Event Title

Watershed Nitrogen Dynamics in the Boise National Forest, Idaho

Presenter Information

Chelsea L. Crenshaw

Location

ECC 303/305

Event Website

https://water.usu.edu/

Start Date

3-31-2008 3:45 PM

End Date

3-31-2008 4:00 PM

Description

Essential nutrients are transported from the terrestrial landscape through freshwater ecosystems. As water moves from the land to the sea, the character of drainage networks can alter the amount and form of these nutrients via biogeochemical interactions. We examined the fate of nitrate in a drainage network in the Sawtooth Mountains, Idaho. We conducted 6 short-term 15N-nitrate injections at different network locations above and below Bull Trout Lake. We also sampled at one site during the injection to examine the transport-basked analysis of nutrient spiraling. Ambient nitrate concentrations were very low in all 6 sites along the watershed ranging from 2-24 μg/l with the highest concentration in the headwater stream. Stream solute spiraling parameters were used to quantify nitrate uptake dynamics. Uptake lengths (Sw) ranged from 100 to 2,000 m with a trend of shortest Sw in the headwaters and increasing to the lake outflow. Uptake rate (U) decreased from the headwaters to the outflow ranging from 0.1 μg m-2 s-1 to 10 μg m- 2 s-1. Longitudinal loss rate was calculated and % loss of nitrate from each reach ranged from 5 % to 100% with the lowest being at the outflow and increasing steadily to the headwaters of the network.

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Mar 31st, 3:45 PM Mar 31st, 4:00 PM

Watershed Nitrogen Dynamics in the Boise National Forest, Idaho

ECC 303/305

Essential nutrients are transported from the terrestrial landscape through freshwater ecosystems. As water moves from the land to the sea, the character of drainage networks can alter the amount and form of these nutrients via biogeochemical interactions. We examined the fate of nitrate in a drainage network in the Sawtooth Mountains, Idaho. We conducted 6 short-term 15N-nitrate injections at different network locations above and below Bull Trout Lake. We also sampled at one site during the injection to examine the transport-basked analysis of nutrient spiraling. Ambient nitrate concentrations were very low in all 6 sites along the watershed ranging from 2-24 μg/l with the highest concentration in the headwater stream. Stream solute spiraling parameters were used to quantify nitrate uptake dynamics. Uptake lengths (Sw) ranged from 100 to 2,000 m with a trend of shortest Sw in the headwaters and increasing to the lake outflow. Uptake rate (U) decreased from the headwaters to the outflow ranging from 0.1 μg m-2 s-1 to 10 μg m- 2 s-1. Longitudinal loss rate was calculated and % loss of nitrate from each reach ranged from 5 % to 100% with the lowest being at the outflow and increasing steadily to the headwaters of the network.

https://digitalcommons.usu.edu/runoff/2008/AllAbstracts/26