THE EFFECTS OF COPPER, ARSENIC AND CHROMIUM ON PLANTS AND THE USE OF THE WATER COOLED ATOM TRAP AS A PRECONCENTRATION TECHNIQUE.

摘要

Available from UMI in association with The British Library.; The dissertation is concerned with: (i) the effects of copper, arsenic and chromium on the growth of plants. (ii) the use of the water cooled atom trap as a preconcentration technique for the determination of environmental samples.; The general introduction is a survey emphasising the occurrence of arsenic, copper and chromium in the environment, their toxicity and chemical forms as well as the uptake of these elements by plants.; In the second chapter, attention is paid to the methods of analysis used in the present work such as AAS, AES, GFAAS, ATAAS and hydride generation-AAS.; The ATAAS technique is discussed in the next two chapters. Thus, in Chapter 3, the Plackett-Burman method was used to determine the significant factors when setting up the water cooled atom trap, i.e. the tube height and the obscuration of the light beam. The modified simplex method was then used to optimise these factors.; Chapter 4 is concerned with the determination of samples by ATAAS. The sensitivities of As, Ag, Au, Bi, Cd, Cu, Mn, Pb, Sb, Se, Tl and Zn in ATAAS were 15-91 times better than in FAAS. Tube coating materials such as Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, La(OH){dollar}sb3{dollar}, V{dollar}sb2{dollar}O{dollar}sb3{dollar} and Fe{dollar}sb3{dollar}O{dollar}sb4{dollar} reduced the interferences caused by extraneous elements; hence, elements were determined in plant, water and soil samples. A burner mounting and an electronic box for the automated operation of the water cooled atom trap are also discussed.; The toxicity of As(V), As(III), Cr(VI), Cr(III) and Cu(II) to Lolium perenne seedlings is examined in Chapter 5. The toxicity of these elements based on the estimation of the critical levels decreases in the following order: As(III) {dollar}>{dollar} As(V) {dollar}>{dollar} Cr(VI) {dollar}>{dollar} Cu(II) {dollar}>{dollar} Cr(III) (roots) As(III) {dollar}>{dollar} Cu(II) {dollar}>{dollar} As(V) {dollar}>{dollar} Cr(VI) {dollar}>{dollar} Cr(III) (shoots). Correlations between the essential plant nutrients and the toxic metals are also discussed.; Interactive effects of As(V), Cr(VI) and Cu(II) upon the yield of plants and uptake of elements are discussed in detail in Chapter 6.