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(T/EH017) Effect of age at sampling on organochlorine concentrations in Grey heron chicks' blood. Valters, Karlis1, Olsson, Anders1, Viksne, Janis2, Bergman, Åke1, 1 2 ABSTRACT- Historically, organochlorine substances (OCS) in birds have been most often analyzed using dead eggs. Nowadays though most populations have recovered from the reproduction crisis and dead eggs can no longer be found. Therefore nestling blood has gained more attention as an alternative sample matrix. A number of questions have to be answered before nestling blood can be used in screening or monitoring programs. Our study was aimed to investigate how age of the chicks at the time of sampling affects OCS concentrations in their blood. Blood was collected from a Grey heron (Ardea cinerea) colony at Lake Engure in Latvia. Blood from the heron chicks was drawn at three occasions with a one-week period between the consecutive samplings. In total 107 samples from 10 nests were collected. The total PCB concentrations in the analyzed samples ranged between 1300 and 3700 ng/g lipid weight (l.w.), whereas CB-153, the major PCB congener, ranged from 240 to 750 ng/g l.w.. The OCS levels varied from one sampling time to another. In the most extreme case the total PCB concentrations in blood of the very same chick, drawn at different sampling occasions, differed as much as 1700 ng/g l.w. or 46%. A significant variation of CB-153, DDE, and HCB concentrations was also observed. This variation is not due to different lipid content in blood since it was essentially the same at all sampling times. Our results indicate that the sampling time (age of the chicks) is an important factor to be considered when sampling blood of bird nestling for OCS quantification. Key words: organochlorines, grey heron, birds, blood |
