CONTAMINANTS IN OSPREYS FROM THE PACIFIC-NORTHWEST - I - TRENDS AND PATTERNS IN POLYCHLORINATED DIBENZO-P-DIOXINS AND -DIBENZOFURANS IN EGGS AND PLASMA

Osprey (Pandion haliaetus) eggs were collected from 1991 to 1997 at ne sts (n = 121) upstream and downstream of bleached kraft pulp mills and at reference sites in the Fraser and Columbia River drainage systems of British Columbia, Washington, and Oregon. Blood samples were collec ted from nestling ospreys during the 1992 breeding season on the Thomp son River. Samples were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and -dibenzofurans (PCDFs). Mean concentrations of 2,3,7,8-TC DD were significantly higher in eggs collected in 1991 at downstream c ompared to upstream nests near pulp mills at Kamloops and Castlegar, B ritish Columbia. There were no significant temporal trends in 2,3,7,8- TCDD, -TCDF or other measured compounds at a sample of nests monitored between 1991 and 1994 downstream of the Castlegar pulp mill, despite changes in bleaching technology (CIO2 substitution). However, by 1997 concentrations of 2,3,7,8-TCDD and -TCDF were significantly lower than previous years in nests sampled downstream at both Castlegar and Kaml oops. An unusual pattern of higher chlorinated PCDDs and PCDFs was fou nd in many of the osprey eggs collected in this study, and considerabl e individual variation in the pattern existed among eggs from the same site. For example, eggs from four different nests at one study area ( Quesnel) on the Fraser River had concentrations of 1,2,3,4,6,7,8-HpCDD ranging from <1 to 1,100 ng/kg and OCDD from <1 to 7,000 ng/kg wet we ight. Higher mean concentrations of HpCDD and OCDD were found in eggs from the Thompson River, a tributary of the Fraser, compared to the Co lumbia River, and concentrations were generally higher at nests upstre am of pulp mills. In plasma samples, 1,2,3,4,6,7,8-HpCDD and OCDD were the main compounds detected, with no significant differences measured between samples upstream versus downstream or earlier versus later in the breeding season. Use of chlorophenolic wood preservatives by lumb er processors was considered the main source of higher chlorinated PCD D/Fs throughout the systems, based on patterns of trace PCDFs in eggs and significant correlations between egg concentrations of pentachloro phenol and both HpCDD (r = 0.891, p < 0.01) and OCDD (r = 0.870 p < 0. 01).