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Speciation and ecological risk of heavy metals and metalloid in the sediments of Zhalong Wetland in China
Ye, H.; Zang, S.; Xiao, H. & Zhang, L.
Abstract
A total of 271 sediments samples from the
Zhalong Wetland were analyzed for concentration and
distribution of Hg, Cd, As, Cu, Pb, Zn, Cr, and Zn; their
speciation according to the modified European Community
Bureau of Reference sequential extraction procedures and
their ecological risk based on Lars Hakanson’s potential
ecological risk assessment and risk assessment code were
made. The results can be summarized as the followings: (1)
Concentrations of all metals measured were above soil
background values of Songnen Plain, and their spatial
distributions were distinctly different. The concentrations
of metals (except Pb) were high in the east, followed by the
north, and were relatively low in the core zone and south.
The concentration of Pb was high in the north, south, and
west, compared with low concentration in the core zone
and east. (2) The dominant proportion of Pb, Zn, and Cr
was in the residual fraction, suggesting that they were
environmental stable. The concentrations of Cu and As in
the reducible fraction, the concentration of Cd in the acidsoluble
fraction, and the concentration of Hg in the oxidizable
fraction were relatively high, indicating they had
greater environmental effects. (3) The evaluation of the
ecological risk showed that Cd, Hg, and As had relatively
high ecological risk index, especially the ecological risk of
Cd should be paid attention to. In general, the ecological
risk of the heavy metals and metalloid by zone was
experimental zone > buffering zone > ecological tourism
zone > core zone.
Keywords
Heavy metals; Speciation; Ecological risk; Spatial distribution; Zhalong Wetland
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