This thesis examines the air-soil and air-water gas exchange of persistent organic pollutants (POPs) with emphasis on organochlorine pesticides (OCPs). The current status of net exchange, factors which influence the exchange process, and different approaches used to estimate the surface exchange were explored. The net exchange of chemicals was evaluated using the fugacity approach, with the aid of chemical tracers (congener profiles of complex mixtures and enantiomer proportions of chiral chemicals) to infer current use vs. legacy sources to the atmosphere. DDT in southern Mexico was undergoing net deposition from air to soil. Occurrence of fresher DDT residues in the south was indicated by a higher proportion of p,p’-DDT relative to p,p’-DDE and racemic o,p’-DDT in air and soils. Congener profiles of toxaphene suggested soil emissions as the source to air. The influence of chemical aging on soil-air exchange and bioaccessibility was studied in a high organic soil. The use of nonexhaustive extraction with hydroxypropyl-beta-cyclodextrin (HPCD) to predict bioaccessibility was optimized for OCPs and polychlorinated biphenyls (PCBs). Reduced volatility of spiked chemicals correlated with reduced HPCD extractability for soil that had been aged under indoor and outdoor conditions for 730 d and infers volatility could be used as a surrogate for bioaccessibility. Measured soil-air partition coefficients (Ksa) were lower than those predicted from the Karickhoff relationship, which considers octanol as a surrogate for soil organic matter. The role of soil moisture, organic carbon, temperature, depth of soil surface horizon and dissolved organic carbon in the fate of organic contaminants in soil were assessed using chemical partitioning space maps. These maps allow instant visual prediction of the phase distribution and transport process of a chemical among the three major phases in soil; i.e., air, water and solid. Net volatilization of alpha-hexachlorocyclohexane from water to air was found in the southern Beaufort Sea using fugacity calculations and flux measurements. The influence of ice cover on volatilization was indicated by a winter-summer shift from racemic to nonracemic alpha-HCH in boundary layer air.

A major goal of this research was to evaluate a variety of cell lines for theirpermissiveness to equine arteritis virus (EAV) infection and then identify the mechanismthat restricts EAV infection in certain cell lines. The cell lines BHK-21, RK-13, andC2C12 were found to support productive infection with EAV strain VBS53, whereasHela, Hep-2, and L-M cell lines exhibited limited susceptibility to infection with thisvirus. In the course of the study, it was found that the Hela cell line became moresusceptible to infection with EAV strain VBS53 after extended serial passage. Therespective cell lines were referred to as Hela High (passage 170-221) and Hela Low(passage 95-115) lines. While the Hela High cell line was more susceptible than the HelaLow cell line, it was still considerably less susceptible than the BHK-21 cell line to EAVinfection. Subsequent studies demonstrated that infection with EAV strain VBS53 wasrestricted at the entry step in Hela, Hep-2, and L-M cell lines.The second major goal of this research was to establish an in vitro model ofpersistent EAV infection using cell culture and then use the persistently infected culturesas a tool to study virus-host cell interactions, and to investigate virus and host cellevolution. Persistent infection was successfully established in the Hela High cell line withthe VBS53 strain of EAV. Properties of the persistently infected Hela High cell line werecharacterized. Virus evolution with respect to virus growth characteristics, ability of thevirus to initiate secondary persistent infection, and genetic changes during persistentEAV infection in Hela cells was investigated. Neutralization phenotypic changes of viruses were observed during the course of persistent EAV infection in Hela cells. Reverse genetics studies identified that amino acid 98 of the GP5 protein is a new neutralization determinant of EAV. Using an in vitro assay, it was found that EAV probably became progressively less virulent during the course of persistent infection in Hela cells. The potential changes in pathogenicity of EAV during persistent infection of Hela cells need to be verified by inoculation of horses.

Mindfulness is a way of managing chronic pain and its consequences as it fosters anaccepting approach to pain that can be beneficial in several aspects of life affected bypain. This study sought to examine whether an online mindfulness training programcould reduce the experience of pain, increase acceptance of pain, and increase qualityof life in a group of individuals suffering from chronic pain. The study was arandomized controlled trial with a partly active control group. Initially 52 participantswere randomized to the intervention group and 55 to the control group. The drop outrates were high, 21 participants from the intervention group and 40 participants fromthe control group completed post measurement. Increased levels of mindfulness,reduced pain related distress, and heightened pain acceptance, as well as increasedquality of life, was observed in the intervention group. A strong tendency towards aperceived reduction of pain intensity was also evident in the intervention group. Asthe mindfulness program had positive effects on the overall experience of pain it mayserve as a cost‐effective and useful method of dealing with chronic pain. / Mindfulness är ett sätt att hantera kronisk smärta och dess konsekvenser då det lär uten accepterande inställning till smärta som kan vara till hjälp i flera aspekter av livetpåverkade av smärta. Denna studie undersökte huruvida ett online‐baseratmindfulnessprogram kunde minska upplevelsen av smärta, öka acceptans av smärtaoch öka livskvaliteten hos en grupp individer med kronisk smärta. Studien varrandomiserad och kontrollerad med en delvis aktiv kontrollgrupp. Initialtrandomiserades 52 deltagare till experimentgruppen och 55 deltagare tillkontrollgruppen. Bortfallet var högt, 21 deltagare från experimentgruppen och 40deltagare från kontrollgruppen fullgjorde eftermätningarna. Ökade nivåer avmindfulness, reducerat smärtrelaterat lidande, ökad acceptans av smärta såväl somökad livskvalitet återfanns i experimentgruppen. En stark tendens till minskadupplevd smärtintensitet var också tydlig hos experimentgruppen. Dåmindfulnessprogrammet hade positiva effekter på den övergripande upplevelsen avsmärta kan det fungera som en kostnadseffektiv och användbar metod att hanterakronisk smärta.

Water resources in South Africa are scarce, and should therefore be protected against pollutants, also from persistent organic pollutants (POPs). POPs are a global concern due to their ubiquitous presence, persistence and toxicity. This is emphasised by the Stockholm Convention on POPs, which aims at reducing and ultimately eliminating them. South Africa signed and ratified the treaty, and it became international law on 17 May 2004, but there is still a lack of information regarding POPs in South Africa. This study focussed on establishing the levels of POPs and other organic pollutants, which included various organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), dioxin-like compounds (DLCs), non-dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ether (PBDE). Sampling regions included the industrial cities – Cape Town, Richards Bay, Durban and Bloemfontein, and low-income, high density residential areas surrounding a wetland in Soweto/Lenasia and Botshabelo. Additionally, rivers flowing into neighbouring countries, rivers in the vicinity of paper and pulp producers and high altitude rivers were included. Sediment samples were firstly screened for the presence of DLCs by the H4IIE-luc bio-assay, whereafter sites eliciting quantifiable responses were selected for further chemical analysis by high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS). Of the 96 sites, only 23 had quantifiable levels of DLCs. These sites were mainly of industrial, semi-industrial or low-income residential nature. PAHs were the predominant class of compounds at most of the sites, while OCPs and PCBs were present in moderate concentrations and PBDEs in minor concentrations. The concentration of pollutants measured in South African soils and sediments were intermediate when compared to the levels measured in some European, Asian and Scandinavian countries, with the exception of a few sites where exceptionally high levels of compounds were measured. The carbon content normalized concentrations of certain compounds at some of the sites exceeded the Canadian sediment quality guidelines. The estimated cancer risk associated with dermal absorption of OCPs measured in this study was negligible when compared to the background cancer risk expected for South Africans due to life style factors. However, it was estimated that dermal exposure to PCBs, DLCs and PAHs may lead to severe increases in cancer cases, and may seriously impact on human health. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Water resources in South Africa are scarce, and should therefore be protected against pollutants, also from persistent organic pollutants (POPs). POPs are a global concern due to their ubiquitous presence, persistence and toxicity. This is emphasised by the Stockholm Convention on POPs, which aims at reducing and ultimately eliminating them. South Africa signed and ratified the treaty, and it became international law on 17 May 2004, but there is still a lack of information regarding POPs in South Africa. This study focussed on establishing the levels of POPs and other organic pollutants, which included various organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), dioxin-like compounds (DLCs), non-dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ether (PBDE). Sampling regions included the industrial cities – Cape Town, Richards Bay, Durban and Bloemfontein, and low-income, high density residential areas surrounding a wetland in Soweto/Lenasia and Botshabelo. Additionally, rivers flowing into neighbouring countries, rivers in the vicinity of paper and pulp producers and high altitude rivers were included. Sediment samples were firstly screened for the presence of DLCs by the H4IIE-luc bio-assay, whereafter sites eliciting quantifiable responses were selected for further chemical analysis by high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS). Of the 96 sites, only 23 had quantifiable levels of DLCs. These sites were mainly of industrial, semi-industrial or low-income residential nature. PAHs were the predominant class of compounds at most of the sites, while OCPs and PCBs were present in moderate concentrations and PBDEs in minor concentrations. The concentration of pollutants measured in South African soils and sediments were intermediate when compared to the levels measured in some European, Asian and Scandinavian countries, with the exception of a few sites where exceptionally high levels of compounds were measured. The carbon content normalized concentrations of certain compounds at some of the sites exceeded the Canadian sediment quality guidelines. The estimated cancer risk associated with dermal absorption of OCPs measured in this study was negligible when compared to the background cancer risk expected for South Africans due to life style factors. However, it was estimated that dermal exposure to PCBs, DLCs and PAHs may lead to severe increases in cancer cases, and may seriously impact on human health. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Elevated polychlorinated biphenyl (PCB) concentrations have been detected in marine mammals inhabiting the Strait of Georgia, British Columbia (Canada) and Puget Sound, Washington State (USA). This raises concerns about adverse health effects and underscores the importance of documenting source, transport, and fate of contaminants. This marine mammal-oriented study- (1) examines dietary exposure to complex mixtures of persistent organic pollutants (POPs); (2) characterizes POP accumulations using congener-specific contaminant analyses, stable isotope ratios, and multivariate statistical methods; and (3) explores some of the influencing factors for POP bioaccumulation in marine mammals. A first application of a food basket approach to assessing real-world dietary exposure to mixtures of chemicals in marine mammals has revealed Puget Sound as a regional “hotspot” for PCB contamination. The consistency between PCB concentrations in Puget Sound and the Strait of Georgia harbour seals (Phoca vitulina) and their food baskets validates the use of this method as a basis for exploring dietary exposure, metabolism, biomagnification, and health risks in marine mammals. Concentration rankings of POPs and estimated daily intakes based on our food baskets suggests that both legacy (e.g., PCB, dichlorodiphenyltrichloroethane [DDT]) and new (polybrominated diphenyl ethers [PBDEs]) POPs may pose potential health risks to seals. Accumulations of PCBs in the Strait of Georgia seal food web demonstrate the bioaccumulative nature and persistence of PCBs. Correlations of PCB concentrations with physicochemical properties and trophic level revealed the important role that metabolism plays in biomagnification in seals, alongside trophic level and log Kow. We estimate a PCB load of 77 kg within the Strait of Georgia biomass, with the largest proportion (36 %) detected in marine mammals. Dietary exposure of POPs to resident killer whales (Orcinus orca) was assessed by measuring POPs in four stocks of chinook salmon (Oncorhynchus tshawytscha), their primary prey. Differences in POP concentrations between chinook smolts and returning adults suggest that the majority of POPs are acquired at sea during the major growth period in their life cycle. Higher POP concentrations and low lipid content were observed among the more southerly stocks suggesting a migration-associated metabolism and loss of lighter congeners, thereby exposing southern residents to more highly contaminated chinook salmon. Consumption on a lipid-weight basis, (higher consumption on a wet weight basis), as well as consuming prey from a more contaminated region, likely increases killer whale exposure to POPs, offering an explanation for higher contaminant burdens in southern residents. While previous research has examined species inhabiting different trophic levels or food chains in other regions, this study has provided an assessment of POP dietary exposure, biomagnification, and influencing factors on trophic accumulations in a North-eastern Pacific marine mammal food web. These results have provided further insight into the influence of such factors as age, sex, lipid content, diet, migration-related metabolism, physicochemical properties (degree of chlorination, log Kow), and chemical structure on POP accumulation in marine mammals. We have identified the largely unregulated PBDEs as posing potential health risks to marine mammals and offered a means to update existing tissue residue guidelines for the protection of wildlife.

The fate and bioaccumulation of a contaminant entering the marine environment through wastewater outfalls depends on the contaminant’s persistence and affinity for particles. The physical characteristics of the receiving environment, e.g. current velocity, sedimentary processes, and the availability of organic carbon are also important. However, these latter effects are not usually evaluated quantitatively. This thesis investigates the near-field accumulation in sediment and biota of particle-reactive polybrominated diphenyl ethers (PBDEs) entering coastal waters via two municipal outfalls: one discharging into a high energy, low sedimentation environment near Victoria, B.C., Canada; the other into a low energy, high sedimentation environment near Vancouver, B.C. We used 210Pb profiles in sediment box cores together with an advection-diffusion model to determine surface mixing and sedimentation rates, and to model the depositional history of PBDEs at these sites. A particularly important finding of this study is that the very high energy environment to the southeast of the Victoria outfall accumulates PBDEs despite not having net sediment accumulation. Although the discharge of PBDEs was much lower from the Victoria outfall than from Vancouver, some sediment PBDE concentrations were higher near Victoria. Most PBDEs were dispersed beyond the near-field at both sites, but a greater proportion was captured in the sediment near the Vancouver outfall where rapid burial was facilitated by inorganic sediment supplied from the nearby Fraser River. Clearly, treating wastewater to the same level, regardless of local oceanographic conditions, will not result in a uniform environmental footprint. Total PBDE concentrations in benthic invertebrate communities were higher near Vancouver than Victoria, despite lower concentrations in sediments, and correlated with organic carbon normalized sediment concentrations. Principal Components Analysis suggested uptake of individual PBDE congeners was determined by sediment properties (TOC, grain size), whereas PCB congener uptake was governed by physico-chemical properties (octanol-water partitioning coefficient). Our results suggest that sediment quality guidelines for PBDEs and likely PCBs may be more relevant if corrected to TOC content in sediment. In addition, where enhanced wastewater treatment increases the ratio of PBDEs to particulate organic carbon in effluent, nearfield benthic invertebrates may face increased PBDE accumulation. This underlines the need for source control of persistent organic contaminants, which cannot be broken down by conventional wastewater treatment. / Graduate

In a multi-agent system (MAS), the overall performance is greatly influenced by both the design and the control of the agents. The physical design determines the agent capabilities, and the control strategies drive the agents to pursue their objectives using the available capabilities. The objective of this thesis is to incorporate control strategies in the early conceptual design of an MAS. As such, this thesis proposes a methodology that mainly explores the interdependency between the design variables of the agents and the control strategies used by the agents. The output of the proposed methodology, i.e. the interdependency between the design variables and the control strategies, can be utilized in the requirement analysis as well as in the later design stages to optimize the overall system through some higher fidelity analyses. In this thesis, the proposed methodology is applied to a persistent multi-UAV surveillance problem, whose objective is to increase the situational awareness of a base that receives some instantaneous monitoring information from a group of UAVs. Each UAV has a limited energy capacity and a limited communication range. Accordingly, the connectivity of the communication network becomes essential for the information flow from the UAVs to the base. In long-run missions, the UAVs need to return to the base for refueling with certain frequencies depending on their endurance. Whenever a UAV leaves the surveillance area, the remaining UAVs may need relocation to mitigate the impact of its absence. In the control part of this thesis, a set of energy-aware control strategies are developed for efficient multi-UAV surveillance operations. To this end, this thesis first proposes a decentralized strategy to recover the connectivity of the communication network. Second, it presents two return policies for UAVs to achieve energy-aware persistent surveillance. In the design part of this thesis, a design space exploration is performed to investigate the overall performance by varying a set of design variables and the candidate control strategies. Overall, it is shown that a control strategy used by an MAS affects the influence of the design variables on the mission performance. Furthermore, the proposed methodology identifies the preferable pairs of design variables and control strategies through low fidelity analysis in the early design stages.

No description available.

ABSTRACT The tropical and subtropical nearshore marine environments of Queensland, Australia sustain diverse and unique marine wildlife. Continuous population growth and land-use changes along the Queensland coastline are known to exert numerous anthropogenic pressures on these marine ecosystems, including the delivery of high sediment loads. Sediments also provide a transport pathway for persistent organic pollutants (POPs) from rural and urban catchments into the marine environment. While such pollutants are known to be elevated in marine sediment and biota from nearshore areas in Queensland, their input and distribution pathways, as well as exposure and associated risks to wildlife populations are only partially understood. Mounting evidence suggests that POPs may contribute to population declines in marine wildlife species; however, limited information is available regarding the accumulation and effects of these contaminants in endangered or threatened marine turtles. This study aimed to redress some of these information gaps using a case study approach in marine turtle habitats of Moreton Bay, and other embayments in Queensland. Among persistent organic pollutants (POPs), dioxins (polychlorinated dibenzo-p-dioxins; PCDDs) and to some extent also dioxin-like PCBs (polychlorinated biphenyls; PCBs) were found to be widespread and often present at elevated (ppb) levels in surface sediments from Moreton Bay. However, while PCDD/F toxic equivalencies (TEQs) are above international (Canadian) sediment quality guidelines at numerous sites in Moreton Bay, in general TEQs across the Bay are relatively low compared to those from contaminated locations near dense industrial activities. POP contamination in surface sediments across Moreton Bay was investigated by a combination of GIS spatial mapping, geostatistical and traditional statistical modalities. High spatial variability and complex spatial distribution patterns were revealed. High resolution GIS kriging model outputs from the mid to southern Bay facilitated identification of distinct sediment contamination zones, with highest PCB and PCDD/F levels present in nearshore locations, associated with nearby river systems. While primarily governed by organic carbon, a multitude of physical, chemical and hydrological factors were identified to influence the spatial variance of PCDD/F concentrations. The main parameters governing PCDD/F spatial distribution were identified as sediment geochemistry, water depth and anthropogenic alterations of the physical environment and, together, all quantifiable explanatory variables (including hydrodynamic flushing) explained ≈75% of spatial PCDD/F variance. Together, the interaction of these parameters results in complex distribution patterns and highly variable concentrations even among neighbouring sites of 1-3 km resolution. These results suggest that prediction models of POP distributions in the nearshore marine environment may require high-resolution validation, and highlights that the design of low resolution monitoring strategies can have profound impacts on the reliability of contaminant information or any subsequent extrapolations. This knowledge and methodology can be utilised to optimise on-going and future near-shore sediment monitoring programs both locally and in other regions around the world. Using the spatial distributions of dioxin-like contaminants within sediments, this study provided an opportunity to assess field-based relationships between habitat contamination and local marine biota contamination. Detectable levels of PCDD/Fs and dioxin-like PCBs were measured in all green, hawksbill, loggerhead and flatback marine turtle tissues. POP concentrations in sediments were found to significantly correlate with those in the herbivorous green turtle from different sediment contamination zones. These findings demonstrate that sediments represent an important secondary contaminant source and lead to redistribution of POPs to the marine food chain. POP concentrations and TEQs clearly increased from sediment to turtles as well as with increasing trophic levels in marine turtle species. The results from this study demonstrate that the extent of sediment contamination within foraging habitats governs marine turtle exposure, while, trophic status and to some extent age influence contaminant exposure within a particular contamination zone. Despite the relatively low TEQ in sediments from Moreton Bay, TEQ levels in green turtle sub-populations foraging from near-shore locations and higher trophic loggerhead and flatback turtles are similar or elevated compared to those reported for other marine wildlife from Moreton Bay and elsewhere, even compared to higher trophic species from locations impacted by dense industrial activities. High bioaccumulation potential of 2,3,7,8-PCDD/F and dioxin-like PCBs compounds were estimated for green turtles using biota to sediment accumulation factors. Selective accumulation of toxicologically more potent (i.e. lower chlorinated) PCDD/Fs was observed for higher trophic marine turtles, resulting in increasing TEQs for the carnivorous species. Biomagnification was also observed for some non-2,3,7,8-substituted dioxin congeners which typically do not accumulate in most biota. These results are proposed to be due to relatively high accumulation efficiency and/or low metabolic capacity for these POP compounds in marine turtles. These findings are also hypothesised to reflect temperature dependant, greater bioavailability of hydrophobic chemicals in sub-tropical and shallow marine systems. An additional pilot study revealed that in contrast to PCDD/Fs and PCBs, levels of persistent flame retardants (polybrominated diphenyl ethers; PBDEs) were relatively low in marine turtles and other marine species (dugong, fish and shellfish) from Moreton Bay. This suggests relatively low level input of these more recent industrial products into the marine environment. However, as elevated levels of PBDEs have been reported in blood from the general population of Australia, ongoing transport from the terrestrial to the marine system and redistribution of these contaminants, similar to PCDD/F and PCBs, would be expected to occur into the future. Limited information is available regarding the sensitivity of reptiles to and effects of POPs, however, studies have shown that reptiles are sensitive to POPs albeit with uncharacterised relative potency. In the absence of robust toxicological information for reptiles or marine turtles, the potential risks associated with PCDD/F and PCB exposure of Queensland turtle populations was evaluated using toxicity for sensitive biological endpoints observed in mammals and birds. Using probabilistic methodology for marine turtles from Queensland, the body burden of up to 31% and 55% of green and loggerhead turtles, respectively, are above the threshold levels where the most sensitive physiological effects are observed in mammals and birds. While this evaluation illustrates that the contaminants investigated have the potential to impact on the health of marine turtle populations, it must be highlighted that it is compromised by the lack of species-specific (and in this case, class-specific) information, the uncertainty of which is often considered to represent a factor of at least 10. The findings of the present study indicate that exposure to POPs has the potential to adversely affect the health of Queensland’s marine turtle populations, and highlight the need for robust information on reptile specific sensitivity to these compounds.