Nutrient loads exported from managed catchments reveal emergent biogeochemical stationarity

Complexity of heterogeneous catchments poses challenges in predicting biogeochemical responses to human alterations and stochastic hydro‐climatic drivers. Human interferences and climate change may have contributed to the demise of hydrologic stationarity, but our synthesis of a large body of observ...

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Veröffentlicht in:	Geophysical research letters Jg. 37; H. 23
Hauptverfasser:	Basu, Nandita B., Destouni, Georgia, Jawitz, James W., Thompson, Sally E., Loukinova, Natalia V., Darracq, Amélie, Zanardo, Stefano, Yaeger, Mary, Sivapalan, Murugesu, Rinaldo, Andrea, Rao, P. Suresh C.
Format:	Journal Article
Sprache:	Englisch
Veröffentlicht:	Washington, DC Blackwell Publishing Ltd 01.12.2010 American Geophysical Union John Wiley & Sons, Inc
Schlagworte:	Annual variations Anthropogenic factors Biogeochemical cycles biogeochemical cycling Biogeochemistry catchment Catchments Climate change Coastal waters Cryosphere Earth Earth sciences Earth, ocean, space Exact sciences and technology Flow pattern Geobiology Hydrology nutrient Nutrient loading Nutrient sources Nutrients Receiving waters River basins stationarity Water quality Watersheds Mississippi United States Atlantic Ocean Louisiana Northeast Atlantic North Atlantic Atchafalaya River Baltic Sea synthesis rainfall emergence concentration exhibits Invariance transport monitoring North America River basins Long term interferences Complexity nutrients Interannual variation drainage basins discharge Geogenic factor alteration flow field export flow climate change Anthropogenic factor MISSISSIPPI RIVER-BASIN DYNAMICS FLUX SOIL DEAD HYPOXIA EUTROPHICATION WATER
ISSN:	0094-8276, 1944-8007, 1944-8007
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Zusammenfassung:	Complexity of heterogeneous catchments poses challenges in predicting biogeochemical responses to human alterations and stochastic hydro‐climatic drivers. Human interferences and climate change may have contributed to the demise of hydrologic stationarity, but our synthesis of a large body of observational data suggests that anthropogenic impacts have also resulted in the emergence of effective biogeochemical stationarity in managed catchments. Long‐term monitoring data from the Mississippi‐Atchafalaya River Basin (MARB) and the Baltic Sea Drainage Basin (BSDB) reveal that inter‐annual variations in loads (LT) for total‐N (TN) and total‐P (TP), exported from a catchment are dominantly controlled by discharge (QT) leading inevitably to temporal invariance of the annual, flow‐weighted concentration, = (LT/QT). Emergence of this consistent pattern across diverse managed catchments is attributed to the anthropogenic legacy of accumulated nutrient sources generating memory, similar to ubiquitously present sources for geogenic constituents that also exhibit a linear LT‐QT relationship. These responses are characteristic of transport‐limited systems. In contrast, in the absence of legacy sources in less‐managed catchments, values were highly variable and supply limited. We offer a theoretical explanation for the observed patterns at the event scale, and extend it to consider the stochastic nature of rainfall/flow patterns at annual scales. Our analysis suggests that: (1) expected inter‐annual variations in LT can be robustly predicted given discharge variations arising from hydro‐climatic or anthropogenic forcing, and (2) water‐quality problems in receiving inland and coastal waters would persist until the accumulated storages of nutrients have been substantially depleted. The finding has notable implications on catchment management to mitigate adverse water‐quality impacts, and on acceleration of global biogeochemical cycles.
Bibliographie:	istex:4CF110C0922AEB2DF3D798AFD2DCFA2BC0F41B8B ark:/67375/WNG-FQ9KQT2J-L ArticleID:2010GL045168 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14
ISSN:	0094-8276 1944-8007 1944-8007
DOI:	10.1029/2010GL045168