Passerine Exposure to Primarily PCDFs and PCDDs in the River Floodplains Near Midland, Michigan, USA

Abstract

House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (ΣPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of ΣPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (ΣTEQsWHO-Avian), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of ΣPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of ΣPCDD/DFs and ΣTEQsWHO-Avian ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of ΣTEQsWHO-Avian were positively correlated with ΣPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69–84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs.Electronic supplementary materialThe online version of this article (doi:10.1007/s00244-009-9416-6) contains supplementary material, which is available to authorized users.

Dietary exposure of three passerine species to PCDD/DFs from the Chippewa, Tittabawassee, and Saginaw River floodplains, Midland, Michigan, USA

“…5). These trends are similar to house wren, tree swallow, and eastern bluebird tissues collected from the same sites (Fredricks et al 2010a). One possible explanation for greater values in both food web items and bolus samples at the T-6 location involves the natural hydrology of the Tittabawassee River.…”

“…Predictions of nestling body burdens ( PCDD/DFs) at fledge based on bolus ADD pot were greater than those measured (Fredricks et al 2010a) for all species studied regardless of study area. Nestling body burdens equaled the sum of the total ingestion of bolus-based dietary PCDD/DFs over the nesting period and measured average total PCDD/DFs per egg divided by the average nestling mass (Fredricks et al 2010b).…”

“…Open symbols are from reference areas (R-1 and R-2); closed symbols are from Tittabawassee River study areas (T-3 to T-6); egg concentration ranges from Tittabawassee River study areas are of fset to the left 2010a). Mean ± SD concentration (nanograms per kilogram ww) of PCDD/DFs in nestlings of house wrens, tree swallows, and eastern bluebirds at reference areas and Tittabawassee River SAs was 2.0 × 10 1 ± 7.5 × 10 0 (n = 12) and 5.6 × 10 2 ± 4.0 × 10 2 (n = 26), 9.4 × 10 1 ± 4.9 × 10 1 (n = 12) and 8.7 × 10 2 ± 1.5 × 10 3 (n = 21), and 3.8 × 10 1 ± 2.4 × 10 1 (n = 12) and 7.6 × 10 2 ± 5.7 × 10 2 (n = 16), respectively (Fredricks et al 2010a). Maternal transfer of total PCDD/DFs per egg contributed <15% of the predicted nestling body burdens at fledge for all species studied regardless of study area or diet type, with the exception of the house wren food web-based exposure where maternal transfer contributed approximately 25%.…”

“…Detailed site descriptions and protocols for collecting and handling samples of eggs and nestlings have been previously presented (Fredricks et al 2010a). Briefly, nest boxes were monitored daily from mid-April through the end of the breeding season from 2005 to 2007.…”

“…By comparing the bolus-based dietary samples with the food web-based dietary estimates based on site-specific percent dietary compositions and concentrations in food web items, it can be determined whether invertebrates collected in the biological sampling areas (BSAs) are truly representative of the congener profile and concentrations fed to on-site nestlings. A secondary objective was to determine how well estimates of dietary exposure based on site-specific dietary composition and accumulation factors from the literature correspond to measured concentrations in nestlings (Fredricks et al 2010a).…”