Iron monosulfide formation and oxidation in drain-bottom sediments of an acid sulfate soil environment

Sedimentary iron geochemistry in acidic waterways associated with coastal lowland acid sulfate soils

“…These concentrations are remarkably consistent with previously reported concentrations for the 10-22 cm depth interval in CLASS drain sediments (Fig. 8 presents data from Smith and Melville, 2004;and from Burton et al, 2006a). This consistency suggests that a specific process or phase may provide a general control on pore-water Fe II solubility.…”

“…showed that the abundance of sedimentary acid-volatile sulfide (AVS; assumed to represent an amorphous FeS (s) phase) in CLASS drains can greatly exceed levels reported from other environments. The widespread, anomalous abundance of sedimentary AVS in such waterways has been further documented by Bush et al (2004b), Smith and Melville (2004), Macdonald et al (2004) and Burton et al (2006a). Recent research has also examined the oxidative transformations of AVS during flood-induced sediment resuspension events in CLASS drains (Burton et al, 2006b).…”

“…However unlike AMD environments where schwertmannite has been previously observed, CLASS drains typically contain abundant labile organic material due to dense growth of aquatic macrophytes (Smith and Melville, 2004;Burton et al, 2006a). This results in the accretion of organic-rich benthic sediments, characterized by a yellow-orange surface layer overlying soft gels (water content >90%) having a black ''oily'' appearance Sullivan et al, 2002;Bush et al, 2004b;Smith and Melville, 2004). showed that the abundance of sedimentary acid-volatile sulfide (AVS; assumed to represent an amorphous FeS (s) phase) in CLASS drains can greatly exceed levels reported from other environments.…”

Improved identification of sulfidic soil materials by a modified incubation method

“…The main sulfide mineral in these soil materials is pyrite (e.g. Harmsen, 1954;Bloomfield and Coulter, 1973;van Breemen, 1973), but other sulfide minerals such as marcasite Bush et al, 2004a), iron monosulfides (Georgala, 1980;Åström and Åström 1997;Bush and Sullivan, 1997;Bush et al, 2000;Sullivan et al, 2002a;Bush et al, 2004b;Sullivan et al, 2004;Österholm andÅström, 2004: Smith andMelville, 2004) especially mackinawite (Burton et al, 2006a), and elemental sulfur (Burton et al, 2006b) can also be present in appreciable amounts.…”

Coastal acid sulphate soils in Poland: a review

“…However, they are largely connected with sulphides, whose intense oxidation in conditions of strong acidification significantly increases their mobility (Sohlenius and Öborn 2004). As a consequence, particularly during heavy rainfall, they can be excessively concentrated in the nearby water courses (Smith and Melville 2004, Roos and Öström 2005, Österholm et al 2005. For example, as estimated by Fältmarsch et al (2008), the amounts of these metals introduced into water by washing out of acid sulphate soils are from 10 to 100 times larger than the amounts supplied by sewage from the entire industry of Finland.…”