摘要
1977～1998年间,在苏格兰西部的艾尔萨克雷格对收集到的塘鹅蛋中的多氯联苯(PCB)同类物进行了回顾性分析。对一些年份所收集的塘鹅蛋中每年选择8～10个对其PCB同类物浓度范围分别进行了分析。所有的同类物在几年之内浓度都降在低,但不同的同类物降解速率不同。这种降解是一阶的,并且其半衰期变化范围在PCB-101的5.4年至PCB-180的10.1年之间。蛋内同类物的浓度反映母体的物质负荷,这种物质负荷是由鸟类的摄入速度(主要由于饮食)和损失(由于新陈代谢和其他机体自净化代谢作用)所控制。因此,蛋中同类物浓度下降概括地反映了塘鹅食物(主要是鲱和马鲛)中物质浓度的减小和塘鹅所栖息水域中PCB浓度的减小。这项研究中塘鹅蛋的PCB浓度变化率,与波罗的海和北美五大湖的食鱼鸟类体中PCB浓度变化速率及英国大气中PCB浓度变化速率很相似。这个结果提供了间接证据,证明了塘鹅蛋概括地反映了地区的/全球的范围内PCB同类物消除/转运机制,此机制控制周围PCB的浓度。
Gannet (Sula bassana) eggs collected from Ailsa Craig, Western Scotland between 1977-1998 have been analyzed retrospectively for several PCB congeners. Concentrations of a range of congeners were determined in 8-10 eggs analyzed separately for several individual years. All congeners declined in concentrations throughout the time period, but the rates of decline differed for different congeners. Declines were first order and half-lives varied between 5.4 years for PCB-101 to 10. 1 years for PCB-180. Egg concentrations reflect the maternal body burden, which itself is controlled by the birds rate of intake (principally via the diet) and losses (via metabolism and other clearance mechanisms). The declining concentra-tions in eggs, therefore, broadly reflect reductions in prey concentrations (principally herring and mackerel) and梚n tum梬ater column concentrations. Rates of change in PCB concentrations from this study were similar to those noted in fish-eating birds from the Baltic Sea and North American Great Lakes, and ambient air in the UK. This provides indirect evidence that gannet eggs are broadly reflecting regional/global scale clearance/removal mechanisms which are controlling ambient PCB concentrations.
