Contaminants in ospreys from the Pacific northwest: II. Organochlorine pesticides, polychlorinated biphenyls, and mercury, 1991-1997

Eggs of ospreys (Pandion haliaetus) were collected over the period 1991 to 1997 at 111 nests in the Eraser and Columbia River drainage systems of Brit ish Columbia, Washington, and Oregon. Contents were analyzed for organochlo rine (OC) pesticides, polychlorinated biphenyls (PCBs), and total mercury. Blood samples were taken from nestling ospreys at two time points during th e 1992 breeding season on the Thompson River and analyzed for non-ortho PCB s. Concentrations of DDE and related compounds showed high variability amon g individual eggs within study areas and no significant differences in mean concentrations among study areas. Some eggs contained high concentrations of DDE, up to 20 mg/kg (wet weight), for which there were no evident local sources, suggesting that exposure occurred outside of the breeding grounds. Most other OC pesticides measured in osprey eggs showed a similar distribu tion, although mean concentrations of chlordane-related compounds were gene rally, and in some cases significantly, higher in samples collected from th e Columbia River sites compared to elsewhere. Significantly greater concent rations of PCBs were found in eggs from the Columbia River basin compared t o the Fraser. This was attributed to extensive development of hydroelectric generation and related industries on the Columbia system. Significant diff erences among sites were also found in the pattern of PCB congeners, e.g., eggs from the lower Columbia River site had proportionally greater concentr ations of less chlorinated, Aroclor 1242-type PCBs compared to other sites. In contrast, eggs from upper reaches of the Columbia River had relatively greater amounts of Aroclor 1254 and 1260 congeners. Mercury concentrations in osprey eggs tended to be uniform among sites and comparable to those rep orted in the literature for ospreys nesting on naturally formed lakes and r ivers. There were no significant temporal changes in mean concentrations of any of the measured compounds at sites monitored from 1991 to 1997.