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

Fe(hydr)oxide dissolution Abiotic (H2S method) Biological 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) Complicated, difficult to quantify The importance of soluble Fe (III) Likely the greatest source of Fe(II) in the marsh (otherwise all FeS)

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

Correlate this! Deborde et al. (2009).

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

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

Winter Creek Bank R=.7942 P=Slope:.1243 Unvegetated R=.88 Vegetated

Summer Creek Bank R=.5540 P=.0138 Unvegetated Slope:.1243 R=.7267