Journal article
Influences of climate, hydrology, and land use on input and export of nitrogen in California watersheds
Biogeochemistry, Vol.94(1), pp.43-62
05/2009
Handle:
https://hdl.handle.net/2376/107225
Abstract
Human activities have greatly increased the input of biologically available nitrogen (N) from land-based sources to aquatic ecosystems; yet few studies have examined how human actions influence N export in regions with a strong seasonality in water availability. In this study, we quantified N inputs and outputs for 23 California watersheds and examined how climate, hydrology, and land use practices influenced watershed N export. N inputs ranged from 581 to 11,234 kg N km−2 year−1 among watersheds, with 80% of total input for the region originating from agriculture (inorganic fertilizer, manure, and legumes). Of the potential N sources examined, mean annual concentrations of dissolved organic N and dissolved inorganic N in study rivers correlated most strongly with manure N input (r
2 = 0.54 and 0.53, respectively). Seasonal N export varied by basin and was correlated with climate, anthropogenic N inputs, and reservoir releases. Fractional export of watershed N inputs by study rivers annually was small (median of 8%) and scaled exponentially with runoff (r = 0.66). Collectively, our results show that anthropogenic activities have altered both the magnitude and timing of watershed N export in California and suggest that targeted management in specific locations and times of the year could reduce N export to downstream systems in the region.
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Details
- Title
- Influences of climate, hydrology, and land use on input and export of nitrogen in California watersheds
- Creators
- Daniel Sobota - School of Earth and Environmental Sciences Washington State University Vancouver Campus, 14204 NE Salmon Creek Avenue Vancouver WA 98686 USAJohn Harrison - School of Earth and Environmental Sciences Washington State University Vancouver Campus, 14204 NE Salmon Creek Avenue Vancouver WA 98686 USARandy Dahlgren - Department of Land, Air and Water Resources University of California Davis CA 95616 USA
- Publication Details
- Biogeochemistry, Vol.94(1), pp.43-62
- Academic Unit
- Harrison Research Group: Global Change and Watershed Biochemistry ; Environment, School of the (CAS)
- Publisher
- Springer Netherlands; Dordrecht
- Identifiers
- 99900547178501842
- Language
- English
- Resource Type
- Journal article