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Mercury concentrations and pools in four adjacent coniferous and deciduous upland forests in Beijing, China
Author(s) -
Zhou Jun,
Wang Zhangwei,
Zhang Xiaoshan,
Gao Yu
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg003776
Subject(s) - environmental science , mercury (programming language) , plant litter , deciduous , environmental chemistry , ecosystem , biogeochemical cycle , terrestrial ecosystem , chemistry , ecology , biology , programming language , computer science
Understanding of forest mercury (Hg) pools is important for quantifying the global atmospheric Hg removal. We studied gaseous elemental Hg (GEM) concentrations, litterfall Hg depositions, and pool sizes in four adjacent stands at Mount Dongling to assess Hg dynamics in the forested catchment and the potential of Hg release during wildfires. The average GEM concentration was 2.5 ± 0.5 ng m −3 , about 1.5 times of the background levels in the Northern Hemisphere. In all four stands, Hg concentrations increase in the following order: bole wood < branch/twig < bark < mineral soil < needles/leaves < litterfall < Oi litter < Oe soil < Oa organic soil. The Hg pools of aboveground biomass were comparable in the forests of larch, oak, and Chinese pine, which were much greater than that of mixed broadleaf stands due to lower biomass. The total Hg pools in ecosystems were similar in the four stands, because of the comparable Hg pool in the soil horizons (0–40 cm), which accounted for over 97% of the total ecosystem Hg storage in the four stands. Although Hg pools of the forest ecosystem in north China were comparable to North America and North Europe, Hg storage in forests constituted a high threat for large Hg emission pulses to the atmosphere by wildfires. The potential Hg emissions from the combustion at the four stands were ranged from 0.675 to 1.696 mg m −2 .