Reactivity and Mobility of New and Old Mercury Deposition in a Boreal Forest Ecosystem during the First Year of the METAALICUS Study

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• 作者：Holger Hintelmann ; Reed Harris ; Andrew Heyes ; James P. Hurley ; Carol A. Kelly ; David P. Krabbenhoft ; Steve Lindberg ; John W. M. Rudd ; Karen J. Scott ; and Vincent L. St.Louis
• 刊名：Environmental Science & Technology
• 出版年：2002
• 出版时间：December 1, 2002
• 年：2002
• 卷：36
• 期：23
• 页码：5034 - 5040
• 全文大小：168K
• 年卷期：v.36,no.23(December 1, 2002)
• ISSN：1520-5851

文摘

The METAALICUS (Mercury Experiment To AssessAtmospheric Loading In Canada and the US) project is awhole ecosystem experiment designed to study the activity,mobility, and availability of atmospherically depositedmercury. To investigate the dynamics of mercury newlydeposited onto a terrestrial ecosystem, an enriched stableisotope of mercury (²⁰²Hg) was sprayed onto a Borealforest subcatchment in an experiment that allowed us, forthe first time, to monitor the fate of "new" mercury indeposition and to distinguish it from native mercury historicallystored in the ecosystem. Newly deposited mercury wasmore reactive than the native mercury with respect tovolatilization and methylation pathways. Mobility throughrunoff was very low and strongly decreased with time becauseof a rapid equilibration with the large native pool of"bound" mercury. Over one season, only ~8% of theadded ²⁰²Hg volatilized to the atmosphere and less than1% appeared in runoff. Within a few months, approximately66% of the applied ²⁰²Hg remained associated withabove ground vegetation, with the rest being incorporatedinto soils. The fraction of ²⁰²Hg bound to vegetation wasmuch higher than seen for native Hg (<5% vegetation),suggesting that atmospherically derived mercury enters thesoil pool with a time delay, after plants senesce anddecompose. The initial mobility of mercury received throughsmall rain events or dry deposition decreased markedlyin a relatively short time period, suggesting that mercurylevels in terrestrial runoff may respond slowly to changes inmercury deposition rates.