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Abstract Measurements of riverine dissolved inorganic carbon, total alkalinity (AT), pH, and the partial pressure of carbon dioxide (pCO2) can provide insights into the biogeochemical function of rivers, including the processes that control biological production, chemical speciation, and air‐water CO2fluxes. The complexity created by these combined processes dictates that studies of inorganic carbon be made over broad spatial and temporal scales. Time‐series data like these are relatively rare, however, because sampling and measurements are labor intensive and, for some variables, good measurement quality is difficult to achieve (e.g., pH). In this study, spectrophotometric pH and ATwere quantified with high precision and accuracy at biweekly to monthly intervals over a four‐year period (2018–2021) along 216 km of the Upper Clark Fork River (UCFR) in the northern Rocky Mountains, USA. We use these and other time‐series data to provide insights into the processes that control river inorganic carbon, with a focus onpCO2and air‐water CO2fluxes. We found that seasonal snowmelt runoff increasedpCO2and that expected increase and decrease ofpCO2due to seasonal heating and cooling were likely offset by an increase and loss of algal biomass, respectively. Overall, the UCFR was a small net source (0.08 ± 0.14 mol m−2 d−1) of CO2to the atmosphere over the four‐year study period with highly variable annual averages (0.0–0.10 mol m−2 d−1). The seasonally correlated, offsetting mechanisms highlight the challenges in predictingpCO2and air‐water CO2fluxes in rivers.
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Superlocal chemical reaction equilibrium in low temperature plasma
Abstract Low temperature plasmas (LTP) are a unique class of open‐driven systems in which chemical reactions are unpredictable using established concepts. The terminal state of chemical reactions in LTP, termed thesuperlocalequilibrium state, is hypothesized to be defined by a proposed set of state variables. Using a LTP reactor wherein the state variables have been measured, it is shown that CO2spontaneously splits and the effluent speciation is independent of the influent speciation if the state variables are held constant and the residence time is long. CO2conversion at long residence times, which is expected to be nominally zero from equilibrium thermodynamics, can be as high as 70% in the LTP. The employed low pressure plasma reactor (P= 10 mbar) had a similar volume, productivity, and energy efficiency compared to an atmospheric pressure dielectric barrier discharge reactor, thanks to reaction rates that were three orders of magnitude faster.
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- PAR ID:
- 10457005
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- AIChE Journal
- Volume:
- 66
- Issue:
- 6
- ISSN:
- 0001-1541
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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