DOI: 10.1002/gbc.20021
Scopus记录号: 2-s2.0-84879204393
论文题名: Mercury isotopes in a forested ecosystem: Implications for air-surface exchange dynamics and the global mercury cycle
作者: Demers J ; D ; , Blum J ; D ; , Zak D ; R
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2013
卷: 27, 期: 1 起始页码: 222
结束页码: 238
语种: 英语
英文关键词: Air-Surface Exchange
; Forested Ecosystems
; Mercury Biogeochemistry
; Mercury Stable Isotopes
Scopus关键词: Air-surface exchanges
; Atmospheric mercury
; Biogeochemical cycling
; Isotopic composition
; Precipitation samples
; Stable isotopes
; Terrestrial ecosystems
; Total gaseous mercuries
; Biogeochemistry
; Carbon dioxide
; Deposition
; Ecosystems
; Forestry
; Isotopes
; Soils
; Mercury (metal)
; atmosphere-biosphere interaction
; biogeochemistry
; foliage
; forest ecosystem
; isotopic composition
; mercury (element)
; stable isotope
; Rhinelander
; United States
; Wisconsin
英文摘要: Forests mediate the biogeochemical cycling of mercury (Hg) between the atmosphere and terrestrial ecosystems; however, there remain many gaps in our understanding of these processes. Our objectives in this study were to characterize Hg isotopic composition within forests, and use natural abundance stable Hg isotopes to track sources and reveal mechanisms underlying the cycling of Hg. We quantified the stable Hg isotopic composition of foliage, forest floor, mineral soil, precipitation, and total gaseous mercury (THg (g)) in the atmosphere and in evasion from soil, in 10-year-old aspen forests at the Rhinelander FACE experiment in northeastern Wisconsin, USA. The effect of increased atmospheric CO2 and O3 concentrations on Hg isotopic composition was small relative to differences among forest ecosystem components. Precipitation samples had δ202Hg values of -0.74 to 0.06‰ and Δ199Hg values of 0.16 to 0.82‰. Atmospheric THg(g) had δ202Hg values of 0.48 to 0.93‰ and Δ199Hg values of -0.21 to -0.15‰. Uptake of THg(g) by foliage resulted in a large (-2.89‰) shift in δ202Hg values; foliage displayed δ202Hg values of -2.53 to -1.89‰ and Δ199Hg values of -0.37 to -0.23‰. Forest floor samples had δ202Hg values of -1.88 to -1.22‰ and Δ199Hg values of -0.22 to -0.14‰. Mercury isotopes distinguished geogenic sources of Hg and atmospheric derived sources of Hg in soil, and showed that precipitation Hg only accounted for ~16% of atmospheric Hg inputs. The isotopic composition of Hg evasion from the forest floor was similar to atmospheric THg(g); however, there were systematic differences in δ202Hg values and MIF of even isotopes (Δ200Hg and Δ204Hg). Mercury evasion from the forest floor may have arisen from air-surface exchange of atmospheric THg (g), but was not the emission of legacy Hg from soils, nor re-emission of wet-deposition. This implies that there was net atmospheric THg(g) deposition to the forest soils. Furthermore, MDF of Hg isotopes during foliar uptake and air-surface exchange of atmospheric THg (g) resulted in the release of Hg with very positive δ202Hg values to the atmosphere, which is key information for modeling the isotopic balance of the global mercury cycle, and may indicate a shorter residence time than previously recognized for the atmospheric mercury pool. ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77608
Appears in Collections: 气候变化事实与影响
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作者单位: University of Michigan, Department of Earth and Environmental Sciences, Ann Arbor, MI 48109, United States; School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI, United States
Recommended Citation:
Demers J,D,, Blum J,et al. Mercury isotopes in a forested ecosystem: Implications for air-surface exchange dynamics and the global mercury cycle[J]. Global Biogeochemical Cycles,2013-01-01,27(1)