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This article in JEQ

  1. Vol. 30 No. 4, p. 1474-1480
    Received: July 14, 2000

    * Corresponding author(s): krr@mail.ifas.ufl.edu
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Phosphorus Sorption Characteristics of Estuarine Sediments under Different Redox Conditions

  1. H.K. Pant and
  2. K.R. Reddy *
  1. University of Florida, Wetland Biogeochemistry Lab., Soil and Water Science Dep., Institute of Food and Agricultural Sciences, 106 Newell Hall, P.O. Box 110510, Gainesville, FL 32611-0510


Phosphorus (P) plays a major role in eutrophication of aquatic systems. Estuarine sediments could function as sources or sinks for P to the overlying water column depending upon their physico–chemical characteristics. Understanding of P sorption phenomena in estuarine sediments is important in regulating the P availability in estuaries. Phosphorus sorption characteristics of sediments from the Indian River Lagoon, Florida, USA, were determined to examine the role of selected physico–chemical properties of the sediments on soluble reactive P status in estuary water. Mean equilibrium P concentrations (EPCo) of 0.75 mg L−1 and mean P sorption maxima (S max) of 32.2 mg kg−1 were obtained under anaerobic conditions, compared with EPCo of 0.05 mg L−1 and S max of 132.7 mg kg−1 under aerobic conditions. The higher EPCo values under anaerobic conditions and the greater S max values under aerobic conditions were associated with amorphous and poorly crystalline iron. These results suggest that sediments enriched with amorphous and poorly crystalline forms of iron act as an excellent reservoir for P by adsorbing excessive P in aerobic sediment zones and releasing it upon burial under anaerobic conditions. This study also indicates that P compounds in sediments independently maintain equilibrium with P in solutions. Thus, heterogeneous systems like soil and sediment simply behave as a mixture of homogeneous surfaces as far as their P sorption characteristics are concerned, and hence can be successfully described by the Langmuir and Freundlich models.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1474–1480.