- Title
- Estimates of surface layer net community production based on underway Lagrangian measurements of the dissolved O2/Ar ratio using Equilibrator Inlet Mass Spectrometry (EIMS), based on both steady-state and non-steady-state assumptions of the mixed-layer biological oxygen budget. Also included are estimates of the potential contribution of vertical fluxes: advection, eddy diffusion, and entrainment.
- Abstract
- The ratio of dissolved oxygen to argon in surface seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar-based method accounts for many physical factors that influence oxygen concentrations in the surface ocean, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the existence of a steady-state balance between net productivity and the air-sea gas exchange of biological oxygen. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a ‘worst-case’ field environment. Quantifying the magnitude of vertical fluxes and comparing NCP estimates obtained using steady-state versus non-steady-state assumptions, we find the importance of the non-steady-state term to be considerable, also observing significant potential effects from vertical flux terms, particularly advection. Additionally, we observe strong diel variability in O2/Ar and calculated NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar-derived NCP data as well as the potentially large effect of non-steady-state conditions, including diel cycles in surface O2/Ar that can bias interpretation of NCP data based on local productivity and the time of day at which measurements were made.
- Keywords
- advection, flux, marine, oceans, production, eddy diffusion, EIMS, entrainment, NCP, O2/Ar
- LTER Data System Record
- http://dx.doi.org/10.6073/pasta/dd428d04ae0132382094a7a3fb67ddef
- Projects
-
California Current Ecosystem LTER
- Creators
-
Wang, Seaver (seaver.wang@duke.edu)
Kelly, Thomas (tbkelly@alaska.edu)
Kranz, Sven (skranz@rice.edu)
- Contact
- CCE LTER Information Manager (ccelter.im@gmail.com)
- Other Personnel
-
Cassar, Nicolas
Co-author
Stukel, Mike Co-author
Song, Hajoon Co-author
Data
| table |
ncp
primary data table |
Rows: 7200 Columns: 16 |
View / Download |