Dissolved manganese in ocean waters: analytical and biogeochemical studies
The aim of this study was to improve our understanding of the natural sources and processes of the dissolved manganese associated with the Southern Ocean and the Tropical North-Eastern (NE) Atlantic Ocean. A flow injection analyser (FIA) with chemiluminescence (CL) detection was first set up for the...
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| Format: | Thesis |
| Language: | English |
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2013
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| Online Access: | https://eprints.soton.ac.uk/363750/ https://eprints.soton.ac.uk/363750/1/Idrus%252C%2520Farah_Dec_13.pdf |
| Summary: | The aim of this study was to improve our understanding of the natural sources and processes of the dissolved manganese associated with the Southern Ocean and the Tropical North-Eastern (NE) Atlantic Ocean. A flow injection analyser (FIA) with chemiluminescence (CL) detection was first set up for the determination of dissolved manganese (DMn, ? 0.2 ?m). Extension work was undertaken to solve problems relating to our limited level of understanding of the CL reaction, and the behaviour of the resins used to either preconcentrate the manganese (i.e. Toyopearl AF-Chelate 650M) or to remove the interfering elements (cleaning resin, i.e. NTA Superflow and 8-Hydroxyquinoline). Using the system built in our laboratory, the determination of the interference of other dissolved trace metals (e.g. Fe, Ni, Cu, Co, Zn and Cd) were possible with dissolved manganese measurement in order to obtain a good measurable CL peak for dissolved manganese. The distribution of manganese around the Crozet Islands was examined and was used to provide a conceptual framework for future studies. Dissolved manganese concentrations were measured in samples collected from nine vertical profiles taken across the Crozet Plateau (80 - ~4500 m water depth) that show evidence of a range of processes influencing the manganese distributions. Dissolved manganese varied between 0.1 and 2.44 nM, and the resulting detailed section showed evidence of an island souce is identified which suggests that the plateau and the associated sediments are a source of manganese. Waters further north also appear to be affected by this input of both coastal and shelf origin, although dissolved manganese decrease as a function of distance to the north of the plateau with a gradient of 0.096 nM/km as a result of dispersion and mixing. This gradient was then combined with short-lived Radium isotopes profiles, allowing the determination of a lateral advective flux of manganese (up to 538 nmol/m2/d). Estimates of atmosphere and vertical fluxes of manganese to surface waters were ... |
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