Studies in the concentrations and chemistry of cadmium in the environment
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Seven surveys were conducted in the city of Christchurch (New Zealand) in order both to obtain comprehensive data describing the concentrations of cadmium in the environment, and determine factors likely to influence these concentrations. In three of the surveys - examining cadmium concentrations in air, riverwater and horse-chestnut leaves - samples were collected over long time periods. Levels of cadmium in dust and soil, house-dust, commercial products and foods were examined in the other four surveys. Concentrations of copper, lead and zinc were also measured in many cases. Cadmium adsorption by - and mobility in - a Christchurch soil, weathering of a cadmium-containing paint and galvanized-iron, the behaviour of cadmium in samples being sequentially extracted, and speciations of cadmium in soils, road-dusts, house-dusts riverwater, and plastics were also studied. High levels of cadmium were found in road-dust in the immediate vicinity of some industrial operations, but concentrations in the wider Christchurch environment were generally low. House-dusts contained higher concentrations of cadmium than typical external dusts. Cadmium concentrations in some commercial products were very high; however, there appeared to be little risk of cadmium being significantly mobilized during the use of most of these products. Probable daily intakes of cadmium were estimated. Numerous factors influenced the levels of cadmium in the various materials examined. A Christchurch soil strongly adsorbed cadmium and the mobility of cadmium in this soil was low. Reagent selectivity for the forms of cadmium during sequential extraction was in some cases good and in some cases poor; little redistribution of cadmium occurred between phases during sequential extractions. Various factors were found to effect the adsorption and mobility of cadmium in soil, the outcome of each sequential extraction, and the weathering of cadmium from cadmium-containing paint and galvanized-iron.