Environmental Engineering Reference
In-Depth Information
EI-Temshah and Joner (
2012
) studied the toxicity of nano zero-valent iron
(nZVI) and AgNPs to ryegrass, barley and flax using seed germination tests
(0-5,000mg/LofnZVIand0-100mg/LofAg)(Table
6
). They reported that nZVI
could be helpful in remediation processes; lower concentrations of nZVI did not
elicit toxicity.
Leeetal.(
2012
) reported that growth and germination rates of two edible plants
(
Phaseolus radiatus
and
Sorghum bicolor
) was decreased in a dose-dependant man-
ner, with increasing concentrations of silver nanoparticles; the test was performed
in both an agar medium and in a soil at the respective concentration ranges s of
0-40mg/Land0-2,000mg/kg.Browntipsandnecrosiswasobservedinrootsof
both plants in agar medium. Higher concentration of citrate-capped silver NPs per
kgofsoilshowed20%inhibitionofseedgerminationofbothplants.EC
50
values of
13mg/Land26mg/Lwerereportedfor
Phaseolus radiatus
and
Sorghum bicolor
,
respectively(Table
6
).
LinandXing(
2007
)studiedthetoxicityofivetypesofNPs,viz.,multiwalled
carbonnanotubes,aluminium,alumina,zincandzincoxide(20,200and2,000mg/L)
tosixdifferentplantspecies(i.e.,radish,rape,rye-grass,lettuce,cornandcucum-
ber).Exposuretonanoscalezincresultedintheinhibitionofseedgerminationin
ryegrass, whereas the exposure to ZnO NPs resulted in the inhibition of seed germi-
nation in corn plants (Table
6
). The pattern of root growth differed from plant to
plant and depended on the type of nanoparticle exposure.
LinandXing(
2008
)studiedrootuptake,cellinternalizationandphytotoxicityin
ryegrass(
Lolium perenne
), in the presence of ZnO NPs at varying concentrations
(10,20,50,100,200and,1,000mg/L).ZnONPsexposurereducedbiomassand
collapsed/vacuolatedepidermalorcorticalcellsofryegrass(Table
6
). In addition,
the ZnO NPs were not only attached to the root surface, but were also found in the
apoplast and protoplast of the root endodermis and stele.
Leeetal.(
2008
)reportedthetoxicityofinsolublecopperoxide(CuO)NPsto
wheat(
Triticum aestivum
)andmungbean(
Phaseolus radiatus
). These NPs showed
aggregation inside the plant cells (Table
6
). The authors reported EC
50
values of
CuONPstobe335mg/Land570mg/L,respectivelyinmungbeanandwheat.They
concluded that wheat might be more tolerant to CuO NPs than mung bean.
Leeetal.(
2010
)reportedtheeffectsoffourmetaloxideNPs,viz.nAl
2
O
3
, nSiO
2
,
nFe
3
O
4
andZnOatthreedifferentconcentrations(400,2,000and4,000mg/L)on
seedgermination,rootelongationandleafformationofmouse-earcress(
Arabidopsis
thaliana
). ZnO NPs were more toxic than nFe
3
O
4
and nSiO
2
NPs. However, nAl
2
O
3
NPsdidnotshowanytoxicity(Table
6
). Nano forms showed more toxic effects than
their corresponding macro forms at the same concentration.
Stampoulis et al. (
2009
) reported the toxicity of five nanomaterials (MWNTs,
Ag,Cu,ZnO,andSi)versustheirbulkcounterpartsonseedgermination,rootelon-
gationandplantbiomassofzucchini(
Cucurbita pepo
)(Table
6
). NPs at the concen-
trationof1,000mg/Ldidnotshowtoxicityonseedgermination,butexposuretothe
CuNPs(1,000mg/L)reducedrootlengthofzucchiniby77%,whileAgandMWNTs
NPs reduced root length by 60% and 75%, respectively.
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