2022/09/21 by Susana Bernal, Matthew J. Cohen, Mathew J. Cohen +5 · 41 citations
Chemistry · Earth and Planetary Sciences · Environmental Science · #Atmosphere (unit) #Biology #Carbon dioxide #Chemistry #Dissolved organic carbon #Ecology #Ecosystem #Environmental chemistry #Environmental science #Fish Ecology and Management Studies #Geology #Groundwater #Hydrology (agriculture) #Marine and coastal ecosystems #Perennial plant #Perennial stream #Primary production #STREAMS #Soil and Water Nutrient Dynamics
paper · pdf · doi:10.1002/lno.12226
published in Limnology and Oceanography 67(12), 2621-2634 (Wiley)
openalex publication_date 2022/09/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Abstract Headwater streams are control points for carbon dioxide (CO 2 ) emissions to the atmosphere, with relative contributions to CO 2 emission fluxes from lateral groundwater inputs widely assumed to overwhelm those from in‐stream metabolic processes. We analyzed continuous measurements of stream dissolved CO 2 and oxygen (O 2 ) concentrations during spring and early summer in two Mediterranean headwater streams from which we evaluated the contribution of in‐stream net ecosystem production (NEP) to CO 2 emission. The two streams exhibited contrasting hydrological regimes: one was non‐perennial with relatively small groundwater inflows, while the other was perennial and received significant lateral groundwater inputs. The non‐perennial stream exhibited strong inverse coupling between instantaneous and daily CO 2 and O 2 concentrations, and a strong correlation between aerobic ecosystem respiration (ER) and gross primary production (GPP) despite persistent negative NEP. At the perennial stream, the CO 2 –O 2 relationship varied largely over time, ER and GPP were uncorrelated, and NEP, which was consistently negative, increased with increasing temperature. Mean NEP contribution to CO 2 emission was 51% and 57% at the non‐perennial and perennial stream, respectively. Although these proportions varied with assumptions about metabolic stoichiometry and groundwater CO 2 concentration, in‐stream CO 2 production consistently and substantially contributed to total atmospheric CO 2 flux in both streams. We conclude that in‐stream metabolism can be more important for driving C cycling in some headwater streams than previously assumed.