Coupling high-frequency stream metabolism and nutrient monitoring to explore biogeochemical controls on downstream nitrate delivery
Jarvie, Helen P. 
ORCID: https://orcid.org/0000-0002-4984-1607; Sharpley, Andrew N.; Kresse, Timothy; Hays, Phillip D.; Williams, Richard J.; King, Stephen M.; Berry, Lawrence G..
2018
Coupling high-frequency stream metabolism and nutrient monitoring to explore biogeochemical controls on downstream nitrate delivery.
Environmental Science & Technology, 52 (23).
13708-13717.
https://doi.org/10.1021/acs.est.8b03074
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Abstract/Summary
Instream biogeochemical process measurements are often short-term and localized. Here we use in situ sensors to quantify the net effects of biogeochemical processes on seasonal patterns in baseflow nitrate retention at the river-reach scale. Dual-station high-frequency in situ nitrate measurements, were coupled with high-frequency measurements of stream metabolism and dissolved inorganic carbon, in a tributary of the Buffalo National River, Arkansas. Nitrate assimilation was calculated from net primary production, and combined with mass-balance measurements, to estimate net nitrification and denitrification. The combined net effects of these instream processes (assimilation, denitrification, and nitrification) removed >30–90% of the baseflow nitrate load along a 6.5 km reach. Assimilation of nitrate by photoautotrophs during spring and early summer was buffered by net nitrification. Net nitrification peaked during the spring. After midsummer, there was a pronounced switch from assimilatory nitrate uptake to denitrification. There was clear synchronicity between the switch from nitrate assimilation to denitrification, a reduction in river baseflows, and a shift in stream metabolism from autotrophy to heterotrophy. The results show how instream nitrate retention and downstream delivery is driven by seasonal shifts in metabolic pathways; and how continuous in situ stream sensor networks offer new opportunities for quantifying the role of stream biota in the dynamics, fate, and transport of nitrogen in fluvial systems.
| Item Type: | Publication - Article |
|---|---|
| Digital Object Identifier (DOI): | https://doi.org/10.1021/acs.est.8b03074 |
| UKCEH and CEH Sections/Science Areas: | Pollution (Science Area 2017-) Water Resources (Science Area 2017-) |
| ISSN: | 0013-936X |
| NORA Subject Terms: | Ecology and Environment |
| Date made live: | 04 Dec 2018 15:44 +0 (UTC) |
| URI: | https://nora.nerc.ac.uk/id/eprint/521792 |
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