Mercury in sediments and vegetation in a moderately contaminated salt marsh (Tagus Estuary, Portugal)

João Canário, Carlos Vale, Laurier Poissant, Marta Nogueira, Martin Pilote, Vasco Branco

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

Depth variations of total mercury (Hg) and methylmercury (MeHg) concentrations were studied in cores from non-colonized sediments, sediments colonized by Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima and belowground biomass, in a moderately contaminated salt marsh (Tagus Estuary, Portugal). Concentrations in belowground biomass exceeded up to 3 (Hg) and 15 (MeHg) times the levels in sediments, and up to 198 (Hg) and 308 (MeHg) times those found in aboveground parts. Methylmercury in colonized sediments reached 35% of the total Hg, 50 times above the maximum values found in non-colonized sediments. The absence of correlations between total Hg concentrations in sediments and the corresponding MeHg levels suggested that methylation was only dependent on the environmental and microbiological factors. The analysis of belowground biomass at high-depth resolution (2 cm) provided evidence that Hg and MeHg were actively absorbed from sediments, with higher enrichment factors at layers where higher microbial activity was probably occurring. The results obtained in this study indicated that the biotransformation of Hg to the toxic MeHg could increase the toxicity of plant-colonized sediments.

Original languageEnglish
Pages (from-to)1151-1157
Number of pages7
JournalJournal of Environmental Sciences
Volume22
Issue number8
DOIs
Publication statusPublished - Aug 2010
Externally publishedYes

Keywords

  • Mercury
  • Methylmercury
  • Portugal
  • Salt marshes
  • Tagus Estuary

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