Vehicle-related ammonia emissions in Hong Kong

Weekly passive sampling of ambient ammonia has been performed at ground or rooftop levels at 12 locations in Hong Kong representing different land use categories. The highest weekly average roadside level of ammonia in Hong Kong was 7.1 μg m⁻³ at a street canyon site. Ambient ammonia concentrations for a rooftop urban-residential site with nearby light traffic were <1 μg m⁻³, being less than at an adjacent road and indoor car-park. Rooftop levels of ammonia showed a significant correlation with nitrogen monoxide concentrations. Honeycomb denuder samplings were also carried out at the rooftop site and the results were consistent with passive sampling. It is concluded that the 0.54 M vehicles in Hong Kong make a considerable contribution to ambient ammonia concentrations, which are otherwise low.     

Heavy metal and nutrient contamination of marine sediments in Hong Kong

A monitoring programme was performed to use marine sediments as an indicator of marine contamination in Hong Kong. A total of 51 samples were collected from eight marine sites and analysed for pH, redox potential, salinity, total‐N, total‐P, total organic carbon, and total Cu, Zn Pb, Cr and Cd. Sites with high industrial or aquacultural activities contained high total organic carbon contents, total‐N and total‐P contents. Sediments from sites with high industrial activities also enriched with heavy metals. Metal speciation results indicate that Cu and Cr existed mainly in the organic fraction, Pb and Zn were distributed approximately equally in both the organic and residual fractions while Cd mainly occurred in the residual fraction. The Cu, Cr and Zn contents were highly correlated with total organic carbon contents. All samples were classified as non‐acid forming according to the net acid generation test and only samples from the industrial site released a high concentration of heavy metals under a complete oxidising condition. The present study reveals that organic and heavy metal pollution is serious in the marine sediments of Hong Kong, and industrial and aquacultural activities are probably the major sources of contamination.     

刈割对香港草地干物质生产的影响

研究了刈割频率对香港草地于物质生产的影响。结果表明，刈割使干物质生产量下降，刈割频率越高生产量下降越大。禾本科植物受刈割影响比木本和非禾本科草本植物大，且停止刚割一年后生物量仍低于对照点。认为常年刈割是华南草地生产力下降的重要原因之一。     

医院门诊室内空气质量评价

医院室内空气质量直接影响着院内每个人的身体健康,对医院空气进行定期监测是预防和控制医院感染的重要措施。对中国南部沿海某城市10所医院门诊空气质量状况进行了调查。结果发现,所调查门诊中室内二氧化碳、一氧化碳和可吸入颗粒物浓度均达至良好级别。但是,分别有两家门诊的室内温度和相对湿度未能达到良好级别,而且有8家门诊的空气中细菌总数未能达到良好级别。因此,本文建议相关医院采取相应的措施加强对门诊室内空气质量（尤其是细菌数量）的控制。     

香港古树名木的调查及保护问题

采用实地调查并结合历史档案记载的方法对香港的古树名木进行了全面的普查,在香港193个地点调查到有古树分布,记录古树名木1 332株,共计141种,隶属于46科95属.其中细叶榕Ficus mtcrocarpa 323株、樟树Cinnamomum camphora157株、荔枝Litchi chinensis 118株、龙眼 Dimocarpus longan 97株,4种古树株数之和超过香港古树名木总数的一半.香港古树主要分布在大埔区、中西区、北区和离岛区,四个区所含株数占古树总株数的60.66%,所含古树种数占香港古树总种数的78.72%.在香港116处风水林中,86处记录有古树分布,古树数量占调查到的古树数量的近50%.根据调查的结果,还对香港古树名木的保护措施进行了分析研究,旨在为其保育提供参考.     

The cadmium adsorption capacity of contaminated marine sediments from Hong Kong

The binding capacity of Cd to the sediment particles determines the potential of Cd release from the sediments. An experiment was performed to evaluate the adsorption of Cd by contaminated sediments collected from three different locations in Hong Kong, i.e. Kwun Tong, North Point and Nam Tam Wan, having different degrees of pollution. Langmuir and Freundlich equations were used to evaluate the adsorption of Cd by the sediments. Adsorption isotherms obtained from the Freudlich and Langmuir equations were generally linear and the adsorption of Cd by the sediments was significantly correlated with the adsorption maximum and binding energy constant of the Langmuir equation, and equilibrium partition constant of the Freundlich equation. All sediments had a high Cd adsorption capacity and the highly organic contaminated sediments from Kwun Tong had the highest adsorption capacity of 24,272 mg kg^‐1 at pH8. The adsorption of Cd for all sediments increased with a rise in pH of the equilibrium solution and the total organic carbon content of the sediments. Therefore, a change in the sediment chemical equilibrium is likely to reduce the binding capacity.     

Selective catalytic reduction of NO x from exhaust of lean-burn engine over Ag-Al2O3/cordierite catalyst

A highly effective Ag-Al₂O₃ catalyst was prepared using the in-situ sol-gel method, and characterized by surface area using nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The catalyst performance was tested on a real lean-burn gasoline engine. Only unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductant (without any external reductant), the maximum NO _x conversion could only reach 40% at 450°C. When an external reductant, ethanol was added, the average NO _x conversion was greater than 60%. At exhaust gas temperature range of 350–500°C, the maximum NO _x conversion reached about 90%. CO and HC could be efficiently oxidized with Pt-Al₂O₃ oxidation catalyst placed at the end of SCR converter. However, NO _x conversion drastically decreased because of the oxidation of some intermediates to NO _x again. The possible reaction mechanism was proposed as two typical processes, nitration, and reduction in HC-SCR over Ag-Al₂O₃.     

粤港澳地区多环芳烃的多介质归趋

以广东省及港澳两地为研究区域,在完全混合和稳态假设下采用多介质逸度模型估算了目前状况下16种优控多环芳烃(PAH16)在环境各相中的质量浓度及跨界面迁移通量,并采用实测质量浓度数据进行模型验证。除个别数据外,预测质量浓度与验证质量浓度的差别在一个数量级以下,且多数在半个量级之内。模型计算结果表明:化石燃料燃烧是当地PAH16的主要来源,大气和土壤中的降解是其消失的主要途径,PAH16在该地区的最重要界面迁移过程是气地(水)交换。     

An assessment of variation in molluscan grazing pressure on Hong Kong rocky shores

Several methods of assessment have been used to document variation in grazing pressure on temperate rocky shores, although often these methods are applied without consideration of local conditions or species. In this study, a comparison was made between abundance counts of inactive molluscan grazers at low tide, direct observations of grazer activity and distribution throughout day and night tidal cycles, and records of grazing marks on wax discs, for the mid-shore of Hong Kong. The abundance of grazers found during low-tide counts varied among dates, sites and species. This method, however, did not record all grazer species that day/night observations showed to migrate from the low shore with the rising tide. Low-tide counts, therefore, underestimate grazing pressure (number of active grazers per unit area) and grazer guild (number of species). Grazing marks on wax discs also recorded a greater number of species than the low-tide counts of inactive grazers, and included grazers that were seen to migrate up shore during day/night observations. Certain limpet species, however, avoided the wax and did not leave grazing marks, showing this method to also underestimate grazing pressure. All methods showed grazing pressure to be variable at spatial scales of tens of metres or less and also temporally variable between sampling dates. The sole use of either low-tide counts or wax discs is likely to underestimate grazing pressure, due to variation in shore topography and grazer foraging behaviour, especially on shores with a narrow tidal range such as in Hong Kong. To gain a more accurate assessment of total grazing pressure, it is suggested that recording of grazing marks on wax discs should be used in conjunction with direct day/night observations.     

香港地区桃金娘灌木林的凋落物及养分回归

香港桃金娘灌木林的年凋落物量在两年的测定中分别为４２９．３和５２５．２ｇ／ｍ２,枯枝和花果的凋落物年间差异十分显著。叶子和杂物则没有明显的年间差异。按１９８９年和１９９０年平均计算,桃金娘灌木林年凋落物中的氮、磷、钾量分别为２８４５、１６４和８９２ｍｇ／ｍ２。灌木林年凋落物量及养分值小于热带、亚热带常绿阔叶林,但可与马尾松林相比。气候因素对灌木林的凋落物及其养分的季节动态影响较大。养分利用效率的研究表明,桃金娘灌木林比常绿阔叶林及马尾松林养分利用效率更高     

The rock oyster Saccostrea glomerata as an indicator of trace metals in Hong Kong

An urgent need for a sub-tropical and tropical indicator organism for use in the biological monitoring of pollutants is recognised. To this end, preliminary studies have been undertaken to test the indicator ability of the rock oyster Saccostrea glomerata (=Crassostrea glomerata Gould) for monitoring the trace metals cadmium, copper, iron and zinc. A survey of these trace metals in rock oysters from 54 sites in Hong Kong waters revealed elevated levels of metals in several areas. Profiles of metal abundance in S. glomerata agreed substantially with the distribution of industrial and domestic discharges in Hong Kong, and also with patterns of contamination found in studies of the Pacific oyster Crassostrea gigas and of sediments. Application of POLYDIV statistical analysis to these data has aided their interpretation and confirmed the relationship between known areas of contamination and elevated metal levels in S. glomerata. This oyster, which exhibits an unusually great capacity to accumulate a range of elements from the ambient environment, thus appears to be a reliable indicator organism, and may be of great value in global monitoring studies.     

The responses and prospects of sustainable development for Guangzhou and Hong Kong

The ability to achieve urban sustainability has become an indication of the competence of a municipal government aiming to gain world class status for the city. While both Guangzhou and Hong Kong are Chinese cities having their own formulation of urban sustainability, the implementation details and the actual sustainability blueprints are very different. As a result, the outcomes and prospects for urban sustainability are also different.

Hong Kong has adopted a less integrative and more institutionally-oriented approach for urban sustainability. Guangzhou has used the conventional approach to formulate an integrated sustainability programme for its local Agenda 21. Hong Kong's action plan emphasizes improving coordination, making objective assessments and achieving consistency in policy-making. Guangzhou, on the other hand, emphasizes the meeting of concrete environmental targets. Unfortunately, the new institutional arrangement and monitoring tools adopted by Hong Kong have not been able to achieve the original intent and neither is there the intention to go too far beyond the weak sustainability approach. On the contrary, Guangzhou has planned and attempted to incorporate industrial ecology in its development regime while heavily investing into pollution control programmes and pushing forward a green community programme at the grass-roots level.     

Primary productivity and particulate organic matter flow in an estuarine mangrove-wetland in Hong Kong

Net primary productivity and organic matter flow of a mangrove-dominated wetland was estimated by following production and detritus dynamics in a tidal pond in north west Hong Kong in 1986–1988 (9.1 ha). Total productivity was 12.47 t dry wt ha^–1 yr^–1, of which >90% was from emergent macrophytes (the mangroveKandelia candel and the reedPhragmites communis). High turbidity and high summer temperatures probably limited respective production by phytoplankton and benthic macroalgae (dominated byEnteromorpha crinata). Despite the high total productivity, little detritus was exported from the emergent macrophyte stands, due to the low inundation frequency. This created a net water column carbon deficit which was provided for by the high organic matter import (mean = 4.42 g ash free dry wt m^–2 d^–1) from the incoming water. This same sediment and particulate organic carbon input giving a high accretion rate of 1.7 cm yr^–1 was probably also the force behind progressive dis-coupling of emergent macrophyte production from water column consumers. This resulted in a tendency to retain production in the emergent macrophyte stands while the water column community increasingly relied on allochthonous carbon. This shift from a net exporter to a net importer of carbon in landward wetlands is probably characteristic of the transition into nutrient-conservative terrestrial systems.     

Temporal genetic variation in populations of the limpet Cellana grata from Hong Kong shores

Variations in the relative contributions of gene flow and spatial and temporal variation in recruitment are considered the major determinants of population genetic structure in marine organisms. Such variation can be assessed through repeated measures of the genetic structure of a species over time. To test the relative importance of these two phenomena, temporal variation in genetic composition was measured in the limpet Cellana grata, among four annual cohorts over 10 years at four rocky shores in Hong Kong. A total of 408 limpets, comprising individuals from 1998, 1999, 2006 and 2007 cohorts were screened for genetic variation using five microsatellite loci. Minor but significant genetic differentiation was detected among samples from the 1998/1999 collection (F _ST = 0.0023), but there was no significant differentiation among the 2006/2007 collection (F _ST = 0.0008). Partitioning of genetic variation among shores was also significant in 1998/1999 but not in the 2006/2007 collection, although there was no correlation between genetic and geographic distances. There was no significant difference between collections made in 1998/1999 and 2006/2007. This lack of clear structure implies a high level of gene flow, but differentiation with time may be the result of stochastic recruitment variation among shores. Estimates of effective population size were not high (599, 95% C.L. 352–11397), suggesting the potential susceptibility of the populations to genetic drift, although a significant bottleneck effect was not detected. These findings indicate that genetic structuring between populations of C. grata in space and time may result from spatio-temporal variation in recruitment, but the potential development of biologically significant differentiation is suppressed by a lack of consistency in recruitment variability and high connectivity among shores.     

Fractionation and Biotoxicity of Heavy Metals in Urban Dusts Collected from Hong Kong and London

Samples of urban dusts, road site dusts and car park dusts, were collected at two selected sites each in Hong Kong and London. Sequential extraction was used to characterise the chemical compositions of these urban dusts. Copper, lead, zinc, pH, electrical conductivity and organic content were measured. Biotoxicity tests of urban dusts were conducted on higher plants (Brassica chinensis and Lolium perenne), a dinoflagellate green alga (Dunaliella tertiolecta) and luminescent bacteria (Photobacterium phosphoreum). A significant correlation was found between total lead (r =; – 0.70, p < 0.01) and zinc (r =; – 0.74, p < 0.05), and the 20 min – EC50 using P. phosphoreum. In addition, there was a significant correlation (r = – 0.72, p < 0.01) between the exchangeable lead content in dust and the 48 h- EC30 using D. tertiolecta. No specific trend was obtained for higher plants. Total lead and zinc contents were higher in dusts from London while the percentage of exchangeable fraction of metal contents was higher in those from Hong Kong.     

Environmental education,community mobilization and sustainable development in Hong Kong: a comparative perspective

SUMMARY

This paper focuses on efforts to promote environmental education and community mobilization around environmental issues in Hong Kong. It is primarily concerned with efforts directed at the broader community (i.e. the population as a whole) rather than with environmental education through formal school and college curricula. The paper draws on a recently completed study commissioned by the Environmental Campaign Committee, the principal source of financial support for such efforts undertaken by environmental NGOs, community groups and educational institutions in Hong Kong. The study examined how and to what effect the Committee had used its financial resources between 1994–1999. It also examined international experience with a view to recommending changes in the overall approach to environmental education and community mobilization initiatives and their funding in Hong Kong.

The paper suggests that the existing approach to community-wide environmental education and its funding in Hong Kong have suffered from various weaknesses, most notably the absence of an integrated and goal-oriented strategy, an over-reliance on a ‘top-down’ campaign-based approach, a failure to establish explicit linkages with the concept of sustainable development and to ground initiatives at the local neighbourhood and community levels, and a preoccupation with the financial inputs provided to support this work at the expense of effective monitoring and auditing of project outputs and benefits.     

Risk assessment of heavy metal contamination in shrimp farming in Mai Po Nature Reserve, Hong Kong

An ecological survey was carried out to determine the sediment concentrations of nutrients and heavy metals and bioaccumulation of heavy metals in fish and shrimp including tilapia (Oreochromis mossambicus×O. nilotica), grey mullet (Mugil cephalus), gei wai shrimp (Metapenaeus ensis) and caridean shrimp (Macrobrachium nipponensis) in the traditional tidal shrimp ponds (gei wais) of Mai Po Nature Reserve, Hong Kong. The sediments collected from the landward sites contained higher nutrient contents, as well as zinc (Zn), chromium (Cr), copper (Cu), nickel (Ni) and cadmium (Cd) than those collected from the seaward sites, but vice versa for lead (Pb) and mercury (Hg). However, the concentrations of all metals were exceptionally high in the two sites located outside the reserve, suggesting that waters from Deep Bay might be the possible source of metal contamination affecting the reserve. All metals studied seemed to accumulate in the viscera of fish. Body size was the determining factor for the accumulation of heavy metals in caridean shrimp and gei wai shrimp but not fish. Concentrations of the metals studied in tissues of grey mullet and gei wai shrimp were found to be safe for human consumption. Concentrations of Cr in tilapia whole body (0.68–1.10 mg kg⁻¹ wet weight) were close to or over the guideline value of 1 mg kg⁻¹ set by the Food Adulteration (Metallic Contamination) Regulations of Hong Kong. Tilapia flesh and small caridean shrimp collected from gei wais were contaminated by Cr and Pb but still fit for human consumption. Caution is required if large caridean shrimp is to be consumed in large amounts continuously because the concentration of Pb exceeded the maximum permitted concentration (6 mg kg⁻¹). The rather high Cr concentrations in tilapia whole body should not be overlooked as the fish will serve as a food source for migratory birds visiting the site.     

A 14-year measurement of toxic elements in atmospheric particulates in Hong Kong from 1995 to 2008

Toxic elements in the atmosphere can enter and accumulate in the human body, seriously impacting human health. In this study, we analyzed a 14-year （1995-2008） measurement of three toxic elements （As, Cd and Cr） in PMlo in Hong Kong, China. The pollution of these toxic elements in Hong Kong was not serious. The trend analysis showed that As and Cr in PM10 increased at a statistically significant level （p〈0.05） during the 14-year period, while the Cd in PM10 did not change significantly. Typical seasonal variations were observed for all three toxic elements, largely in relation to the Asian monsoon. Hourly 10-day backward trajectories were computed and cate- gorised into four groups. The continental air masses showed much higher concentrations of the three toxic elements than the marine air masses. The abundances of As and Cd in the PM10 were much higher in the continental air masses than those in the marine air masses, while the abundances of Cr showed an opposite pattern. The trends of the three toxic elements in East China＇s air mass were consistent with those in the overall data set ofHong Kong. Examination of the toxic element data recorded at urban sites and a roadside site also indicated a large contribution of external air masses to particulate As and Cd in Hong Kong. These results suggest that the long-range transport from the mainland of China is the dominant contributor to particulate As and Cd, while both local and long-distance sources determine the particulate Cr in Hong Kong.     

Annual cycle of biomass of a threatened population of the intertidal seagrass Zostera japonica in Hong Kong

The phenology and primary productivity of a population of Zostera japonica (Aschers. & Graebn.) threatened by the construction of Hong Kong's new international airport were studied over a 12-month period. The need to conserve the population, and the small leaf size of Z. japonica rendered traditional destructive or marking techniques inapplicable for percentage cover and biomass estimation. A nondestructive method based on image analysis techniques was therefore devised for repeated estimation of percentage cover, biomass and leaf area index. This technique, which involved random quadrat sampling, photographic recording and image analysis, was able to provide data on the three parameters with acceptable precision and was cost-effective in the field. Z. japonica demonstrated a strongly seasonal cycle of vegetative growth, with different patterns for leaf density (peak in March) and overall bed area (peak in June). Total (above- and below-ground) net primary productivity was estimated at between 344 and 688 g AFDW m⁻² yr⁻¹. Percentage cover of Z. japonica was negatively correlated with total suspended solids (TSS) in the water column while total bed area was negatively correlated with water salinity. Increased sedimentation associated with the new airport project was identified as one important factor affecting the growth of the seagrass, as TSS reached the high level of ≈1 g DW l⁻¹ during the first half of the study period. Sediment traps set in the beds also recorded potential sedimentation rates at between 2.89 and 14.5 mg cm⁻² d⁻¹. This high turbidity resulted in a sharp decrease in the density of Clithon spp., the dominant grazers of epiphytic algae on Z. japonica. Effects of sedimentation and shading on growth of Z. japonica were investigated by field manipulative experiments. Experimental increase of sedimentation rate and shade both resulted in larger decreases in percentage cover and above-ground AFDW compared with the control. Received: 3 March 1997 / Accepted: 14 March 1997     

Antibiotic distribution,risk assessment,and microbial diversity in river water and sediment in Hong Kong

Environmental Geochemistry and Health - For the past fewer years, environment antibiotic residues have got more and more attention. The occurrence and distribution of eight common antibiotics,...