Biogenic silica dissolution in seawater : in vitro chemical kinetics

• Published in: Progress in oceanography Vol. 48; no. 1; pp. 1 - 23
• Main Authors: GREENWOOD, J. E, TRUESDALE, V. W, RENDELL, A. R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 2001
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Geochemistry; Marine; Mineralogy; Physical and chemical properties of sea water; Physics of the oceans; Silicates; Water geochemistry; sea water; experimental studies; models; silica; Plantae; mathematical models; algae; Reaction rate; Chemical reaction kinetics; saturation; diatom flora; suspended materials; biogenic origin; diatoms; dissolved materials; Surface area; kinetics; Thallophyta
• ISSN: 0079-6611; 1873-4472
• DOI: 10.1016/S0079-6611(00)00046-X

The experimental and mechanistic approaches available for the study of the kinetics of in vitro biogenic silica dissolution are synthesised to provide rigorous guidance for future investigation. Batch and flow-through reactors are discussed, as are the four mechanisms which have been proposed previously within the marine domain. In recognition of success with similar problems in mineral weathering and hydro-metallurgy, the applicability of the Activated Complex Theory is also considered. Full mathematical derivations are presented for the mechanisms before they are evaluated according to contemporary needs. At each stage the problems inherent in fitting mathematical models to experimental data are highlighted. The decrease in reaction rate with time observed in batch reactors is discussed in terms of both the approach towards saturation and decrease in surface area of the dissolving frustules. In appreciating this distinction, optimum combinations of experimental design are suggested for mimicking silica dissolution in either the water column or sediment. The role of organic frustule components, micro-organisms and faecal pellets in the dissolution process are discussed.