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This article in SSSAJ

  1. Vol. 35 No. 2, p. 244-249
    Received: Aug 19, 1970
    Accepted: Oct 23, 1970

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Sorption of Inorganic Phosphate by Lake Sediments1

  1. S. S. Shukla,
  2. J. K. Syers,
  3. J. D. H. Williams,
  4. D. E. Armstrong and
  5. R. F. Harris2



Twenty-five sediments from nine soft-water and five hard-water Wisconsin lakes sorbed between 20 and 100% of the inorganic P added at a level of 830 µg P/g oven-dried sediment and between 14 and 99% of that added at a level of 6,700 µg P/g oven-dried sediment. Noncalcareous sediments usually sorbed more added P than calcareous sediments. P sorption fended to be inversely related to the CaCO3 content of the calcareous sediments. Treatment with oxalate destroyed or virtually eliminated the ability of noncalcareous sediments to sorb added P and greatly reduced that of the calcareous sediments. Oxalate extracted widely varying amounts of Fe (3 to 131 mmoles/100 g) and Al (6 to 26 mmoles/100 g) from the noncalcareous sediments; an appreciable proportion of the total Fe in the noncalcareous sediments was oxalate-extractable. One noncalcareous sediment, high in oxalate-extractable Fe, sorbed over 80% of inorganic P added at a level of 16,700 µg P/g oven-dried sediment. With one exception, two treatments with citrate-dithionite-bicarbonate or one oxalate extraction had similar effects on the P-sorption capacity and released comparable amounts of Fe, suggesting that the extractable Fe is derived from an amorphous iron oxide complex. The proportion of added P sorbed was closely related to the amount of oxalate Fe and to the levels of native total inorganic P in the sediments. It is postulated that a gel complex of hydrated Fe oxide which contains small amounts of Al2O3, Si(OH)4, and organic matter, is the major P-sorbing component of sediments.

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