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Title: The impact of mining activities on the pedosphere and a critical evaluation of bioaccumulation
Author: Wilson, Robert
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2005
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The research has demonstrated the dispersion and dilution of copper, zinc, lead and cadmium from open pit metalliferous mine workings in UK, British Columbia and Arizona during and since the working lives of the mines concerned. Standard operating procedures were developed for the collection and preparation of soil and varying vegetation tissues. Five processes for the digestion of such environmental samples including the use of microwaves were critically evaluated and the use of aqua regia on a hot plate was found to be the most precise and accurate method for subsequent analysis of copper, zinc, lead and cadmium by flame atomic absorption spectrophotometry. Limits of detection and quantitation were also determined. Similar experiments were carried out to determine the most precise method of analysing the resulting extracts from environmental samples and the similarity of FAAS and ICP-AES data demonstrated. Analysis using ion chromatography, energy dispersive x-ray analysis and ICP-MS were found to be less satisfactory. Mine workings of varying ages were chosen in different climatic areas for examination. Cessation of dispersal from older mine workings was demonstrated by the use of epiphytic lichens which are capable of accumulating heavy metals emitted by atmospheric dispersion. The effects of sheet and gulley erosion were considered and other factors affecting atmospheric pollution from mine workings were examined. Temporal effects on the presence of heavy metals in the pedosphere were considered and the persistence and abundance of such pollution adequately demonstrated. Land in tlie vicinity of all of the mines was found to be heavily polluted and in many cases exceeded the heavy metal concentrations the soil contamination limits of the European Union and Canada especially where the sample sites were in domestic housing and park areas in adjacent towns. Evidence of bioaccumulation in different plant tissues is presented together with substantiation of partitioning within various plant tissues. Indications of suitable tissues of the plants under examination for biomonitoring of copper, zinc and lead are proposed. Heavy metal speciation related to bioavailability was closely examined using sequential and EDTA extraction procedures and the possible occurrence of homeostatic processes in plants is discussed together with indications of movement through trophic levels to animals including humans. It was also projected that metal tolerant plant tissues preferentially accumulate heavy metals in order to protect seeds. A novel way of calculating an accumulation factor of metals in plants is proposed and its relevance to metal speciation in the soil investigated. Where appropriate international and national standards relating to heavy metal concentrations in soil were demonstrated and their relevance to the current research is indicated. Further work on metal speciation, leaching mechanisms and plant accumulation processes is suggested together with investigations into subsequent accumulation of the target metals by mammals including humans.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available