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Environmental Chemistry of Urban Canal Sediments

Environmental Chemistry of Urban Canal Sediments. Environmental Analytical Chemistry Project. The Problem. Canals are an Urban Resource Ecological corridors, recreation(walking fishing etc) Desirable development areas

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Environmental Chemistry of Urban Canal Sediments

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  1. Environmental Chemistry of Urban Canal Sediments Environmental Analytical Chemistry Project

  2. The Problem • Canals are an Urban Resource • Ecological corridors, recreation(walking fishing etc) • Desirable development areas • Water quality may be vulnerable to deterioration due to highly contaminated sediment

  3. Urban Canal – Today

  4. Urban Canal - Historical View

  5. Question • Is the quality of the canal water at risk from the canal bed sediment?

  6. Objective • To evaluate • What processes operate in the sediment? • What solid species host the P? • Do sediments act as a source or sink of P? • What factors influence P transfer? • Are other contaminants of concern?

  7. Data • Seasonal sediment pore water and canal water anion and cation concentrations. • Field observation notes • Temperature, pH and Eh • TOC

  8. Data Collection • Sediment cores collected in perspex core barrels. • Extruded under a nitrogen atmosphere to avoid oxidation. • Centrifuged then prepared for analysis in an anaerobic cabinet using de-oxygenated reagents.

  9. Sample Collection Core Barrel is pushed into the canal sediment and removed Bung is inserted into base of perspex core barrel. Core removed and bung inserted into top of barrel

  10. Sample Collection

  11. Key Elements of Concern • Phosphorus – causes eutrophication • Reduced heavy and transition metals • Sulphate – a potential organic matter oxidant in the sediment.

  12. Processes in Sediment. • Organic matter degradation – releases nutrients e.g. P, N • Iron reduction – Fe3+/Fe2+ • Sulphate reduction – SO4/H2S • Diagenetic processes – the formation and dissolution of solids/minerals in the sediment

  13. Diagenetic Minerals Ca5(PO4)3(OH) Vivianite Fe(PO4)2.8H2O

  14. Report • You are expected to produce a research report in the form of an academic paper. • You are provided with an example manuscript in the form of an SEGH paper - Dodd et al (2000).

  15. Additional Resources • PHREEQCI – a geochemical modelling program. • A selection of papers on freshwater sediment chemistry

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