期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 660, 期 -, 页码 1502-1512出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2019.01.058
关键词
Tundra; Vegetation; Mercury; Stable Hg isotopes; Arctic; Alaska
资金
- U.S. National Science Foundation's (NSF) Office of Polar Programs [1304305, 1739567]
- NSF's Division of Atmospheric and Geospace Sciences [1848212]
- European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant [657195]
- Marie Curie Actions (MSCA) [657195] Funding Source: Marie Curie Actions (MSCA)
- Directorate For Geosciences
- Office of Polar Programs (OPP) [1304305] Funding Source: National Science Foundation
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1848212] Funding Source: National Science Foundation
- Office of Polar Programs (OPP)
- Directorate For Geosciences [1739567] Funding Source: National Science Foundation
Vegetation uptake of atmospheric mercury (Hg) is an important mechanism enhancing atmospheric Hg deposition via litterfall and senescence. We here report Hg concentrations and pool sizes of different plant functional groups and plant species across nine tundra sites in northern Alaska. Significant spatial differences were observed in bulk vegetation Hg concentrations at Toolik Field station (52 +/- 9 mu g kg(-1)), Eight Mile Lake Observatory (40 +/- 0.2 mu g kg(-1)), and seven sites along a transect from Toolik Field station to the Arctic coast (36 +/- 9 mu g kg(-1)). Hg concentrations in non-vascular vegetation including feather and peat moss (58 +/- 6 mu g kg(-1) and 34 +/- 2 mu g kg(-1), respectively) and brown and white lichen (41 +/- 2 mu g kg(-1) and 34 +/- 2 mu g kg(-1), respectively), were three to six times those of vascular plant tissues (8 +/- 1 mu g kg(-1) in dwarf birch leaves and 9 +/- 1 mu g kg(-1) in tussock grass). A high representation of non-vascular vegetation in above ground biomass resulted in substantial Hg mass contained in tundra above ground vegetation (29 mu g m(-2)), which fell within the range of foliar Hg mass estimated for forests in the United States (15 to 45 mu g m(-2)) in spite of much shorter growing seasons. Hg stable isotope signatures of different plant species showed that atmospheric Hg(0) was the dominant source of Hg to tundra vegetation. Mass-dependent isotope signatures (delta Hg-202) in vegetation relative to atmospheric Hg (0) showed pronounced shifts towards lower values, consistent with previously reported isotopic fractionation during foliar uptake of Hg(0). Mass-independent isotope signatures (Delta Hg-199) of lichen were more positive relative to atmospheric Hg(0), indicating either photochemical reduction of Hg(II) or contributions of inorganic Hg (II) from atmospheric deposition and/or dust Delta Hg-199 and Delta Hg-200 values in vascular plant species were similar to atmospheric Hg(0) suggesting that overall photochemical reduction and subsequent re-emission was relatively insignificant in these tundra ecosystems, in agreement with previous Hg(0) ecosystem flux measurements. (C) 2019 Elsevier B.V. All rights reserved.
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