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Foliage/atmosphere exchange of mercury in a subtropical coniferous forest in south China
Author(s) -
Luo Yao,
Duan Lei,
Driscoll Charles T.,
Xu Guangyi,
Shao Mengshu,
Taylor Mariah,
Wang Shuxiao,
Hao Jiming
Publication year - 2016
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2016jg003388
Subject(s) - mercury (programming language) , environmental chemistry , atmosphere (unit) , transpiration , biogeochemical cycle , environmental science , pinus massoniana , deposition (geology) , canopy , chemistry , photosynthesis , botany , meteorology , biology , paleontology , biochemistry , sediment , computer science , programming language , physics
Foliage/atmosphere exchange is an important pathway of deposition and loss in the biogeochemical mercury (Hg) cycle of terrestrial ecosystems. The foliage/atmosphere fluxes of Hg 0 were observed over four seasons in a Masson pine ( Pinus massoniana ) forest in south China. Hg 0 exchange showed a bidirectional process but without clear compensation point. Hg 0 emissions peaked midday in all four seasons, probably associated with Hg photoreduction on needle surface. Peaks in Hg 0 adsorption/deposition often occurred in the morning, especially in spring and autumn. Although current‐year needles accumulated Hg at a rate of 19.4 µg m −2 yr −1 , they were a net Hg 0 source of 1.7 µg m −2 yr −1 to the atmosphere as their release of Hg exceeded inputs. In addition, previous‐year needles emitted Hg 0 at an average rate of 9.2 µg m −2 yr −1 . Based on the mass balance of Hg in the forest canopy, the dry deposition of Hg was estimated 52.5 µg m −2 yr −1 , much higher than the wet deposition (to 14.4 µg m −2 yr −1 ). Although Hg in the atmosphere is considered the main source of Hg in folia, soil water may contribute to Hg 0 emission by plant transpiration. These processes should be further studied in the future.