Environmental Engineering Reference
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Pb in frond (4,829 mg/kg) after 2 months of
growth (Soongsombat et al.
2009
). The high Pb
accumulation and tolerance indicated that
P. vittata
can be potentially useful for phytoremediation
and phytomining of Pb-contaminated soil.
A glasshouse study was conducted to compare
growth performance, metal tolerance, and metal
uptake by two grasses,
Thysanolaena maxima
and
Vetiveria zizanioides
. The grasses suited for
phytostabilization in tropical Pb-contaminated
areas of Bo Ngam Pb mine, which contain high
concentrations of Pb (up 1 % total Pb) and low
amounts of organic matter and major nutrients
(N, P, K) (Rotkittikhun et al.
2007
). Pot and fi eld
experiments showed that
T. maxima
and
V. zizani-
oides
had a high potential for phytostabilization
Pb in mine tailing pond of KEMCO Pb mine,
which ceased to operate in 2009 due to the expiry
of concession. The tailing soils are poor in
nutrients with high porosity to hold water but
rich in Pb (Meeinkuirt et al.
2013
). In pot
experiment, application of pig manure increased
electrical conductivity (EC) and reduced DTPA-
extractable Pb concentration in the soils. The
uptake by roots and transport of Pb to shoot of
T.
maxima
and
V. zizanioides
were reduced when
soil was amended with pig manure (Rotkittikhun
et al.
2007
). However, the amendment to the Pb
mine soils with organic (cow manure, organic
fertilizer) and inorganic fertilizer increased root
biomass and Pb accumulation in the field
application. Massive and complex root systems
of these grasses can be pioneer plants in
Pb-contaminated soil before revegetation with
tree species (Meeinkuirt et al.
2013
).
The potential of six tree species (
Leucaena
leucocephala
,
Acacia mangium
,
Peltophorum
pterocarpum
,
Pterocarpus macrocarpus
,
Lagerstroemia fl oribunda
, and
Eucalyptus
camaldulensis
) for phytoremediation of Pb in
sand tailings (total Pb >9,850 mg/kg) from the
KEMCO mine were investigated employing a
pot experiment (3 months) and fi eld trial experi-
ment (12 months).
A. mangium
with the addi-
tion of organic fertilizer was the best option for
phytostabilization of Pb-contaminated mine
tailing because it retained higher Pb concentration
in the roots (Meeinkuirt et al.
2012
). To promote
woody plant
E. camaldulensis
, three Pb-tolerant
bacteria (
Microbacterium paraoxydans
BN-2,
Ochrobactrum intermedium
BN-3, and
Bacillus
fusiformis
BN-4) were isolated from the
rhizosphere of
E. camaldulensis
grown in
Pb-contaminated soils in the Bo Ngam Pb mine.
Inoculation of
O. intermediu
BN-3 signifi cantly
increased the biomass and Pb accumulation by
E. camaldulensis
compared to the uninoculated
control (Waranusantigul et al.
2011
). A potential
of growing sunfl ower (
Helianthus annuus
) in
Pb-contaminated soil for biodiesel was tested
in a pot experiment. The experiment indicated
that sunfl ower tolerated a high Pb concentration
(1,419 mg/kg) with 142 mg/kg of Pb accumulated
in shoots (Sukyankij and Panichpat
2012
).
6
Cadmium Contamination
in Mae Sot and Reclamation
Zinc (Zn) mining was established in Mae Sot
District, Tak Province, northwestern Thailand, in
1998. Paddy fi elds were irrigated from two creeks
of Mae Tao and Mae Ku, which passed through an
area where a Zn mine had been actively operated
for >30 years (Pollution Control Department
2004
). The Cd-contaminated areas were discov-
ered in 12 rural villages of the district. Paddy soil
samples contained Cd content above the maxi-
mum permissible level of 3.0 mg/kg during the
surveys in 2001-2004 (Simmons et al.
2005
). The
villagers are being reported on metal toxic symp-
toms (Swaddiwudhipong et al.
2012
). The govern-
ment has supported the production of nonfood
crops. Nevertheless, some residents reverted to
rice cultivation mainly for their own consumption
and local sale after the compensatory payment had
been curtailed. Thus, it may be possible to treat
rice plants with Cd-tolerant bacteria, (KKU2500-
3) which could transform toxic-soluble Cd to
insoluble CdS, to decrease the Cd content of rice
grains and to remediate Cd-contaminated soil in
the rice fi elds (Siripornadulsil and Siripornadulsil
2013
). However, heaps of mine tailings have to be
decontaminated to recover land and prevent erosion
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