Evidence for Elevated Production of Methylmercury in Salt Marshes

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• 作者：Joã ; o Caná ; rio ; Miguel Caetano ; Carlos Vale ; Rute Cesá ; rio
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：November 1, 2007
• 年：2007
• 卷：41
• 期：21
• 页码：7376 - 7382
• 全文大小：151K
• 年卷期：v.41,no.21(November 1, 2007)
• ISSN：1520-5851

文摘

Depth variations of total mercury (Hg) and methylmercury(MeHg) concentrations were obtained in cores fromnonvegetated sediments, sediments colonized by Sarcocorniafruticosa, Halimione portulacoides, and Spartina maritimaand below-ground biomass in three Portuguese estuaries.Similar analyses were also performed on the above-groundplant tissues. Concentrations in below-ground biomassexceeded up to 9 (Hg) and 44 (MeHg) times the levels insediments. Mercury and MeHg in below-ground biomasswere up to 400 (Hg) and 4700 (MeHg) times higher thanthose found in above-ground parts, indicating a weak upwardtranslocation. Methylmercury in colonized sedimentsreached 18% of the total Hg, which was 70 times abovethe maximum values found in nonvegetated sediments.Concentrations of MeHg in vegetated sediments were notrelated to plant type but were linearly proportional tothe total mercury levels. The analysis of below-groundbiomass at high depth resolution (2 cm) provided evidencethat Hg and MeHg were elevated. The higher enrichmentfactors were found where the shifting of redox conditionssuggested high microbial activity. Mercury and MeHg inbelow-ground tissues were a function of total levels insediments and again were not plant-specific. These resultssuggest that the bioremediation of mercury-contaminatedsediments is likely to increase the formation of methyl-mercury.