METAL RESIDUES IN TISSUES AND FOOD OF A JUVENILE PURPLE-HERON, ARDEA-PURPUREA (ARDEIDAE)

Tissues as well as the stomach contents of an apparently sick, male, j uvenile Purple Heron Ardea purpurea (477 g body weight) were analysed for 13 metals. The bird was caught in the industrial area of Germiston on the East Rand of Johannesburg. The gross pathological abnormalitie s observed in this heron were similar to those found in birds that die d from exposure to acute concentrations of lead-containing compounds. The aluminium and lead residues were considered to be indicative of ac ute exposure whilst the concentration of cadmium was indicative of chr onic exposure. Silver was not detected in all the samples analysed. Co ncentrations of cobalt, manganese and strontium were generally smaller than 100 mu g/g dry mass whilst chromium, copper, nickel, zinc and an timony were smaller than 500 mu g/g. Iron occurred in the highest conc entrations in all tissues. Comparisons with other Ardeidae indicated t hat this juvenile Purple Heron generally had higher metal residues tha n either fledgling, juveniles or adults from unpolluted and polluted a reas. Therefore, the death of this Purple Heron might be attributed to the synergistic action of a combination of metals.