Linking denitrification with ecosystem respiration in mountain streams

Hilary L. Madinger, Robert O. Hall

Research output: Contribution to journalLetterpeer-review

Abstract

Rivers denitrify a portion of their nitrate ((Formula presented.)) load, but estimates are difficult using microcosm or reach-scale measurements that require specific biogeochemical and hydrologic conditions. Measuring reach-scale oxygen (O2) respiration fluxes is easier than nitrogen (N2) fluxes, thus we paired microcosm estimates of denitrification by N2 production with estimates of aerobic respiration. The median molar ratio of ΔN2:−ΔO2 from 13 streams was 0.011 (95% credible interval 0.0002–0.027 mol:mol). We then measured diel O2 concentrations from 11 streams and converted to ecosystem respiration (ER) using a multiday oxygen model. Given reach-scale ER of −160 mmol O2 m−2 d−1, the estimated median denitrification was 1.5 mmol N2 m−2 d−1 (credible interval (CI): 0.18–4.21) across our streams. Our estimates of denitrification constituted 19% of gross (Formula presented.) uptake (CI: 0–51%). In streams, ΔN2:−ΔO2 was lower than in estuarine and marine ecosystems. Despite multiple sources of error, this approach estimates reach-scale denitrification and variation with (Formula presented.) concentrations.

Original languageEnglish
Pages (from-to)145-154
Number of pages10
JournalLimnology And Oceanography Letters
Volume4
Issue number5
DOIs
StatePublished - Oct 2019

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