Pore water and solid phase samples were collected from the upper 50 cm of a peat profile at four sites within a 10 m 2 area in Kleinstuck Marsh, a minerotropic fen located in Kalamazoo, MI. Although the chosen sites are in close proximity to each other, they differ with respect to vegetation species and density. Pore water analyses for a suite of redox sensitive species (pH, alkalinity, dissolved Mn(II), Fe(II), Fe(III), sulfide, sulfate), together with Fe and Mn distributions inferred from operationallydefined sequential extractions, demonstrate that Fe(III) and Mn(IV) reduction occurs in the shallow peat at three of the four sites. At the fourth site, the only site containing the invasive purple loosestrife (Lythrum salicaria), accumulation of dissolved sulfide in the pore waters and increased levels of oxidizable phases in the shallow peat point to increased net sulfate reduction relative to the other three sites. Speciation calculations indicate that pore water concentrations of phosphate, especially below *10 cm depth, are largely controlled by the solubility of phases such as strengite or hydroxylapatite, and that at all but the loosestrife site, dissolved Ca and Mg are likely determined by carbonate solubility.Fe and Mn distribution among operationally defined solid phase fractions are consistent with reductive dissolution of FMO in the uppermost peat, leading to precipitation of Fe sulfides and Mn carbonates deeper in the peat profile. Zn, Co, Cr and Ni distributions are consistent with release from FMO to form sulfides or organic associations deeper in the peat. Pb and Cu may also be released by reductive dissolution of FMO, or more likely, shift from primary association with organic matter to increased association with sulfides under more sulfidic conditions. This study highlights the existence of extreme lateral variations in peat pore water and solid phase geochemical profiles, even over quite small areas.

No abstract

No abstract

The best yields and productivities of 0.38 g . g-' and 0.35 g . I-' h-I, respectively, for the propionic acid production in a batch system using sugar-cane final molasses as carbon source were obtained when an initial TRS concentration of 50 g . I-' was used.It was obvious that this process is severely inhibited by the acids produced and the most drastic effect (p = 0) was at a TVA concentration near to 250 mmol . I-', independently of the initial TRS concentration employed. A generalizated equation of noncompetitive inhibition was adjusted:and kinetic inhibition constants for each initial TRS concentration studied were estimated.