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 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