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Total depletion of Hg° in the upper troposphere–lower stratosphere
Author(s) -
Talbot R.,
Mao H.,
Scheuer E.,
Dibb J.,
Avery M.
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl031366
Subject(s) - troposphere , stratosphere , tropopause , atmospheric sciences , mercury (programming language) , environmental science , mixing ratio , sink (geography) , chemical transport model , atmospheric chemistry , climatology , ozone , meteorology , geology , physics , cartography , computer science , geography , programming language
Our current understanding of atmospheric mercury lacks fundamental details. Gas phase elemental mercury (Hg°) was measured aboard the NASA DC‐8 research aircraft during the Intercontinental Chemical Transport Experiment‐Phase B (INTEX‐B) conducted in spring 2006 over the North Pacific. Our data confirm efficient chemical cycling of Hg° in the tropopause region and show that it is strongly anti‐correlated with O 3 there, yielding a tropospheric‐stratospheric mixing curve of ∼−0.20 ppqv Hg°/ppbv O 3 . In addition, we found frequent total depletion of Hg° in upper tropospheric (8–12 km) air masses impacted by stratospheric influence. When O 3 mixing ratios were >300 ppbv, Hg° was rarely detected. It appears that in the tropopause and stratosphere Hg° is oxidized on the order of days followed by heterogeneous transformation to particulate mercury. These processes constitute an effective chemical sink for Hg° at the top of the troposphere, which may recycle mercury back to the gas phase as stratospheric aerosols are eventually dispersed into the troposphere.