published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Earth Sciences / Master / Master of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science

by Kwok Yuk Chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 105-124). / Text in English; abstracts in English and Chinese. / by Kwok Yuk Chun. / Acknowledgements --- p.i / Abstract --- p.ii / Contents --- p.vi / List of Figures --- p.x / List of Tables --- p.xiii / List of Plates --- p.xiv / List of Appendices --- p.xv / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Hong Kong --- p.1 / Chapter 1.2 --- Sediment --- p.1 / Chapter 1.3 --- Pore water --- p.5 / Chapter 1.4 --- Toxicity identification evaluation (TIE) --- p.10 / Chapter 1.4.1 --- Phase 1: Toxicity characterization --- p.11 / Chapter 1.4.2 --- Phase 2: Toxicity identification --- p.11 / Chapter 1.4.3 --- Phase 3: Toxicity confirmation --- p.13 / Chapter 1.5 --- Bioassay --- p.15 / Chapter 1.6 --- Microtox® test --- p.16 / Chapter 2. --- OBJECTIVES --- p.18 / Chapter 3. --- MATERIALS AND METHODS --- p.19 / Chapter 3.1 --- Source of sediment samples --- p.19 / Chapter 3.2 --- Preparation of pore water --- p.19 / Chapter 3.3 --- Phase 1 Toxicity characterization: Baseline toxicity test --- p.22 / Chapter 3.3.1 --- Microtox® test --- p.22 / Chapter 3.3.2 --- Phase 1 Toxicity characterization --- p.26 / Chapter 3.3.3 --- pH adjustment test --- p.27 / Chapter 3.3.4 --- pH adjustment filtration test --- p.28 / Chapter 3.3.5 --- pH adjustment aeration test --- p.29 / Chapter 3.3.6 --- pH adjustment C18 solid phase extraction (SPE) test --- p.30 / Chapter 3.3.7 --- Cation exchange test --- p.32 / Chapter 3.3.8 --- Anion exchange test --- p.33 / Chapter 3.4 --- Phase 2 Toxicity identification --- p.34 / Chapter 3.4.1 --- Determination of metal ions by inductively coupled plasma emission spectroscopy (ICP-ES) --- p.35 / Chapter 3.4.2 --- Determination of anions by ion chromatography (IC) --- p.36 / Chapter 3.4.3 --- Determination of organic compounds by a total organic carbon (TOC) --- p.36 / Chapter 3.4.4 --- Determination of organic compounds by gas chromatography-mass spectroscopy (GC-MS) --- p.37 / Chapter 3.4.5 --- Determination of organic compounds by liquid chromatography-mass spectroscopy (LC-MS) --- p.38 / Chapter 3.4.6 --- Determination of sulphide by colorimetric method --- p.41 / Chapter 3.5 --- Phase 3 Toxicity confirmation --- p.41 / Chapter 3.5.1 --- Mass balance test --- p.44 / Chapter 3.5.2 --- Spiking test --- p.44 / Chapter 4. --- RESULTS --- p.45 / Chapter 4.1 --- General characteristics of the sediment collected in Kwun Tong Typhoon Shelter --- p.45 / Chapter 4.2 --- General characteristics of the pore water after the centrifugation of sediment --- p.45 / Chapter 4.3 --- Phase 1-Toxicity characterization: Baseline toxicity test --- p.45 / Chapter 4.4 --- Phase 1-Toxicity characterization --- p.48 / Chapter 4.4.1 --- Effect of manipulations on Sample S1 --- p.48 / Chapter 4.4.2 --- Effect of manipulations on Sample S2 --- p.50 / Chapter 4.4.3 --- Effect of manipulations on Sample S3 --- p.50 / Chapter 4.4.4 --- Effect of manipulations on Sample S4 --- p.52 / Chapter 4.4.5 --- Effect of manipulations on Sample S5 --- p.55 / Chapter 4.4.6 --- Effect of manipulations on Sample S6 --- p.57 / Chapter 4.4.7 --- Summary of the Phase 1 manipulations on the Microtox® test --- p.59 / Chapter 4.5 --- Phase 2-Toxicity identification --- p.59 / Chapter 4.5.1 --- Summary of the Phase 2 toxicity identification --- p.70 / Chapter 4.6 --- Phase 3-Toxicity confirmation --- p.70 / Chapter 4.6.1 --- Result of Phase 3 for Sample S3 --- p.70 / Chapter 4.6.2 --- Result of Phase 3 for Sample S4 --- p.73 / Chapter 4.6.3 --- Result of Phase 3 for Sample S5 --- p.76 / Chapter 4.6.4 --- Result of Phase 3 for Sample S6 --- p.79 / Chapter 4.6.5 --- Summary of the Phase 3 toxicity confirmation --- p.79 / Chapter 5. --- DISCUSSION --- p.82 / Chapter 5.1 --- Phase 1 Toxicity characterization: Baseline toxicity test --- p.82 / Chapter 5.1.1 --- Baseline toxicity of whole pore water samples on the Microtox® test --- p.82 / Chapter 5.2 --- Phase 1-Toxicity characterization: Manipulations --- p.83 / Chapter 5.2.1 --- Effect of manipulations on the Microtox® test --- p.83 / Chapter 5.2.2 --- pH adjustment test --- p.83 / Chapter 5.2.3 --- pH adjustment filtration test --- p.84 / Chapter 5.2.4 --- pH adjustment aeration test --- p.85 / Chapter 5.2.5 --- Cation exchange test --- p.85 / Chapter 5.2.6 --- Anion exchange test --- p.86 / Chapter 5.2.7 --- pH adjustment C18 solid phase extraction (SPE) test --- p.86 / Chapter 5.3 --- Phase 2-Toxicity identification --- p.87 / Chapter 5.4 --- Phase 3-Toxicity confirmation --- p.88 / Chapter 5.4.1 --- Mass balance on the Microtox® test --- p.89 / Chapter 5.4.2 --- Spiking test on the Microtox® test --- p.90 / Chapter 5.5 --- Explanation of S as the major toxicant in Phase 1，Phase 2 and Phase3 --- p.90 / Chapter 5.6 --- Characteristics of Sulphide (S2-) --- p.91 / Chapter 5.6.1 --- Sources of S2- --- p.91 / Chapter 5.6.2 --- Harmful effect of S “ and its toxicity --- p.93 / Chapter 5.6.3 --- Sulphide determination by colorimetric method --- p.94 / Chapter 5.6.4 --- Sulphide determination by other methods --- p.95 / Chapter 5.6.5 --- Sulphide preservation --- p.95 / Chapter 5.7 --- Synergistic effect of S2- and C18 SPE test elutriate --- p.96 / Chapter 5.8 --- Treatment of contaminated marine sediment in Hong Kong --- p.97 / Chapter 5.9 --- Treatment of contaminated marine sediment in Kwun Tong Typhoon Shelter --- p.98 / Chapter 5.10 --- Treatment of sediment contaminated with sulphide in Hong Kong --- p.99 / Chapter 5.11 --- Other treatment method of sediment contaminated with sulphide --- p.100 / Chapter 5.12 --- Current limitations and abilities in identification of toxicants in pore water --- p.101 / Chapter 5.13 --- Improvement and Recommendations --- p.102 / Chapter 6. --- CONCLUSIONS --- p.104 / Chapter 7. --- REFERENCES --- p.105 / Chapter 8. --- APPENDICES --- p.125

Ever-growing discharges of various emerging chemical contaminants are imposing a great threat of pollution to the coastal environment. Adsorption by sediment plays an essential role in the transport and fate of pollutants in the aquatic system. The sorption of emerging contaminants onto sediment is believed to be largely dependent on the sediment organic matter (SOM). In the present study, laboratory experiments were carried out on the changes of the adsorption behavior of sediment during the sediment aging and diagenesis process. A few EDCs and antibiotics were selected as the model emerging compounds for the adsorption tests. The results demonstrated that both the quantity and the quality of the SOM affected the adsorption of the model pollutants, such as 17α-ethinyl estradiol (EE2) and bisphenol A (BPA), onto the marine sediment collected from Victoria Harbour, Hong Kong. The adsorption isotherms can be well described by the linear partition model. Natural and artificial sediment with a high SOM content was incubated for 4-6 months to simulate the natural diagenesis process. The most rapid degradation of labile SOM occurred in the first 1 month or so and afterward, SOM reduction became slower. Microbial activity played an important role in SOM degradation and transformation. A rapid initial bacterial growth was observed in the sediment, followed by a slow endogenous decay. The dynamics of biomass growth and decay first transformed the labile SOM into biomass and microbial byproducts. After the exhaust of readily biodegradable SOM, the biomass decay produced humic-like substances, resulting in more refractory and condensed SOM residues in the sediment. More importantly, the degradation and transformation of SOM displayed a profound impact on the adsorption behavior of the sediment. For the selected EDCs and antibiotics, including BPA, EE2, nonylphenol (NP), phenanthrene (PHE) and tetracyclines (TCs), the adsorption capacity indicated by the partition coefficient, Kd, decreased at the beginning of SOM diagenesis. The Kd values for different chemicals recovered lately to different extents as the result of the SOM condensation and humification. All of the organic matter normalized partition coefficients, KOM, of the concerned pollutants increased considerably in the late phase of SOM diagenesis. Based on the experimental results, a general conceptual model was established to describe SOM diagenesis and its impact on chemical adsorption by the sediment. According to the model prediction, the SOM profile would become more dominated by the condensed and refractory fractions during sediment diagenesis with an increasing affinity and partition capacity for organic contaminants. Moreover, the release of adsorbed contaminants from marine sediment in the simulated digestive fluids was investigated. In general, the presence of gastric pepsin and bile salts helped the desorption of hydrophobic pollutants from the sediment into the digestive solutions. The influence of the SOM diagenetic status on chemical desorption from the sediment varied between EDCs of different chemical properties. It is apparent that aged sediment could bring more emerging pollutants into the digestive system of receiving organisms, imposing a potential risk to human health through the food chain. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

A study of marine palaeo-landscape development through a sediment core in the western Hong Kong waters has been carried out in this project as the sedimentation record could reflect the environmental changes during the Holocene period. The objectives of this study was to reveal the influences of Holocene post-glacial sea-level fluctuations and the monsoonal freshwater discharge changes to the sedimentation processes in the mouth region of the Pearl River Estuary. These are the two important factors which shape the palaeo-landscape development. Data has been obtained from a ground-truthing vibrocore to 35m below the seafloor at the south of the Shek Pik Reservoir, south Lantau Island. The sediment core was subsampled for elemental analysis to study the sources of the organic carbon by use of stable carbon isotope ratio (Ϭ13C) and for particle size analysis to reveal the energy state of the sedimentary environment. Shell fragments were chosen for radiocarbon analysis to construct the core chronology and marine seismic profiles were obtained to present the sub-bottom geological layers. The data is presented in the form of graphs and tables in showing the sediment changes along the core in different period of time. The data has been interpreted in relation to the knowledge of post-glacial sea-level rise and the proposed model of the Pearl River Estuary evolution from previous studies. Comparison is also made with other sediment cores around the Lantau Island to reveal the regional palaeo-environmental changes in the Holocene period. It is concluded that the sediment core has revealed four major phases of environmental change which is in general agreement with the previous studies except this data set has also shown a few localized climatic events in the mid-Holocene period. The sea-level low stand in the late Pleistocene had incised a network of drainage system on the exposed continental shelf which is the north South China Sea in present time. The rapid rising sea-level by Melt Water Pulse 1B filled the palaeo-valleys with alluvium deposits from 10600 to 9000 cal. yr BP at high sedimentation rate and the East Asian Monsoon was strengthened from 8800 to 5500 cal. yr BP as shown by the freshwater organic carbon deposited in the marine environment. Unconfined deposition occurred when the sediments spilled out of the palaeo-valleys and slowly covered the basin in stable sea-level and low hydrodynamic conditions. / published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Earth Sciences / Master / Master of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science