Measurement of the diffusion coefficients of sparingly soluble gases in water

Jähne, Bernd; Heinz, Gerhard; Dietrich, Wolfgang

doi:10.1029/jc092ic10p10767

Cited by 757 publications

(563 citation statements)

References 25 publications

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“…k was calculated from k 600 for low wind speeds (Equation 4) (Cole and Caraco, 1998) and from Schmidt numbers ratio (Equation 5) (Jähne et al, 1987): (4)…”

Section: Sampling and Calculationsmentioning

confidence: 99%

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Reis

Barbosa

2014

Braz. J. Biol.

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It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO 2 because they receive allochthonous carbon inputs. However, autotrophy and CO 2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO 2 and CO 2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO 2 and CO 2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO 2 dynamics in tropical lakes. Net heterotrophy and CO 2 outgassing from the lake were registered only at night, while significant CO 2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO 2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO 2 emissions from tropical lakes.Keywords: pCO 2 , CO 2 flux, diurnal variations, tropical productive lake.Amostragem diurna demonstra variação significativa na emissão de CO 2 em um lago tropical produtivo Resumo É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO 2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO 2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO 2 e no fluxo de CO 2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO 2 quanto o fluxo de CO 2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO 2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO 2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO 2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO 2 por lagos tropicais.Palavras-chave: pCO 2 , fluxo de CO 2 , variações diurnas, lago tropical produtivo.

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“…k was calculated from k 600 for low wind speeds (Equation 4) (Cole and Caraco, 1998) and from Schmidt numbers ratio (Equation 5) (Jähne et al, 1987): (4)…”

Section: Sampling and Calculationsmentioning

confidence: 99%

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Reis

Barbosa

2014

Braz. J. Biol.

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“…6CO 2 + 6H 2 O, then O 2 will be consumed and CO 2 produced at equal molar rates. If gases are regulated solely by in-stream processes then the concentration of CO 2 can be calculated from oxygen as [CO 2 [Jähne et al, 1987], respectively, and n as 0.7 [Genereux and Hemond, 1992]. To account for variation in oxygen saturation due to elevation and atmosphere pressure effects, CO 2 concentration was calculated with oxygen saturation at sea level and 1000 m (315 mM and 275 mM at 15°C, respectively).…”

Section: Chemical Analysesmentioning

confidence: 99%

Long‐term decline in carbon dioxide supersaturation in rivers across the contiguous United States

Jones

Stanley

Mulholland

2003

Geophysical Research Letters

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[1] The partial pressure CO 2 ( pCO 2 ) in streams and rivers reflects both internal carbon dynamics and external biogeochemical processes in terrestrial ecosystems. CO 2 is typically supersaturated in streams because rates of organic matter decomposition exceed photosynthetic uptake, and because of inflow of CO 2 supersaturated ground waters. Using the U.S. Geological Survey's NASQAN database, we calculated pCO 2 and dissolved inorganic carbon (DIC) concentration in 417 streams and rivers distributed across the contiguous United States over a 22-year period. In addition to demonstrating widespread supersaturation and distinct regional variation in pCO 2 across the U.S., our analysis revealed that pCO 2 significantly declined 78.4 ppmv y À1 from 1973 to 1994. This decline is not attributable to changes in terrestrial weathering or instream processes, but instead suggests large-scale declines in terrestrial CO 2 production and import into aquatic ecosystems during this 22-year period.

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“…With the tortuosity of the clay unknown, the approximation of D e % q 2 D o was applied. Values of the free-solution diffusion coefficient (D o ) at 5°C and 15°C are 5.10 Â 10 À5 cm 2 s À1 (0.16 m 2 yr À1 ) and 6.30 Â 10 À5 cm 2 s À1 (0.20 m 2 yr À1 ), respectively [Jähne et al, 1987]. A 4 He effective diffusion coefficient (D e ) of 0.01 -0.02 m 2 yr À1 was estimated for the till.…”

Section: Steady State Modelmentioning

confidence: 99%

Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario

Sheldon

Solomon

Poreda

et al. 2003

Water Resources Research

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[1] Profiles of 4 He in pore water were measured in clay aquitards in SW Ontario. The 4 He distributions are consistent with groundwater velocities that are <6 mm yr À1 , and thus diffusion is the dominant transport mechanism for 4 He. Modeling indicates that the effective diffusion coefficient for 4 He is 6.3 ± 1.6 Â 10 À6 cm 2 s À1 . Furthermore, the profiles are consistent with the internal release of 4 He from aquitard sediments at a rate of 0.03-0.13 mcc(STP) kg À1 yr À1 . These rates are also consistent with laboratory release experiments and, on average, are 600 times greater than the production of 4 He from U/Th decay. Modeling and the ratio of 21 Ne to 4 He within the sediments indicate that although the aquitards were deposited about 13 kA BP, the sediments released >70% of initial 4 He for 50 to 60 kA prior to incorporation into the till.

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Measurement of the diffusion coefficients of sparingly soluble gases in water

Cited by 757 publications

References 25 publications

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Long‐term decline in carbon dioxide supersaturation in rivers across the contiguous United States

Radiogenic helium in shallow groundwater within a clay till, southwestern Ontario

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