Trace metals in waters, sediments and biota of the Solent system: a synopsis of existing information
Statham, P.J. (2000). Trace metals in waters, sediments and biota of the Solent system: a synopsis of existing information, in: Collins, M. et al. Solent science: a review. Proceedings in Marine Science, 1: pp. 149-161 In: Collins, M.; Ansell, K. (Ed.) (2000). Solent science: A review. Proceedings in Marine Science, 1. Elsevier: Amsterdam. ISBN 0-444-50465-6. 385 pp., more In: Proceedings in Marine Science. Elsevier: New York. ISSN 1568-2692; e-ISSN 2352-2860, more |  |
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| Abstract | The Solent and Southampton Water region appear to be relatively uncontaminated with dissolved trace metals, in relation to current EQS values, with the exception of tributyltin levels in the Test estuary. Metal concentrations offshore rapidly decline to values typical of uncontaminated coastal waters. There is clearly a need for the long-term monitoring of tributyl tin in the estuary, together with its impact on biota. The change in ship and boat antifouling materials, which will occur as TBT paints are phased out, may lead to replacement by other potentially harmful materials which are likely to be released into solution. From the point of view of metal-based antifouling materials, copper is of particular importance; concentrations of this in waters and biota will require careful monitoring, particularly close to marinas and other areas with a high vessel density. Speciation of dissolved metals is also an important issue, as regards the biological impact of metals. The sediments in Southampton Water, particularly on the western shore, show the legacy of contamination from the early days of industrialisation in the area. Thus copper and, to lesser extent zinc and lead, concentrations are elevated in the organic rich muds of this zone. The reduction in industrial inputs of metals in recent years is demonstrated elegantly in sedimentary cores obtained from saltmarshes in the Hythe area. The impact of metal and hydrocarbon contamination on, in particular, molluscs in the sediments is reflected in the abundance and growth of these organisms relative to less contaminated areas. There have been a limited number of studies on metals in sediments and organisms in Poole Bay, Portsmouth Harbour and adjacent zones. Future work on these areas would be useful, in terms of assessing the overall environmental quality of the region. An important issue is whether or not the metals in sediments are effectively locked away on long time-scales, or if they may be released back into the water column in dissolved, potentially biologically available, forms; this would occur through slow diffusive mechanisms or through more episodic activities such as dredging. The implications of bottom sediment disturbance through fishing activities, which have similar implications to dredging, have recently been considered by Pilskaln et al. (1998). New data collection tools, such as in situ monitoring buoys for trace metals, are required to provide information on estuarine waters; this will allow the short time-and space-scale changes in metals to be followed and more fully understood. A long-term objective for the Solent region is to develop predictive models that will effectively describe the behaviour of metals (and other chemical species) in this system, and the understanding of processes such as sediment exchange will play an important role in developing such tools. |
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