Nuisance nanoparticles

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http://www.e4engineering.com/Articles/292846/Nuisance+nanoparticles+.htm

 

 

A nanoparticle commonly used in industry could have a damaging effect

on plant life, according to a report by an environmental scientist at

New Jersey Institute of Technology (NJIT).

 

The report, published in a recent issue of Toxicology Letters, shows

that nanoparticles of aluminium oxide slowed the growth of roots in

corn, cucumber, cabbage, carrot and soybean.

 

Aluminium nanoparticles are commonly used in scratch-resistant

transparent coatings, sunscreen lotions that provide transparent-UV

protection and environmental catalysts that reduce pollution, said

Daniel J. Watts, PhD, the lead author of the study.

 

" Before this study there was an assumption that nanoparticles had no

effect on plants, " said Watts, executive director of the York Center

for Environmental Engineering and Science and Panasonic Chair in

Sustainability at NJIT. " This study makes the observation that

seedlings can interact with nanoparticles such as aluminium, which can

have a harmful effect on seedlings and perhaps stunt the growth of

plants. " Other nanoparticles included in the study, such as silica,

did not show this effect, " Watts added. He did the study with Ling

Yang, a doctoral student who recently graduated from NJIT.

 

The authors conducted the study by allowing seeds to germinate on wet

filter paper in Petri dishes, after which they added known quantities

of nanosized aluminium suspended in water. The control portion of the

experiment was treated only with water, and the authors observed the

experiment for seven days. During that time, they measured the

differences in the growth of the plants' roots, which were shown to be

statistically significant.

 

" We suppose that the surface characteristics of the nanoparticles

played an important role in slowing the growth of the roots, " said

Watts. " The smaller the particle, the larger is the total amount of

surface area per unit weight. So the smaller you make the particles,

the larger is the surface area, which we suspect is what contributes

to the growth-slowing interaction between the seeds and the

nanoparticles. The small size of the nanoparticles may be changed by

the nanoparticles aggregating or clumping together. "

 

But what is still not understood, said Watts, is the nature of the

interaction between the nanoparticle and the root of the seed. " What

is the mechanism of the interaction between the particle and the root?

That we don't know as yet, " he said.

 

Nanoparticles can be deposited into air by exhaust systems, chimneys

or smoke stacks, said Watts. The particles can also mix with rainwater

and snow and gradually work their way into soil.

 

It is difficult to take results from a lab experiment and conclude

that is what happens in the real world, said Watts. " But we speculate

that air deposits of nanoparticles or water transport of them are ways

in which nanoparticles could mix with plant life, " he said.