Riverine Export of Aged Carbon Driven by Flow Path Depth and Residence Time

2018 ◽  
Vol 52 (3) ◽  
pp. 1028-1035 ◽  
Author(s):  
Rebecca T. Barnes ◽  
David E. Butman ◽  
Henry F. Wilson ◽  
Peter A. Raymond
Keyword(s):  
Residence Time ◽  
Flow Path ◽  
Riverine Export

scholarly journals Direct Coal-Fueled Combustion Turbines

1987 ◽  
Author(s):  
Richard A. Wenglarz
Keyword(s):  
Residence Time ◽  
Flow Path ◽  
Past Experience ◽  
Short Residence Time ◽  
Combustion Emissions ◽  
Turbine Flow Path

Technology requirements for direct coal-fueled turbine systems are discussed. Combustion, emissions, and turbine life considerations are emphasized. Compact, short residence time combustors must provide acceptable combustion efficiencies and emissions using the coal fuels. The turbine flow path exposed to the products of combustion (POC) from those combustors must achieve acceptable deposition, erosion, and corrosion (DEC) lifetimes. Initial combustion and POC requirements are reviewed based on past experience and the results of a recent program to evaluate combustion, emissions, and DEC from a subscale turbine combustor.

scholarly journals Optical properties and bioavailability of dissolved organic matter along a flow-path continuum from soil pore waters to the Kolyma River mainstem, East Siberia

2016 ◽  
Vol 13 (8) ◽  
pp. 2279-2290 ◽  
Author(s):  
Karen E. Frey ◽  
William V. Sobczak ◽  
Paul J. Mann ◽  
Robert M. Holmes
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Residence Time ◽  
Flow Path ◽  
The Arctic ◽  
Pore Waters ◽  
Water Types ◽  
Kolyma River ◽  
Dom Composition

Abstract. The Kolyma River in northeast Siberia is among the six largest Arctic rivers and drains a region underlain by vast deposits of Holocene-aged peat and Pleistocene-aged loess known as yedoma, most of which is currently stored in ice-rich permafrost throughout the region. These peat and yedoma deposits are important sources of dissolved organic matter (DOM) to inland waters that in turn play a significant role in the transport and ultimate remineralization of organic carbon to CO2 and CH4 along the terrestrial flow-path continuum. The turnover and fate of terrigenous DOM during offshore transport largely depends upon the composition and amount of carbon released to inland and coastal waters. Here, we measured the ultraviolet-visible optical properties of chromophoric DOM (CDOM) from a geographically extensive collection of waters spanning soil pore waters, streams, rivers, and the Kolyma River mainstem throughout a  ∼  250 km transect of the northern Kolyma River basin. During the period of study, CDOM absorption coefficients were found to be robust proxies for the concentration of DOM, whereas additional CDOM parameters such as spectral slopes (S) were found to be useful indicators of DOM quality along the flow path. In particular, the spectral slope ratio (SR) of CDOM demonstrated statistically significant differences between all four water types and tracked changes in the concentration of bioavailable DOC, suggesting that this parameter may be suitable for clearly discriminating shifts in organic matter characteristics among water types along the full flow-path continuum across this landscape. However, despite our observations of downstream shifts in DOM composition, we found a relatively constant proportion of DOC that was bioavailable ( ∼  3–6 % of total DOC) regardless of relative water residence time along the flow path. This may be a consequence of two potential scenarios allowing for continual processing of organic material within the system, namely (a) aquatic microorganisms are acclimating to a downstream shift in DOM composition and/or (b) photodegradation is continually generating labile DOM for continued microbial processing of DOM along the flow-path continuum. Without such processes, we would otherwise expect to see a declining fraction of bioavailable DOC downstream with increasing residence time of water in the system. With ongoing and future permafrost degradation, peat and yedoma deposits throughout the northeast Siberian region will become more hydrologically active, providing greater amounts of DOM to fluvial networks and ultimately to the Arctic Ocean. The ability to rapidly and comprehensively monitor shifts in the quantity and quality of DOM across the landscape is therefore critical for understanding potential future feedbacks within the Arctic carbon cycle.

Residence Time in Hyporheic Bioactive Layers Explains Nitrate Uptake in Streams

2020 ◽  
Author(s):  
Angang Li ◽  
Susana Bernal ◽  
Brady Kohler ◽  
Steven A. Thomas ◽  
Eugènia Martí ◽  
...  
Keyword(s):  
Residence Time ◽  
Nitrate Uptake

Modeling the Effect of Flow Structures on Canal System Residence Time

2008 ◽  
Author(s):  
N. P. Benfer ◽  
B. A. King ◽  
C. J. Lemckert ◽  
S. Zigic
Keyword(s):  
Residence Time ◽  
Flow Structures ◽  
Canal System
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