SEDIMENTARY IRON GEOCHEMISTRY IN ACIDIC WATERWAYS ASSOCIATED WITH COASTAL LOWLAND ACID SULFATE SOILS
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dc.contributor.author | Burton E.D. | |
dc.contributor.author | Bush R.T. | |
dc.contributor.author | Sullivan L.A. | |
dc.date.accessioned | 2024-04-20T09:00:49Z | |
dc.date.available | 2024-04-20T09:00:49Z | |
dc.date.issued | 2006 | |
dc.identifier | https://elibrary.ru/item.asp?id=12091608 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2006, 70, 22, 5455-5468 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/43735 | |
dc.description.abstract | We examined the solubility, mineralogy and geochemical transformations of sedimentary Fe in waterways associated with coastal lowland acid sulfate soils (CLASS). The waterways contained acidic (pH 3.26-3.54), FeIII-rich (27-138 ?M) surface water with low molar Cl:SO4 ratios (0.086-5.73). The surficial benthic sediments had high concentrations of oxalate-extractable Fe(III) due to schwertmannite precipitation (kinetically favoured by 28-30% of aqueous surface water Fe being present as the FeIIISO4+ species). Subsurface sediments contained abundant pore-water HCO3 (6-20 mM) and were reducing (Eh < -100 mV) with pH 6.0-6.5. The development of reducing conditions caused reductive dissolution of buried schwertmannite and goethite (formed via in situ transformation of schwertmannite). As a consequence, pore-water FeII concentrations were high (>2 mM) and were constrained by precipitation-dissolution of siderite. The near-neutral, reducing conditions also promoted SO4-reduction and the formation of acid-volatile sulfide (AVS). The results show, for the first time for CLASS-associated waterways, that sedimentary AVS consisted mainly of disordered mackinawite. In the presence of abundant pore-water FeII, precipitation-dissolution of disordered mackinawite maintained very low (i.e. <0.1 ?M) S-II concentrations. Such low concentrations of S-II caused slow rates for conversion of disordered mackinawite to pyrite, thereby resulting in relatively low concentrations of pyrite (<300 ?mol g-1 as Fe) compared to disordered mackinawite (up to 590 ?mol g-1 as Fe). This study shows that interactions between schwertmannite, goethite, siderite, disordered mackinawite and pyrite control the geochemical behaviour of sedimentary Fe in CLASS-associated waterways. | |
dc.subject | ACID WATER | |
dc.subject | GEOCHEMISTRY | |
dc.subject | IRON | |
dc.subject | LOWLAND ENVIRONMENT | |
dc.subject | SEDIMENT CHEMISTRY | |
dc.subject | SOIL CHEMISTRY | |
dc.subject | SULFATE | |
dc.subject | SURFACE WATER | |
dc.subject | SURFICIAL SEDIMENT | |
dc.subject | WATERWAY TRANSPORT | |
dc.title | SEDIMENTARY IRON GEOCHEMISTRY IN ACIDIC WATERWAYS ASSOCIATED WITH COASTAL LOWLAND ACID SULFATE SOILS | |
dc.type | Статья | |
dc.identifier.doi | 10.1016/j.gca.2006.08.016 |
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