The ecotoxicology of nanoparticles in Daphnia magna

Rosenkranz, Philipp (2010) The ecotoxicology of nanoparticles in Daphnia magna. PhD thesis, Edinburgh Napier University.


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Manufactured nanoparticles are increasingly being used in the production of
consumer products and appliances. A release in the environment, either
intended through remediation or unintended through a spill at production sites,
through wastewater or product degradation, is most likely to occur. Due to their
small size, nanoparticles have a far greater surface area to unit mass ratio than
conventional substances, rendering them potentially more reactive. This project
aims to obtain key data on the ecotoxicology of nanoparticles in the aquatic
environment. Initially, data from acute and chronic toxicity tests were gathered
by exposing the invertebrate Daphnia magna to nanoparticles of carbon black,
cerium dioxide, silver and titanium dioxide. The endpoints were mortality,
moulting frequency, growth and number of offspring. The results indicate that a
gradient of toxicity can be drawn, with cerium dioxide being the least toxic, to
silver being the most toxic. Also a size dependent increase of toxicity was
observed, with exposures to nano sized particles being more toxic than micro
sized particles. Uptake and fate of nano sized materials were studied by
exposing D. magna to fluorescent polystyrene beads of 20 nm and 1000 nm
sizes and the results were compared. Both particle sizes were readily taken up
in the gut and relocated in storage droplets within the body of D. magna. A
quantification of the results showed that the mass of 1000 nm sized particles
taken up was higher at equal exposure concentrations than the 20 nm sized
particle but the excretion rate was higher as well for the 1000 nm particles.
However, when assessing uptake as surface area or particle number dose,
uptake of 20 nm particles exceeds uptake of 1000 nm particles. To assess the
effect of nanoparticles on oxidative stress, the total antioxidant capacity was
measured as well as the glutathione concentration of exposed D. magna. A
decrease in total glutathione in D. magna was detected due to exposure to nano
sized carbon black, while measuring the total oxidant capacity proved to be
impossible due to interferences with the method used.
The results show that, when negative effects are observed, these are more
severe in exposures to nanoparticles than their micro sized counterparts and
furthermore a clear route of uptake of nanoparticles in the body of D. magna
can be observed.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Nanoparticles; ecotoxicology; Daphnia magna;
University Divisions/Research Centres: Faculty of Health, Life & Social Sciences > School of Life Sciences
Dewey Decimal Subjects: 500 Science > 570 Life sciences; biology > 570 Life sciences; biology
Library of Congress Subjects: Q Science > QH Natural history > QH301 Biology
Item ID: 3808
Depositing User: Users 696 not found.
Date Deposited: 02 Aug 2010 10:38
Last Modified: 12 Jan 2011 04:55

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