Estuaries and Coasts

, Volume 30, Issue 5, pp 773–790 | Cite as

Characterization of nutrient, organic carbon, and sediment loads and concentrations from the Mississippi River into the northern Gulf of Mexico

  • R. E. Turner
  • N. N. Rabalais
  • R. B. Alexander
  • G. McIsaac
  • R. W. Howarth
Article

Abstract

We synthesize and update the science supporting the Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi River/Gulf of Mexico Watershed Nutrient Task Force 2001) with a focus on the spatial and temporal discharge and patterns of nutrient and organic carbon delivery to the northern Gulf of Mexico, including data through 2006. The discharge of the Mississippi River watershed over 200 years varies but is not demonstrably increasing or decreasing. About 30% of the Mississippi River was shunted westward to form the Atchafalaya River, which redistributed water and nutrient loads on the shelf. Data on nitrogen concentrations from the early 1900s demonstrate that the seasonal and annual concentrations in the lower river have increased considerably since then, including a higher spring loading, following the increase in fertilizer applications after World WarII. The loading of total nitrogen (TN) fell from 1990 to 2006, but the loading of total phosphorus (TP) has risen slightly, resulting in a decline in the TN:TP ratios. The present TN:TP ratios hover around an average indicative of potential nitrogen limitation on phytoplankton growth, or balanced growth limitation, but not phosphorus limitation. The dissolved nitrogen:dissolved silicate ratios are near the Redfield ratio indicative of growth limitations on diatoms. Although nutrient concentrations are relatively high compared to those in many other large rivers, the water quality in the Mississippi River is not unique in that nutrient loads can be described by a variety of land-use models. There is no net removal of nitrogen from water flowing through the Atchafalaya basin, but the concentrations of TP and suspended sediments are lower at the exit point (Morgan City, Louisiana) than in the water entering the Atchafalaya basin. The removal of nutrients entering offshore waters through diversion of river water into wetlands is presently less than 1% of the total loadings going directly offshore, and would be less than 8% if the 10,093 km2 of coastal wetlands were successfully engineered for that purpose. Wetland loss is an insignificant contribution to the carbon loading offshore, compared to in situ marine production. The science-based conclusions in the Action Plan about nutrient loads and sources to the hypoxic zone off Louisiana are sustained by research and monitoring occurring in the subsequent 10 years.

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Literature Cited

  1. Alexander, R. B. andR. A. Smith. 2006. Trends in the nutrient enrichment of U.S. rivers during the late 20th century and their relation to changes in probable stream trophic conditions.Limnology and Oceanography 51:639–654.Google Scholar
  2. Alexander, R. B., R. A. Smith, andG. E. Schwarz. 2000. Effect of stream channel size on the delivery of nitrogen to the Gulf of Mexico.Nature 403:758–761.CrossRefGoogle Scholar
  3. Arbuckle, K. E. andJ. A. Downing. 2001. The influence of watershed land use on lake N:P in a predominantly agricultural landscape.Limnology and Oceanography 46:970–975.Google Scholar
  4. Aulenbach, B. T., H. T. Buxton, W. A. Battaglin, and R. H. Coupe. 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 2007-1080. Denver, Colorado, (http://toxics.usgs.gov/pubs/of-2007-1080).Google Scholar
  5. Baumann, R. H. andR. E. Turner. 1990. Direct impacts of outer continental shelf activities on wetland loss in the central Gulf of Mexico.Environmental Geology and Water Resources 15:189–198.CrossRefGoogle Scholar
  6. Benner, R. andS. Opsahl. 2001. Molecular indicators of the sources and transformations of dissolved organic matter in the Mississippi River plume.Organic Geochemistry 32:597–611.CrossRefGoogle Scholar
  7. Bianchi, T. S., T. Filley, K. Dria, andP. G. Hatcher. 2004. Temporal variability in sources of dissolved organic carbon in the lower Mississippi River.Geochimica et Cosmochimica Acta 68: 959–967.CrossRefGoogle Scholar
  8. Bianchi, T. S., S. Mitra, andB. A. McKee. 2002. Sources of terrestrially-derived organic carbon in lower Mississippi River and Louisiana shelf sediments. Implications for differential sedimentation and transport at the coastal margin.Marine Chemistry 77:211–223.CrossRefGoogle Scholar
  9. Boyer, E. W., C. L. Goodale, N. A. Jaworski, andR. W. Howarth. 2002. Anthropogenic nitrogen sources and relationships to riverine nitrogen export in the northeastern USA.Biogeochemistry 57:137–169.CrossRefGoogle Scholar
  10. Caraco, N. F. 1995. Influence of human populations on P transfers to aquatic systems: A regional scale study using large rivers, p. 235–247.In H. Tiessen (ed.), Phosphorus in the Global Environment. SCOPE 54. John Wiley and Sons Ltd., New York.Google Scholar
  11. Caraco, N. F. andJ. J. Cole. 1999. Human impact on nitrate export: An analysis using major world rivers.Ambio 28:167–170.Google Scholar
  12. Cohn, T. A., D. L. Caulder, E. J. Gilroy, L. D. Zynjuk, andR. M. Summers. 1992. The validity of a simple statistical model for estimating fluvial constituent loads: An empirical study involving nutrient loads entering Chesapeake Bay.Water Resources Research 28:2353–2363.CrossRefGoogle Scholar
  13. Curtis, W. F., J. K. Culbertson, and E. B. Chase. 1973. Fluvialsediment discharge to the oceans from the conterminous United States. U.S. Geological Survey Circular 670. Washington, D.C.Google Scholar
  14. Dagg, M. J., T. S. Bianchi, G. Breed, W. Cai, S. Duan, H. Liu, B. A. McKee, R. T. Powell, andC. M. Stewart. 2005. Biogeochemical characteristics of the lower Mississippi River USA during June 2003.Estuaries 28:664–674.Google Scholar
  15. Demas, C. andP. Curwick. 1988. Suspended sediment and associated chemical transport characteristics of the lower Mississippi River, Louisiana. Technical Report 45. Louisiana Department of Water Research, Baton Rouge, Louisiana.Google Scholar
  16. Dodds, W. K. 2003. Misuse of inorganic N and soluble reactive P concentrations to indicate nutrient status of surface water.Journal of the North American Benthological Society 22:171–181.CrossRefGoogle Scholar
  17. Dole, R. B. and H. Stabler. 1909. Denudation, p. 78–93.In Papers on the Conservation of Water Resources. U.S. Geological Survey Water-Supply Paper 234. Washington, D.C.Google Scholar
  18. Donner, S. D. 2003. The impact of cropland cover on river nutrient levels in the Mississippi River basin.Global Ecology and Biogeography 12:341–355.CrossRefGoogle Scholar
  19. Donner, S. D., M. T. Coe, J. D. Lenters, T. E. Twine, andJ. A. Foley. 2002. Modeling the impact of hydrological changes on nitrate transport in the Mississippi River Basin from 1955 to 1994.Global Biogeochemical Cycles 16: 10.10292001GB001396.CrossRefGoogle Scholar
  20. Donner, S. D. andC. J. Kucharik. 2003a. Evaluating the impacts of land management and climate variability on crop production and nitrate export across the Upper Mississippi Basin.Global Biogeochemical Cycles 17:1043, doi:10.1029/2001GB001396.CrossRefGoogle Scholar
  21. Donner, S. D. and C. J. Kucharik. 2003b. The distribution of the primary crops in the U.S. since 1950 and the relationship to river nutrient levels.Global Biogeochemical Cycles 17: 10.1029/ 2001GB1808.Google Scholar
  22. Dortch, Q., N. N. Rabalais, R. E. Turner, andN. A. Qureshi. 2001. Impacts of changing Si/N ratios and phytoplankton species composition, p. 37–48.In N. N. Rabalais and R. E. Turner (eds.), Coastal Hypoxia: Consequences for living resources and ecosystems, Volume 58. American Geophysical Union, Washington D.C.Google Scholar
  23. Duan, S. andT. S. Bianchi. 2006. Seasonal changes in the abundance and composition of plant pigments in particulate organic carbon in the lower Mississippi and Pearl Rivers.Estuaries and Coasts 29:427–442.Google Scholar
  24. Dunn, D. D. 1996. Trends in Nutrient Inflows to the Gulf of Mexico from Streams Draining the Conterminous United States 1972–1993. U.S. Geological Survey, Water-Resources Investigations Report 96-4113. Prepared in cooperation with the U.S. Environmental Protection Agency, Gulf of Mexico Program, Nutrient Enrichment Issue Committee, U.S. Geological Survey, Austin, Texas.Google Scholar
  25. Fisk, H. N. 1952. Geological investigation of the Atchafalaya basin and the problems of Mississippi River diversion. Volume 1. U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, Mississippi.Google Scholar
  26. Gedney, N., P. M. Cox, R. A. Betts, O. Boucher, C. Huntingford, andP. A. Stott. 2006. Detection of a direct carbon dioxide effect in continental river runoff records.Nature 439:835–838.CrossRefGoogle Scholar
  27. Goni, M. A., K. C. Ruttenberg, andT. I. Eglinton. 1997. Sources and contribution of terrigenous organic matter to surface sediments in the Gulf of Mexico.Nature 289:275–278.CrossRefGoogle Scholar
  28. Goni, M. A., K. C. Ruttenberg, andT. I. Eglinton. 1998. A reassessment of the sources and importance of land-derived organic matter in surface sediments from the Gulf of Mexico.Geochimica et Cosmochimica Acta 62:3055–3075.CrossRefGoogle Scholar
  29. Goolsby, D. A., W. A. Battaglin, B. T. Aulenbach, andR. P. Hooper. 2000. Nitrogen flux and sources in the Mississippi River.Science of the Total Environment 248:75–86.CrossRefGoogle Scholar
  30. Goolsby, D. A., W. A. Battaglin, G. B. Lawrence, R. S. Artz, B. T. Aulenbach, R. P. Hooper, D. R. Keeney, andG. J. Stensland. 1999. Flux and sources of nutrients in the Mississippi-Atchafalaya River basin. Topic 3 Report of the Integrated Assessment on Hypoxia in the Gulf of Mexico. National Oceanic and Atmospheric Administration Coastal Ocean Program Decision Analysis Series Number 17. NOAA Coastal Ocean Program, Silver Spring, Maryland.Google Scholar
  31. Gordon, E. A. andM. A. Goni. 2003. Sources and distribution of terrigenous organic matter delivered by the Atchafalaya River to sediments in the northern Gulf of Mexico.Geochimica et Cosmochimica Acta 67:2359–2375.CrossRefGoogle Scholar
  32. Guildford, S. J. andR. E. Hecky. 2000. Total nitrogen, total phosphorus, and nutrient limitation in lakes and oceans: Is there a common relationship?Limnology and Oceanography 45: 1213–1223.Google Scholar
  33. Hooper, R. P., D. A. Goolsby, D. A. Rickert, and S. W. McKenzie. 1997. A river-basin perspective on monitoring water quality. U.S. Geological Survey Fact Sheet FS-055-97. Reston, Virginia.Google Scholar
  34. Horowitz, A. J. 2003. An evaluation of sediment rating curves for estimating suspended sediment concentrations in subsequent flux calculations.Hydrologic Processes 17:3387–3409.CrossRefGoogle Scholar
  35. Howarth, R. W. 1998. An assessment of human influences on fluxes of nitrogen from the terrestrial landscape to the estuaries and continental shelves of the Atlantic Ocean.Nutrient Cycling in Agroecosystems 51:213–223.CrossRefGoogle Scholar
  36. Howarth, R. W., G. Billen, D. Swaney, A. Townsend, N. Jaworski, K. Lajtha, J. A. Downing, R. Elmgren, N. Caraco, T. Jordan, F. Berendse, J. Freney, V. Kudeyarov, P. Murdoch, andZ. Zhao-Liang. 1996. Regional nitrogen budgets and riverine N & P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences.Biogeochemistry 35:75–139.CrossRefGoogle Scholar
  37. Howarth, R. W., E. W. Boyer, R. Marino, D. Swaney, N. Jaworski, andC. Goodale. 2006. The influence of climate on average nitrogen export from large watersheds in the northeastern United States.Biogeochemistry 79:163–186.CrossRefGoogle Scholar
  38. Jones, J. R., B. P. Borofka, andR. E. Bachmann. 1976. Factors affecting nutrient loads in some Iowa streams.Water Research 10: 117–122.CrossRefGoogle Scholar
  39. Jordan, T. E., D. L. Correll, andD. E. Weller. 1997. Relating nutrient discharges from watersheds to land use and streamflow variability.Water Resources Research 33:2579–2590.CrossRefGoogle Scholar
  40. Judson, S. andD. F. Ritter. 1964. Rates of denudation in the United States.Journal of Geophysical Research 69:3395–3401.CrossRefGoogle Scholar
  41. Justić, D., V. J. Bierman Jr.,D. Scavia, andR. Hetland. 2007. Forecasting Gulf’s Hypoxia: The next 50 years?Estuaries and Coasts 30:791–801.Google Scholar
  42. Justić, D., N. N. Rabalais, andR. E. Turner. 1995. Stoichiometric nutrient balance and origin of coastal eutrophication.Marine Pollution Bulletin 30:41–66.CrossRefGoogle Scholar
  43. Keown, M. P., E. A. Dardeau Jr., andE. M. Causey. 1986. Historic trends in the sediment flow regime of the Mississippi River.Water Resources Research 22:1555–1564.CrossRefGoogle Scholar
  44. Kesel, R. H. 1988. The decline in the suspended load of the lower Mississippi River and its influence on adjacent wetlands.Environmental Geology and Water Science 11:271–281.CrossRefGoogle Scholar
  45. Lurry, D. L. and D. D. Dunn. 1997. Trends in nutrient concentration and load for streams in the Mississippi River Basin, 1974–94. U.S. Geological Survey, Water-Resources Investigations Report 97-4223. Austin, Texas.Google Scholar
  46. Malcom, R. L. andW. H. Durum. 1976. Organic carbon and nitrogen concentrations and annual organic carbon load of six selected rivers of the United States. United States Geological Survey Water-Supply PAPER 1817-F. U.S. Government Printing Office, Washington, D.C.Google Scholar
  47. McCabe, G. J., M. A. Palecki, andJ. L. Betancourt. 2004. Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States.Proceedings of the National Academy of Sciences USA 101:4136–4141.CrossRefGoogle Scholar
  48. McCabe, G. J. and D. M. Wolock. 2002. A step increase in streamflow in the conterminous United States.Geophysical Research Letters 29: doi:10.1029/2002GL015999.Google Scholar
  49. McCoy, C., D. R. Corbett, B. A. McKee, andZ. Top. 2007. An evaluation of submarine groundwater discharge along the continental shelf of Louisiana using a multiple tracer approach.Journal of Geophysical Research —Oceans 112, C03013, doi: 10.1029/2006/2006JC003505.CrossRefGoogle Scholar
  50. McIsaac, G. F., M. B. David, G. Z. Gertner, andD. A. Goolsby. 2001. Eutrophication: Nitrate flux in the Mississippi River.Nature 414:166–167.CrossRefGoogle Scholar
  51. McIsaac, G. F., M. B. David, G. Z. Gertner, andD. A. Goolsby. 2002. Relating net nitrogen input in the Mississippi River basin to nitrate flux in the lower Mississippi River: A comparison of approaches.Journal of Environmental Quality 31:1610–1622.Google Scholar
  52. McIsaac, G. F. andX. Hu. 2004. Net N input and riverine N export from Illinois agricultural watersheds with and without extensive tile drainage.Biogeochemistry 70:251–271.CrossRefGoogle Scholar
  53. Meade, R. H. andR. S. Parker. 1985. Sediment in rivers of the United States, p. 49–60.In U.S. Geological Survey Water-Supply Paper 2275, National Water Summary 1984. U.S. Government Printing Office, Washington, D.C.Google Scholar
  54. Milliman, J. D. andR. H. Meade. 1983. World-wide delivery of river sediment to the oceans.Journal of Geology 91:1–21.CrossRefGoogle Scholar
  55. Mississippi River/Gulf of Mexico Watershed Nutrient Task Force. 2001. Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico. Office of Wetlands, Oceans, and Watersheds, U.S. Environmental Protection Agency, Washington, D.C.Google Scholar
  56. Mitsch, W. J., J. W. Day Jr.,J. W. Gilliam, P. M. Groffman, D. L. Hey, G. W. Randall, andN. Wang. 2001. Reducing nitrogen loading to the Gulf of Mexico from the Mississippi River Basin: Strategies to counter a persistent ecological problem.BioScience 51:373–388.CrossRefGoogle Scholar
  57. Morton, T. A., J. C. Bernier, J. A. Barras, andN. F. Ferina. 2005. Rapid subsidence and historical wetland loss in the Mississippi Delta Plain: Likely causes and future implications. U.S. Geological Survey Open-File Report 2005-1215. U.S. Government Printing Office, Washington, D.C.Google Scholar
  58. Mossa, J. 1996. Sediment dynamics in the lowermost Mississippi River.Engineering Geology 45:457–479.CrossRefGoogle Scholar
  59. Onstad, G. D., D. E. Canfield, P. D. Quay, andJ. L. Hedges. 2000. Sources of particulate organic matter in rivers from the continental USA: Lignin, phenol and stable carbon isotope compositions.Geochimica et Cosmochimica Acta 64:3539–3546.CrossRefGoogle Scholar
  60. Peierls, B., N. Caraco, M. Pace, andJ. Cole. 1991. Human influence on river nitrogen.Nature 350:386–387.CrossRefGoogle Scholar
  61. Perkins, B. D., K. Lohman, E. Van Nieuwenhuyse, andJ. R. Jones Jr. 1998. An examination of land cover and stream water quality among physiographic provinces of Missouri, U.S.A. Verh.International Vereinigung fur Limnologie 26:940–947.Google Scholar
  62. Poore, R. Z., J. Darling, H. J. Dowsett, and L. Wright. 2006. Variations in river flow to the Gulf of Mexico: Implications for paleoenvironmental studies of Gulf of Mexico marine sediments. U.S. Geological Survey, Reston, Virginia, http:// pubs.usgs.gov/bul/b2187/contents.html.Google Scholar
  63. Rabalais, N. N. and R. E. Turner (eds.). 2001. Coastal hypoxia: Consequences for living resources and ecosystems. Coastal and Estuarine Studies Volume 58. American Geophysical Union, Washington, D.C.Google Scholar
  64. Rabalais, N. N., R. E. Turner, andD. Scavia. 2002a. Beyond science into policy: Gulf of Mexico hypoxia and the Mississippi River.BioScience 52:129–142.CrossRefGoogle Scholar
  65. Rabalais, N. N., R. E. Turner, B. K. Sen Gupta, D. F. Boesch, P. Chapman, andM. C. Murrell. 2007. Hypoxia in the northern Gulf of Mexico: Does the science support the plan to reduce, mitigate, and control hypoxia?Estuaries and Coasts 30:753–772.Google Scholar
  66. Rabalais, N. N., R. E. Turner, andW. J. Wiseman Jr. 2002b. Hypoxia in the Gulf of Mexico, a.k.a. “The Dead Zone”.Annual Review of Ecology and Systematics 33:235–263.CrossRefGoogle Scholar
  67. Redfield, A. C. 1958. The biological control of chemical factors in the environment.American Scientist 46:205–222.Google Scholar
  68. Sklar, F. H. andR. E. Turner. 1981. Plankton production in the Louisiana coastal zone as influenced by the Mississippi River.Contributions in Marine Science 24:93–106.Google Scholar
  69. Smart, M. M., J. R. Jones, andJ. L. Sebaugh. 1985. Streamwatershed relations in the Missouri Ozark Plateau Province.Journal of Environmental Quality 14:77–82.CrossRefGoogle Scholar
  70. Smith, R. A., R. B. Alexander, and K. J. Lanfear. 1993. Stream water quality in the conterminous United States —Status and trends of selected indicators during the 1980s. USGS Water Supply Paper 2400, Washington, D.C.Google Scholar
  71. Smith, S. V., R. O. Sleezer, W. H. Renwick, andR. W. Buddemeier. 2005. Fates of eroded soil organic carbon: Mississippi Basin case study.Ecological Applications 15:1929–1940.CrossRefGoogle Scholar
  72. Soileau, C. W., B. J. Garrett, andB. J. Thibodeaux. 1989. Drought induced saltwater intrusion of the Mississippi River, p. 2823–2836.In O. T. Magoon (ed.), Proceedings of the 6th. Symposium on Coastal Zone Management. American Society of Civil Engineers, New York.Google Scholar
  73. Sparks, R. E., J. C. Nelson, andY. Yin. 1998. Naturalization of the flood regimes in natural rivers: The case of the upper Mississippi River.BioScience 48:706–720.CrossRefGoogle Scholar
  74. Sutula, M., T. S. Bianchi, andB. McKee. 2004. Effect of seasonal sediment storage in the lower Mississippi River on the flux of reactive particulate phosphorus to the Gulf of Mexico.Limnology and Oceanography 49:2223–2235.Google Scholar
  75. Trefry, J. H., S. Metz, R. P. Trogine, andB. J. Eadie. 1994. Transport of particulate organic carbon by the Mississippi River and its fate in the Gulf of Mexico.Estuaries 17:839–849.CrossRefGoogle Scholar
  76. Trimble, S. W. 1999. Decreased rates of alluvial sediment storage in the Coon Creek Basin, Wisconsin, 1975–93.Science 285:1244–1246.CrossRefGoogle Scholar
  77. Turner, R. E. 1997. Wetland loss in the northern Gulf of Mexico: Multiple working hypotheses.Estuaries 20:1–13.CrossRefGoogle Scholar
  78. Turner, R. E. 1999a. Inputs and outputs of the Gulf of Mexico, p. 64–73.In H. Kumpf, K Steidinger, and K. Sherman (eds.), The Gulf of Mexico Large Marine Ecosystem. Blackwell Science, Oxford, U.K.Google Scholar
  79. Turner, R. E. 1999b. A comparative mass balance budget (C, N, P and suspended solids) for a natural swamp and overland flow systems, p. 61–71.In J. Vymazal (ed.), Nutrient Cycling and Retention in Natural and Constructed Wetlands. Backhuys Publishing Inc., Leiden, The Netherlands.Google Scholar
  80. Turner, R. E. 2004. Coastal wetland subsidence arising from local hydrologic manipulations.Estuaries 27:265–273.CrossRefGoogle Scholar
  81. Turner, R. E., N. Qureshi, N. N. Rabalais, Q. Dortch, D. Justić, R. Shaw, andJ. Cope. 1998. Fluctuating silicate:nitrate ratios and coastal plankton food webs.Proceedings of the National Academy of Sciences (USA) 95:13048–13051.CrossRefGoogle Scholar
  82. Turner, R. E. andN. N. Rabalais. 1991. Changes in the Mississippi River this century: Implications for coastal food webs.BioScience 41:140–147.CrossRefGoogle Scholar
  83. Turner, R. E. andN. N. Rabalais. 2003. Linking landscape and water quality in the Mississippi River Basin for 200 years.BioScience 53:563–572.CrossRefGoogle Scholar
  84. Turner, R. E. andN. N. Rabalais. 2004. Suspended sediment, C, N, P, and Si yields from the Mississippi River Basin.Hydrobiologia 511:79–89.CrossRefGoogle Scholar
  85. Turner, R. E., N. N. Rabalais, andD. Justić. 2006. Predicting summer hypoxia in the northern Gulf of Mexico: Riverine N, P and Si loading.Marine Pollution Bulletin 52:139–148.CrossRefGoogle Scholar
  86. Turner, R. E., N. N. Rabalais, D. Justić, andQ. Dortch. 2003a. Global patterns of dissolved silicate and nitrogen in large rivers.Biogeochemistry 64:297–317.CrossRefGoogle Scholar
  87. Turner, R. E., N. N. Rabalais, D. Justić, andQ. Dortch. 2003b. Future aquatic nutrient limitations.Marine Pollution Bulletin 46: 1032–1034.CrossRefGoogle Scholar
  88. Turner, R. E., N. N. Rabalais, D. Scavia, and G. F. McIsaac. 2007. Corn belt landscapes and the ecology of the Gulf of Mexico, p. 10–17.In J. I. Nassauer, M. V. Santelmann, and D. Scavia (eds.), From the Corn Belt to the Gulf: Ecological and Societal Implications of Alternative Agricultural Futures. Resources for the Future, Washington, D.C.Google Scholar
  89. Turner, R. E., E. M. Swenson, and C. S. Milan, Organic and inorganic contributions to vertical accretion in salt marsh sediments, p. 583–595.In M. Weinstein and K. Kreeger (eds.), Concepts and Controversies in Tidal Marsh Ecology. Kluwer Academic Publishing, Dordrecht, Netherlands.Google Scholar
  90. Turner, R. E., E. M. Swenson, C. S. Milan, andJ. M. Lee. 2007. Hurricane signals in salt marsh sediments: Inorganic sources and soil volume.Limnology and Oceanography 52:1231–1238.CrossRefGoogle Scholar
  91. U.S. Commission on Ocean Policy. 2004. An Ocean Blueprint for the 21st Century: Final report of the U.S. Commission on Ocean Policy, Washington, D.C.Google Scholar
  92. U.S. Geological Survey. 2004. Nutrient load estimates for 2004. U.S. Geological Survey, Reston, Virginia, http://co.water.usgs. gov/hypoxia/html/nutrients_new.html.Google Scholar
  93. Wiseman Jr.,W. J., N. N. Rabalais, R. E. Turner, andD. Justić. 2004. Hypoxia and the physics of the Louisiana Coastal Current, p. 359–372.In J. C. J. Nihoul, P. O. Zavialov, and P. O. Micklin (eds.), Dying and Dead Seas, NATO Advanced Research Workshop, Liége, Belgium, NATO ASI Series, Kluwer Academic Publishers, Dordrecht, Netherlands.Google Scholar
  94. Xu, Y. J. 2006. Organic nitrogen retention in the Atchafalaya river swamp.Hydrobiologia 560:133–143.CrossRefGoogle Scholar
  95. Zhang, Y.-K. andK. E. Schilling. 2006. Increasing streamflow and baseflow in Mississippi River since the 1940s: Effects of land use change.Journal of Hydrology 324:412–422.CrossRefGoogle Scholar

Copyright information

© Estuarine Research Federation 2007

Authors and Affiliations

  • R. E. Turner
    • 1
  • N. N. Rabalais
    • 2
  • R. B. Alexander
    • 3
  • G. McIsaac
    • 4
  • R. W. Howarth
    • 5
  1. 1.Louisiana State University, Coastal Ecology InstituteBaton Rouge
  2. 2.Louisiana Universities Marine ConsortiumChauvin
  3. 3.U.S. Geological SurveyReston
  4. 4.Department of Natural Resources and Environmental Sciences, W-503 Turner HallUniversity of IllinoisUrbana
  5. 5.Department of Ecology and SystematicsCarson Hall, Cornell UniversityIthaca, New York

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