The key components of
S. triqueter
root exudates
involved 4-oxo-pentanoic acid, succinic acid, glutaric acid,
phthalate acid, citric acid, vanillic acid, myristic acid, pentadecanoic
acid, decanoic acid, 14-methyl-pentadecanoic
acid, hexadecanoic acid, octadecanoic acid and oleic acid, and
the content of the water-soluble organic acids (citric acid,
succinic acid and glutaric acid) significantly increased in
pyrene and lead co-contaminated rhizosphere soil.These three
water-soluble organic acids including citric acid, succinic acid
and glutaric acid were detected as the specific root exudates of
S. triqueter under stress of pollutants for pyrene and lead, so
they were chosen as the research objects, and they were added
into the bioremediation systems of pyrene and lead co-contaminated
wetland soils. Compared with the control, the
treatments added the three organic acids always improved the
quantity of the bioavailable fraction of pyrene and lead in
wetland soils and greatly influenced other chemical states of
pyrene and lead fractions in the test concentration range.
Under the 50 g kg
-1 of organic acids concentration, the
amount of the bioavailable fraction of pyrene and lead
increased 41.0 and 872.7 % by citric acid, respectively. The
enhancement of bioavailability of pyrene and lead in the
wetland soil by adding organic acids generally decreased in
the following order: citric acid > succinic acid > glutaric
acid. Enhancing effects of organic acids on the bioavailability
improvement of pyrene and lead is remarkable.