Water quality and the impacts of megacities on aquatic ecosystems

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Table of contents

CHAPTER 1. LITERATURE REVIEW
1. Water quality and the impacts of megacities on aquatic ecosystems
1.1. Water quality in South East Asian Countries and in Vietnam
1.2. The megacities and their impacts on the environment in Vietnam, with a focus on HCMC
1.2.1. Characteristics of megacities
1.2.2. The effects of megacities on aquatic ecosystems
2. River systems in tropical area
3. Nutrients in tropical estuaries
3.1. Nitrogen
3.1.1. Nitrogen cycle
3.1.2. Nitrogen sources
3.1.3. Nitrification-denitrification processes
3.2. Phosphorus
3.2.1. Phosphorus cycle
3.2.2. Phosphorus sources
3.2.3. The factors influencing the adsorption-desorption of phosphorus onto sediments
3.3. Silica
3.3.1. Silica cycle
3.3.2. Silica sources
3.4. Nutrients fluxes
4. Carbon
4.1. Carbon cycle
4.2. Anthropogenic influences
5. Eutrophication: causes, consequences and assessment
5.1. Causes of eutrophication
5.2. Physical factors supporting the development of eutrophication
5.3. Consequences and effects of eutrophication
5.4. Assessment of eutrophication
6. Sediments in estuary
CHAPTER 2. MATERIALS AND METHODOLOGY
1. Field study
1.1. The Saigon – Dongnai Rivers hydrosystem
1.2. The Ho Chi Minh City
2. Methodology
2.1. Monitoring and sampling strategy
2.1.1. Bi-monthly monitoring
2.1.2. Diurnal sampling surveys
2.1.3. Longitudinal and salinity profile surveys
2.1.4. Atmospheric deposition
2.2. Water quality and hydrological database of DONRE
3. Measurement and analytical methods
3.1. In-situ measurements of physico-chemical parameters
3.2. Filtration and preservation of samples in laboratory
3.3. Sediment preparation
3.4. Analytical methods
3.4.1. Total suspended solid (TSS)
3.4.2. Chlorophyll a and phaeopigments
3.4.3. Dissolved nutrients
3.4.3.1. Nitrogen
3.4.3.2. Total phosphorus (TP) and Orthophosphates (PO4 3-)
3.4.3.3. Silica
3.4.4. Organic matter
3.4.5. Particulate nutrients in deposit and suspended sediment
3.4.6. Phytoplankton identification and counting
3.4.7. Physical characteristic of sediment
4. Assessment of phosphorus mobility from laboratory experiments
4.1. Experiment design
4.2. Sorption isotherm
CHAPTER 3. NUTRIENT DYNAMICS AND EUTROPHICATION ASSESSMENT IN THE TROPICAL RIVER SYSTEM OF SAIGON – DONGNAI (SOUTHERN VIETNAM)
1. Introduction
2. Materials and methods
2.1. Study area
2.2. Monitoring and sampling strategy
2.3. Laboratory analyses
2.4. Hydrological database
3. Results
3.1. Seasonal hydrological variability
3.2. Interannual variations of water quality in the Saigon River
3.2.1. Physico-chemical parameters
3.2.2. Dissolved and total nutrients
3.2.3. Organic carbon, chlorophyll-a, and phaeopigments
3.3. Longitudinal profile in the Saigon River
3.4. Nutrient ratios
4. Discussion
4.1. Level of nutrient contamination
4.2. Eutrophication status and limiting factors
4.3. Impact of HCMC on the water quality of the Saigon River
5. Conclusions
CHAPTER 4. PHOSPHORUS ADSORPTION-DESORPTION PROCESSES IN THE TROPICAL SAIGON RIVER ESTUARY (SOUTHERN VIETNAM) IMPACTED BY A MEGACITY
1. Introduction
2. Material and methods
2.1. Study area
2.2. Sampling campaigns
2.3. Measurement and analytical methods
2.3.1. In-situ sampling and measurements
2.3.2. Sediment preparation
2.3.3. TSS and phosphorus measurement
2.4. Experimental designs
2.5. Sorption isotherm
3. Results
3.1. Physico-chemical parameters distribution along the Saigon River
3.2. Phosphorus levels along the Saigon River
3.3. Phosphorus distribution in the salinity gradient
3.4. Phosphorus adsorption capacity onto sediment from laboratory experiments
3.5. Physical characteristics of sediments
4. Discussion
4.1. The effect of physical characteristic of sediment on the P adsorption capacity
4.2. Impact of HCMC on the P concentrations
4.3. Implication for the understanding of P dynamics within estuaries
5. Conclusions
CHAPTER 5. NUTRIENTS BUDGET IN THE SAIGON – DONGNAI RIVERS BASIN: PAST TO FUTURE INPUTS FROM THE DEVELOPING MEGACITY OF HO CHI MINH (VIETNAM)
1. Introduction
2. Material and methods
2.1. Description of the Saigon – Dongnai River basin
2.2. Database from the Vietnamese water quality survey
2.3 Additional monitoring program
2.4. Suspended sediment and nutrient budgets calculation
2.4.1. Nutrients export by rivers
2.4.2. Domestic inputs
2.4.2.1. Gross nutrients inputs from urban areas
2.4.2.2. Net nutrients inputs from WWTPs
2.4.2.3. Net flux from urban canals to the rivers
2.4.3. Industrial inputs
2.4.4. Atmospheric depositions
2.4.5. Assumption on TSS and nutrients budgets
2.4.6. Expected nutrients inputs in 2025, 2040 and 2050
3. Results
3.1. Seasonal variation of TSS and nutrients concentrations
3.2. Seasonal and inter-annual variations of river fluxes and the effect of climatic conditions on the river fluxes
3.2.1. Seasonal variation of river fluxes
3.2.2. Inter-annual variations of river fluxes
3.3. Mean TSS and nutrient budgets in the Saigon River
3.4 Comparison between past and future nutrients inputs
4. Discussions
4.1. Budgets in contemporary Ho Chi Minh City 2012-2016
4.2. Nutrients fluxes ratios as an indicator of potential eutrophication
4.3. Future nutrients emissions from Ho Chi Minh City by 2025-2050 and recommendation for better management
5. Conclusions
GENERAL CONCLUSIONS AND PERSPECTIVES