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Trace metal speciation and contamination in an intertidal estuary
A O Ibhadon1, P Wright, R Daniels
1Hull Environment Research Institute and Centre for Coastal Studies, Faculty of Science and the Environment, University of Hull, Scarborough Campus, Filey Road, Scarborough, YO11 3AZ, England.
Journal of Environmental Monitoring : JEM
|August 5, 2004
Summary
Tees estuary sediments show high trace metal levels, primarily from human activities. While total metal concentrations are decreasing, understanding metal speciation is key to assessing bioavailability and environmental risk.
Area of Science:
- Environmental Chemistry
- Geochemistry
- Marine Science
Background:
- Tees estuary sediments are rich in organic clay silts.
- Trace metal concentrations in sediments surpass those in the water column.
- Anthropogenic sources are identified as the primary contributors to estuary contamination.
Purpose of the Study:
- To analyze the geochemical distribution of trace metals in Tees estuary sediments.
- To determine the geochemical phases and bioavailability of selected metals.
- To investigate the sources and trends of metal contamination.
Main Methods:
- Sequential extraction technique was employed for metal speciation.
- Differential Stripping Voltammetry was used for metal analysis.
- Sediment samples were analyzed for trace metal partitioning.
Main Results:
- Lead (Pb) and Zinc (Zn) are mainly found in reducible, residual, and oxidisable fractions.
- Cadmium (Cd) speciation mirrors Pb and Zn, with minor exchangeable and carbonate-bound fractions.
- Copper (Cu) is predominantly in oxidisable and residual fractions.
- Bioavailable metal forms are identified as free inorganic ions.
- Total metal concentrations in the estuary have shown a declining trend since the 1970s.
Conclusions:
- Sediment geochemistry reveals significant anthropogenic trace metal contamination in the Tees estuary.
- Understanding metal speciation is crucial for assessing ecological risks and bioavailability.
- The observed downward trend in total metal concentrations suggests successful pollution control measures over time.