The Role of Ecology in Creating Diel Nitrate Concentration Patterns in Streams and Rivers

Heffernan, James B

Chamberlin, Catherine

2020-06-09T17:59:03Z

2022-05-27T08:17:20Z

2020

Ecology

Diel patterns in river solute concentrations can be derived through diurnal behaviors of organisms living in and around the water. Examples involving nitrate include nutrient uptake by autotrophs during the day and denitrification when oxygen levels are lowest during the night. Due to these biological origins, diel patterns provide information about important biogeochemical processes happening in rivers at broader timescales as well. Studies of diel behavior have been limited to intensively studied reach-scale analyses. This dissertation broadens the scale of these analyses in several ways. First, in an experimental manipulation of nutrient limitation, I demonstrate that diel patterns are indicative of nutrient repletion in an aquatic ecosystem. Second, I develop a method for isolating diel solute concentration patterns from timeseries that also include variability at other scales. I apply this method to high-frequency data at 82 sites around the United States, and find that diel oscillations are greatest during the summer months, and that rivers with higher turbidity, mean nitrate concentration and pH are more likely to exhibit oscillations consistent with dissimilatory processes than consistent with autotrophic processes. Lastly, I summarize high-frequency nitrate timeseries from 142 sites and find that diel patterns are frequent and wide spread within this dataset. The combination of this work broadens the scale at which diel patterns can be studied and adds to the process knowledge that can be derived from them.

https://hdl.handle.net/10161/20930

Ecology

Biogeochemistry

Limnology

autotrophy

diel

high-frequency

Nitrate

signal decomposition

The Role of Ecology in Creating Diel Nitrate Concentration Patterns in Streams and Rivers

Dissertation

23.572602739726026