The origin and development of a minerotrophic soak on an Irish raised bog: an interpretation of depth profiles of hydrochemistry and peat chemistry

• Published in: Holocene (Sevenoaks) 2009-09, Vol.19 (6), p.921-935
• Main Authors: Crushell, P.H., Smolders, A.J.P., Schouten, M.G.C., Roelofs, J.G.M., van Wirdum, G.
• Format: Article
• Language: English
• Subjects: carbon isotopes; delta-n-15; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochemistry; Geological time; groundwater; Hydrology; Marine and continental quaternary; Mineralogy; nitrogen; organic-matter; peatlands; phosphorus limitation; plants; restoration; Silicates; sphagnum; Surficial geology; Water geochemistry; Wetlands
• ISSN: 0959-6836; 1477-0911
• DOI: 10.1177/0959683609336561

The peat and pore-water biogeochemistry of an Irish oceanic raised bog are reported with a view to understanding the origin and development of a minerotrophic soak contained within an ombrotrophic bog. Depth profiles of electrical conductivity, pore-water chemistry and peat chemistry were recorded from the mire surface down to a maximum depth of 10 m (approximately 1 m into the underlying mineral soil) from the centre of Lough Roe, a minerotrophic soak on Clara Bog in the Irish midlands, and from a location in the surrounding bog. Distinct differences in the hydrochemistry and peat chemistry between both sites are evident in the upper 5 m of the profile, indicating that conditions differed during the latter development of the mire, despite both sites being located on the apex of the raised bog dome. As expected, the profiles recorded from the ombrotrophic bog are characterised by low ionic concentrations in the upper bog peat with an increase in the concentration of calcium and other ions in the lower fen peat (from 5.5 m depth). At the Lough Roe site, the profile shows relatively high concentrations of calcium and other ions in the upper part of the profile. To our knowledge, this is the first report of such detailed minerotrophic chemical profiles from the central area of a raised bog dome. We hypothesize that the relevant minerals originate from the underlying clay layer and fen peat within the basin of the bog and the minerals prevailed within the soak because of (1) the generation of a flow of water from the developing bog through the minerotrophic fen peat towards the soak during its early development, and (2) increased rates of decomposition within the soak throughout its existence. The implications for the future conservation management of the site are discussed.