ABSTRACT
Phytoremediation is a plants-using environmental cleaning tech-
nique applicable to organic and inorganic pollutants in the soil and
water. The typical functions of the plants in the phytoremediation
system are summarized to the absorption/adsorption and accumu-
lation of inorganic matters. And we also have to pay attention to
one more important mechanism of phytoremediation, the biodegra-
dation or bioconversion of pollutants by rhizo-microorganisms.
The water purification activities of more than 60 kinds of water
plants against eutrophication have been studied from 1960s.1 For
the soil purification, phytoremediation of organic and heavy metal
contaminants have been mainly studied.2−5 But we cannot find out any study on application of phytoremediation techniques to
the boron polluted site. Soil quality criteria of boron in Japan
(dissolved amount by elution test) is 1.0 mg/L, and its content
criteria is 4000 mg/L. Generally, boron content in natural soil
is below 100 mg/kg. This element exist as borate and widely
used for raw materials of enamel, glass, or insecticide. In 2006,
4.7% of soil contaminations exceeding the soil criteria were boron
contamination in Japan. Boron is a bio-essential element and
accumulated in the terrestrial tissue including leaves in the plants.
Recent studies6,7 indicate that boron form the rhamnogalacturonan
II-borate dimer in pectin, and this structure contributes to the cell
wall stability. These fundamental characters of plant boron usage
show the possibility of boron phytoremediation by the plant uptake,
accumulation and removal of the contaminants with biomass
recovery.
