Sediment Quality Guidelines (SQGs) serve as scientific benchmarks, or reference points of chemical contaminants levels for evaluating the possibility of occurrence of adverse biological responses in the aquatic environment. SQGs are important because the quality of sediment has significant influences on the health of aquatic organisms, and the use of SQGs is a critical means to protect and manage various aquatic ecosystems. In this study, nine conventional derivation methods are described and contrasted. Their uses and limitations, which in general reduce the ecological relevance of SQGs in applications, are discussed. Improvements can be made through implementing elements like site-specific, field-based, chemical mixtures assessments, etc. in the SQG derivation process. The Hong Kong sediment management system, which focuses on classification of dredged sediment for their disposal options, is reviewed. I suggest that the current system shall be subject to major review. First, SQG values (i.e., LCEL and UCEL) shall be reviewed with the establishment of a new database. Second, a new set of guidelines shall be derived site-specifically for the disposal area. Third, the chemical priority list shall be expanded to include other contaminants of environmental concerns. Forth, a tier of evaluating bioavailability of the target contaminant can be incorporated in the classification framework in order to assess the portion of chemicals that causes toxicity in the sediment. Finally, the biological test can be improved by using ecologically relevant local species. The need of the site-specificity in SQG derivation is justified in this study, by deriving two sets of SQGs (i.e., ERL, ERM, TEL, PEL and AET) using data from two geologically distinct areas in Hong Kong, which are the Hong Kong-Zhuhai-Macao Bridge (HZMB) area and the Kai Tak development area. The derived SQGs of arsenic, chromium, nickel and zinc are higher in the HZMB areas, but those of copper, mercury, lead and silver are higher in the Kai Tak area. In addition, the incidence rates of effect data with the same contaminants concentrations are different between the HZMB and Kai Tak area. The discrepancies among the derived SQGs and the incidence rates indicate that site-specific SQGs are essential. Furthermore, the analysis of incidence rates of effect data with different contaminants concentrations shows that the HKSQG (i.e., LCEL and UCEL) has to be reviewed, especially for arsenic, because high toxicity is not resulted at a high arsenic concentration range in the dataset. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Deep Bay is located in the northwestern coast of Hong Kong (HK), where brackish water from the Pearl River Estuary meets and interacts with fresh water from Shenzhen River and Yuen Long Creek. A review of published material in this study indicates rapid economic and industrial developments can be found in Hong Kong and Pearl River Delta (PRD) region in the last 60years, which would have contaminated the sediment in Deep Bay with heavy metals. To examine the nature of metal contamination history, two 2m-long sediment cores are collected from the mud flat of Deep Bay, and the chemical and physical properties of the sediment sequence analyzed. Small disturbance of sediment profile is observed by the fluctuation of 210Pb signal, and constant rate of supply (CRS) model is applied for the calculation of sedimentation rate which is estimated to be 1.82cm/year.137Cs dating resolves two peaks for the radionuclide at 28cm and 109cm, as well as the onset of excessive 137Cs activity at 135cm, which are connected to the Chernobyl accident in 1986 and the banning and beginning of atmospheric testing of nuclear weapons in 1963 and 1950 respectively. Particle size analysis shows the core sediments are predominantly silt (4-64μm) and clay(<4μm). Enrichment factor of metal concentration displays that Cd, Cr, Cu and Zn has been significantly enriched since the 1950s, and hence 3 phases of metal enrichment could be identified: 1) insignificant anthropogenic input in preindustrial period before 1950, 2) significant enrichment of metal from anthropogenic sources during industrial stage in HK from 1950 to 1980, and 3) a further increase of metal enrichment after the introduction of new town development in northwestern part of HK and Chinese economic reform since 1980. Among the metals in the sediments at depth over 70cm, Cu and Zn are found to be exceeded the Lower Chemical Exceedance Level of the sediment quality criteria given by the Hong Kong Environmental Protection Department; hence, the metals would impose threats to the natural environment once they are released back to water column by changes to physical conditions. To evaluate the extent of environmental threats, future studies could focus on the bioavailability of the metals and the interaction of metals in sediments and water with organisms in the ecosystem of Deep Bay. / published_or_final_version / Earth Sciences / Master / Master of Philosophy

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

Tang Wai Lun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 199-220). / Abstracts in English and Chinese. / Abstract --- p.ii / 摘要 --- p.iv / Acknowledgements --- p.vi / Table of contents --- p.vii / List of Abbreviations --- p.xi / List of Tables --- p.xii / List of Figures --- p.xv / Chapter Chapter One --- Literature Review --- p.1 / Chapter 1.1 --- Marine pollution in Hong Kong --- p.1 / Chapter 1.2 --- Contamination of sediments --- p.3 / Chapter 1.2.1 --- Metals contamination in coastal sediments in Hong Kong --- p.4 / Chapter 1.2.2 --- Other contaminants in sediments --- p.7 / Chapter 1.3 --- Sediment toxicity assessment --- p.9 / Chapter 1.4 --- Fish as examples for the measurement of biological responses to contaminants --- p.9 / Chapter 1.5 --- Biomarkers for toxicity assessment --- p.11 / Chapter 1.5.1 --- Metallothionein (MT) --- p.11 / Chapter 1.5.2 --- Cytochrome P450 1A (CYP1A) --- p.13 / Chapter 1.5.3 --- Vitellogenin (Vtg) --- p.13 / Chapter 1.5.4 --- Enzyme biomarkers: Alanine transaminase (ALT); aspartate transaminase (AST) and creatine kinase (CK) --- p.14 / Chapter 1.5.5 --- DNA damage detected by the comet assay --- p.16 / Chapter 1.6 --- Multi biomarkers for sediment toxicity assessments --- p.16 / Chapter 1.7 --- Objectives --- p.16 / Chapter Chapter Two --- "Concentrations of Heavy Metals and Trace Organics in Coastal Sediments Collected from Victoria Harbour, Deep Bay, Tolo Harbour and Lai Chi Wo" --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Materials and Methods --- p.19 / Chapter 2.2.1 --- Sediment collection --- p.19 / Chapter 2.2.2 --- Treatment of sediment samples --- p.21 / Chapter 2.2.3 --- Acid wash of apparatus --- p.21 / Chapter 2.2.4 --- Acid digestion of sediment sample --- p.21 / Chapter 2.2.5 --- Sequential extraction of heavy metals in sediment samples --- p.22 / Chapter 2.2.6 --- Heavy metals measurement --- p.23 / Chapter 2.2.7 --- Trace organic measurement in sediments --- p.24 / Chapter 2.2.8 --- Statistical Analysis --- p.24 / Chapter 2.3 --- Results --- p.25 / Chapter 2.3.1 --- Concentrations of total Metals in sediments --- p.25 / Chapter 2.3.2 --- Speciation of metals in sediments --- p.27 / Chapter 2.3.3 --- Metal abundance in different fractions of sediment --- p.33 / Chapter 2.3.4 --- Concentrations of trace organic in sediments --- p.33 / Chapter 2.3.5 --- Results summary --- p.36 / Chapter 2.4 --- Discussion --- p.36 / Chapter 2.4.1 --- Comparison with international standards --- p.38 / Chapter 2.4.2 --- Comparison with international studies of coastal sediments --- p.39 / Chapter 2.4.3 --- Comparison of the present study with other studies concerning Hong Kong coastal sediments --- p.45 / Chapter Chapter Three --- "Heavy Metals Accumulation in Tissues of Tilapia Exposed to Coastal Sediments Collected from Victoria Harbour, Deep Bay, Tolo Harbour, and Lai Chi Wo" --- p.51 / Chapter 3.1 --- Introduction --- p.51 / Chapter 3.2 --- Materials and Methods --- p.52 / Chapter 3.2.1 --- Collection and treatment of coastal sediments --- p.52 / Chapter 3.2.2 --- Sediment exposure tests with Tilapia --- p.53 / Chapter 3.2.3 --- Dissection of fish samples --- p.54 / Chapter 3.2.4 --- Acid digestion of fish samples --- p.54 / Chapter 3.2.5 --- Statistical Analysis --- p.55 / Chapter 3.3 --- Results --- p.55 / Chapter 3.3.1 --- Metal accumulation --- p.55 / Chapter 3.3.2 --- "Dose, duration and source of sediments affecting metals uptake" --- p.95 / Chapter 3.3.3 --- Results summary --- p.99 / Chapter 3.4 --- Discussion --- p.99 / Chapter 3.4.1 --- Site comparison --- p.99 / Chapter 3.4.2 --- Comparison with other studies --- p.100 / Chapter 3.4.3 --- Safety limits --- p.112 / Chapter Chapter Four --- "Expression of Biomarker Genes (MT, CYP1 A, Vtg) in Tissues of Male Tilapia After Eexposure to Coastal Sediments Collected from Victoria Harbour, Deep Bay, Tolo Harbour and Lai Chi Wo" --- p.115 / Chapter 4.1 --- Introduction --- p.115 / Chapter 4.2 --- Materials and Methods --- p.116 / Chapter 4.2.1 --- Sample collection --- p.116 / Chapter 4.2.2 --- Preparation of apparatus --- p.117 / Chapter 4.2.3 --- mRNA expression analysis --- p.117 / Chapter 4.2.3.1 --- Isolation of RNA --- p.117 / Chapter 4.2.3.2 --- Reverse transcription --- p.118 / Chapter 4.2.3.3 --- Real time PCR --- p.118 / Chapter 4.2.4 --- Vitellogenin (Vtg) --- p.120 / Chapter 4.2.5 --- Statistics analysis --- p.121 / Chapter 4.3 --- Results --- p.121 / Chapter 4.3.1 --- MT mRNA expression in tissues of male Tilapia exposed to sediments --- p.121 / Chapter 4.3.2 --- CYP1A mRNA expression in tissues of male Tilapia exposed to sediments --- p.129 / Chapter 4.3.3 --- Vtg expression in tissues of male Tilapia exposed to sediments --- p.137 / Chapter 4.3.4 --- Dose and time dependent relationships --- p.137 / Chapter 4.3.5 --- Results summary --- p.137 / Chapter 4.4 --- Discussion --- p.142 / Chapter 4.4.1 --- Correlation of MT and CYP1A expression with metals uptake in gills and liver --- p.142 / Chapter 4.4.2 --- MT as a biomarker of metals exposure --- p.144 / Chapter 4.4.3 --- CYP1A as a biomarker of trace organics exposure --- p.145 / Chapter 4.4.4 --- Real-time PCR --- p.147 / Chapter 4.4.5 --- Vtg as a biomarker of xenoestrogen exposure --- p.147 / Chapter Chapter Five --- "Expression of Enzyme Biomarkers (ALT, AST and CK) in Tissues of Male Tilapia After Exposure to Coastal Sediments Collected From Victoria Harbour, Deep Bay, Tolo Harbour and Lai Chi Wo" --- p.149 / Chapter 5.1 --- Introduction --- p.149 / Chapter 5.2 --- Materials and Methods --- p.150 / Chapter 5.2.1 --- Samples collection --- p.150 / Chapter 5.2.2 --- Alanine transaminase (ALT) and Aspartate transaminase (AST) --- p.151 / Chapter 5.2.3 --- Creatine kinase (CK) --- p.152 / Chapter 5.2.4 --- Statistical analysis --- p.153 / Chapter 5.3 --- Results --- p.153 / Chapter 5.3.1 --- ALT --- p.153 / Chapter 5.3.2 --- AST --- p.157 / Chapter 5.3.3 --- CK in gills --- p.157 / Chapter 5.3.4 --- CK in muscle --- p.164 / Chapter 5.3.5 --- "Dose, duration and source of sediments affecting metals uptake" --- p.164 / Chapter 5.3.6 --- Results summary --- p.169 / Chapter 5.4 --- Discussion --- p.169 / Chapter Chapter Six --- "DNA Damage in Liver of Male Tilapia After Exposure to Coastal Sediments Collected from Victoria Harbour, Deep Bay, Tolo Harbour and Lai Chi Wo" --- p.174 / Chapter 6.1 --- Introduction --- p.174 / Chapter 6.2 --- Materials and Methods --- p.176 / Chapter 6.2.1 --- Samples collection --- p.176 / Chapter 6.2.2 --- Tissue Preparation --- p.176 / Chapter 6.2.3 --- Single Cell Gel Electrophoresis (Comet) Assay --- p.176 / Chapter 6.2.4 --- Image analysis --- p.177 / Chapter 6.2.5 --- Statistical analysis --- p.178 / Chapter 6.3 --- Results --- p.180 / Chapter 6.4 --- Discussion --- p.187 / Chapter Chapter Seven --- General Discussion and Conclusion --- p.190 / Chapter 7.1 --- General discussion --- p.190 / Chapter 7.2 --- Conclusion --- p.198 / References --- p.199 / Appendix --- p.221

published_or_final_version / abstract / toc / Ecology and Biodiversity / Master / Master of Philosophy