Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xii, 99 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 80-83).

Thesis (M.S.)--University of North Carolina at Wilmington, 2003.

The study area of Deep Bay in the Southern China has been recognized as ecologically important site. This study presents a wetland change detection analysis incorporating both geographic information system (GIS) and remote sensing techniques. Both natural and artificial wetlands are considered as part of the Deep Bay wetland system. For instance, mangrove forests, fish ponds and shrimp ponds (gei wai) are all considered as wetlands in this study. This study is to find out how much area of the wetland system has been lost due to the conversion of land cover types in recent decades. In particular, this study uses supervised classification and change detection analysis on the satellite images which were acquired in three different time periods (1975, 1994, and 2009). It is a quantitative result which was based on the numbers of pixel changed on the images. The result shows that 39.76 % of fishpond and 20.47% of mangrove in terms of pixels have been changed to urban or residential area between 1975 and 2009. The result implies both Shenzhen and Hong Kong side of Deep Bay has significant wetland loss in recent decades. Moreover, the Deep Bay in Hong Kong includes an Aerial Photos area change analysis. This study presents three different sets of land use data which was created according to the manual interpretation of aerial photos in three different time periods (1973, 1986, and 2011). The aerial photos mainly focus on the fishpond and mangrove change in recent decades. The qualitative results show that a lot of locations were no longer mapped as wetlands in recent decades. The quantitative results illustrate the total wetland areas in the Hong Kong side of Deep Bay were continuously decreased from 1973 to 2011 by 19.06%. Additionally, the study also presents a change analysis of the nightlight imageries. Previous research found that urban development and the brightness value of nightlight imageries are highly correlated. The study uses two nightlight imageries which were acquired from 1992 and 2009 to examine whether Deep Bay has a rapid increase in urban developments. The result shows that the brightness value has continuously increased during the period with more changes in the western side of the study area. Moreover, the average brightness value of the study area has increased by 17.6%. It can show that there is an increase of urban activities in recent years. Based on the change detection analysis, it can be concluded that urban development such as reclamation is the major threat to the Deep Bay wetland system. Furthermore, there are more changes occurred in the Wetland Conservation Area and Wetland Barrier Area in Hong Kong. Both of them are either close to or around the Ramsar site. The area may not be able to support further wetland loss in the future. This study can definitely provide some information to the government and policy-makers on strategic planning of land use in Deep Bay. Sustainable development in Hong Kong is crucial in balancing the ecology and development of the city. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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Elevated arsenic (As) concentrations in surface water from storing mine tailings in lakes can have a negative impact on local and downstream vegetation and aquatic life. At Terra Mine, an abandoned silver and copper mine in the Northwest Territories, tailings storage in Ho-Hum Lake has resulted in dissolved As concentrations of 50-80 μg/L, exceeding the 5 μg/L maximum guideline for aquatic life. A natural wetland located downstream appears to be attenuating As from surface water. The objectives of this study was to understand the sources of As to the wetland, the effectiveness of the wetland to sequester As, the form and stability of As in the sediments, the processes controlling As mobility, and the effect of seasonal changes in the wetland in the dissolved phase. Arsenic bound to the sediments was determined by analyzing for bulk composition, and As speciation and element association were identified using synchrotron-based bulk XANES and ESEM analysis. Arsenic enters the wetland by surface flow from Ho-Hum Lake, subsurface flow through the waste rock airstrip, and by windblown dust. In spring, dissolved As concentrations in surface water increased downstream. In late summer, a decrease in concentration was observed in the upstream portion of the wetland, however As returned to lake concentrations further downstream. Sediment As concentrations increased over the summer. ESEM and bulk XANES indicate that As was associated with (oxy)hydroxides and secondary sulphides. In the spring, when water levels were high from snow melt, (oxy)hydroxides formed and captured As, while sulphide oxidation in the sediments lead to the release of As into surface water. Over the summer, the onset of reducing conditions from microbial activity drove the formation of As-bearing sulphides and dissolution of (oxy)hydroxides. While As was accumulating in the sediments at most sites in the wetland over the summer, these results suggest that the wetland was not effectively sequestering dissolved As from the surface water, and that sediment-water cycling of As in the wetland as a result of seasonal redox variations were contributing As in the surface water. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2011-06-24 12:46:26.649

No description available.

Wetlands are very valuable ecosystems as they play an integral role in wildlife habitat, water management and greenhouse gas exchange. The exchange of carbon dioxide between prairie wetlands and the atmosphere is poorly understood. The purpose of this study was to identify rates and trends in the growing season carbon dioxide flux from the riparian and open-water zone of a prairie pothole wetland. In addition to providing core open water and riparian zone CO2 flux measurements, relationships between variations in CO2 flux and characteristics of the wetland’s biological, biochemical and hydrometeorological state were assessed. The CO2 effluxes from the pond during the summer of 2006 were approximately four times greater than in 2005, but were much lower in the early fall. Algal chlorophyll-a concentrations were greater in 2005 than 2006 for all three algal assemblages. The mean chlorophyll-a concentrations in 2005 for epiphyton, phytoplankton and metaphyton were 2.75 ± 0.62 g m-2, 87 ± 24 µ L-1, and 318 ± 187 g m-2 respectively. In 2006 mean concentrations for the same assemblages were 0.008 ± 0.001 g m-2, 8 ± 2 µ L-1, and 27 g m-2 respectively. The amount of DOC in the open water in August of 2005 (140 mg DOC L-1) was 70 times greater than in July of 2005 (2 mg DOC L-1). DOC ranged from 30 to 52 mg DOC L-1 in 2006. Although highly productive, the pond proper appeared to be a source of DOC which is concurrent with literature from littoral zone and shallow inland waters. Soil respiration increased upslope from the wetland to the cropped upland in 2005. Net ecosystem exchange was greater in the cattail ring surrounding wetland than the grass and sedge zone beyond the cattails. The riparian vegetation may have been water stressed in late-July (at the climax of the dry period) when net ecosystem exchange decreased. Diurnal net ecosystem exchange in the riparian zone indicates uptake during the day and emissions at night. From this data it appears that the riparian zone may have acted as a CO2 sink in June, July and August and a source in April.

No description available.

No description available.

Wetlands are very valuable ecosystems as they play an integral role in wildlife habitat, water management and greenhouse gas exchange. The exchange of carbon dioxide between prairie wetlands and the atmosphere is poorly understood. The purpose of this study was to identify rates and trends in the growing season carbon dioxide flux from the riparian and open-water zone of a prairie pothole wetland. In addition to providing core open water and riparian zone CO2 flux measurements, relationships between variations in CO2 flux and characteristics of the wetland’s biological, biochemical and hydrometeorological state were assessed. The CO2 effluxes from the pond during the summer of 2006 were approximately four times greater than in 2005, but were much lower in the early fall. Algal chlorophyll-a concentrations were greater in 2005 than 2006 for all three algal assemblages. The mean chlorophyll-a concentrations in 2005 for epiphyton, phytoplankton and metaphyton were 2.75 ± 0.62 g m-2, 87 ± 24 µ L-1, and 318 ± 187 g m-2 respectively. In 2006 mean concentrations for the same assemblages were 0.008 ± 0.001 g m-2, 8 ± 2 µ L-1, and 27 g m-2 respectively. The amount of DOC in the open water in August of 2005 (140 mg DOC L-1) was 70 times greater than in July of 2005 (2 mg DOC L-1). DOC ranged from 30 to 52 mg DOC L-1 in 2006. Although highly productive, the pond proper appeared to be a source of DOC which is concurrent with literature from littoral zone and shallow inland waters. Soil respiration increased upslope from the wetland to the cropped upland in 2005. Net ecosystem exchange was greater in the cattail ring surrounding wetland than the grass and sedge zone beyond the cattails. The riparian vegetation may have been water stressed in late-July (at the climax of the dry period) when net ecosystem exchange decreased. Diurnal net ecosystem exchange in the riparian zone indicates uptake during the day and emissions at night. From this data it appears that the riparian zone may have acted as a CO2 sink in June, July and August and a source in April.