2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
6/07/2017 | 9:30 AM - 9:45 AM | HIGH FREQUENCY MEASURES OF NITRATE AND OXYGEN ALLOW PARSING OF STREAM CONTROL ON WATERSHED NITRATE EXPORT | 306A
HIGH FREQUENCY MEASURES OF NITRATE AND OXYGEN ALLOW PARSING OF STREAM CONTROL ON WATERSHED NITRATE EXPORT
Elements leave watersheds in part via the streams that drain them, thus processing by streams has the final control over patterns of small watershed nutrient export. We used diel variation in nitrate concentration as a proxy for autotrophic nitrate uptake in a small Rocky Mountain stream. Prior to snowmelt, we installed nitrate and oxygen sensors to recorded at sub-hourly time intervals. Nitrate data peaked in concentration from snowpack flushing immediately after snowmelt followed by a steady dilution decline and then an increase in concentration at autumn baseflow. At the daily scale, nitrate concentrations declined 15% each day; this decline corresponded exactly with light suggesting control by stream autotrophs. Using oxygen data, we estimated reach-scale gross primary production and calculated the nitrogen demand from this carbon fixation at 1.4 mmol N m-2d-1. Calculated uptake from the diel nitrate decline was close at 0.5 to1.0 mmol N m-2d-1. Annual export was 800 mol nitrate-N/y, while biotic uptake was only 2%. High frequency N measures allow parsing biotic and hydrologic controls on watershed N export.
- S24 Towards a predictive freshwater ecology: using time-series data to understand and forecast responses to a changing environment
- C14 Hydroecology
- C10 Biogeochemistry
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Presenters/Authors
Robert O. Hall
(), Flathead Lake Biological Station, University of Montana, bob.hall@flbs.umt.edu;
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Elizabeth Traver
(), University of Wyoming, TRAVER@uwyo.edu;
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