<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Earl, Stevan R.</style></author><author><style face="normal" font="default" size="100%">Valett, H. Maurice</style></author><author><style face="normal" font="default" size="100%">Webster, Jackson R.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Nitrogen saturation in stream ecosystems.</style></title><secondary-title><style face="normal" font="default" size="100%">Ecology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">CWT</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://cwt33.ecology.uga.edu/publications/3021.pdf</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">87(12)</style></volume><pages><style face="normal" font="default" size="100%">3140-3151.</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extended the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15 NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menton kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams.  Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the time, uptake velocity was highest in the low</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2006-80259</style></accession-num></record></records></xml>