This project investigated the traditional treatment of chromium by oxidation-reduction reaction using Fe (II) and Mn (II). It was found that FE (II) was a potential remediation to stabilise chromium and reduce Cr (VI) to Cr (III), but Mn (II) oxidised Cr (III) to Cr (VI) mobilising it to the leachate. The characteristic of chromium leaching from soil was studied and showed there was fast release followed by a slow release. After a dry period the initial leachate had a high chromium concentration, this points out that the leaching of chromium is a long-term process. Those aspects of fast and slow release and the high chromium concentration at the initial pulse have been a concern for designing a system of fixed bed, low cost material such as (charcoal, coir, peat and wood bark) for adsorbing chromium from the leachate. The adsorption – desorption properties were studied, as both are of equal concern, and the Langmuir equation was applied for the various sorbent materials. Charcoal had a high percentage of Cr (VI) adsorbed, but on the other hand also had a high percentage of Cr (VI) desorbed. When applied to the column leach charcoal could not adsorb Cr (VI) properly. Wood bark had the lowest percentage of chromium released to the solution; therefore it was selected for further studies. The wood bark was studied with different contact times by both batch and flow through systems. The results showed that more chromium was adsorbed with longer contact time. The system using 2500g of wood bard completely retained chromium from a solution of about 100 litres of 30 mg Cr/l with a flow rate of 60 ml/h. The experimental results can be applied to larger scale systems; however, the system needs further development.

This research focuses on atmospheric and fluvial dispersal of Pb and Zn from an abandoned mine at Tyndrum, Scotland, which potentially acts as a significant source of contamination to the surrounding area. Concentrations of Pb and Zn in tree bark samples and peat profiles were measured to assess aerial deposition and fallout around the main mine site. Dispersal of contaminants through fluvial transport was assessed by analysis of river water and sediment on site and in the main river system draining the area, extending 25 km downstream from the mine area. Attempts were also made to determine whether the contamination is due to contemporary dispersal of material from the abandoned mine waste dumps, or originates from past deposition. Pb and Zn concentrations in tree bark from Scots pine (Pinus sylvestris) were high, but decreased with increasing distance up to approximately 100 m from the main dumpsite. Concentrations reduced markedly beyond this distance, possibly owing to the density of the forest stand. It is suggested that tree bark samples provide a useful medium for monitoring and quantifying contemporary aerial dispersal. Distributions of Pb and Zn within peat soil profiles provide information of past atmospheric deposition. Subsurface peaks of Pb and Zn can be linked to the period when mining was active during the 19th and early 20th centuries using the 210Pb dating method. The dispersal of Pb and Zn within the fluvial system was assessed by measuring concentrations of the contaminants in the solution, suspended particle and bed sediment phases. It was found that Pb and Zn are mainly transported in suspension in the 1.2-53 m suspended sediment fraction and are consequently deposited throughout the dispersion pathway in riverbed, lake and riverbank sediments. The contaminant Pb in an overbank core was confirmed as originating from the Tyndrum mine on the basis of its 206Pb/207Pb isotope ratio characteristics. This confirms a previous hypothesis that waste from the mine is an important contributor to Pb contamination over the entire length of the river system as far as Loch Tay. Thus overall, the investigation concludes that although the atmospheric dispersal of the contaminants is mostly contained within the vicinity of the Tyndrum main mine, the fluvial system remains a significant pathway for dispersal of Pb and Zn from the Tyndrum waste and that the presence of these metals within the river may persist for many years to come.

Road Deposited Sediment (RDS) is an important pathway of pollution material in the urban environment. Traditional particulate matter (PM) monitoring methods are typically expensive and time consuming. To date, urban sediment studies have not fully explored the application of mineral magnetic technologies as an alternative to characterise RDS or, perhaps more importantly, their use as particle size proxy. Therefore, this study addresses these issues by determining the extent of any linkages between magnetic properties and the physio-chemical concentrations of RDS. Investigations have focussed on a spatial temporal study (2008-10) of RDS from the City of Wolverhampton (n = 546) and a similar ‘snap-shot’ study of eight selected town and cities across the UK (n = 306), plus a comparison investigation linked to regional monitoring of air sampling units (ASU) (n = 208). A suite of analytical approaches, namely mineral magnetism, laser diffraction, X-Ray Fluorescence spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Loss on Ignition (LOI), were employed to characterize sample properties. Data interrogation identified mainly weak correlations exist between most mineral magnetic parameters and particle size classes (i.e. sand, silt and clay) and respiratory health-related size classes (i.e. PM10, PM2.5 and PM1.0). The few strongest correlations (p <0.001) were found between mineral magnetic concentration and <PM10 parameters. In Wolverhampton this occurred for samples collected during the spring months (March and May), indicating possible seasonal influences on RDS dynamics and sources. Elsewhere in the UK, and at ASU stations, results revealed mainly limited or insignificant (p >0.05) correlations exist between mineral magnetic parameters and particle size. However, for some locations (most notably, London and Scunthorpe), results exhibit signatures perceived to be associated with environmental factors. Detailed multivariate Factor Analysis plots and Geographical Information System (GIS) images have been used to explore these findings further. These illustrate RDS properties of road types (arterial and residential) display significantly different characteristics, with raised mineral magnetic concentrations for arterial roads, compared to lesser concentrations for residential roads, which corresponds to traffic flow data. This is supported by SEM analyses that reveal elevated concentrations of iron oxide spheres in samples collected from arterial roads, which are indicative of inputs from anthropogenic combustion sources. Contextualising these findings within the framework of existing knowledge, a conceptual approach has been presented that explores factors (i.e. sampling area, topography, land use, sediment source and potential mixing), which influence the reliability of using mineral magnetic techniques a particle size proxy. This demonstrates that any increase in the complexity of these factors (sampling area dynamics) can be used to predict the likelihood of being able to employ mineral magnetic measurements as a proxy. To surmise the work overall, despite mineral magnetic technologies offering an inexpensive and rapid means of analysing RDS, its use as a proxy measure for particulate matter appears to be limited by a series of site-related factors but the technique seems to offer valuable insights for pollution source studies.

Bibliography: leaves 395-473. / xxiii, 473 leaves : ill. (chiefly col.), maps (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Research is directed toward demonstrating spatial variability in dust lead contamination patterns both statically and dynamically within the confines of vacant test houses, thus eliciting specific entrance pathways. / Thesis (Ph.D.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1999