Scavenging of 234Th in the Eastern Irish Sea |
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| Institution: | 1. Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa;2. Spectrum Analytical Facility, University of Johannesburg, Johannesburg, South Africa;1. Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada;2. Freshwater Institute, Fisheries & Oceans, Winnipeg, MB, Canada;3. Deparment of Earth & Atmospheric Science, University of Alberta, Edmonton, AB, Canada |
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| Abstract: | Measurements of the disequilibria of 234Th/238U in seawater and in suspended particulate and seabed sediment in the eastern Irish Sea reveal that the residence time of dissolved 234Th (0·5–7·7 days) is controlled by the concentration of particles in suspension (0·4–6·9 mg litre?1, which reflects the rate of sediment resuspension (0·5–5·9 kg m?2y?1). The residence time of 234Th with respect to removal to the seabed is longer (7–50 d) and is less dependent on variations in the suspended load. Anthropogenic sources of 238U contribute up to 8–15% of the water column production of 234Th. Enhanced scavenging occurs near the coast and there appears to be a net horizontal flux of 234Th within this region. |
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