Contaminant concentrations in bald eagles nesting on Lake Superior, the upper Mississippi River, and the St. Croix River

Abstract

ABSTRACT We measured concentrations of DDE, total PCBs, and mercury in bald eagle (Haliaeetus leucocephalus) nestlings at three locations in the upper Midwest: Lake Superior, the upper Mississippi River, and the St. Croix River, 2006–2008. We also analyzed trends in concentrations of these contaminants for eagles on the southern shore of Lake Superior, from 1989 to 2008, using the current and previously published data.' Concentrations of DDE in nestling blood plasma samples were greatest on Lake Superior (geometric mean: 16.2 µg/kg, n = 29), whereas concentrations of total PCBs were highest in Mississippi River samples (88.6 µg/ kg, n = 51). Mercury concentrations were highest along the upper St. Croix River (6.81 µg/g wet weight in feathers, n =19). For Lake Superior, DDE concentrations declined significantly in nestling blood plasma samples from 1989 to 2008, an average of 3.0% annually. Similarly, total PCBs in Lake Superior eaglets decreased 4.0% annually from 1989 to 2008, and mercury concentrations ...