Pollution of soils by lead and its uptake and pathways in the ecosystem.

The thesis reviews literature relating to lead in the environment with particular reference to the distribution and pathways of lead in the soil and plant ecosystem. Methods of conducting large area soil surveys and assessing the distribution of lead and other heavy metals including cadmium, copper and zinc are also examined. A survey was conducted over a 370 km2 area of North East Derbyshire, England. Maps showing the distribution of the metals reveal anomalously high concentrations related in many instances to past industrial activity. A simple reliable and rapid acid digestion procedure was developed and the procedure evaluated through an interlaboratory survey involving 22 laboratories. This demonstrated that analysts should seek to improve analytical performance through achieving better interlaboratory correlation rather than intralaboratory precision. A stratified random sampling protocol was developed and evaluated which allowed an estimate of precision to be placed on the results of the trace metal soil survey. An assessment was carried out of the contribution that lead fromaerially deposited dust and soil sources makes to the distribution of lead in potato plants. A micro sampling cup technique was developed which permitted (for the first time as far as can be ascertained) the analysis of lead in discrete sections of solid plant tissue from single plants grown under field conditions. This overcomes the problems of sensitivity which normally requires that samples are bulked or dosed with lead salts. Results are presented for the distribution of lead in potato plants grown in several field locations and in soils containing varying concentrations of lead. The major source of lead in the plants via the soil with aerial sources having a negligible effect on tissue distribution. Comparisons are made between results obtained by conventional flame atomic absorption spectrometry and the microsampling cup procedure.