Agriculture Reference
In-Depth Information
regardless of the surface properties of CeO
2
NPs. The effect of soil organic matter
was more significant on uncoated CeO
2
NPs than alginate-coated CeO
2
NPs.
Following the exposure of 0-4,000 mg/L CeO
2
NP to alfalfa, corn, cucumber,
and lettuce growth for 7 days, ICP-OES analysis confirmed the ceria presence
within the seedlings tissue of these four plants (Lopez-Moreno et al.
2010b
).
After dilute acid rinsing, XAS confirmed that the oxidation state was unaltered in
the root tissues of these four plant species. In a separate study in which 2,000 mg/L
CeO
2
NP was exposed to cucumber for 3 weeks, minimal root to shoot translocation
was observed (Zhang et al.
2012
). However, soft X-ray scanning transmission
microscopy (STXM) and near edge X-ray absorption fine structure (XANES)
analysis did show measurable accumulation and biotransformation of CeO
2
NPs
to CePO
4
in roots and cerium carboxylates in shoot tissue. The authors hypothe-
sized that root exudate-mediated dissolution of nanoparticles precedes ion uptake,
subsequently followed by in planta reduction to nanoceria and/or biotransformed
products. The hypothesis, however, was not scientifically confirmed.
14.5 Engineered Nanomaterials Mitigated Uptake
of Environmental Chemicals by Agricultural Crops
Once released into the environment, ENMs closely interact with the coexisting
environmental chemicals and may substantially alter their fate and uptake by
agricultural crops. The first evidence that ENMs may change the uptake of envi-
ronmental pollutants was provided by a study conducted in our lab in which we
reported that the presence of nC
60
fullerene significantly enhanced the uptake of
trichloroethylene by some wetland plants (Ma and Wang
2010
). Recent work with
agricultural crops grown in vermiculite confirmed that fullerene exposure signifi-
cantly increased the accumulation of pesticide residues by cucumber in both root
and shoot tissues (Torre-Roche et al.
2012
). The presence of fullerene also
increased the root accumulation of pesticides by soybean and tomato by 30-
65 %, but the shoot accumulation of pesticides by soybean was reduced by 48 %
by the presence of fullerene. The shoot accumulation of pesticides by tomato was
unaltered by fullerene, demonstrating the variances between different plant species.
A similar work with AgNPs was conducted and the results showed that AgNPs
suppressed the accumulation of these pesticides by soybean plants by up to 40 %
and the effect was significantly higher for AgNPs than bulk Ag (Torre-Roche
et al.
2013a
). In a subsequent study with actual soil containing aged pesticides,
the same group of researchers demonstrated that nC
60
fullerene again displayed
species-specific impact on the accumulation of weathered pesticides by four agri-
cultural crops (cucumber, soybean, corn, and tomato); however, the presence of
MWCNTs consistently suppressed the uptake and accumulation of aged pesticides
by all four crops (Torre-Roche et al.
2013b
). Clearly, the nature of nanoparticles
