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 11:38
    Last Modified: 12 Jan 2011 04:55

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