Mercury concentrations in bald eagles across an impacted watershed in Maine, USA
Mercury (Hg) exposure was evaluated in bald eagles (Haliaeetus leucocephalus) in the lower Penobscot River watershed (PRW) in Maine to assess whether Hg discharges from a chlor-alkali plant (HoltraChem) influenced Hg concentrations in nestling tissues. Mean Hg concentrations in nestling blood and br...
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| Published in: | The Science of the total environment Vol. 627; pp. 1515 - 1527 |
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| Main Authors: | , , , , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Netherlands
Elsevier B.V
15-06-2018
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Mercury (Hg) exposure was evaluated in bald eagles (Haliaeetus leucocephalus) in the lower Penobscot River watershed (PRW) in Maine to assess whether Hg discharges from a chlor-alkali plant (HoltraChem) influenced Hg concentrations in nestling tissues. Mean Hg concentrations in nestling blood and breast feathers sampled in marine and estuarine areas potentially contaminated with Hg from HoltraChem (the potential Hg impact zone) were significantly greater than those from reference sites spanning the Maine coast. To place Hg exposure in the potential Hg impact zone into a broader context, Hg exposure in bald eagle nestlings from four habitat types in the PRW was assessed. Mercury concentrations varied significantly across habitat types within the PRW, generally following the pattern: marine=estuarine<freshwater river<lake. While findings suggest that Hg inputs from HoltraChem elevated Hg concentrations in eagles in the potential Hg impact zone, those Hg concentrations were still significantly lower than those of nestlings raised in freshwater river and lake habitats in the PRW and elsewhere in Maine not contaminated by HoltraChem. Breast feathers had 31% higher statistical power to detect Hg differences among habitat types compared to nestling blood, demonstrating their higher value in biomonitoring efforts. Nestling tissue Hg concentrations in the PRW were within the range of reported Hg values for bald eagles, but were generally higher than most population comparisons within habitats. Mercury concentrations in lake-nesting bald eagles in the PRW were impacted primarily by inputs from atmospheric deposition, and Hg exposure in nestlings associated with this habitat type in the PRW often had similar or higher Hg exposure than those associated with point sources elsewhere. Mercury concentrations in bald eagle nestlings and a small sample of adults in our study commonly exceeded levels associated with adverse health effects in other bird species.
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•We compared the influence of a chlor-alkali plant and habitat on eagle Hg exposure.•Hg exposure was higher in the zone impacted by the plant than the reference.•Eagle Hg differed significantly among lake, river, estuarine and marine habitats.•Habitat type was more important than the chlor-alkali plant in influencing eagle Hg.•Eagle Hg exposure was high relative to other populations and effects concentrations. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0048-9697 1879-1026 |
| DOI: | 10.1016/j.scitotenv.2018.01.023 |