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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The signiflcance of indoor air as a source of human exposure to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs)

Hazrati, Sadegh January 2006 (has links)
In order to investigate the significance of indoor air as a source of human exposure to PBDEs and PCBs, 94 indoor microenvironments from 4 major indoor environment categories (i.e. offices, homes, public environments, and cars) were monitored in the West Midlands area between 2003 and 2005. Seasonal and within building variability in PCB and PBDE concentrations were studied by monitoring 8 indoor environments for a period of 12 months. The impact of contaminated indoor air on PCB and PBDE concentrations in outdoor air was also evaluated using both chiral techniques and a simple box model. The average concentration of 2PCB in homes, offices, and public indoor environments combined was 11.65 ng m"3 (median = 3.54 ng m"3 ), ranging from 0.49 to 101.8 ng m'3 . The most contaminated indoor environment category was public environments, followed by offices, homes, and cars. The average concentration of ZPBDE for all indoor *% <5 __ microenvironments studied was 0.269 ng m", ranging from 0.004 to 8.2 ng m" . Excluding cars, this figure for all other indoor microenvironments combined ranged from 0.004 to 1.416 ng m" 3 with average value of 0.109 ng m" 3 . Unlike PCBs, cars were identified as the most contaminated indoor microenvironment category studied with an average concentration of 0.709 ng m'3 . Based on records of time activity patterns and concentrations of PCBs and PBDEs found in indoor environments, the relative significance of inhalation exposure to ZPCB compared to diet ranged from 3.3 to 66.2% (average = 30.6%) for adults and from 0.98 to 20% (average = 7.4%) for toddlers. This figure for ZPBDE was between 0.2 and 15.3% (average = 2.3%) for adults and between 0.04 and 3.9% (average = 0.59%) for toddlers. The results obtained from monitoring 8 selected indoor microenvironments revealed that PCB and PBDE concentrations in warmer months are generally higher than those measured in colder months. Concentrations of some PCB and PBDE congeners also showed statistically significant (p<0.05) seasonal variations in some monitoring locations. The highest ZPCB concentrations were found in buildings constructed between 1950 and 1979 (average EPCB = 19.9 ng m" 3 and SD = 5 ng m"3 ) followed by those constructed prior to 1950 (average SPCB = 5.8 ng m' 3 and SD = 4 ng m' 3 ) and post 1979 (average EPCB = 2 ngm" 3 , and SD = 1.8 ng m" 3 ). ZPCB concentrations in buildings constructed in 1950-1979 were statistically significantly higher than those built post 1979 (pO.OOl). Concentrations of the major PBDE congeners were significantly positively correlated with the construction year of the buildings (p<0.05). However, although concentrations of PBDEs in one office fell appreciably following replacement of a PC manufactured in 1998 with one manufactured in 2003; no significant relationships were detected between concentrations of either PCBs or PBDEs and room contents such as numbers of PCs, other items of electronic equipment, or items of PUF-containing furniture. This suggests that the influence of room contents on the contamination of indoor environments with such compounds is complex, and that factors such as the age of electronic equipment and room ventilation may play an important role. Chiral signatures of PCBs in indoor air were essentially racemic with average EF values of 0.496 ± 0.003, 0.500 ± 0.003, and 0.500 ± 0.004 for PCBs 95, 136, and 149, respectively. EF values of all PCB atropisomers in one office microenvironment in monthly samples taken over a 12 month monitoring period displayed no statistically significant variations between warmer months and colder months (p>0.10). Direct comparison of EFs in indoor air, outdoor air, and soil for chiral PCBs revealed that on average >80% of atmospheric concentrations of PCB 95, 136, and 149 at the EROS monitoring site is derived from the ventilation of contaminated indoor air, which is consistent with the results obtained using a simple box model in the West Midlands. Applying the box model for PBDEs revealed an estimate of daily mass flux of 9.98x10 8 ng ZPBDE from indoor to outdoor air, which provides a predicted concentration of ~5 pg EPBDE m" 3 in outdoor air. This value is line with observed values reported elsewhere for the West Midlands, and suggests that ventilation of indoor air makes a significant contribution to outdoor air contamination with PBDEs.
2

Diversity, structure and functioning of freshwater biofilms in response to herbicides

Rosenkranz, Helen January 2014 (has links)
Various approaches have been published aimed at assessing the impact of herbicides on river biofilms, by conducting field and laboratory experiments. The vast majority focusses on laboratory standardised growth inhibition tests conducted on isolated single species, rather than on whole communities. In this thesis three different consecutive experimental approaches were conducted integrating different ecological complexities to determine the impact of herbicides on phototrophic river biofilms. Chlorotoluron and the glyphosate formulation Roundup®, two herbicides with different modes of action, were used to investigate single, as well as combined, impacts on the structure (biomass, biodiversity and architecture) and functioning (photosynthetic rates and light utilization efficiency) of biofilms. Furthermore, the combined impact of herbicides and freshwater viruses on these biofilm communities was investigated. In field experiments on biofilms, single glyphosate (Roundup®) and the combined herbicide treatment (glyphosate + chlorotoluron) significantly reduced the total biomass (dry weight) as well as the photosynthetic biomass (total chlorophyll) of biofilms compared to controls. In contrast, both herbicides (single and combined) significantly increased the biomass-specific rate of photosynthesis. Both effects resulted in the observation of a shift in community composition towards green algal dominance at the expense of diatoms, along with a reduction in taxonomic diversity. In single species cultures, isolated from the field, diatoms showed the greatest resistance to chlorotoluron and glyphosate (Roundup®), while cyanobacteria showed the highest sensitivity during toxicity tests. Both green algae cultures were negatively impacted by chlorotoluron, but only at concentrations greater than those applied in the field. When treated with Roundup® a significant increase in biomass was measured. Biofilms were exposed to viruses, either singly or in combination with herbicides. A significant increase in the ratios of diatoms to green algae and a decrease in taxonomic diversity was found upon virus application, and a partial cancellation of these effects was observed when combined with herbicides. These three consecutive studies not only broaden our knowledge on the impacts of herbicides on freshwater biofilm communities, but also illustrate the key importance of multilayered approaches. The research has shown that a specie's sensitivity may vary depending on its location in the biofilm, a factor not realised in single species toxicity testing. Combined interactions between viruses and herbicides were found to play a role in structuring biofilm communities and therefore underline the requirement for further research on the interaction of herbicides with other environmental factors. Using community assessments as described in this study in combination with traditional single species tests, a more reliable prediction of the environmental toxicity of herbicides can be obtained.
3

Global justice, natural resources and climate change

Blomfield, Megan January 2014 (has links)
In this thesis I examine the problem of climate change in the light of a theory of justice for natural resources. I discuss the implications of this theory regarding how to deal with climate change fairly, and consider the relevance of historical injustices in natural resource use to our current attempts to achieve climate justice. In presenting this account, I discuss a number of arguments in the climate justice literature that draw on a principle of equal shares for certain natural resources - the atmosphere, for example, or resources that can be conceptualised in terms of ecological space. I argue that though natural resources are appropriate objects of egalitarian distribution, justice does not entitle individuals to equal shares of these resources. In place of the principle of equal shares, I defend a contractualist justification of natural resource rights; according to which these rights should be allocated to enable all human beings to satisfy their basic needs as members of self-determining political communities. Resources have not been used justly in the past, given that the history of our world is one of colonialism, the resource curse, and the dispossession of indigenous peoples. To deal with climate change fairly, I argue that we must seek to ensure that individuals and collectives can exercise adequate control over what happens to the world's natural resources in the future - both within their territory and further afield. I use this alternative conception of natural resource justice to consider the question of where to set the ceiling on future greenhouse gas emissions, how to share the resulting emissions budget, and how to understand historical accountability in the face of unavoided climate impacts.
4

Modelling aircraft emissions and their impact on atmospheric composition and ozone

Wasiuk, Donata Katarzyna January 2014 (has links)
Emissions of NOx ' from aircraft influence global atnl0spheric composition, chemistry and ultimately our climate via tropospheric 0 3 production. They are increasing the global tropospheric concentration of NOx with continuing intensity as we fly more and more of us fly. Here, the 3-D Lagrangian CTM STOCHEM-CRI with the novel CRIv2- R5 chemistry scheme was used to evaluate the impact of current global , aircraft NOx emissions on atmospheric composition as well as the concentration and global spatial distribution of tropospheric NOx and 0 3 , Further, an operational mitigation strategy for commercial aircraft impact on air quality and climate referred to as the turBoprop replacement strategy (TRS) in which jets on short-haul missions were replaced with turboprops was investigated. These assessments were based on the 4-D Aircraft Fuel Burn and Emissions Inventory spanning the time period 2005-2011 created with the Aircraft Performance Model Implementation (APMI) software which was developed in support of this project.
5

Climate change and internal displacement : a critical analysis of land rights in the context of slow-onset impact

Dutta, Ashirbani January 2014 (has links)
Climate change disasters and human impact in recent times have been largely obvious, causing massive damage and destruction. Out of the millions of people affected by the various impacts such as flash flooding, cyclones and hurricanes across the globe, many have already suffered from displacement. In the future, many more people will suffer the long, slow effects of incremental environmental change affecting their living conditions, food security and lives more broadly. In many of the regions, local population particularly the communities are struggling to maintain their livelihood, and other basic conditions of survival as environment, land, soil quality and local resources continues to degrade, threatening local population with the risks of potential displacement. In few extreme cases such as desertification, I people are already forced to leave their home. In some of the Pacific Island atolls, people are already forced to relocate to some of the neighbouring islands.2 These are the people that this thesis will focus upon, and, in particular, their human rights as regards displacement from their homes and lands, as well as when impacted by potential threats of displacement. The thesis analyses this particular group of persons and aims to establish from a human rights perspective what their rights are due to climate change impacts and displacement and seek to analyse the extent to which it is addressed by the legal framework.
6

Studies on the air/plant exchange of persistent organic pollutants (POPs)

Barber, Jonathan Lee January 2003 (has links)
No description available.
7

Modelling the fate and environmental distribution of persistent organic pollutants at the local and regional scale

Prevedouros, Konstantinos January 2004 (has links)
No description available.
8

Modelling persistent organic pollutants (POPS) at the local, regional and global scales

Valle, Matteo Dalla January 2004 (has links)
No description available.
9

Sources and environmental transfers of polychlorinated dibezo -p- dioxins, dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) and their distribution in the terrestrial environment

Hassanin, Ashraf Mohamed Sami January 2005 (has links)
No description available.
10

Road salting effects on upland soils, soil solutions and freshwaters

Green, Sophie-Marie January 2007 (has links)
No description available.

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