Mercury Methylation in the Epilithon of Boreal Shield Aquatic Ecosystems
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- 作者：Mé ; lanie Desrosiers ; Dolors Planas ; and Alfonso Mucci
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：March 1, 2006
- 年：2006
- 卷：40
- 期：5
- 页码：1540 - 1546
- 全文大小：118K
- 年卷期：v.40,no.5(March 1, 2006)
- ISSN：1520-5851
文摘
Methylation rates by periphyton growing on the rockyshore of a remote boreal shield lake were measured overdiurnal cycles at temperatures representative of summerand fall conditions. The measurements were carried out invitro with natural communities grown on artificial Teflonsubstrates submerged along the lake's shore for 1-2 years.At temperatures above 20 
C, epilithon Hg methylationrates were fast and reached a steady state within 12 h uponexposure to 2 ng L-1 of inorganic mercury. A variety ofinhibitors were used to identify which microorganisms inthe epilithic biofilm are responsible for the methylation. Theaddition of molybdate, which is believed to suppress theactivity of sulfate-reducing bacteria, decreased methylmercuryproduction rates by 60% in both light and dark experiments.The prokaryote inhibitor chloramphenicol reduced themethylation rate by 40% only during dark periods whereasan algal inhibitor (DCMU), which suppresses photosynthesis,decreased the methylation rate by 60% during lightperiods. Results of this study reveal that epilithon communitiesmay be a significant source of MeHg to higher aquaticorganisms in lakes and that the integrity of the epilithicbiofilm is important for its ability to methylate Hg.
C, epilithon Hg methylationrates were fast and reached a steady state within 12 h uponexposure to 2 ng L-1 of inorganic mercury. A variety ofinhibitors were used to identify which microorganisms inthe epilithic biofilm are responsible for the methylation. Theaddition of molybdate, which is believed to suppress theactivity of sulfate-reducing bacteria, decreased methylmercuryproduction rates by 60% in both light and dark experiments.The prokaryote inhibitor chloramphenicol reduced themethylation rate by 40% only during dark periods whereasan algal inhibitor (DCMU), which suppresses photosynthesis,decreased the methylation rate by 60% during lightperiods. Results of this study reveal that epilithon communitiesmay be a significant source of MeHg to higher aquaticorganisms in lakes and that the integrity of the epilithicbiofilm is important for its ability to methylate Hg.