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

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Architecture / Master / Master of Landscape Architecture

Lai, Yuk Fo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 169-191). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iv / Dedication --- p.v / Acknowledgement --- p.vi / Table of contents --- p.viii / List of tables --- p.xii / List of figures --- p.xiii / List of plates --- p.xv / List of symbols and abbreviations --- p.xvi / Chapter Chapter One --- Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Research background --- p.1 / Chapter 1.2.1 --- Wetlands and water quality --- p.1 / Chapter 1.2.2 --- The role of sediments in eutrophication control --- p.3 / Chapter 1.2.3 --- Wetlands in ecological mitigation --- p.4 / Chapter 1.2.4 --- Previous studies of wetland pollution in Hong Kong --- p.6 / Chapter 1.3 --- Conceptual framework --- p.8 / Chapter 1.4 --- Objectives of the study --- p.12 / Chapter 1.5 --- Significance of study --- p.13 / Chapter 1.6 --- Organization of the thesis --- p.14 / Chapter Chapter Two --- Literature Review / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Quantification of phosphorus retention in wetlands --- p.16 / Chapter 2.2.1 --- Input-output concentration approach --- p.16 / Chapter 2.2.2 --- Mass balance approach --- p.18 / Chapter 2.2.3 --- Phosphorus removal efficiency --- p.19 / Chapter 2.3 --- Phosphorus sorption by wetland sediments --- p.20 / Chapter 2.3.1 --- Sorption and its significance --- p.20 / Chapter 2.3.2 --- Phosphorus sorption maxima --- p.22 / Chapter 2.3.3 --- Adsorption-desorption equilibrium --- p.23 / Chapter 2.3.4 --- Phosphorus sorption kinetics --- p.24 / Chapter 2.4 --- Phosphorus exchange across the sediment-water interface --- p.24 / Chapter 2.4.1 --- Phosphorus mobilization and transport mechanisms --- p.25 / Chapter 2.4.2 --- Phosphorus flux from aquatic sediments --- p.26 / Chapter 2.5 --- Phosphorus fractionation in wetland sediments --- p.29 / Chapter 2.5.1 --- Major sediment phosphorus fractions --- p.29 / Chapter 2.5.2 --- Phosphorus fractionation methods --- p.30 / Chapter 2.5.3 --- Relationships between phosphorus fractions and bioavailability . --- p.32 / Chapter 2.6 --- Factors affecting sediment-water phosphorus exchange --- p.33 / Chapter 2.6.1 --- pH --- p.34 / Chapter 2.6.2 --- Redox potential --- p.34 / Chapter 2.6.3 --- Temperature --- p.35 / Chapter 2.6.4 --- Salinity --- p.35 / Chapter 2.6.5 --- Sediment properties --- p.36 / Chapter Chapter Three --- Methodology / Chapter 3.1 --- Overall study approach --- p.38 / Chapter 3.2 --- Geographical setting of Hong Kong --- p.41 / Chapter 3.2.1 --- Climate --- p.42 / Chapter 3.2.2 --- Geology and landform --- p.44 / Chapter 3.2.3 --- Soil --- p.45 / Chapter 3.2.4 --- Vegetation --- p.45 / Chapter 3.3 --- Study sites --- p.46 / Chapter 3.3.1 --- Site selection --- p.46 / Chapter 3.3.2 --- Site description --- p.48 / Chapter 3.3.2.1 --- The Hong Kong Wetland Park --- p.48 / Chapter 3.3.2.2 --- Mai Po Marshes Nature Reserve --- p.50 / Chapter 3.4 --- Sampling strategy --- p.53 / Chapter 3.4.1 --- Sampling locations --- p.53 / Chapter 3.4.2 --- Sampling dates --- p.57 / Chapter 3.4.3 --- Sample collection and treatment --- p.58 / Chapter 3.5 --- Sample analysis --- p.60 / Chapter 3.5.1 --- Analysis of sediment samples --- p.61 / Chapter 3.5.1.1 --- Sediment texture --- p.61 / Chapter 3.5.1.2 --- Sediment pH --- p.61 / Chapter 3.5.1.3 --- Redox potential --- p.61 / Chapter 3.5.1.4 --- Sediment moisture --- p.62 / Chapter 3.5.1.5 --- Organic matter --- p.62 / Chapter 3.5.1.6 --- Total Kjeldahl nitrogen --- p.63 / Chapter 3.5.1.7 --- "Total Fe, Al, and P" --- p.63 / Chapter 3.5.1.8 --- "Oxalate-extractable Fe, Al, and P" --- p.63 / Chapter 3.5.2 --- Analysis of water samples --- p.64 / Chapter 3.5.2.1 --- "Water pH, conductivity, salinity, turbidity, temperature and DO" --- p.64 / Chapter 3.5.2.2 --- Orthophosphate --- p.64 / Chapter 3.5.2.3 --- Total nitrogen and phosphorus --- p.65 / Chapter 3.5.3 --- Determination of phosphorus exchange characteristics --- p.65 / Chapter 3.6 --- Statistical analysis --- p.65 / Chapter Chapter Four --- Phosphorus Fractionation in Wetland Sediments in Hong Kong / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2 --- Methodology --- p.68 / Chapter 4.2.1 --- Sample collection and analysis --- p.68 / Chapter 4.2.2 --- Phosphorus fractionation --- p.69 / Chapter 4.2.3 --- Statistical analysis --- p.72 / Chapter 4.3 --- Results and discussion --- p.72 / Chapter 4.3.1 --- Physico-chemical properties of sediments --- p.72 / Chapter 4.3.2 --- Physico-chemical properties of overlying water --- p.78 / Chapter 4.3.3 --- Phosphorus fractionation in sediments --- p.82 / Chapter 4.3.3.1 --- Phosphorus fractions in sediments of the Hong Kong Wetland Park --- p.82 / Chapter 4.3.3.2 --- Phosphorus fractions in sediments of the Mai Po Marshes --- p.89 / Chapter 4.3.3.3 --- Phosphorus fractions in relation to mobility and bioavailability --- p.96 / Chapter 4.4 --- Conclusions --- p.100 / Chapter Chapter Five --- Phosphorus Sorption by Wetland Sediments in Hong Kong / Chapter 5.1 --- Introduction --- p.103 / Chapter 5.2 --- Methodology --- p.104 / Chapter 5.2.1 --- Sample collection and analysis --- p.104 / Chapter 5.2.2 --- Batch incubation experiments --- p.105 / Chapter 5.2.3 --- Sorption kinetics --- p.106 / Chapter 5.2.4 --- Effects of selected environmental factors on phosphorus sorption --- p.106 / Chapter 5.2.5 --- Estimation of sorption parameters --- p.107 / Chapter 5.2.6 --- Statistical analysis --- p.109 / Chapter 5.3 --- Results and discussion --- p.109 / Chapter 5.3.1 --- Phosphorus sorption parameters of wetland sediments --- p.109 / Chapter 5.3.1.1 --- Phosphorus adsorption isotherms --- p.109 / Chapter 5.3.1.2 --- The role of sediments in phosphate buffering --- p.116 / Chapter 5.3.1.3 --- Relationships between phosphorus sorption parameters and physico-chemical properties of sediments --- p.121 / Chapter 5.3.2 --- Kinetics of phosphorus adsorption --- p.124 / Chapter 5.3.3 --- Effects of environmental factors on phosphorus sorption --- p.128 / Chapter 5.3.3.1 --- Effects of pH --- p.128 / Chapter 5.3.3.2 --- Effects of salinity --- p.131 / Chapter 5.3.3.3 --- Effects of temperature --- p.133 / Chapter 5.4 --- Conclusions --- p.136 / Chapter Chapter Six --- Phosphorus Flux from Wetland Sediments in Hong Kong / Chapter 6.1 --- Introduction --- p.139 / Chapter 6.2 --- Methodology --- p.140 / Chapter 6.2.1 --- Sample collection and analysis --- p.140 / Chapter 6.2.2 --- Core incubation experiments --- p.141 / Chapter 6.2.3 --- Estimation of phosphorus flux --- p.142 / Chapter 6.2.4 --- Statistical analysis --- p.142 / Chapter 6.3 --- Results and discussion --- p.143 / Chapter 6.3.1 --- Phosphorus flux from wetland sediments --- p.143 / Chapter 6.3.1.1 --- Phosphorus flux from sediments in the Hong Kong Wetland Park --- p.143 / Chapter 6.3.1.2 --- Phosphorus flux from sediments in the Mai Po Marshes --- p.147 / Chapter 6.3.2 --- Effects of redox conditions on sediment phosphorus flux --- p.152 / Chapter 6.4 --- Conclusions --- p.156 / Chapter Chapter Seven --- Conclusion / Chapter 7.1 --- Introduction --- p.159 / Chapter 7.2 --- Summary of major findings --- p.159 / Chapter 7.3 --- Limitations of study --- p.166 / Chapter 7.4 --- Suggestions for future study --- p.166 / References --- p.169

published_or_final_version / Architecture / Master / Master of Landscape Architecture