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Catchment and in-stream influences on metal concentration and ochre deposit density in upland streams, Northern Ireland

Macintosh, Katrina A and Griffiths, David (2013) Catchment and in-stream influences on metal concentration and ochre deposit density in upland streams, Northern Ireland. Environmental Earth Sciences, 70 (7). pp. 3023-3030. [Journal article]

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DOI: 10.1007/s12665-013-2363-6


Metal concentrations from stream waters in two geological blocks in Northern Ireland were compared to determine the contributions of catchment characteristics and in-stream conditions. One block is composed of metamorphosed schist and unconsolidated glacial drift with peat or peaty podzol (mainly humic) soils, while the other block consists of tertiary basalt with brown earth and gley soils. Water samples were collected from 52 stream sites and analysed for Fe, Mn and Al as well as a range of other chemical determinands known to affect metal solubility. Densities of metal-rich ochre deposit were determined for stream bed stone samples. Higher conductivities and concentrations of bicarbonate, alkalinity, Ca and Mg occurred on basalt than on schist. Despite higher Fe and Mn oxide concentrations in basalt-derived non-humic soils, stream water concentrations were much lower and ochre deposit densities only one third of those on schist overlain by humic soils. Neither rock nor soil type predicted Al concentrations, but pH and dissolved oxygen did. Peat-generated acidity and the limited acid neutralising capacity of base-poor metamorphosed schist have resulted in elevated concentrations of metals and ochre deposit in surface waters.

Item Type:Journal article
Keywords:Metals • Ochre deposits • Geology • Soil • pH • Dissolved oxygen
Faculties and Schools:Faculty of Life and Health Sciences > School of Geography and Environmental Sciences
Faculty of Life and Health Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
Environmental Sciences Research Institute > Freshwater Sciences
ID Code:28044
Deposited By: Dr Katrina MacIntosh
Deposited On:27 Nov 2013 13:38
Last Modified:27 Nov 2013 13:38

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