Trace metal chemical speciation and acute toxicity to Pacific oyster larvae
Access to the full-text thesis is no longer available at the author's request, due to 3rd party copyright restrictions. Access removed on 28.11.2016 by CS (TIS). Metadata merged with duplicate record (http://hdl.handle.net/10026.1/2252) on 20.12.2016 by CS (TIS). Controlled laboratory studies s...
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| Format: | Thesis |
| Language: | English |
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University of Plymouth
2008
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| Online Access: | http://hdl.handle.net/10026.1/701 https://doi.org/10.24382/4980 |
| Summary: | Access to the full-text thesis is no longer available at the author's request, due to 3rd party copyright restrictions. Access removed on 28.11.2016 by CS (TIS). Metadata merged with duplicate record (http://hdl.handle.net/10026.1/2252) on 20.12.2016 by CS (TIS). Controlled laboratory studies showed that the toxicity induced by biologically relevant trace metal species of Cu, Cd, Pb and Zn on embryo-larval development occurred at concentrations in excess of those found in the natural environinent, except for Cu in metal perturbed areas. Average free ion concentrations inducing 50% abnormal development( EC50feew) ere determineda s 0.23 nM CU2+8, 8.0 rim Cd2+,1 28 nM Zn2+a nd 3 62 nM Pb 2+ . However, the response to some binary metal combinations indicated enhanced (synergy) toxicity at concentrations relevant for estuarine waters (e. g. EC5of'. for Cu2+i n the presenceo f C(ý: +, Zn2+a nd Pb2 +w as 0.004,0.02 and 0.04 nM, respectively). A comparison of voltarnmetric instrumentation (voltammetric in situ profiling (VIP) system versus Hanging Mercury Drop Electrode with potentiostat) highlighted the advantage of high resolution measurements (ca. 20-60 min intervals) for environmental studies and the minimisation of artefacts associated with discrete sampling methodologies. Field-based studies were carried out in two contrasting estuaries in SW England, one heavily impacted with metal contaminants (Fal Estuary) and another subject to greater variety of anthropogenic influences (Tamar Estuary). High resolution in situ trace metal speciationm easurementsc, arried out over tidal cycles, identified important information on the temporal and spatial distributions of biologically relevant dynamic (<4 nm) metal species of Cd, Pb and Cu. Variation in embryo-larval responses to discrete samples from these estuaries, effectively paralleled the metal speciation measurements showing enhanced toxicity when the marine water influence was at its lowest. In both systems, the results indicated that the combined effect of the ... |
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