Thesis (M.Hous.M.)--University of Hong Kong, 2004. / Also available in print.

<p> Today billions of people live without access to basic sanitation facilities, and thousands die every week due to diseases caused by fecal contamination associated with improper sanitation. It has thus become crucial for decision makers to have access to relevant and sufficient data to implement appropriate solutions to these problems. The Global Water Pathogen Project <u> http://www.waterpathogens.org/</u> is dedicated to providing an up-to-date source of data on pathogen reduction associated with different sanitation technologies that are important if the world is to achieve the Sustainable Development Goals (SDGs) related to health and sanitation provision. In this research, a subset of the Global Water Pathogen Project (GWPP) data is used to access the reduction of bacteria and viruses across different mechanical and natural sanitation technologies. The order of expected removal for bacteria during wastewater treatment was reported as highest for a membrane bioreactor (4.4 log10), waste stabilization pond (2.3 log10), conventional activated sludge (1.43 log10), anaerobic anoxic oxic activated sludge (1.9 log10), trickling filter (1.16 log10), and upflow anaerobic sludge blanket reactor (1.2 log10). </p><p> Furthermore, the order of expected removal for viruses was reported as highest for a membrane bioreactor (3.3 log10), conventional activated sludge (1.84 log10), anaerobic anoxic oxic activated sludge (1.67 log10), waste stabilization pond (1 log10), upflow anaerobic sludge blanket reactor (0.3 log10) and trickling filter (0.29 log10). It was found that hydraulic retention time (HRT) had a statistically significant relation to the reduction of bacteria in an anaerobic, anoxic oxic treatment system. Similarly, a significant relation was found between the number of waste stabilization ponds in series and the expected reduction of bacteria. HRT was also found to be a significant factor in virus reduction in waste stabilization ponds. Additionally, it was observed that waste stabilization ponds, trickling filters, and UASB reactors could obtain a greater reduction in bacteria (5&ndash;7 log10) when combined with additional treatment (e.g., chemical disinfection or use of maturation ponds). Also, mechanized systems, such as activated sludge systems and membrane bioreactors, obtained a greater reduction (2&ndash;3 log10) of viruses when compared to a natural system. It was concluded that the selection of the best suitable technology for pathogen reduction depends on environmental, design, and operational factors as well as considering the performance of specific wastewater treatment systems individually as well as when combined with other treatment technologies that may provide added removal of microbial constituents. </p><p>

The global trend towards sustainability is influencing humankind on a daily basis. One of the aspects of human life that is significantly influenced by this trend is decision making with regard to travel and holidays. The investigation was initiated in an attempt to monitor the sustainability of community-based ecotourism in southern Africa and to set a baseline for future comparison. A comprehensive inventory of 331 community-based tourism ventures across southern Africa was compiled as part of the study. A spatial selection was undertaken to refine the selection of ventures which could be safely and economically visited in southern Africa. A telephonic interview was carried out with each of the remaining 241 community-based tourism ventures in order to determine which ventures may be categorized as community-based ecotourism ventures. The results of the telephonic interview were used to classify the community-based ecotourism ventures into types. A random selection within types followed to select six case studies for further investigation. An evaluation framework was constructed to monitor the sustainability of the selected community-based ecotourism ventures. The evaluation framework made use of a number of sustainability issues and their associated indicators. The evaluation framework was then tested for its applicability to investigate the social, economic and environmental sustainability of the six case studies. Thereafter a cross-case analysis was undertaken to compare the results and to obtain baseline data for future comparison. The utility of the constructed evaluation framework was subsequently commented on and changes were recommended. The study provided a time- and cost-effective evaluation framework for monitoring the sustainability performance of community-based ecotourism ventures. The constructed framework also makes an important contribution as a departure point in the adaptive learning cycle for the development and implementation of sustainable tourism indicators for community-based ecotourism ventures. Case study specific recommendations were made in order to improve the sustainability performance of the investigated case studies. The results of this study serve as a benchmark against which future investigations into the sustainability of community-based ecotourism ventures in southern Africa may be compared. Conclusions relating to the sustainability of community-based ecotourism ventures in southern Africa are drawn, and a number of recommendations for further research are made.

<p> Russian olive is an exotic actinorhizal tree intentionally introduced to the U.S. in the early 1900&rsquo;s. It has become a dominant component of riparian ecosystems throughout the western U.S. Unlike most other riparian trees in the semi-arid west, Russian olive germinates and grows both in the open and in the understory of mature cottonwood stands. As an actinorhizal species, it forms an endosymbiosis with soil actinobacteria in the genus <i>Frankia</i> that allows for atmospheric N₂-fixation. This leads to higher soil N concentrations and mineralization rates underneath the tree&rsquo;s canopy than outside. Russian olive&rsquo;s high abundance and impact on soil N suggest it may alter plant communities, but these impacts have not been previously demonstrated. I investigated the impacts of Russian olive on shading, soil N availability, and plant communities and documented how those impacts varied across a semi-arid riparian ecosystem along the South Fork of the Republican River in eastern Colorado. Of the suite of environmental variables I measured, presence or absence of cottonwood canopy had the largest effect on Russian olive impacts. Russian olive increased shading, soil N availability, and proportion exotic plant and forb cover more in the open than underneath a cottonwood overstory.</p><p> Actinorhizal endosymbioses provides an important N source in terrestrial ecosystems, but N₂-fixation rates decrease due to high exogenous N and low photosynthetically active radiation (PAR). The amount that these environmental variables reduce N₂-fixation in host-<i>Frankia </i> symbiosis types dictates the strength and duration of those symbioses&rsquo; impacts on ecosystems. To understand how the two main types of endosymbioses (<i>Alnus-</i> and <i>Elaeagnus-Frankia</i>) differ in their response to environmental variability, I conducted a greenhouse experiment comparing growth and nodulation between two genera of actinorhizal species, <i> Elaeagnus</i> and <i>Alnus,</i> across exogenous N and PAR levels. Overall, <i>Elaeagnus</i> species had higher nodulation rates and tissue % N than <i>Alnus</i> species. Nodulation rate and growth response to nodulation were both lower at low PAR than high PAR for both genera. The reduction in the growth response to nodulation at high exogenous N was lower in <i>Elaeagnus-Frankia</i> symbiosis than <i> Alnus-Frankia</i> symbiosis. These results suggest that <i>Elaeagnus </i> species are more likely to cause a greater and longer-lasting increase in soil N than <i>Alnus</i> species.</p><p> A main objective of exotic species management is to increase native plant cover. However, few studies monitor plant community response to exotic species management, and the few that have suggest secondary invasion is likely, particularly when effects of the target invasive persists and management efforts cause disturbance. To measure the role of these two factors in plant community response to Russian olive removal, I monitored soil N availability and plant communities along the South Fork of the Republican River two years before and three years after the tree&rsquo;s removal. Russian olive&rsquo;s impact on soil N availability persisted, with levels staying high around removed Russian olive stems three years after removal. The plant community around removed Russian olive also had no increase in native plant cover but a dramatic increase in kochia (<i> Bassia scoparia</i>) cover following removal. My research demonstrates that Russian olive increases exotic plant cover in areas it invades and simply removing the tree does not promote native species recovery.</p><p>

The need for a procedure to design chemical plants for pollution prevention results from a recent emphasis on pollution prevention at the source. The conceptual design procedure of Douglas (1985) has been extended to consider process alternatives for pollution prevention. Waste penalties become another criteria in the economic evaluation of flowsheet alternatives. New heuristics are presented that lead to process alternatives that reduce or eliminate waste streams. Twenty processes comprising a total of 79 individual plants have been studied, and their waste loads have been summarized. This analysis shows that the majority of the waste from chemical processes can be classified as either waste from the reaction chemistry or waste from the separation system. Because much of this waste is waste water, water reuse should be considered to reduce the total waste load. The aqueous waste load from these twenty processes could be reduced by an average of 63% if all fresh water streams could be replaced with recycled water. By identifying the decisions having the greatest impact on waste loads in a chemical processes, alternative decisions for pollution prevention can be made, leading to alternative flowsheet designs. This is shown through a discussion of the styrene process, in which flowsheet alternatives using steam as a heat carrier are compared to those using either methane or toluene. Several feasible flowsheets are for each case, each having roughly the same economic potential. Heat integration should be considered to identify to best few candidates for a more rigorous design. The StreamCosts screening method targets wasteloads resulting from the reaction chemistry, by screening reaction pathway alternatives based on the costs of the feed and exit streams, including the waste penalties. Those pathways with large amounts of waste byproducts can be eliminated early in the design procedure. Finally, the PIPII computer package has been extended for pollution prevention. The production of Bis (2-Hydroxyethyl) Terephthalate serves as a case study to demonstrate the use of the code. The total waste penalty of 58.5 MM$/yr for the base case alternative leads to an economic potential of $-$47.3 MM\$/yr, showing a strong incentive for waste reduction.

<p> Groundwater is an essential input to agriculture world-wide, but it is clear that current rates of groundwater use are unsustainable in the long term. This dissertation assesses both current use of groundwater for country- to global-scale agriculture, and looks at the future of groundwater. The focus is on 1) quantifying food directly produced as a result of groundwater use across spatially-varying agricultural systems, 2) projecting future groundwater demands with consideration of climate change and human decision-making, and 3) understanding the system dynamics of groundwater re-use through surface water systems. All three are addressed using a process-based model designed to simulate both natural and human-impacted water systems. </p><p> Irrigation can significantly increase crop production. Chapter 1 combines a hydrology model (WBM) with a crop model to quantify current crop production that is directly attributed to groundwater irrigation in China. Unsustainably-sourced groundwater &mdash; defined as groundwater extracted in excess of recharge &mdash; accounted for a quarter of China&rsquo;s crop production, and had significant spatial variability. Climate variability and groundwater demand magnified one another in hot and dry years, causing increased irrigation demand at the same time as limited surface water supplies. </p><p> Human decisions about water resource management can impact both the demand and sustainability of groundwater use. Chapter 2 takes an interdisciplinary approach to projecting India&rsquo;s future (to 2050) groundwater demands, combining hydrology and econometric modeling. The econometric model projects how humans make decisions to expand or contract the irrigated land area of crops in response to climate change. Even in areas with precipitation increases, human decisions to expand irrigated areas led to increasing demands for groundwater. We additionally assessed the potential impact of a large water infrastructure project to alleviate groundwater demands in India, and found that maximum alleviation (up to 16%) was dependent upon the storage volume and location of new reservoirs. </p><p> One proposed method for reducing the world&rsquo;s demand for groundwater is to increase the efficiency of agricultural water use. However, these same inefficiencies cause a portion of extracted groundwater to enter surface water systems; it can then be reused, creating a complex system in which groundwater demand does not linearly decline with increased water use efficiency. Chapter 3 quantifies the amount of groundwater that enters surface water systems, the number of times this water is reused for agriculture, and the minimum amount of groundwater required by current agricultural systems in the hypothetical scenario of perfect irrigation efficiency.</p>

<p> The coastal zone of Louisiana is changing due to multiple pressures associated with sea-level rise, subsidence, and the inability of sediment or organic accretion to keep pace. The expected increases in sea level and salinity may affect the distribution of the existing plant communities. In addition, these changes in the environment could lead to shifts in plant community composition. During the summer of 2014, I researched how changes in salinity and water levels may change the establishment of vegetation in Louisiana marshes. Randomly selected Coastwide Reference Monitoring System (CRMS) sites were used to collect vegetation data and soil samples. The collected soil samples from fresh, intermediate, brackish, and saline marsh sites were used in a seed bank study. The seed bank study evaluated the effects of different levels of salinity and flooding on seed germination and species richness. Seed germination was highest in soil samples collected from fresh and intermediate sites when these samples were exposed to low salinity (0.0 ppt) and non-flooded conditions. My study only found 43 seedlings in the 10 ppt treatment of 336 total seed germinations, and only 2 seedlings were found in the 20 ppt salinity treatment. Salinity was the dominant factor governing seed germinations and species richness. I also determined that the parent plants for the species found in my seed bank study were more likely to be found within the study site. However, the species data showed at least one species or genus was not present in either the historical or the field collected data. Therefore, the dispersal distance of some seeds from their parental seed provider could have been several hundred meters.</p>

<p>Ecological risk assessment (ERA) is a framework for monitoring risks of exposure and adverse effects of environmental stressors to populations or communities of interest. One tool of ERA is the biomarker, which is a characteristic of an organism that reliably indicates exposure to or effects of a stressor like chemical pollution. Traditional biomarkers which rely on characteristics at the tissue level and higher often detect only acute exposures to stressors. Sensitive molecular biomarkers may detect lower stressor levels than traditional biomarkers, which helps inform risk mitigation and restoration efforts before populations and communities are irreversibly affected. In this study I developed gene expression-based molecular biomarkers of exposure to metals and insecticides in the model toxicological freshwater amphipod Hyalella azteca. My goals were to not only create sensitive molecular biomarkers for these chemicals, but also to show the utility and versatility of H. azteca in molecular studies for toxicology and risk assessment. I sequenced and assembled the H. azteca transcriptome to identify reference and stress-response gene transcripts suitable for expression monitoring. I exposed H. azteca to sub-lethal concentrations of metals (cadmium and copper) and insecticides (DDT, permethrin, and imidacloprid). Reference genes used to create normalization factors were determined for each exposure using the programs BestKeeper, GeNorm, and NormFinder. Both metals increased expression of a nuclear transcription factor (Cnc), an ABC transporter (Mrp4), and a heat shock protein (Hsp90), giving evidence of general metal exposure signature. Cadmium uniquely increased expression of a DNA repair protein (Rad51) and increased Mrp4 expression more than copper (7-fold increase compared to 2-fold increase). Together these may be unique biomarkers distinguishing cadmium and copper exposures. DDT increased expression of Hsp90, Mrp4, and the immune response gene Lgbp. Permethrin increased expression of a cytochrome P450 (Cyp2j2) and decreased expression of the immune response gene Lectin-1. Imidacloprid did not affect gene expression. Unique biomarkers were seen for DDT and permethrin, but the genes studied were not sensitive enough to detect imidacloprid at the levels used here. I demonstrated that gene expression in H. azteca detects specific chemical exposures at sub-lethal concentrations, making expression monitoring using this amphipod a useful and sensitive biomarker for risk assessment of chemical exposure.

<p> Lake Atitlan in Guatemala is a vital source of drinking water. The deteriorating conditions of water quality in this lake threaten human and ecological health as well as the local and national economy. Given the sporadic and limited measurements available, it is impossible to determine the changing conditions of water quality. The goal of this thesis is to use Hyperion satellite images to measure water quality parameters in Lake Atitlan. For this purpose <i> in situ</i> measurements and satellite-derived reflectance data were analyzed to generate an algorithm that estimated Chlorophyll concentrations. This research provides for the first time a quantitative application of hyperspectral satellite remote sensing for water quality monitoring in Guatemala. This approach is readily transferable to other countries in Central America that face similar issues in the management of their water resources.</p>

This thesis is the study of the perception and management of pollution risks in Taiwan's electric utility in terms of a social science paradigm of risk. It represents the first examination of Feng Shui belief impact on Taiwanese risk behaviour in electric risk settings. The deep seated culture and widespread practice of Feng Shui in traditional Chinese society would lead to the assumption that Feng Shui belief should strongly influence Taiwan risk behaviour. This empirical study research revealed that Feng Shui belief is much less important to Taiwanese risk behaviour than might have been thought. Most of the variation in electric risk acceptability resulted from the influence of social equity and justice. This study also examined the literature between Feng Shui and risk. What emerged from this is the notion that Feng Shui can be regarded as helpful complementary thinking in a social science paradigm of risk. This study suggests a number of important implications for Taipower Company and risk regulators. The choice about siting of a power plant should take account of the concept of Feng Shui the boundary rather than the concept of the fixed and administrative boundary. Implication also emerged in relation to social trust and the understanding of local residents' risk perception