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Titolo:
Multiscale effects of surface-subsurface exchange on stream water nutrientconcentrations
Autore:
Dent, CL; Grimm, NB; Fisher, SG;
Indirizzi:
Arizona State Univ, Dept Biol, Tempe, AZ 85287 USA Arizona State Univ Tempe AZ USA 85287 niv, Dept Biol, Tempe, AZ 85287 USA
Titolo Testata:
JOURNAL OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY
fascicolo: 2, volume: 20, anno: 2001,
pagine: 162 - 181
SICI:
0887-3593(200106)20:2<162:MEOSEO>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
SONORAN DESERT STREAM; VERTICAL HYDROLOGIC EXCHANGE; 4TH-ORDER MOUNTAIN STREAM; HYPORHEIC ZONE; ECOSYSTEM PERSPECTIVE; CONVECTIVE-TRANSPORT; NITROGEN DYNAMICS; RIPARIAN ZONES; STORM DYNAMICS; RIVER;
Keywords:
nutrient retention; hyporheic zone; scale; hierarchy; nitrogen; phosphorus; stream;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
79
Recensione:
Indirizzi per estratti:
Indirizzo: Dent, CL Univ Wisconsin, Ctr Limnol, 680 N Pk St, Madison, WI 53706 USA Univ Wisconsin 680 N Pk St Madison WI USA 53706 son, WI 53706 USA
Citazione:
C.L. Dent et al., "Multiscale effects of surface-subsurface exchange on stream water nutrientconcentrations", J N AMER BE, 20(2), 2001, pp. 162-181

Abstract

Stream-riparian ecosystems are landscapes composed of dynamic interacting terrestrial and aquatic patches. Patch composition and configuration affects both the form of transported materials and the amount of nutrient retention and export. We describe spatial patterns of nutrients in the surface water of an arid-land stream using surveys conducted at 3 different scales, ranging from 30 m to 10 km in extent and from 1 m to 25 m in grain. We then relate these patterns to connections with subsurface patches at channel subunit, channel unit, and reach scales. Our objectives were to compare spatialvariation in nutrients across scales, to determine the causes of downstream changes in nutrient concentration in terms of intervening patches, and toinvestigate whether subsurface patches at different scales behaved similarly in terms of net nutrient processing. Nutrients varied spatially at all scales sampled. The highest variation was observed in nitrate-N (NO3,-N) in the survey with the smallest grain (CV = 161%) and the lowest was observed ed in soluble reactive P (SRP) in the same survey (CV = 17%). We hypothesized that downstream changes in nutrient concentrations were caused by upwelling of high-nutrient water from the subsurface To test this hypothesis, we identified locations of hydrologic inputs to surface water from the subsurface using geomorphic features of the stream such as gravel bar edges (channel subunit scale), riffle-run transitions (channel unit scale), and permanent groundwater sources (reach scale). As surface water passed over these locations, nutrient concentrations generally increased, particularly during late succession when subsurface patches acted as sources of NO3-N at all 3 scales and as sources of SRP at the channel unit and reach scales. A hierarchical approach allowed us to decompose effects of subsurface upwellings at different scales and to consider interactions between them. Processes occurring in subsurface patches influenced surface water nutrient patterns at scales from a few meters to several kilometers.

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Documento generato il 07/04/20 alle ore 23:06:11