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This article in SSSAJ

  1. Vol. 59 No. 6, p. 1782-1788

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Phosphorus Sorption Characteristics of Everglades Soils along a Eutrophication Gradient

  1. C. J. Richardson and
  2. P. Vaithiyanathan
  1. Wetland Center, School of the Environment, Duke Univ., Durham, NC 27706
    Duke Univ. Wetland Center, (curtr@env.duke.edu)



We examined the P sorption characteristics of northern Everglades peat soils along a eutrophication gradient to understand the P retention efficiency of the soils. The amount of phosphate adsorbed on the soils (Q) and the zero equilibrium phosphate concentration supported by the soils (EPCo) exhibited a linear decrease with distance from the inflow structures supplying agricultural drainage (r2 = 0.74 and 0.71, respectively; P < 0.05; n = 18). Values of Q and EPCo for the enriched soils are an order of magnitude higher than for unenriched soils. Estimated Q values of the soils compare well with the exchangeable P fraction determined by KCl and HCO3 extraction. Comparison of soil EPCo and pore water PO4-P values with the surface water PO4-P concentrations suggests that soils may serve as an additional internal source of P to the overlying water column in nutrient-enriched areas. Linear phosphate adsorption coefficient (K) of the alkaline Everglades soils is higher than that of acidic pocosin bog peat soils of North Carolina but lower than wetland soils and sediments with a high mineral content. Phosphorus sorption characteristics of the Everglade soils are most likely regulated by CaCO3.

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