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This article in SSSAJ

  1. Vol. 35 No. 4, p. 556-561
    Received: Dec 17, 1970



Characterization of Inorganic Phosphate in Noncalcareous Lake Sediments1

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



Inorganic P added with 0.5M NH4F to noncalcareous sediments was recovered in the NH4F and succeeding 0.1N NaOH extractions. Values of NH4F-P, corrected on the basis of the recovery of P added with the NH4F reagent, underestimated the total amount of inorganic P capable of interacting with NH4F, but by less than the corresponding uncorrected values. The amounts of inorganic P extracted by 0.5M NH4F followed by 0.1N NaOH, by citrate-dithionite-bicarbonate, and by 0.3N NaOH were very similar, the means of the three quantities varying by only 11 ppm. Oxalate-extractable inorganic P exceeded these quantities by an average of 250 ppm but exceeded the sum of NH4F-P, 1st NaOH-P, and reductant-soluble P by an average of 60 ppm, the difference in the latter comparison being ascribed to the partial or complete dissolution of apatite by the oxalate reagent. Although NH4F-Al was moderately well correlated with oxalate-Al (r = 0.70) neither variable was related to NH4F-P. The very high correlations between NH4F-P, 1st NaOH-P, and reductant-soluble P, on the one hand, and between these three fractions and oxalate- and citrate-dithionite-bicarbonate-extractable Fe, on the other, indicate a common origin for the inorganic P in the three fractions as part of a short range order Fe-rich complex. Apatite was low in all sediments.

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