Using stable isotopes of dissolved oxygen for the determination of gas exchange in the Grand River, Ontario, Canada.

Gas exchange can be a key component of the dissolved oxygen (DO) mass balance in aquatic ecosystems. Quantification of gas transfer rates is essential for the estimation of DO production and consumption rates, and determination of assimilation capacities of systems receiving organic inputs. Currently, the accurate determination of gas transfer rate is a topic of debate in DO modeling, and there are a wide variety of approaches that have been proposed in the literature. The current study investigates the use of repeated measures of stable isotopes of O₂ and DO and a dynamic dual mass-balance model to quantify gas transfer coefficients (k) in the Grand River, Ontario, Canada. Measurements were conducted over a longitudinal gradient that reflected watershed changes from agricultural to urban. Values of k in the Grand River ranged from 3.6 to 8.6 day⁻¹, over discharges ranging from 5.6 to 22.4 m³ s⁻¹, with one high-flow event of 73.1 m³ s⁻¹. The k values were relatively constant over the range of discharge conditions studied. The range in discharge observed in this study is generally representative of non-storm and summer low-flow events; a greater range in k might be observed under a wider range of hydrologic conditions. Overall, k values obtained with the dual model for the Grand River were found to be lower than predicted by the traditional approaches evaluated, highlighting the importance of determining site-specific values of k. The dual mass balance approach provides a more constrained estimate of k than using DO only, and is applicable to large rivers where other approaches would be difficult to use. The addition of an isotopic mass balance provides for a corroboration of the input parameter estimates between the two balances. Constraining the range of potential input values allows for a direct estimate of k in large, productive systems where other k-estimation approaches may be uncertain or logistically infeasible.

[1]  S. Chapra.  Surface Water-Quality Modeling , 1996 .

[2]  R. Wilcock.  Study of River Reaeration at Different Flow Rates , 1988 .

[3]  C Neal,et al.  Temporal and small-scale spatial variations of dissolved oxygen in the Rivers Thames, Pang and Kennet, UK. , 2000, The Science of the total environment.

[4]  D. Wilbur,et al.  Kinetic isotopic fractionation during air‐water gas transfer of O2, N2, CH4, and H2 , 1992 .

[5]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[6]  G. McBride,et al.  Characterisation of lowland streams using a single‐station diurnal curve analysis model with continuous monitoring data for dissolved oxygen and temperature , 1998 .

[7]  H. Craig,et al.  Atmospheric Oxygen: Isotopic Composition and Solubility Fractionation , 1972, Science.

[8]  T. Jamieson.  Quantification of Oxygen Dynamics in the Grand River Using a Stable Isotope Approach , 2010 .

[9]  J. C. Goldman,et al.  Isotopic fractionation of oxygen by respiring marine organisms , 1993 .

[10]  R. A. Buckingham,et al.  The prediction of stream reaeration rates , 1962 .

[11]  S. Schiff,et al.  Aquatic community metabolism response to municipal effluent inputs in rivers quantified using diel δ18O values of dissolved oxygen , 2010 .

[12]  P. Servais,et al.  Annual cycle of gross primary production and respiration in the Viroin River (Belgium) , 1984, Hydrobiologia.

[13]  Donald J. O'Connor,et al.  Mechanism of Reaeration in Natural Streams , 1958 .

[14]  D. Wilbur,et al.  The δ18O of dissolved O2 in the surface waters of the subarctic Pacific: A tracer of biological productivity , 1993 .

[15]  P. V. Danckwerts.  Significance of Liquid-Film Coefficients in Gas Absorption , 1951 .

[16]  Richard D. Pomeroy,et al.  Oxygen Absorption in Streams , 1972 .

[17]  A. B. Sullivan,et al.  Assessment of diel chemical and isotopic techniques to investigate biogeochemical cycles in the upper Klamath River, Oregon, USA , 2010 .

[18]  Bruce B. Benson,et al.  The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere1 , 1984 .

[19]  J. Clark,et al.  GAS EXCHANGE IN A CONTAMINATED ESTUARY INFERRED FROM CHLOROFLUOROCARBONS , 1992 .

[20]  Xue-feng Wang,et al.  Respiration-photosynthesis balance of terrestrial aquatic ecosystems, Ottawa area, Canada , 2000 .

[21]  Steven C. Chapra,et al.  Closure of "Delta Method for Estimating Primary Production, Respiration, and Reaeration in Streams" , 1991 .

[22]  N. Crossland,et al.  Measurement of community photosynthesis and respiration in outdoor artificial streams , 1996 .

[23]  R. Rathbun,et al.  Reaeration Coefficients of Streams—State-of-the-Art , 1977 .

[24]  J. Bicudo,et al.  Closure of "Measurement of Reaeration in Streams: Comparison of Techniques" , 1989 .

[25]  J. Böhlke,et al.  The oxygen‐18 isotope approach for measuring aquatic metabolism in high productivity waters , 2007 .

[26]  J. Berry,et al.  Photosynthetic Fractionation of the Stable Isotopes of Oxygen and Carbon , 1993, Plant physiology.

[27]  J. Bennett,et al.  Reaeration in open-channel flow , 1972 .

[28]  B. Forsberg,et al.  The 18O:16O of dissolved oxygen in rivers and lakes in the Amazon Basin: Determining the ratio of respiration to photosynthesis rates in freshwaters , 1995 .

[29]  R. French.  Open Channel Hydraulics , 1985 .

[30]  Harold F. Hemond,et al.  Determination of gas exchange rate constants for a small stream on Walker Branch Watershed, Tennessee , 1992 .

[31]  M. Owens,et al.  SOME REAERATION STUDIES IN STREAMS. , 1964, Air and water pollution.

[32]  J. Meyer,et al.  Metabolism of a sub-tropical low gradient black water river , 1987 .

[33]  S. Schiff,et al.  Dynamics of dissolved oxygen isotopic ratios: a transient model to quantify primary production, community respiration, and air–water exchange in aquatic ecosystems , 2007, Oecologia.

[34]  J. Elwood,et al.  Gas exchange rates for a first‐order stream determined with deliberate and natural tracers , 1990 .

[35]  R. Weiss.  The solubility of nitrogen, oxygen and argon in water and seawater , 1970 .

[36]  L. Wassenaar,et al.  An On-Line Technique for the Determination of the δ(18)O and δ(17)O of Gaseous and Dissolved Oxygen. , 1999, Analytical chemistry.

[37]  S. R. Parker,et al.  Biogeochemical controls on Diel cycling of stable isotopes of dissolved O2 and dissolved inorganic carbon in the Big Hole River, Montana. , 2005, Environmental science & technology.

[38]  C. Melching,et al.  Reaeration equations derived from U.S. geological survey database , 1999 .