Environ. Sci. Technol. 2003, 37, 3071-3077
Dioxins, Furans, and Non-Ortho PCBs in Canadian Arctic Seabirds BIRGIT M. BRAUNE* AND MARY SIMON Canadian Wildlife Service, Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, Ontario, Canada K1A 0H3
This is the first account of PCDDs, PCDFs, and non-ortho PCBs in Canadian Arctic seabirds. Livers and eggs of thickbilled murres, northern fulmars, and black-legged kittiwakes were collected in 1975 and 1993 from Prince Leopold Island in Lancaster Sound, Canada. Detectable concentrations of PCDDs, PCDFs, and non-ortho PCBs were found in all the Arctic seabird samples analyzed. Of the PCDD congeners assayed, only 2,3,7,8-substituted PCDDs were detected in the samples, whereas non-2,3,7,8-substituted PCDFs were found in addition to 2,3,7,8-substituted PCDFs in some of the samples. The predominant PCDD/F congener found in the livers of all three species was 2,3,4,7,8PnCDF, both in 1975 and 1993. Concentrations of most dioxins and furans decreased in the fulmars and kittiwakes between 1975 and 1993 but increased in the murres. Of the non-ortho PCBs measured, PCB-126 occurred in the highest concentrations and contributed the majority of the nonortho PCB-TEQ in all three species in both years. The highest concentrations of dioxins and furans as well as the highest TEQ values were found in the northern fulmar livers in both 1975 and 1993. Concentrations of some of the PCDDs and PCDFs are among the highest reported for Canadian Arctic biota.
Introduction Polychorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) enter the environment as byproducts of industrial processes. The tetra- to octachlorinated PCDDs and PCDFs have lower vapor pressures and Henry’s law constants than PCBs and are, therefore, not expected to undergo long-range transport to the same extent as PCBs (1). The major sources of PCDDs and PCDFs to air are the following: (i) low-temperature incineration of chlorinecontaining waste such as plastics, particularly where incomplete combustion occurs, (ii) wood burning and other combustion, and (iii) metallurgical industries (2, 3). Such activities located in or near the Arctic are suspected as local sources of PCDDs and PCDFs to the Arctic environment (3), but long-range transport is still considered to be the main dispersion mechanism of persistent organochlorines to remote marine regions (2, 4). PCDDs, PCDFs, and PCBs are highly lipophilic. PCDDs and PCDFs with chlorine substitution at the 2, 3, 7, and 8 positions show a high resistance toward metabolic breakdown and, therefore, high levels of these compounds can accumulate in predators at the top of a food chain (5). The 3,3′,4,4′ non-ortho-substituted PCBs are structurally similar to 2,3,7,8-TCDD and act through the same mechanism of * Corresponding author phone: (613)998-6694; fax: (613)998-0458; e-mail:
[email protected]. 10.1021/es021082p CCC: $25.00 Published on Web 06/10/2003
Published 2003 by the Am. Chem. Soc.
toxicity as TCDD (6). In the Canadian Arctic, TCDD concentrations up to 40 ng/kg have been found in ringed seal (Phoca hispida) blubber and up to 18 ng/kg in polar bear (Ursus maritimus) fat (7), both top predators in the marine food web. This is in sharp contrast with the terrestrial food web where concentrations of PCDDs, PCDFs, and non-ortho PCBs in Canadian Arctic caribou (Rangifer tarandus) are among the lowest ever reported in wildlife (8). Eggs and tissues of seabirds have been used to monitor contamination of the Canadian Arctic marine environment since 1975 (9, 10). At the time of egg formation, organochlorine compounds are transferred along with lipid to the eggs thus reflecting the contaminant burden in the female at the time of laying (11). Contaminant burden is comprised of residues assimilated over a long time period and, particularly in migratory species, may represent exposure from a number of different locations (12, 13). Interpretation of contaminant concentrations in seabirds may also be confounded if seabird populations shift their dietary patterns over trophic levels through time. Fortunately, retrospective analysis of trophic level in seabirds is possible through the measurement of naturally occurring stable isotopes of nitrogen (δ15N) (14, 15). In the Canadian Arctic, residue data are available for organochlorines and mercury in seabird eggs and tissues collected from Prince Leopold Island in Lancaster Sound, Canada (9, 10). Although measurements of 2,3,7,8-TCDD have been reported for eggs of ivory gulls (Pagophila eburnea) from Seymour Island in the western Canadian Arctic (16), this is the first comprehensive account of PCDDs, PCDFs, and non-ortho PCBs in Canadian Arctic seabirds.
Methods Sample Collection. Adult northern fulmars (Fulmaris glacialis), black-legged kittiwakes (Rissa tridactyla), and thickbilled murres (Uria lomvia) were collected from the Prince Leopold Island Migratory Bird Sanctuary (74°02′ N, 90°05′ W) in Lancaster Sound, Nunavut, Canada (Figure 1) during 1975 and 1993. All birds were collected using quick-kill techniques. Eggs of all three species collected in 1993 (10) were also analyzed for this study. No attempt was made to collect eggs laid by adult females which had been sampled. All eggs and adult birds were shipped to the Canadian Wildlife Service (CWS) laboratories at the National Wildlife Research Centre in Hull, Quebec, where the birds were dissected under chemically clean conditions and their livers removed. Livers and egg contents were homogenized, transferred to acetonehexane rinsed glass vials, and stored at -40 °C. This method of storage has been shown to avoid changes in contaminant and moisture content over time (17, 18). Samples were retrieved from storage and analyzed retrospectively during 1999-2000. Chemical Analysis. Liver and egg homogenates were analyzed as pooled samples, i.e., one pool per tissue per species per year. Numbers of samples in each pool varied according to availability (Table 1). Liver pools were comprised of both male and female birds. Samples were analyzed for polychorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non-ortho substituted polychlorinated biphenyls (NOPCBs) using HRGC/HRMS Selected Ion Monitoring (SIM) according to CWS Method No. MET-CHEM-PCDD-01 (19). Briefly, samples were ground with anhydrous sodium sulfate, transferred to a chromatographic column, and eluted with solvent. Extracts were cleaned up and fractionated by gel permeation chromatography and alumina column cleanup followed by carbon/glass fiber column separation. Further VOL. 37, NO. 14, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Concentrations and TEQs for PCDDs, PCDFs, and Non-Ortho PCBs (ng/kg Lipid Weight) in Arctic Seabird Livers and Eggs from Prince Leopold Island species
black-legged kittiwake
northern fulmar
thick-billed murre
tissue no. samples in pool year % lipid
liver 5 1975 9.0
liver 10 1993 4.3
egg 2 1993 5.1
liver 10 1975 2.6
liver 10 1993 4.4
egg 3 1993 8.9
liver 10 1975 8.6
liver 10 1993 3.3
egg 3 1993 6.8
PCDDs 2378-TCDDa 12378-PnCDDa 123478-HxCDDa 123678-HxCDDa 123789-HxCDDa 1234678-HpCDDa OCDDa ΣPCDD PCDD-TEQb
195 187
