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Estuaries

, Volume 17, Issue 4, pp 796–808 | Cite as

Transport of dissolved organic nitrogen in Mississippi River plume and Texas-Louisiana continental shelf near-surface waters

  • Diego López-Veneroni
  • Luis A. Cifuentes
Article

Abstract

Dissolved organic nitrogen (DON) in near-surface (<20 m depth) waters of the Texas-Louisiana continental shelf is the predominant form of total dissolved nitrogen that is advected by the Mississippi-Atchafalaya River plume. Relatively high DON concentrations associated with low-salinity (<33 psu) waters throughout the year can be traced within the plume along the Texas-Louisiana inner shelf. DON concentrations throughout the shelf were significantly higher near the Mississippi-Atchafalaya outflow region relative to downstream inner Gulf shelf locations. Significant intercruise variations were also evident, with the highest concentrations during May 1992 and lower values in October 1992. At a fixed location off the Mississippi River outflow region DON concentration covaried inversely with salinity on time scales of hours to months, confirming that source water is a determining factor for variations of bulk DON concentrations in the region. Similar variations in upper water DON concentrations at different locations and seasons occurred in both plume and nonplume waters, which resembled the seasonal concentration changes of riverine nitrogen, and show that this pool is useful in tracing the influence of riverine-derived nitrogen on the overall nitrogen balance of the NW Gulf of Mexico’s continental shelf. Plume and nonplume DON concentrations deviated from mixing lines between riverine and oceanic endmembers, suggesting that plume waters may be a sink and nonplume waters may be a source of a labile fraction of DON in the region.

Keywords

Dissolve Inorganic Nitrogen Dissolve Organic Nitrogen Dissolve Organic Nitrogen Concentration Plume Water Mississippi River Plume 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Estuarine Research Federation 1994

Authors and Affiliations

  • Diego López-Veneroni
    • 1
  • Luis A. Cifuentes
    • 1
  1. 1.Department of OceanographyTexas A&M UniversityCollege Station

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