caa a22 4500 467885982 CHVBK 20180406152734.0 cr unu---uuuuu 170328e20060801xx s 000 0 eng 10.1007/s10021-006-0076-3 doi (NATIONALLICENCE)springer-10.1007/s10021-006-0076-3 Does Anthropogenic Nitrogen Enrichment Increase Organic Nitrogen Concentrations in Runoff from Forested and Human-dominated Watersheds? [Elektronische Daten] [Brian Pellerin, Sujay Kaushal, William McDowell] Although the effects of anthropogenic nitrogen (N) inputs on the dynamics of inorganic N in watersheds have been studied extensively, "the influence of N enrichment on organic N loss” is not as well understood. We compiled and synthesized data on surface water N concentrations from 348 forested and human-dominated watersheds with a range of N loads (from less than 100 to 7,100 kg N km−2 y−1) to evaluate the effects of N loading via atmospheric deposition, fertilization, and wastewater on dissolved organic N (DON) concentrations. Our results indicate that, on average, DON accounts for half of the total dissolved N (TDN) concentrations from forested watersheds, but it accounts for a smaller fraction of TDN in runoff from urban and agricultural watersheds with higher N loading. A significant but weak correlation (r 2 = 0.06) suggests that N loading has little influence on DON concentrations in forested watersheds. This result contrasts with observations from some plot-scale N fertilization studies and suggests that variability in watershed characteristics and climate among forested watersheds may be a more important control on DON losses than N loading from atmospheric sources. Mean DON concentrations were positively correlated, however, with N load across the entire land-use gradient (r 2 = 0.37, P < 0.01), with the highest concentrations found in agricultural and urban watersheds. We hypothesize that both direct contributions of DON from wastewater and agricultural amendments and indirect transformations of inorganic N to organic N represent important sources of DON to surface waters in human-dominated watersheds. We conclude that DON is an important component of N loss in surface waters draining forested and human-dominated watersheds and suggest several research priorities that may be useful in elucidating the role of N enrichment in watershed DON dynamics. Springer Science+Business Media, Inc., 2006 dissolved organic nitrogen nationallicence nitrogen deposition nationallicence agriculture nationallicence forest nationallicence watersheds nationallicence urbanization nationallicence Pellerin Brian US Geological Survey, 6000 J Street, Placer Hall, 95819, Sacramento, California, USA aut Kaushal Sujay University of Maryland Center for Environmental Science, Appalachian Laboratory, 21532, Frostburg, Maryland, USA aut McDowell William Department of Natural Resources, University of New Hampshire, 03824, Durham, New Hampshire, USA aut Ecosystems Springer-Verlag; www.springer-ny.com 9/5(2006-08-01), 852-864 1432-9840 9:5<852 2006 9 10021 https://doi.org/10.1007/s10021-006-0076-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-006-0076-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pellerin Brian US Geological Survey, 6000 J Street, Placer Hall, 95819, Sacramento, California, USA aut NATIONALLICENCE 700 1- Kaushal Sujay University of Maryland Center for Environmental Science, Appalachian Laboratory, 21532, Frostburg, Maryland, USA aut NATIONALLICENCE 700 1- McDowell William Department of Natural Resources, University of New Hampshire, 03824, Durham, New Hampshire, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag; www.springer-ny.com 9/5(2006-08-01), 852-864 1432-9840 9:5<852 2006 9 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer