Organochlorine contaminant assessment in great blue herons using traditional and nonlethal monitoring techniques

A nonlethal method is discussed for the evaluation of contaminant concentrations in whole eggs. Concentrations of pentachlorobenzene, hexachlorobenzene, DDE, and the PCB congeners, BZ-60, BZ-118, BZ-138, BZ-180, and BZ-170 were quantified in tissue samples from great blue herons (Ardea herodias). All tissues within whole eggs from two colonies were homogenized together and analysed for these chlorinated contaminants. Contents and chorio-allantoic membranes (CAMs) of additional whole eggs were separated and analysed. Contaminant distributions were determined for the CAM and contents of whole eggs from the same colonies. CAM tissues remaining in hatched eggs were also analysed for comparative purposes. Utilizing the distributions derived for contaminants between CAM and egg contents and the chemical concentrations determined in CAMs from hatched eggs, contaminant burdens in whole eggs were calculated. This process produced concentration estimates that described actual, whole egg burdens of chlorinated contaminants within a factor of 2 (1.03-3.7). Contaminant burdens in eggs from the two colonies were also statistically different for DDE and total PCB concentrations.