Affiliations: School of Life Sciences, Xiamen University, Xiamen
361005, China | State Key Laboratory of Marine Environmental Science,
Xiamen University, Xiamen 361005, China] | Biology Department of Quanzhou Normal College,
Quanzhou 362000, China
Abstract: In order to investigate distributions of heavy metal pollution in
Quanzhou Bay wetland, the total concentration and chemical partitioning of a
number of heavy metals (Cu, Zn, Cd, Pb, Cr, Hg) in sediments of three sampling
sites of Quanzhou Bay wetland and their availability to Suaeda australis were
analyzed. The Geoaccumulation Index (I_{geo}) values reveal
that the sediments of three sampling sites may all be considered as moderately
contaminated for Pb and Zn, and all sediments might be strongly contaminated
with cadmium. The partitioning analyses revealed the measured heavy metals in
three sites are bound to the exchangeable fraction at lower concentrations. The
measured metals in a considerable amount are bound to the reducible and
oxidizable fractions, and a high proportion of the measured heavy metals were
distributed in the residual fraction in the sediment samples. The
concentrations of Cd in each chemical phase extracted from the sediments are
above natural global background levels and should be further investigated
because of its toxicity. Suaeda australis has different accumulation abilities
for the measured heavy metals. For the root and stem, the bioaccumulation
ability assessed by bioaccumulation factor (BA F) for the measured heavy metals
follows the decreasing order as: Cu>Cr>Zn>Cd, Pb, Hg. In the leaf,
stronger bioaccumulation ability for Hg is exhibited. The heavy metal
concentrations in Suaeda australis roots have positive correlations with their
available fractions, while the exchangeable fraction of Cu and Cd might have be
more important to both mature plant roots and seedling roots uptake than other
fractions; as for Cr, the oxidizable fraction might make a greater contribution
to the plant root uptake; as for Zn, the reducible fraction might make so
contribution; and for Pb, the oxidizable fraction might make a significant
contribution to the mature plant root uptake, however, the exchangeable
fraction might have a significant contribution to the seedling root uptake.
Keywords: bioavailability, geoaccumulation factor, partitioning, heavy metals, Suaeda austrdis, sediment, Quanzhou Bay wetland
