Methods and Estimates of Gas Exchange for National Ecological Observatory Network (NEON) Streams

Accurate estimation of gas exchange rates across the air-water boundary is critical in quantifying stream metabolic processes (e.g., primary production and respiration) as well as emission of greenhouse gas fluxes (e.g., carbon dioxide, methane, and nitrous oxide).  Collection and processing of NEON measurements are standardized, and data are quality-controlled, and freely available through a publicly accessible online data portal (www.data.neonscience.org). With at least 3 years of Reaeration (DP1.20190.001) and Continuous discharge (DP4.00130.001) data for each NEON stream site, we have begun evaluating the relationship between metrics, such as k₆₀₀, travel time, mean wetted width, and mean depth, with continuous discharge. The relationships between these metrics and discharge vary across site types with some showing increasing gas exchange rates with increasing discharge (e.g., LeConte Creek in Great Smokey Mountains National Park) while others do not show a strong relationship with discharge (e.g., Caribou Creek in Alaska). The range of k₆₀₀ values cover a wide range, from < 3 m/d at a low gradient stream (Pringle Creek) to > 100 m/d at a high gradient stream during high discharge (Pringle Creek). This presentation outlines the methods and results used by NEON to calculate gas exchange metrics using rearRate, an R software package and Bayesian model developed for working with NEON Reaeration (DP1.20190.001)  data, which is publicly available on GitHub at www.github.com/NEONScience/NEON-reaeration.

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Primary Presenter: Kaelin Cawley, NEON project operated by Battelle (kcawley@battelleecology.org)

Authors:

Kaelin Cawley, Battelle, NEON project  (kcawley@battelleecology.org)

Robert Hensley, Battelle, NEON project  (hensley@battelleecology.org)

Kelly Aho, Michigan State University  (kellyaho@msu.edu)

Robert Hall, University of Montana  (bob.hall@flbs.umt.edu)

Keli Goodman, Battelle, NEON project  (kgoodman@battelleecology.org)