Document Detail

Mercury methylation and bacterial activity associated to tropical phytoplankton.
MedLine Citation:
PMID:  16169057     Owner:  NLM     Status:  MEDLINE    
The methylated form of mercury (Hg), methylmercury (MeHg), is one of the most toxic pollutants. Biotic and/or abiotic methylation, often associated to sulfate-reducing bacteria metabolism, occurs in aquatic environments and in many tropical areas, mostly in the periphyton associated to floating macrophyte roots. Data about mercury methylation by phytoplankton are scarce and the aim of this study was to verify the biotic influence in the methylation process in Microcystis aeruginosa and Sineccocystis sp. laboratory strains and in natural populations of phytoplankton from two different aquatic systems, the mesotrophic Ribeirão das Lajes reservoir and hypereutrophic oligohaline Jacarepaguá lagoon, Rio de Janeiro state, Brazil. Adapted radiochemical techniques were used to measure sulfate-reduction, mercury methylation and bacterial activity in phytoplankton samples. Methyl-(203)Hg formation from added inorganic (203)Hg and (3)H-Leucine uptake were measured by liquid scintillation as well as sulfate-reduction, estimated as H(2)(35)S produced from added Na(2)(35)SO(4). There was no significant difference in low methylation potentials (0.37%) among the two cyanobacterium species studied in laboratory conditions. At Ribeirão das Lajes reservoir, there was no significant difference in methylation, bacterial activity and sulfate-reduction of surface sediment between the sampling points. Methylation in sediments (3-4%) was higher than in phytoplankton (1.5%), the opposite being true for bacterial activity (sediment mean 6.6 against 150.3 nmol gdw(-1) h(-1) for phytoplankton samples). At Jacarepaguá lagoon, an expressive bacterial activity (477.1 x 10(3) nmol gdw(-1) h(-1) at a concentration of 1000 nM leucine) and sulfate-reduction ( approximately 21% H(2)(35)S trapped) associated to phytoplankton (mostly cyanobacteria M. aeruginosa) was observed, but mercury methylation was not detected.
Sérgio A Coelho-Souza; Jean R D Guimarães; Jane B N Mauro; Marcio R Miranda; Sandra M F O Azevedo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-09-16
Journal Detail:
Title:  The Science of the total environment     Volume:  364     ISSN:  0048-9697     ISO Abbreviation:  Sci. Total Environ.     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-05-30     Completed Date:  2006-08-01     Revised Date:  2013-01-24    
Medline Journal Info:
Nlm Unique ID:  0330500     Medline TA:  Sci Total Environ     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  188-99     Citation Subset:  IM    
Laboratório de Traçadores Wolfgang Pfeiffer, SL 62, Instituto de Biofísica Carlos Chagas Filho, Bloco G, Ilha do Fundão, Universidade Federal do Rio de Janeiro (IBCCF/UFRJ), RJ, CEP 21949-900, Brasil.
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MeSH Terms
Leucine / metabolism
Mercury / analysis,  metabolism*
Methylmercury Compounds / analysis*
Microcystis / metabolism*
Phytoplankton / metabolism,  microbiology*
Sulfates / metabolism
Tropical Climate*
Water Pollution, Chemical / analysis*
Reg. No./Substance:
0/Methylmercury Compounds; 0/Sulfates; 0YPR65R21J/sodium sulfate; 61-90-5/Leucine; 7439-97-6/Mercury

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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