Fate of nitrogen and phosphorus entering a Gulf coast freshwater lake: A case study

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Water Resources Bulletin; (USA)

DOI:https://doi.org/10.1111/j.1752-1688.1990.tb01399.x· OSTI ID:6039756

DeLaune, R D; Lindau, C W; Knox, R S; Smith, C J ^[1]

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1. Louisiana State Univ., Baton Rouge (USA)

Nitrogen and P fluxes, transformations and water quality functions of Lake Verret (a coastal Louisiana freshwater lake), were quantified. Ortho-P, total-P, NH{sub 4}{sup +}-N NO{sub 3}{sup {minus}}-N and TKN in surface water collected form streams feeding Lake Verret averaged 104, 340, 59, 185, and 1,060 mg l{sup {minus}1}, respectively. The higher N and P concentrations were located in areas of the lake receiving drainage. Nitrification and denitrification processes were significant in removing appreciable inorganic N from the system. In situ denitrification rates determined from acetylene inhibition techniques show the lake removes 560 mg N m{sup {minus}2} yr{sup {minus}1}. Laboratory investigations using sediment receiving 450 {mu}g NH{sup +}{sub 4}-N (N-15 labeled) showed that the lake has the potential to remove up to 12.8 g N m{sup {minus}2} yr{sup {minus}1}. Equilibrium studies of P exchanges between the sediment and water column established the potential or adsorption capacity of bottom sediment in removing P from the overlying water. Lake Verret sediment was found to adsorb P from the water column at concentrations above 50 {mu}g P 1{sup {minus}1} and the adsorption rates were as great as 300 {mu}g P cm{sup {minus}2} day{sup {minus}1}. Using the {sup 137}C s dating techniques, approximately 18 g N m{sup {minus}2} yr{sup {minus}1} and 1.2 g P m{sup {minus}2} yr{sup {minus}1} were removed from the system via sedimentation. Presently elevated nutrient levels are found only in the upper reaches of the lake receiving nutrient input from runoff from streams draining adjacent agricultural areas. Nitrification, denitrification, and adsorption processes at the sediment water interface over a relatively short distance reduces the N and P levels in the water column. However, if the lake receives additional nutrient loading, elevated levels will likely cover a larger portion of the lake.

• OSTI ID: 6039756
• Journal Information: Water Resources Bulletin; (USA), Vol. 26:4; ISSN 0043-1370
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
NITROGEN
CHEMICAL REACTION KINETICS
PHOSPHORUS
DENITRIFICATION
NITRIFICATION
SEDIMENT-WATER INTERFACES
SEDIMENTS
WATER QUALITY
CHEMICAL REACTIONS
ELEMENTS
ENVIRONMENTAL QUALITY
INTERFACES
KINETICS
NONMETALS
REACTION KINETICS
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)