1 research outputs found
Isotopic Composition of Atmospheric Mercury in China: New Evidence for Sources and Transformation Processes in Air and in Vegetation
The
isotopic composition of atmospheric total gaseous mercury (TGM)
and particle-bound mercury (PBM) and mercury (Hg) in litterfall samples
have been determined at urban/industrialized and rural sites distributed
over mainland China for identifying Hg sources and transformation
processes. TGM and PBM near anthropogenic emission sources display
negative δ<sup>202</sup>Hg and near-zero Δ<sup>199</sup>Hg in contrast to relatively positive δ<sup>202</sup>Hg and
negative Δ<sup>199</sup>Hg observed in remote regions, suggesting
that different sources and atmospheric processes force the mass-dependent
fractionation (MDF) and mass-independent fractionation (MIF) in the
air samples. Both MDF and MIF occur during the uptake of atmospheric
Hg by plants, resulting in negative δ<sup>202</sup>Hg and Δ<sup>199</sup>Hg observed in litter-bound Hg. The linear regression resulting
from the scatter plot relating the δ<sup>202</sup>Hg to Δ<sup>199</sup>Hg data in the TGM samples indicates distinct anthropogenic
or natural influences at the three study sites. A similar trend was
also observed for Hg accumulated in broadleaved deciduous forest foliage
grown in areas influenced by anthropogenic emissions. The relatively
negative MIF in litter-bound Hg compared to TGM is likely a result
of the photochemical reactions of Hg<sup>2+</sup> in foliage. This
study demonstrates the diagnostic stable Hg isotopic composition characteristics
for separating atmospheric Hg of different source origins in China
and provides the isotopic fractionation clues for the study of Hg
bioaccumulation