Devonian fluviodeltaic sedimentation in Hong Kong

Twenty-three distinct sedimentary facies have been distinguished in the Devonian Bluff Head Formation exposed around the Tolo Channel area of northeastern Hong Kong. These facies have been combined into five facies associations: channel, aeolian, sheetflood, deltaic and palaeosol, with the bulk of the formation belonging to the channel association. The lower part of the Bluff Head Formation, around Plover Cove, consists of upwards-coarsening cycles, each typically 3 m thick. The basal parts of some cycles contain distinctive marine fossils of Early to Middle Devonian age. Sedimentation occurred on a marine-influenced delta plain, with eustatic sea level rises controlling cycle development. The middle and upper parts of the formation contrast strongly with the lower part and show a distinct change to alluvial plain sedimentation. Upward-fining cycles, each approximately 40 m thick, comprise basal multistorey, braided, conglomerate-filled channel deposits at the base passing upwards into finer-grained sheetflood, aeolian and channel sandstones at the top. Palaeosols in the higher parts of the cycles indicate periods of non-deposition under semi-arid climatic conditions. These cycles represent repeated abandonments of the fluvial system which we suggest were controlled by tectonic pulses.     

Long-Term and Seasonal Changes in Nutrients,Phytoplankton Biomass,and Dissolved Oxygen in Deep Bay,Hong Kong

Deep Bay is a semienclosed bay that receives sewage from Shenzhen, a fast-growing city in China. NH₄ is the main N component of the sewage (>50% of total N) in the inner bay, and a twofold increase in NH₄ and PO₄ concentrations is attributed to increased sewage loading over the 21-year period (1986–2006). During this time series, the maximum annual average NH₄ and PO₄ concentrations exceeded 500 and 39 μM, respectively. The inner bay (Stns DM1 and DM2) has a long residence time and very high nutrient loads and yet much lower phytoplankton biomass (chlorophyll (Chl) <10 μg L⁻¹ except for Jan, July, and Aug) and few severe long-term hypoxic events (dissolved oxygen (DO) generally >2 mg L⁻¹) than expected. Because it is shallow (~2 m), phytoplankton growth is likely limited by light due to mixing and suspended sediments, as well as by ammonium toxicity, and biomass accumulation is reduced by grazing, which may reduce the occurrence of hypoxia. Since nutrients were not limiting in the inner bay, the significant long-term increase in Chl a (0.52–0.57 μg L⁻¹ year⁻¹) was attributed to climatic effects in which the significant increase in rainfall (11 mm year⁻¹) decreased salinity, increased stratification, and improved water stability. The outer bay (DM3 to DM5) has a high flushing rate (0.2 day⁻¹), is deeper (3 to 5 m), and has summer stratification, yet there are few large algal blooms and hypoxic events since dilution by the Pearl River discharge in summer, and the invasion of coastal water in winter is likely greater than the phytoplankton growth rate. A significant long-term increase in NO₃ (0.45–0.94 μM year⁻¹) occurred in the outer bay, but no increasing trend was observed for SiO₄ or PO₄, and these long-term trends in NO₃, PO₄, and SiO₄ in the outer bay agreed with those long-term trends in the Pearl River discharge. Dissolved inorganic nitrogen (DIN) has approximately doubled from 35–62 to 68–107 μM in the outer bay during the last two decades, and consequently DIN to PO₄ molar ratios have also increased over twofold since there was no change in PO₄. The rapid increase in salinity and DO and the decrease in nutrients and suspended solids from the inner to the outer bay suggest that the sewage effluent from the inner bay is rapidly diluted and appears to have a limited effect on the phytoplankton of the adjacent waters beyond Deep Bay. Therefore, physical processes play a key role in reducing the risk of algal blooms and hypoxic events in Deep Bay.     

Land reclamation in Singapore,Hong Kong and Macau

The spatial and temporal significance of land reclamation from the sea in relation to the development of the three SE Asian small coastal territories of Singapore, Hong Kong and Macau are examined and compared. In all three territories the rate of reclamation has been an index of the rate of economic development. Four phases of land reclamation are identified: (1) pre-1900: involved relatively unplanned and uncostly projects in shallow water and swamplands around the main focus of settlement; (2) 1900–1945: involved military projects outside the main settlement core; (3) 1945–1980: this phase of large-scale projects unconstrained by natural conditions because of advances in technology and high rate of reclamation was driven by rapid industrial and population growth; (4) 1980 to date: a period marked by large infrastructure projects designed to maintain and extend the status of the territories as world economic and commercial centres. Currently 10%, 5% and 33% of the total land surfaces of Singapore, Hong Kong and Macau respectively comprise land reclaimed from the sea and these proportions will continue to rise.     

香港区域地层划分

本文在研究前人大量工作的基础上,以香港地区的地质演变历史为主要线索,重新拟定了泥盆纪以来香港的地层层序;对各主要地层单位,尤其是近年来新建的地层单位进行了讨论;将香港的地层与广东和中国南方进行了对比,并对香港今后进一步地层工作的方向提出了一些建议。本文的目的是建立一个简要的、索引式的有关香港地层的回顾,以便使读者能迅速掌握香港地层划分和对比的概况以及基本的地质演化历史。     

Rain-induced slope instability in Hong Kong

Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures (also referred to as obliquely inclined bedding slopes), where the apparent dip sliding is not readily visible. This phenomenon has become a focal point in landslide research. Yet, there is a lack of studies on the failure modes and mechanisms of hidden, steep obliquely inclined bedding slopes. This study investigated the Shanyang landslide in Shaanxi Province, China. Using field investigations, laboratory tests of geotechnical parameters, and the 3DEC software, this study developed a numerical model of the landslide to analyze the failure process of such slopes. The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity. The landslide, initially following a dip angle with the support of a stable inclined rock mass, shifted direction under the influence of argillization in the weak interlayer, moving towards the apparent dip angle. The slide resistance effect of the karstic dissolution zone was increasingly significant during this process, with lateral friction being the primary resistance force. A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced. Notably, deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force, leading to the eventual buckling failure of the landslide. This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide, highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism. These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.     

Gamma emitters in Hong Kong water

Water samples, representing seawater, river water, reservoir water, drinking water, and underground water were studied through gamma-ray spectral analysis. Only gamma emitters in the²³⁸U and²³²Th series and⁴⁰K were detected. No fission product was detected with specific activity above 0.1 Bq/kg. The present data could be the baseline for future monitoring of the radioactivity released from a nuclear plant being built at a 50-km distance from Hong Kong. The variation of detected specific activities may be due to geological differences and the effect of plants.     

Investigation and numerical simulation of summer sedimentation in Jiaozhou Bay,China

In recent years, development activities have had a significant impact on the environment of the Jiaozhou Bay, China. To ensure the sustainable economic and social development of the Jiaozhou Bay area, it is necessary to strengthen corresponding control measures. The important prerequisite is to properly understand the environmental conditions laws of natural change, especially the dynamic processes of sediment and the characteristics of landform evolution. Based on the data of continuous observation at 6 stations in Jiaozhou Bay for 25 hours, the Hydrodynamic Eutrophication Model (HEM-3D) was used to simulate the sediment erosion and deposition. The results show that the maximum suspended sediment concentration in the sea area of Jiaozhou Bay is about 40 mg/L, which appears in the northwestern area of the bay top and the Cangkou watercourse area, and the low concentration is located in the area of the central Jiaozhou Bay towards the bay mouth. The suspended sediment is 6–10 mg/L. Affected by a decrease in seawater material, the direction of the prevailing current in the Jiaozhou Bay area is different from that of the sediment transport. The velocity of the flood current is higher than that of the ebb current. However, during flood tide, the flux of resuspended seafloor sediment outside and at the mouth of the bay is limited and cannot contribute significantly to the suspended sediment in the bay. During ebb tide, the resuspended sediment at the shallow-water bay head and the east and west sides spreads toward the bay mouth with the ebb current, although it extends beyond the bay through the bay mouth. The research results can provide scientific support for the Jiaozhou Bay project construction and environmental protection.     

Inspection and stabilisation of the Mid-levels cliffs, Hong Kong

Since 1976 the Geotechnical Engineering Office (GEO) of the Hong Kong Government has had a landslip preventive measures (LPM) programme under which man-made features comprising cut slopes, fill slopes and retaining walls are investigated in priority order and upgraded to modern safety standards where necessary. During 1991–1992 the programme included work to improve the stability of selected rock outcrops and very large boulders on a natural cliff face in the Mid-levels area of Hong Kong Island. This unusual site, with a near-vertical often densely vegetated terrain, posed a number of design and contractual challenges which had to be tackled in a limited time frame due to the climatic conditions prevalent in Hong Kong. Detailed aerial and ground inspections were made, and the need for improvement work determined. Contract tendering took place, and a contract to carry out improvement work was let. Work was completed in mid-1992 at a cost of HK$2.5 million.     

Ecological modernisation and policy learning in Hong Kong

Whilst ecological modernisation theory emphasizes the potential for modern societies to recognize and respond to their environmental impacts by finding new ways of governing environment-economy relations, concepts of policy learning focus on the scope for new forms of environmental policy to be generated within and transferred between different contexts. Within this paper we explore the conceptual and practical linkages between the two areas of debate - a hitherto neglected area in the literature - and we set this discussion in the context of environmental policy-making in Hong Kong. We suggest that the practical relevance of the concepts of ecological modernisation and policy learning depends upon the presence of a reflexive society with rational, responsive institutions. While many theorists assume that such institutions exist, our analysis of policies for water and air quality management in Hong Kong highlights the need for theories to consider the embeddedness of existing institutions and the significance of the capacities for, and the barriers to, change more fully. We find that capacities for some forms of ecological modernisation and policy learning do exist in Hong Kong. However, we argue that the nature of these capacities often limits the potential for change to those local environmental problems that can be addressed through more technically and economically viable forms of policy intervention and that can be easily accommodated within existing political and economic structures. We also conclude that the capacities for ecological modernisation and policy learning that are needed if Hong Kong is to tackle the effects of the trans-boundary environmental problems that it is increasingly encountering have yet to emerge.     

香港的考古文物、古迹与岩画

香港地区考古发现多种石器及离岛的"石壁画龙"-岩画,均属新石器时代文物.发现铜器、陶器等也不少,有些有隶书年号,为周、秦时代文物.香港自南北朝以来,与两广、福建和中原地区来往密切,遗留许多名胜古迹.     

Trace metals in particulate and dissolved phases in Victoria Harbour, Hong Kong

Marine water samples, including both surface and bottom samples, were collected from the five sampling sites in Victoria Harbour during December 2004 and February 2005. The concentrations of trace metals （Cd, Co, Cr, Cu, Ni, Pb and Zn） in the suspended particulate matter （SPM） and dissolved phases as well as the Pb isotopic compositions of the suspended particulates were determined to assess the potential sources and transport pathways of metal contaminants in the harbour. The results showed that sewage discharges along the harbour dominated the SPM loadings in water, particularly in the dry season. The total concentrations of Co, Cr, Cu, Ni and Zn in water showed a close association with the SPM loadings, indicating that SPM was important in transporting these metals in the coastal environment. Dissolved phase was predominant for Cd in Victoria Harbour. The particulate phase was the major form of Pb in marine water.     

香港安山-英安质古火山颈群

香港中侏罗世屯门组火山岩主要由安山质熔岩、凝灰岩和凝灰角砾岩夹少量凝灰质砂岩组成。其中凝灰角砾岩初期曾误认为是沉积砾岩。1990年香港地质调查组重新研究后,确认是火山成因的凝灰角砾岩。按岩相分析,屯门组火山岩可分为火山通道相安山-英安质熔岩和爆发角砾岩,还有爆发空落相凝灰角砾岩。火山通道相又可分为火山颈相和岩墙相,分布在屯门组东西两侧。在青山东麓,出露一列NNW向呈断续、线状分布的火山颈群。近年来新出版的《香港地质考察指引》和《香港工程地质实践》等地质著作仍将该区爆发角砾岩误认为是沉积成因的砾岩,在地质勘探和工程设计上造成混乱,导致不应有的经济和时间上的损失。本文综合最新研究成果并与世界各地同类火山岩的特征进行对比,确证火山通道相爆发角砾岩的存在,并发现呈线状分布的古火山颈群。     

香港岩石的硬度与点荷载指标和强度的关系

无损硬度测试——施密特锤及肖氏硬度实验和点荷载试验是三种经常用来间接测定岩石强度指标的方法。目前很多学者已提出了不同的经验关系,这些关系主要是把硬度指标、点荷载指标和单轴抗压强度、单轴抗拉强度与间接拉伸强度联系起来。但是在应用这些关系时,必须首先用当地的岩石特性数据加以验证,查看地质变化的影响,才可确保使用无误。本文的主要目的是根据大量香港岩石（包括花岗岩、石灰岩、大理岩和凝灰岩）的实验数据,提出一套适用于香港地区岩石的经验关系,另外也对其他经验关系作了考证。     

香港地区边坡防护与治理

自开埠以来香港地区边坡事故一直不断。香港政府多年来积极进行边坡的防护治理,成效显著。讨论了香港地区岩土边坡破坏的主要原因、防治滑坡的工程措施及边坡管理系统。香港的边坡防治经验值得内地借鉴。     

Fluvial sedimentation in the lower carboniferous of Clew Bay,County Mayo,Ireland

A succession of about 300 m of fluvial sediments from the Lower Carboniferous of northwest Ireland is described and interpreted. A lower, mainly red, formation contains fluvial channel deposits dominated by flat laminated sandstone. These are separated by interbedded sandstones and mudrocks with local caliche horizons and abundant mudcracks interpreted as levee and flood basin deposits. An upper, mainly non-red, formation contains fluvial channel deposits with common trough cross-stratification and epsilon cross-stratification also separated by interbedded sandstones and mudrocks. Evidence of desiccation is less common in the uppermost beds which pass transitionally upwards into marine sediments.The change in fluvial channel style is interpreted as due to increasing sinuosity and permanence of flow which may have been partly temporally and partly spatially controlled. The predominance of coarse sediments is thought to be largely controlled by limited subsidence. The Lower Carboniferous transgression was the major overall control of alluviation.     

Macrobenthic Community in Tolo Harbour,Hong Kong and its Relations with Heavy Metals

The present study investigated the macrobenthic community in Tolo Harbour, Hong Kong, aiming at linking heavy metal concentrations to differences in macrobenthic community. The stations investigated in Tolo Harbour have widely contrasting features, with some areas located in the Plove Cove displaying both high species richness and abundance while other areas displaying quite impoverished or even void of macrobenthos. High diversity and abundance of macrobenthos in areas with low heavy metal concentrations were recorded. Strong negative correlation between macrobenthic diversity and heavy metal concentrations was found, and this implicated the pollution-induced degradation of macrobenthos in some locations in Tolo Harbour. These results support the Pearson–Rosenberg model for succession along a pollution gradient.     

Spatio-temporal trends of heavy metals and source apportionment in Tolo Harbour,Hong Kong

This study provided a picture of the spatial and temporal distributions of Cr, Co, Ni Cu, Zn, As, Cd and Pb in bottom sediments of Tolo Harbour. The concentrations of the eight heavy metals differed significantly between sites due to the poor tidal flushing in Tolo Harbour. The levels of Cu, Zn, Cd and Pb were generally enriched in sediments from inner Tolo Harbour, while sediments from outer Tolo Harbour (Tolo Channel) had higher levels of Cr, Co and Ni. The redox sensitive element arsenic showed no distinct spatial pattern in Tolo Harbour. The decreasing levels of Cu, Zn, Pb and Cd in sediments with increasing distance from land demonstrated a typical diffusion pattern from land to the direction of sea. Two hot spots of Cu, Zn, Pb and Cd in sediments were located near Tai Po and Sha Tin new town, indicating that Cu, Zn, Pb and Zn were from land-derived sources. The sites with relatively high levels of Cr, Co and Ni in sediments were located in areas close to waste spoil in sea floor. The natural and anthropogenic inputs from Sha Tin and Tai Po to Tolo Harbour were mostly responsible for Cu, Zn, Cd and Pb enrichment in sediments from inner Tolo Harbour. The waste spoil in sea floor was believed to contribute to the Cr, Co and Ni in outer Tolo Harbour. The results of correlation coefficient between the eight heavy metals showed that Cu, Zn, Cd and Pb were strongly positively correlated, and Cr, Co and Ni were also significantly correlated with each other. The best explanation of strong correlation was their similar source. As, however, is not well correlated with the other seven heavy metals. The average concentrations of Cu and Zn displayed general increasing trends from 1978 to 2006 in Tolo Harbour, while the mean levels of Cr and Pb displayed a substantial decrease from 1978 to 1987, then a slight increase after 1987. No distinct temporal trends of the concentrations of Ni and As were observed from 1978 due to the inconsecutive data. On the other hand, the increasing trends of Cr, Cu, Zn, Cd and Pb were observed since 1996.