Mercury methylation in sediments of a Brazilian mangrove under different vegetation covers and salinities.
The presence and formation of methylmercury (MMHg), a highly toxic form of Hg, in mangrove ecosystems is poorly studied. Therefore the aim of this study was to evaluate mercury methylation potentials in sediment, litter and root samples (Avicennia shaueriana and Spartina alterniflora) from different regions of a mangrove ecosystem, as well as the influence of salinity on methylation. Sediment was sampled under different depths and in mangrove regions with different plant covers and salinities. All samples were incubated with (203)Hg and MM(203)Hg was extracted and measured by liquid scintillation. MMHg was formed in all samples and sites tested including plant roots and litter. Higher Hg methylation was found in the superficial fraction of sediments (0.47-7.82%). Infralittoral sandy sediment had low MMHg formation (0.44-1.61%). Sediment under Rhizophora mangle had lower MMHg formation (0.018-2.23%) than under A. shaueriana (0.2-4.63%) and Laguncularia racemosa (0.08-7.82). MMHg formation in sediment tended to increase with salinity but the differences were not significant. Therefore, MMHg formation occurs in different sites of mangrove ecosystems and may be an important threat that requires further study.
Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil. Electronic address: diciannella@yahoo.com.br.
Diana Ciannella Martins
DC
de Oliveira
Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil. Electronic address: raquel@biof.ufrj.br.
Raquel Rose Silva
RR
Correia
Laboratório de Limnologia, Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Bloco A/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil. Electronic address: clcamar@biologia.ufrj.br.
Claudio Cardoso
CC
Marinho
Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ) CEP: 21941-902, Brazil. Electronic address: jeanrdg@biof.ufrj.br.
Jean Remy Davée
JR
Guimarães
D032407:Avicennia / Q000737:chemistry* / Q000254:growth & development; D001938:Brazil; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry*; D008628:Mercury / Q000032:analysis; D008745:Methylation; D008767:Methylmercury Compounds / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry / Q000254:growth & development; D006109:Poaceae / Q000737:chemistry* / Q000254:growth & development; D058441:Rhizosphere; D054712:Salinity
D008767:Methylmercury Compounds; D008628:Mercury
Biogeochemistry; Coastal ecosystems; Liquid scintillation; Methylmercury; Radioisotope