THE UPTAKE AND DISTRIBUTION OF COPPER SULPHATE BY THE FRESHWATER SNAIL BULINUS (BULINUS) TROPICUS The copper concentration found in the haemolymph, shell and the whole snail was determined by atomic absorption spectrophotometry. These concentration values were designated as the background copper con= centration. No copper was found in the snail haernolymph or the shell after a six hour exposure of snails to 1 ppm Cuso 4 . This exposure to Cuso 4 was done at a pH of 7,2 and 8,4. Because of differences in the solubility of copper= sulphate at different pH levels the amount of cop= per available in aquarium water at pH 4, 7,2 and 8,4 was determined by atomic absorption spectrophotometry. Snails were exposed for six hours to 1 ppm Cuso 4 . It was found that copper accumulated in the snails within the first 20 minutes. After this period no further accumulation occurred. Snails which have accumulated copper do not release the copper into the water. For this experiment the water was analysed for copper for a period of 24 hours. This test was done using an atomic absorption spectrophotometer and radio-active copper. Snails were also exposed to increasing concentrations of Cuso 4 and at the same ti me the decrease of copper from the water was monitored, The relationship between copper uptake by the snail and its increasing metabolic rate showed that the rate of copper uptake does not increase with increasing metabolic activity. An experiment to measure the adsorption of copper by dead snail tissue was performed. It was found that no adsorption of copper took place on this tissue. Adsorption of copper on Perspex and Pyrex glass containers was demonstrated in a series of experiments. Transmission electron microscopy showed historical changes in the sub-epithelial tissues. Large vacuoles appeared just below the basement membrane. These changes were found in tissues of both the head and the tentacles of the snail. The results obtained from the various experiments indicate that copper is adsorbed on the exposed body wall of the snail. It is suggested that chemisorption and not physisorption could be the underlying a mechanism of adsorption of copper on the snails outer epithelium

DSc, North-West University, Potchefstroom Campus

Doctoral