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Phosphate and Iron correlations in an intertidal Georgia saltmarsh

Phosphate and Iron correlations in an intertidal Georgia saltmarsh. By Colin Dean. Fe(hydr)oxide dissolution. Abiotic (H 2 S method). Biological. Complicated, difficult to quantify The importance of soluble Fe (III) Likely the greatest source of Fe(II) in the marsh (otherwise all FeS).

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Phosphate and Iron correlations in an intertidal Georgia saltmarsh

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  1. Phosphate and Iron correlations in an intertidal Georgia saltmarsh By Colin Dean

  2. Fe(hydr)oxide dissolution Abiotic (H2S method) Biological Complicated, difficult to quantify The importance of soluble Fe (III) Likely the greatest source of Fe(II) in the marsh (otherwise all FeS) • Surface controlled by chemisorbed HS- and S2- • ≡FeOH + HS-  ≡FeS- + H2O • ≡ FeS-  ≡Fe(II)S • Fe(II) is then hydrated and leaves the surface into solution. (Afonso and Stumm 1991)

  3. Orthophosphate: PO43- Phosphate salts are (weak) buffers Dominant form at pH 7: HPO4- , H2PO4- • Inorganic form • H3P04, etc. • Pka’s: 2.16, 7.21, 12.32 -Negative charge in solution, and readily adsorbs to metal oxides, mostly aluminum and iron (hydr)oxides (as a bidentate ligand).

  4. Correlate this! • Deborde et al. (2009).

  5. Winter mud flat R=.7942 P=2.9e-5 Slope:.1948 Unvegetated R=.88 P=2.79e-7 Slope:.1935 Vegetated

  6. Summer mud flat R=.8076 P=2.9e-5 Slope:.1326 Unvegetated Vegetated R=.8434 P=5.7e-6 Slope:.1368

  7. Winter Creek Bank R=.7942 P=Slope:.1243 Unvegetated R=.88 P=2.79e-7 Slope:.1935 Vegetated

  8. Summer Creek Bank R=.5540 P=.0138 Slope:.1243 Unvegetated R=.7267 P=.0004 Slope:.1043 Vegetated

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