, Volume 109, Issue 1–3, pp 233–252 | Cite as

Sediment-water fluxes of dissolved inorganic carbon, O2, nutrients, and N2 from the hypoxic region of the Louisiana continental shelf

  • John C. LehrterEmail author
  • David L. BeddickJr.
  • Richard Devereux
  • Diane F. Yates
  • Michael C. Murrell


Globally, hypoxic areas (<63 mmol O2 m−3) in coastal waters are increasing in number and spatial extent. One of the largest coastal hypoxic regions has been observed during the summer in the bottom-water of the Louisiana continental shelf. The shelf receives the sediments, organic matter, and nutrients exported from the Mississippi River watershed, and much of this material is ultimately deposited to the sea floor. Hence, quantifying the rates of sediment-water dissolved inorganic carbon (DIC), oxygen (O2), and nutrient fluxes is important for understanding how these processes relate to the development and maintenance of hypoxia. In this study, the sediment-water fluxes of DIC, O2, nutrients, and N2 (denitrification) were measured on the Louisiana shelf during six cruises from 2005 to 2007. On each cruise, three to four sites were occupied in or directly adjacent to the region of the shelf that experiences hypoxia. DIC fluxes, a proxy for total sediment respiration, ranged from 7.9 to 21.4 mmol m−2 day−1 but did not vary significantly either spatially or as a function of bottom-water O2 concentration. Overall, sediment respiration and nutrient flux rates were small in comparison to water-column respiration and phytoplankton nutrient demand. Nitrate fluxes were correlated with bottom-water O2 concentrations (r = 0.69), and there was evidence that decreasing O2 concentrations inhibited coupled nitrification-denitrification. Denitrification rates averaged 1.4 mmol N m−2 day−1. Scaled to the area of the shelf, the denitrification sink represented approximately 39% of the N load from the Mississippi River watershed. The sediment-water fluxes reported from this study add substantial information on the spatial and temporal patterns in carbon, O2, and nutrient cycling available for the Louisiana continental shelf and, thus, improve the understanding of this system.


Sediment-water DIC O2 and nutrient flux Denitrification Hypoxia LOUISIANA shelf 



We thank A. Almario, J. Aukamp, M. Barron, J. Campbell, G. Craven, L. Oliver, R. Quarles, J. Scott, and R. Stanley for assistance in the collection and analysis of sediment samples. We thank J. Cornwell and M. Owens for analyzing N2, O2, and Ar samples from several of the early cruises. We thank the US EPA Office of Water and Gulf of Mexico Program Office for their support of ship time, and the crews of the OSV Bold and the R/V Longhorn which made this work possible. We thank C. Peacher, P. Caraballo, D. Bullock, and the facilties’ staff for designing and building the sediment incubation systems, and for all the other facilities support for this work. Critical reviews by R. Greene, W. Gardner, J. Melack and three anonymous reviewers greatly improved this manuscript. We dedicate this contribution to the memory of our friend and EPA colleague R.L. Quarles. This study was funded, reviewed, and approved for publication by the US EPA, National Health and Environmental Effects Research Laboratory; however, the contents are solely the views of the authors. Use of trade names or commercial products does not constitute endorsement by the US EPA. Contribution number 1373 from the US EPA, Gulf Ecology Division.


  1. Aller JY, Aller RC (1986) Evidence for localized enhancement of biological activity associated with tube and burrow structures in deep-sea sediment at the HEBBLE site, western North Atlantic. Deep-Sea Res I 33:755–790CrossRefGoogle Scholar
  2. Aller RC, Blair NE, Xia Q, Rude PD (1996) Remineralization rates, recycling, and storage of carbon in Amazon shelf sediments. Cont Shelf Res 16:753–786CrossRefGoogle Scholar
  3. American Public Health Association (APHA) (1989) Standard methods for the examination of water and wastewater, 17th Edition. American Public Health Association. Washington, D.CGoogle Scholar
  4. Aspila KI, Agemain H, Chau ASY (1976) A semi-automated method for the determination of inorganic and total phosphate in sediments. Analyst 101:187–197CrossRefGoogle Scholar
  5. Aulenbach BT, Buxton HT, Battaglin WT, Coupe RH (2007) Streamflow and nutrient fluxes of the Mississippi-Atchafalaya River Basin and subbasins for the period of record through 2005: U.S. Geological Survey Open-File Report 2007–1080Google Scholar
  6. Bianchi TS, DiMarco SF, Cowan JH, Hetland RD, Chapman P, Day JW, Allison MA (2010) The science of hypoxia in the Northern Gulf of Mexico: a review. Sci Total Environ 408:1471–1484CrossRefGoogle Scholar
  7. Bouldin DR (1968) Models for describing the diffusion of oxygen and other mobile constituents across the mud-water interface. J Ecol 56:77–87CrossRefGoogle Scholar
  8. Cai W-J, Sayles FL (1996) Oxygen penetration depths and fluxes in marine sediments. Mar Chem 52:123–131CrossRefGoogle Scholar
  9. Childs CR, Rabalais NN, Turner RE, Proctor LM (2002) Sediment denitrification in the Gulf of Mexico zone of hypoxia. Mar Ecol Prog Ser 240:285–290CrossRefGoogle Scholar
  10. Cook PLM, Wenzöfer F, Glud RN, Huettel M (2007) Benthic solute exchange and carbon mineralization in two shallow subtidal sandy sediments: impact of advective porewater exchange. Limnol Oceanogr 52:1943–1963CrossRefGoogle Scholar
  11. Cowan JLW, Boynton WR (1996) Sediment-water oxygen and nutrient exchanges along the longitudinal axis of Chesapeake Bay: seasonal patterns, controlling factors and ecological significance. Estuaries 19:562–580CrossRefGoogle Scholar
  12. Dagg MJ, Ammerman JW, Amon RMW, Gardner WS, Green RE, Lohrenz SE (2007) A review of water column processes influencing hypoxia in the northern Gulf of Mexico. Estuar Coasts 30:735–752Google Scholar
  13. Dale VH, Kling CL, Meyer JL, Sanders J, Stallworth H, Armitage T, Wangsness D, Bianchi TS, Blumberg A, Boynton W (2010) Hypoxia in the Northern Gulf of Mexico. Springer-Verlag Inc, New YorkCrossRefGoogle Scholar
  14. Deutsch B, Forster S, Wilhelm M, Dippner JW, Voss M (2010) Denitrification in sediments as a major sink in the Baltic Sea: an extrapolation using sediment characteristics. Biogeosciences 7:3259–3271CrossRefGoogle Scholar
  15. Devol AH, Christensen JP (1993) Benthic fluxes and nitrogen cycling in sediments of the continental margin of the eastern North Pacific. J Mar Res 51:345–372CrossRefGoogle Scholar
  16. Devol AH, Codispoti LA, Christensen JP (1997) Summer and winter denitrification rates in western arctic shelf sediments. Cont Shelf Res 17:1029–1050CrossRefGoogle Scholar
  17. Diaz RJ, Rosenberg R (2008) Spreading dead zones and the consequences for marine ecosystems. Science 321:926–929CrossRefGoogle Scholar
  18. Dortch Q, Rabalais N, Turner RE, Rowe GT (1994) Respiration rates and hypoxia on the Louisiana shelf. Estuaries 17:862–872CrossRefGoogle Scholar
  19. Eldridge PM, Morse JW (2008) Origins and temporal scales of hypoxia on the Louisiana shelf: Importance of benthic and sub-pycnocline water metabolism. Mar Chem 108:159–171CrossRefGoogle Scholar
  20. Fennel K, Brady D, DiToro D, Fulweiler RW, Gardner WS, Giblin A, McCarthy MJ, Rao A, Seitzinger S, Thouvenot-Korppoo M, Tobias C (2009) Modeling denitrification in aquatic sediments. Biogeochemistry 93:159–178CrossRefGoogle Scholar
  21. Ferguson AJP, Eyre BD (2007) Seasonal discrepancies in denitrification measured by isotope pairing and N2:Ar techniques. Mar Ecol Prog Ser 350:19–27CrossRefGoogle Scholar
  22. Gardner WS, Escobar Briones E, Cruz Kaegi E, Rowe GT (1993) Ammonium excretion by benthic invertebrates and sediment-water nitrogen flux in the Gulf of Mexico near the Mississippi River outflow. Estuaries 16:799–808CrossRefGoogle Scholar
  23. Glud RN (2008) Oxygen dynamics of marine sediments. Marine Biology Research 4:243–289CrossRefGoogle Scholar
  24. Glud RN, Blackburn N (2002) The effects of chamber size on benthic oxygen uptake measurements: a simulation study. Ophelia 56:23–31Google Scholar
  25. Glud RN, Berg P, Fossing H, Jørgensen BB (2007) Effect of the diffusive boundary layer (DBL) on the benthic mineralization of O2 distribution: a theoretical modeling exercise. Limnol Oceanogr 52:547–557CrossRefGoogle Scholar
  26. Goñi MA, Gordon ES, Monacci NM, Clinton R, Gisewhite R, Allison MA, Kineke G (2006) The effect of Hurricane Lili on the distribution of organic matter along the inner Louisiana shelf (Gulf of Mexico, USA). Cont Shelf Res 26:2260–2280CrossRefGoogle Scholar
  27. Green RE, Bianchi T, Dagg MJ, Walker ND, Breed GA (2006) An organic carbon budget for the Mississippi River turbidity plume and plume contributions to air-sea CO2 fluxes and bottom water hypoxia. Estuar Coasts 29:579–597Google Scholar
  28. Greene RM, Lehrter JC, Hagy JD (2009) Multiple regression models for hindcasting and forecasting midsummer hypoxia in the Gulf of Mexico. Ecol Appl 19:1161–1175CrossRefGoogle Scholar
  29. Holmes RM, Aminot A, Kerouel R, Hooker B, Peterson BJ (1999) A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Can J Fish Aquat Sci 56:1801–1808Google Scholar
  30. Hopkinson CS Jr, Smith EM (2005) Estuarine respiration: an overview of benthic, pelagic. and whole system respiration. Oxford University Press, OxfordGoogle Scholar
  31. Huettel M, Webster IT (2001) Porewater flow in permeable sediments. In: Boudreau B, Jörgensen BB (eds) The Benthic boundary bayer. New York, Oxford University Press, pp 144–179Google Scholar
  32. Jørgensen BB (1982) Mineralization of organic matter in the sea bed—the role of sulfate reduction. Nature 296:643–645CrossRefGoogle Scholar
  33. Kana TM, Darkangelo C, Hunt MD, Oldham JB, Bennett GE, Cornwell JC (1994) Membrane inlet mass spectrometer for rapid high-precision determination of N2, O2, and Ar in environmental water samples. Anal Chem 66:4166–4170CrossRefGoogle Scholar
  34. Laursen AE, Seitzinger SP (2002) The role of denitrification in nitrogen removal and carbon mineralization in Mid-Atlantic Bight sediments. Cont Shelf Res 22:1397–1416CrossRefGoogle Scholar
  35. Lehrter JC, Murrell MC, Kurtz JC (2009) Interactions between freshwater input, light, and phytoplankton dynamics on the Louisiana continental shelf. Cont Shelf Res 29:1861–1872CrossRefGoogle Scholar
  36. McCarthy MJ, McNeal KS, Morse JW, Gardner WS (2008) Bottom water hypoxia effects on sediment-water interface nitrogen transformations is a seasonally hypoxic, shallow bay (Corpus Christi Bay, TX, USA). Estuar Coasts 31:521–531CrossRefGoogle Scholar
  37. Middelburg JJ, Levin LA (2009) Coastal hypoxia and sediment biogeochemistry. Biogeosciences 6:1273–1293CrossRefGoogle Scholar
  38. Middelburg JJ, Soetart K, Herman PMJ, Heip C (1996) Denitrification in marine sediments: a model study. Global Biogeochem Cycles 10:661–673CrossRefGoogle Scholar
  39. Miller-Way T, Boland GS, Rowe GT, Twilley RR (1994) Sediment oxygen consumption and benthic nutrient fluxes on the Louisiana continental shelf: a methodological comparison. Estuaries 17:809–815CrossRefGoogle Scholar
  40. Morse JW, Rowe GT (1999) Benthic biogeochemistry beneath the Mississippi River plume. Estuaries 22:206–214CrossRefGoogle Scholar
  41. Murrell MC, Lehrter JC (2011) Sediment and lower water-column respiration in the seasonal hypoxic region of the Louisiana continental shelf. Estuar Coasts. doi:  10.1007/s12237-010-9351-9
  42. Nielsen LP (1992) Denitrifcation in sediments determined from nitrogen isotope pairing. FEMS Microbiol Ecol 86:357–362CrossRefGoogle Scholar
  43. Nowicki BL, Requintina E, van Keuren D, Kelly JR (1997) Nitrogen losses through sediment denitrification in Boston Harbor and Massachusetts Bay. Estuaries 20:626–639CrossRefGoogle Scholar
  44. Pelegri S, Nielsen LP, Blackburn TH (1994) Denitrification in estuarine sediment stimulated by the irrigation activity of the amphipod Corphium volutator. Mar Ecol Prog Ser 105:285–290CrossRefGoogle Scholar
  45. Quiñones-Rivera Z, Wissel B, Justic D, Fry B (2007) Partitioning oxygen sources and sinks in a stratified, eutrophic coastal ecosystem using stable oxygen isotopes. Mar Ecol Prog Ser 342:69–83CrossRefGoogle Scholar
  46. Rabalais NN, Turner RE, Scavia D (2002) Beyond science into policy: Gulf of Mexico hypoxia and the Mississippi River. Bioscience 52:129–142CrossRefGoogle Scholar
  47. Rabalais NN, Turner RE, Gupta BK, Boesch DF, Chapman P, Murrell MC (2007) Hypoxia in the northern Gulf of Mexico: does the science support the plan to reduce, mitigate, and control hypoxia? Estuar Coasts 30:753–772Google Scholar
  48. Roden EE, Edmonds JW (1997) Phosphate mobilization in iron-rich anaerobic sediments: microbial Fe(III) oxide reduction vs. iron-sulfide formation. Archiv für Hydrobiol 139:347–378Google Scholar
  49. Rowe GT, Chapman P (2002) Continental shelf hypoxia: some nagging questions. Gulf Mexico Sci 2:153–160Google Scholar
  50. Rowe GT, Cruz Kaegi ME, Morse JW, Boland GS, Escobar Briones EG (2002) Sediment community metabolism associated with continental shelf hypoxia, northern Gulf of Mexico. Estuaries 25:1106–1907CrossRefGoogle Scholar
  51. Røy H, Hüttel M, Jørgensen BB (2005) The influence of topography on the functional exchange surface of marine soft sediments, assessed from sediment topography measured in situ. Limnol Oceanogr 50:106–112CrossRefGoogle Scholar
  52. Sampere TP, Bianchi TS, Wakeham SG, Allison MA (2008) Sources of organic matter in surface sediments of the Louisiana Continental margin: effects of major depositional/transport pathways and Hurricane Ivan. Cont Shelf Res 28:2472–2487CrossRefGoogle Scholar
  53. Sampou P, Oviatt CA (1991) A carbon budget for a eutrophic marine ecosystem and the role of sulfur metabolism in sedimentary carbon, oxygen and energy dynamics. J Mar Res 49:825–844CrossRefGoogle Scholar
  54. Seitzinger S, Harrison JA, Bohlke JK, Bouwman AF, Lowrance R, Peterson B, Tobias C, Van Drecht G (2006) Denitrification across landscapes and waterscapes: a synthesis. Ecol Appl 16:2064–2090CrossRefGoogle Scholar
  55. Trimmer M, Nicholls JC (2009) Production of nitrogen gas via anammox and denitrification in intact sediment cores along a continental shelf to slope transect in the North Atlantic. Limnol Oceanogr 54:577–589CrossRefGoogle Scholar
  56. Walker ND, Hammack AB (2000) Impacts of winter storms on circulation and sediment transport: Atchafalaya-Vermilion Bay region, Louisiana, USA. J Coastal Res 16:996–1010Google Scholar
  57. Welschmeyer NA (1994) Fluormetric analysis of chlorophyll a in the presence of chlorophyll b and phaeopigments. Limnol Oceanogr 39:1985–1992CrossRefGoogle Scholar
  58. Wiseman WJ, Rabalais NN, Turner RE, Dinnel SP, MacNaughton A (1997) Seasonal and interannual variability within the Louisiana coastal current: stratification and hypoxia. J Mar Syst 12:237–248CrossRefGoogle Scholar

Copyright information

© Society of Wetland Scientists (outside the USA) 2011

Authors and Affiliations

  • John C. Lehrter
    • 1
    Email author
  • David L. BeddickJr.
    • 1
  • Richard Devereux
    • 1
  • Diane F. Yates
    • 1
  • Michael C. Murrell
    • 1
  1. 1.Gulf Ecology DivisionUS EPA, NHEERLGulf BreezeUSA

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