Event Title

Lakes Within Stream Networks: Regulators of Dissolved Organic Matter (DOM) Transport in Mountain Watersheds

Presenter Information

Keli J. Goodman

Location

ECC 216

Event Website

https://water.usu.edu/

Start Date

3-31-2008 5:55 PM

End Date

3-31-2008 6:00 PM

Description

We evaluate how the presence of a lake within stream networks regulates DOM (both dissolved organic carbon (DOC) and nitrogen (DON)) dynamics. We hypothesize that lakes act as a buffer to snowmelt DOC flushing in outflow streams, as well as act as a source of high quality DOM (low DOC:DON) to outflow streams. We tested these hypotheses by weekly measurements of DOC and DON quantity and quality in 1) Bull Trout Lake (BTL) inflow and outflow over a 6-month time period and 2) inflows and outflows of three other lakes in different watersheds over a shorter summer sampling period (3-months). BTL inflow and outflow DOC concentrations peaked in late May. BTL flushing (i.e. linear declines in DOC) was evaluated as ln[DOC] from 22-May to 20- July. Inflow DOC recession was 2.5X faster than the outflow, indicating lake buffering of snowmelt DOC flushing. Outflow DON concentrations increased over the summer, while lake inflow DON decreased. DOC and DON quantity in the three additional lake inflows and outflows showed similar trends to those of BTL. During baseflow, DOC and DON concentrations were greater in outflows than inflows, (~2 and 3X, respectively). In general, DOC:DON ratios were lower in outflows than inflows, indicating higher quality DOM in lake outflows. Our results suggest that mountain lakes produce both DOC and DON and alter the timing and character of DOM export to downstream locations.

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Mar 31st, 5:55 PM Mar 31st, 6:00 PM

Lakes Within Stream Networks: Regulators of Dissolved Organic Matter (DOM) Transport in Mountain Watersheds

ECC 216

We evaluate how the presence of a lake within stream networks regulates DOM (both dissolved organic carbon (DOC) and nitrogen (DON)) dynamics. We hypothesize that lakes act as a buffer to snowmelt DOC flushing in outflow streams, as well as act as a source of high quality DOM (low DOC:DON) to outflow streams. We tested these hypotheses by weekly measurements of DOC and DON quantity and quality in 1) Bull Trout Lake (BTL) inflow and outflow over a 6-month time period and 2) inflows and outflows of three other lakes in different watersheds over a shorter summer sampling period (3-months). BTL inflow and outflow DOC concentrations peaked in late May. BTL flushing (i.e. linear declines in DOC) was evaluated as ln[DOC] from 22-May to 20- July. Inflow DOC recession was 2.5X faster than the outflow, indicating lake buffering of snowmelt DOC flushing. Outflow DON concentrations increased over the summer, while lake inflow DON decreased. DOC and DON quantity in the three additional lake inflows and outflows showed similar trends to those of BTL. During baseflow, DOC and DON concentrations were greater in outflows than inflows, (~2 and 3X, respectively). In general, DOC:DON ratios were lower in outflows than inflows, indicating higher quality DOM in lake outflows. Our results suggest that mountain lakes produce both DOC and DON and alter the timing and character of DOM export to downstream locations.

https://digitalcommons.usu.edu/runoff/2008/Posters/18