THE ENVIRONMENT
update the baseline on Hong Kong's radiation levels so that unusual levels subsequent to the commissioning of the nuclear power plant can be detected. Ambient gamma dose rates are measured in various parts of Hong Kong using high-pressure ionisation chambers and thermoluminescent dosimeters. Additionally, a specially-fitted vehicle is used to conduct regular territory-wide radiological surveys.
To monitor earthquakes and seismicity, three short-period seismometers are operated at Cheung Chau, High Island and Tsim Bei Tsui. Long-period seismographs record tremors from all over the world. Strong-motion accelerographs are operated at the observatory and Tate's Cairn which are two locations with different soil properties. About 140 earthquakes with epicentres within 320 kilometres of Hong Kong are detected annually and made known to the public via the mass media. Seismic data are used by structural engineers in the design of earthquake-resistant buildings. Such data are also made available to local and overseas scientific institutions for their studies.
The Hong Kong Time Standard is provided by a caesium beam atomic clock at the observatory and accuracy of fractions of a microsecond a day is maintained. The time service is operated by the relay of a six-pip time signal to Radio Television Hong Kong for transmission.
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Environmental Problems
- Eike any modern commercial and industrialised city, Hong Kong produces daily a wide variety of wastes of varying quantities as by-products of its activities. It is these wastes which lead to different environmental pollution problems. Depending on the concentration of the pollutant and the duration of exposure to it, the health risk posed by a specific pollutant can range from minimal to life-threatening.
(Various aspects of the pollution problems are illustrated in the end-paper map at the end of this book.)
Water and Wastes
The manufacturing industries make a significant contribution to the economy of Hong Kong. These industries consume a wide range of chemicals and chemical products, most of which are hazardous to health. Indiscriminate disposal of untreated trade effluents from the factories directly to surface drains, sewers and other watercourses poses a threat to the environment. Such a disposal practice adversely affects the safety of workers in sewer- age and drainage systems, the fabric of sewers and the operation of sewage treatment downstream. Eventually this leads to contamination of coastal waters and, subsequently, accumulation of toxic chemicals in the bottom sediments and transfer to humans through the food chain.
Further pollution of the water bodies is caused by direct discharge of sewage into the ordinary storm-water drains which subsequently reaches the sea without any treatment. The raw sewage is rich in organic matter which depletes the water of its oxygen content resulting in malodorous conditions and also contains nutrients which encourage bacterial growth. Serious sewage contamination is reflected by a poor grading of beach water quality and in some cases results in the closure of affected beaches.
Waste quantities to be handled by disposal authorities continue to rise as a result of the economic growth of the territory and the gradual introduction of tighter controls over