNERS projects; the United Kingdom NERC DOMAINE program (Yates et al, 2019) and the N speciation data set compiled for the European N Assessment as reported in Durand et al (2011); the Finnish Environment Institute (SYKE; partly described in Kortelainen et al, 2006;Mattsson et al, 2005); the Oak Ridge National Laboratory (Walker Branch; Griffiths & Mulholland, 2021); the NSF-sponsored Lotic Intersite Nitrogen eXperiment (LINX II; [Mulholland et al, 2008]); the Lamprey River Hydrological Observatory (Wymore et al, 2021); the US Geological Survey (USGS) as presented in Helton et al (2015); with additional data synthesized from Brookshire et al (2017), Lewis (2003, 2005) and Spencer et al (2016). See Supplemental Table S3 for the full citation list.…”