Atmospheric deposition of trace metals to the oceans is investigated in this study with analysis of aerosol samples collected during cruises from the UK to the Falklands and from South Africa to Australia. The readily soluble concentrations of Cu, Ni, Ba, Zn, Cd and Pb were measured in the aerosols, along with crustal elements and major ions to evaluate the sea spray and crustal contributions. Air mass back trajectories suggested most of the aerosol samples had spent several days over the ocean prior to collection. The highest metal concentrations were observed in aerosols close to South Africa, Australia and major cities in South America, although these concentrations were lower than had been reported previously in the literature. Apart from Ba, which had a major crustal source, the trace metals were enriched above both crustal and sea salt sources in most samples including some collected 1000s of km from emission sources. The mean trace metal concentrations in the remote Indian Ocean were lower than those measured in the Atlantic Ocean. Even lower concentrations are reported in the literature for the remote Pacific Ocean. The dry deposition rates calculated from the aerosol data were similar for the North and South Atlantic and South Indian Oceans reflecting the increase in industrialisation and atmospheric emissions in the southern hemisphere. Lead isotope ratios were measured in the aerosols with Multi Collector- Inductively Coupled Plasma - Mass Spectrometry. These results showed real differences in the isotopic ratios of aerosols collected in different marine regions and enabled the source of remote samples to be tentatively identified. Copper complexation was investigated in rain samples collected in Norwich, UK, and during the cruises. Humic material was also investigated as a potential organic ligand. The complexation was measured with Chelex resin, Sep-Pak columns and Adsorptive Cathodic Stripping Voltammetry with tropolone as a competing ligand. Strong organic complexation was observed in semi-urban and marine rain samples with conditional stability constants between 10" and 1014. Model solutions of copper and humic matter found organic complexes of a similar strength to those observed in the rain samples suggesting humic material as a potential source. A large proportion of the copper in the rains was associated with strong organic complexes over the pH range 4-8 in both filtered and unfiltered rain samples suggesting complexation is an important process both in the atmosphere and on arrival to oceans.

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Some persistent organic pollutants (POPs) are chiral in nature (e.g. α-HCH, and some PCBs) and are well recognised in different environmental samples. The effects of this property on their environmental behaviour are not well understood. This research specifically deals with chirality, a characteristic exhibited by asymmetric molecules which can exist as non-superimposable mirror images of one another. Chirality influences chemical behaviour in a number of ways including differences in environmental toxicity and persistence between enantiomers.

This research has investigated a number of topics pertaining to the effects of metalliferous mining. The combination of these has shown that past mining activities and their resultant waste have led to the accumulation of metals through trophic levels. During visits to Blanchdown Wood, Devon, UK and Snailbeach, Shropshire, UK, samples were collected to examine the effects of the spoil tips on the surrounding ecosystem. Samples of vegetation, soil and animal materials were extracted and analysed by inductively coupled plasma-optical emission spectrometry for the presence of heavy metals and were found to contain varying concentrations of lead, copper, arsenic, tin, tungsten and zinc. Laboratory investigations followed to determine the toxicity effects of lead, copper, and tungsten on Pandorina morum. This demonstrated that although single elements have effects on population growth, a combination of the three cations had pronounced and cumulative effects. It was found that the algae reduced the concentration of lead in the nutrient media, but it was not possible to determine whether lead was accumulated by the algae or adhered to the surface of the cells. In either case it is hypothesized that lead could then be transferred to the succeeding trophic levels. Further samples examined included archaeological finds, such as Anglo-Saxon human skeletons from a non-mining area. The concentrations of lead in these samples indicated that the population had been exposed to lead, and this is further explored. Since the population resided in a non-mining area, it is suggested that the contaminant was ingested via trophic level inputs; thus, providing further evidence certain metals are available to be transferred through the trophic levels to be stored in the human skeleton.

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