Mercury Stable Isotopes in Seabird Eggs Reflect a Gradient from Terrestrial Geogenic to Oceanic Mercury Reservoirs

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• 作者：Rusty D. Day ; David G. Roseneau ; Sylvain Berail ; Keith A. Hobson ; Olivier F. X. Donard ; Stacy S. Vander Pol ; Rebecca S. Pugh ; Amanda J. Moors ; Stephen E. Long ; Paul R. Becker
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：May 15, 2012
• 年：2012
• 卷：46
• 期：10
• 页码：5327-5335
• 全文大小：446K
• 年卷期：v.46,no.10(May 15, 2012)
• ISSN：1520-5851

文摘

Elevated mercury concentrations ([Hg]) were found in Alaskan murre (Uria spp.) eggs from the coastal embayment of Norton Sound relative to insular colonies in the northern Bering Sea-Bering Strait region. Stable isotopes of Hg, carbon, and nitrogen were measured in the eggs to investigate the source of this enrichment. Lower 未¹³C values in Norton Sound eggs (鈭?3.3鈥?to 鈭?0.0鈥? relative to eggs from more oceanic colonies (鈭?0.9鈥?to 鈭?8.7鈥? indicated that a significant terrestrial carbon source was associated with the elevated [Hg] in Norton Sound, implicating the Yukon River and smaller Seward Peninsula watersheds as the likely Hg source. The increasing [Hg] gradient extending inshore was accompanied by strong decreasing gradients of 未²⁰²Hg and 螖¹⁹⁹Hg in eggs, indicating lower degrees of mass-dependent (MDF) and mass-independent Hg fractionation (MIF) (respectively) in the Norton Sound food web. Negative or zero MDF and MIF signatures are typical of geological Hg sources, which suggests murres in Norton Sound integrated Hg from a more recent geological origin that has experienced a relatively limited extent of aquatic fractionation relative to more oceanic colonies. The association of low 未²⁰²Hg and 螖¹⁹⁹Hg with elevated [Hg] and terrestrial 未¹³C values suggested that Hg stable isotopes in murre eggs effectively differentiated terrestrial/geogenic Hg sources from oceanic reservoirs.