Wave attenuation by vegetation is a highly dynamic process and its quantification is important for accurately understanding and predicting coastal hydrodynamics. However, the influence of vegetation on wave dissipation is not yet fully established nor implemented in current hydrodynamic models. A series of laboratory experiments were conducted at the Haynes Coastal Engineering Laboratory and in a two-dimensional flume at Texas A and M University to investigate the influence of relative vegetation height, stem density, and stem spacing uniformity on wave attenuation. Vegetation fields were represented as random cylinder arrays where the stem density and spatial variation were based on collected field specimens. Experimental results indicate wave attenuation is dependent on relative vegetation height, stem density, and stem spacing standard deviation. As stems occupy more of the water column, an increase in attenuation occurred given that the highest wave particle velocities are being impeded. Sparse vegetation fields dissipated less wave energy than the intermediate density; however, the extremely dense fields dissipated very little, if any, wave energy and sometimes wave growth was observed. This is possibly due to the highest density exceeding some threshold where maximum wave attenuation capabilities are exceeded and lowering of damping ensues. Additionally, wave attenuation increased with higher stem spatial variation due to less wake sheltering. A one-dimensional model with an analytical vegetation dissipation term was developed and calibrated to these experimental results to capture the wave transformation over the vegetation beds and to investigate the behavior of the vegetation field bulk drag coefficient. The best fit between predicted and measured wave heights was obtained using the least squares method considering the bulk drag coefficient as the single calibration parameter. The model was able to realistically capture the wave transformations over vegetation. Upon inspection, the bulk drag coefficient shared many of the dependencies of the total wave dissipation. The bulk drag coefficient increased with larger relative vegetation heights as well as with higher stem spacing standard deviation. Higher densities resulted in a lowering of the bulk drag coefficient but generally an increase in wave attenuation. These parameters and their influences help in identifying the important parameters for numerical studies to further our understanding of wave attenuation by wetlands.

In modern democratic country, the complexity of public affairs is a difficult topic of public policy. Only admires the objective analysis technology is insufficient to in accordance to the complex public decision-making. Therefore, the public policy formulation needs the suitable political judgment. But populace's policy-making cognition mode then is the key to carry out the policy formulation. Today Taiwan society had the certain democratized degree and the economic basis, the populace had opportunity to participate in public affairs. As a result of is extremely insufficient in the participation public affairs training, the populace has not been able by rational when discuss the public subject that he faces. Here cognition is uncoordinated and possible to initiate the policy-making conflict. If we want to reduce the policy-making conflict to achieve higher policy-making quality, it is the necessary thorough understanding common populace's policy-making cognition mode. This research is based on the Cognitive Continuum Theory, take sets up a wetland park as the example, designs a quasi-experiment to directly compares efficacies of analytical, intuitive and quasi-rational cognition mode of the populace in the public decision-making. The research target lies in to regards the analytical cognition and the intuitive cognition is dichotomous proposes the counter-evidence, proved they are the beginnings and ends of the cognitive continuum. The findings showed that, (1) the characteristic policy-making judgment cognition mode of the populace to the wetland park judgment is a continuous distribution state. (2) The cognition identity of judgment method to be able to induce the cognition identity of the policy-making judgment. (3) The populace's policy-making judgment behavior has the analysis cognition identity that they can depend on analytical judgment method to carry on the policy-making judgment. (4) The policy-making cognition mode can come under cognition of identity influence the policy-making judgment method. The better correlation of judgment method and the goal cognition identity, the more consistent policy-making performance.

Upflow anaerobic sludge blanket (UASB) has been developed and commercially used for treating high-strength wastewaters since 1971, and this process has been extended its applications to domestic sewage treatment since 1980. Constructed wetlands (CWL) can be treated as a simulated natural treatment system, which use solar radiation as the energy source. By analogy with some removal mechanisms in natural wetlands, constructed wetlands are able to transform and remove pollutants from the wastewater. Other features provided by the constructed wetland include wildlife support, hydrologic modification, erosion protection, and open space and aesthetics. It has been applied for domestic wastewater purification for decades. In this study, a pilot UASB-CWL reactor was built to test its performance for the removal of organic compounds and nutrients from a sewage with COD (Chemical oxygen demand) in the range of 200-300 mg/L. The UASB reactor has an active liquid volume of 2.5 liters and the CWL includes a 56 L-tank (CWL-1) followed by a 80 L-tank (CWL-2) in which emergent macrophyte (reed, Phragmites australis L.) and floating macrophyte (Pistia stratiotes L.), respectively, were planted. Effects of hydraulic retention time (HRT) of the test water in the reactor on the pollutant removal were tested. Results indicate that with HRTs of 2, 45, and 64 hours, respectively, in the UASB, CWL-1, and CWL-2, the system exhibited good performances for pollutant removal. The HRTs are equivalent to CODt loadings of 3.06, 0.065, and 0.026 kg/m3.day to the UASB, CWL-1, and CWL-2, respectively. Average total COD (CODt), soluble COD (CODs), total biochemical oxygen demand (BODt), suspended solids (SS), and phosphate-P (P) were 121, 62, 33, 130, and 0.10 mg/L, respectively, and these are equivalent to the removal efficacies of 45-65, 60-80,65-75, 30-50, and 85-95%, respectively. With the operation conditions, average CODt = 28 , CODs = 18, BODt = 10, SS = 18, NH3-N = 18, NO2--N =12 , NO3--N = 1.0, and P = 0.0 mg/L were obtained, and the average removal total efficacies were 93, 93, 90, 75, 72, 95, and 100%, respectively. Effluent qualities are far superior to the national effluent standards for domestic sewage in Taiwan.

Taiwan is an island surrounded by sea. Due to the topography, the coastal wetlands distribute almost around the west seashore, and some at the estuary of the east seashore. The coastal wetland is a transitional area between territory ecosystem and marine ecosystem. The environment of the coastal wetland is influenced by tide and season, thus the distribution of vegetations here exhibits a dynamic equilibrium. This study attempts to investigate the distribution and composition of the vegetation and the appearance of the habitat environment at the coastal wetland of Taiwan. According to the results, 173 species belonging to 50 families have been recorded. This indicates that the diversity of the marsh vegetation at the coastal wetland is low. Most of the species belong to Gramineae, Compositae and Cyperaceae. Paspalum vaginatum and Phragmites karka are the most dominant plant at coastal marsh environments. According to the results of detrended correspondence analysis (DCA) and cluster analysis (CA), 16 vegetation types including one subtype and one transitional type are classified. The habitats of these vegetation types can be classified into five types, namely tidal fresh water marsh, fresh water-salt marsh, wet meadow, salt marsh and submerged environment. Most of these vegetation types have only one major dominant species. The distribution of the marsh vegetation features a belting pattern, which is mainly limited by the maximum of their salt tolerance from coastal toward inland, or estuary toward headwaters. Subsequently, it can by influenced by soil moisture and pH value. Furthermore, the vegetations are influenced by many additional environmental factors, resulting in a mosaic distribution of vegetation types. The marsh vegetation is processing at an unstable and developing period. Because the coastal wetland is seriously disturbed by human activities, the environmental variation becomes greater. Therefore, the transitional vegetations were observed frequently. Finally, the development pressure due to economic demand is the major cause that makes coastal wetland disappeared. It is urgently needed to protect this sensitive natural resource.

In most cases, data from petroleum industry wetland studies indicate that treatment wetlands are equally or more effective at removing pollutants from petroleum industry wastewaters than from other types of wastewater. In this study, we discussed the treatment efficiencies of oil-refinery industry wastewater by pilot-scale constructed wetland systems .The constructed wetland systems were one free water surface system filled with the sandy media and one subsurface flow system filled with the gravel media operated in parallel. Each system planted with Phragmites communis. The hydraulic retention time for the treatment wetland was controlled in turn at 0.96, 0.48, and 0.72 days. The experimental results showed that all of these contaminants could be reliably removed from wastewater by treatment wetland, especially the FWS. The effluents from the constructed wetland systems reusing and recovering were feasible.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.

Proefschrift--Utrecht. / "Stellingen": 2 l. laid in. "Literatuur": p. [358]-367.

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Methylmercury (MeHg) is the most toxic species of mercury (Hg), and is an important ecosystem contaminant. In wetlands on the Canadian Shield, in NW Ontario, MeHg concentrations in peat and peat porewater ranged from 0.3 to 53 ng $ rm g sp{-1}$ and $<$0.1 to $ rm 7.3 ng l sp{-1},$ respectively. The greatest concentrations of MeHg occurred just below the water table, emphasizing the importance of redox reactions in Hg methylation. Methylmercury partition coefficients between peat and peat porewater ranged from $1.6 times 10 sp3$ to $8.6 times 10 sp5.$ No significant correlations between MeHg and concentrations of $ rm H sp+, NH sb4 sp+, NO sb3 sp-, NO sb2 sp-,$ total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), $ rm SO sb4 sp{2-},$ and dissolved organic carbon (DOC) in the porewater of the wetlands were found. / Following shallow impoundment of a wetland, MeHg concentrations in the upper metre of peat porewater increased from $ rm 0.2 pm 0.2 ng l sp{-1}$ to $ rm 0.8 pm 0.8 ng l sp{-1}.$ Total mercury (T-Hg) and MeHg concentrations were determined in decomposing sedge, spruce needles, and Sphagnum moss, placed in a headwater wetland and the impounded wetland. The amount of T-Hg decreased in all tissues regardless of location. the amount of MeHg increased by as much as an order of magnitude in the tissues placed in the impounded wetland and wet areas (hollows and lawns) of the headwater wetland, but decreased in tissue placed in the dry areas (hummocks) of the headwater wetland. Therefore, it is during anaerobic decomposition of plant material that MeHg is produced in wetlands. / Incubations of peat were performed with addition of Hg, molybdate, $ rm SO sb4 sp{2-}, S sp{2-}, NH sb4NO sb3,$ pyruvate, and upland DOC. Methylmercury production was increased only after addition of $ rm SO sb4 sp{2-}$ and retarded only by $ rm NH sb4NO sb3.$ Although $ rm SO sb4 sp{2-}$ may not be required to methylate Hg, the increased availability of $ rm SO sb4 sp{2-}$ may influence the size and composition of the population of sulfate reducing bacteria in peat, thereby increasing the potential for Hg methylation.

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