title: Pseudomorphs of barite and biogenic ZnS after phyto-crystals of calcium oxalate (whewellite) in the peat layer of a poor fen.
abstract: Pseudomorphs of barite (BaSO4) and Cd-rich ZnS after whewellite (CaC2O4·H2O) occur within remnants of Scots pine bark tissues in the peat layer of a poor fen located near a zinc smelter in south Poland. A two-step formation of the pseudomorphs is postulated based on SEM observations: (1) complete dissolution of whewellite, possibly caused by oxalotrophic bacteria, and (2) subsequent bacterially induced precipitation of barite and spheroidal aggregates of ZnS together with galena (PbS) in voids left by the dissolved whewellite crystals. Local increase in pH due to microbial degradation of whewellite, elevated concentrations of Zn(II) and Ba(II) in pore water due to the decomposition of atmospheric particles of sphalerite and barite in the acidic (pH 3.5-3.8) environment, oxidation of S species during drying and rewetting of the peat layer, and subsequent partial reduction of sulfate anions by sulfur-reducing bacteria were all factors likely involved in the crystallization of ZnS and barite in the microenvironment of the post-whewellite voids.
authors.affiliation: Faculty of Earth Sciences, University of Silesia, Będzińska 60, 41-200, Sosnowiec, Poland, beata.smieja-krol@us.edu.pl.
authors.forename: Beata
authors.initials: B
authors.lastname: Smieja-Król
authors.forename: Janusz
authors.initials: J
authors.lastname: Janeczek
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wiedermann
mesh_terms: D001466:Barium Sulfate / Q000032:analysis* / Q000737:chemistry; D002129:Calcium Oxalate / Q000737:chemistry / Q000378:metabolism*; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis; D008669:Metallurgy; D010084:Oxidation-Reduction; D011044:Poland; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis; D013440:Sulfides / Q000032:analysis*; D016999:Sulfur-Reducing Bacteria; D017967:Zinc Compounds / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; D017967:Zinc Compounds; C016189:whewellite; C018391:lead sulfide; D001466:Barium Sulfate; D002129:Calcium Oxalate; D007854:Lead; C031238:zinc sulfide