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Pyrite and siderite oxidation in swamp sediments
Author(s) -
POSTMA DIEKE
Publication year - 1983
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1983.tb00821.x
Subject(s) - pyrite , siderite , jarosite , weathering , gypsum , chemistry , environmental chemistry , sediment , pyrrhotite , pore water pressure , sulfur , mineralogy , inorganic chemistry , geology , geochemistry , paleontology , geotechnical engineering , organic chemistry
Summary Differences in the processes of pyrite and siderite oxidation, in reclaimed swamp sediments of the Skjernå delta (Denmark), are described from sediment chemistry, mineralogy and pore water chemistry. Pyrite oxidation leads to extreme soil acidification, with pH dropping to about 2, the release of large amounts of weathering products to the pore water, and the precipitation ofiron oxides, jarosite and gypsum. Siderite oxidation results only in moderate soil acidification where the pH does not drop below 3.5, while part of the acidification is due to the oxidation of small amounts of sulphur compounds together with siderite. The release of weathering products to the pore water is limited and only iron oxide is precipitated. Calculations indicate that equilibrium with amorphous FeOOH, gypsum and amorphous Al(OH) 3 sets an upper limit to the Fe 3+ , SO 4 and Al concentrations in the pore water.