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Title: Impact of engineered nanoparticles on aquatic microbial processes
Author: Poole, Jessica Grace
Awarding Body: University of Essex
Current Institution: University of Essex
Date of Award: 2013
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The recent and rapid expansion of nanotechnology is expected to benefit mankind, yet certain nanomaterials have the potential to disrupt in situ microbial communities following their rel ease into the environment. This study characterised four engineered nanomaterials (capped and uncapped silver nanoparticles (cAgNP and uAgNP), titanium dioxide nanoparticles (TiO,NP) and multi-walled carbon nanotubes (MWCNT)) and measured their toxicity to bacterial pure cultures and aquatic microbial communities, with focus on two key processes (i.e. hydrocarbon-degradation and ammonia oxidation). Whilst the TiO,NP and MWCNT were non-toxic up to 50 mg both the cAgNP and uAgNP demonstrated bacterial toxicity between 5-50 mg with differential toxic responses obseNed by a range of different bacterial species tested. In general, a greater toxic response was elicited by the smaller cAgNP compared to the larger uAgNP. Freshwater and marine microbial communities demonstrated some resilience to AgNP in terms of cell viability, enzyme activity and hydrocarbon biodegradation rates. Furthermore, microbial nitrification potential in estuarine sediments demonstrated recovery following an initial decline in response to 50 mg L·1 cAgNP. Aquatic microbial community compositions were in general, sensitive to uAgNP and cAgNP between 0.5 to 50 mg. Since the nanoparticle concentrations tested herein are greater than current predicted environmental concentrations, it is suggested that microbial-mediated processes such as hydrocarbon-deg radation and ammonia oxidation are unlikely to be impacted by exposure to AgNP at present. However, aquatic microbial community compositions may be at risk in the event of a point-source AgNP spillage, or by future environmental concentrations, if the production and use of AgNP is not properly regulated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available