Multi-scale Atmospheric Dispersion Modelling by Use of Adaptive Gridding Techniques

An accurate prediction of the transport-reaction behaviour of atmospheric chemical species is required to fully understand the impact on the environment of pollution emissions. Elevated levels of secondary pollutants such as ozone in the lower atmosphere can be harmful to the health of both plants and animals, and can cause damage to property present in the urban environment. Detailed models of pollution mechanisms must therefore be developed through comparisons with field measurements to aid the selection of effective abatement policies. Such models must satisfy accuracy requirements both in terms of the number of species represented, and the spatial resolution of species profiles. Computational expense often compels current models to sacrifice detail in one of these areas. This paper attempts to address the latter point by presenting an atmospheric transport-reaction modelling strategy based upon a finite volume discretisation of the atmospheric dispersion equation. The source terms within this equation are provided by an appropriate reduced chemical scheme modelling the major species in the boundary layer. Reaction and transport discretisations are solved efficiently via a splitting technique applied at the level of the non-linear equations. The solution grid is generated using time dependant adaptive techniques, which provide a finer grid around regions of high spatial error in order to adequately resolve species concentration profiles. The techniques discussed are applied in two dimensions employing emissions from both point and area sources. Preliminary results show that the application of adaptive gridding techniques to atmospheric dynamics modelling can provide more accurately resolved species concentration profiles, accompanied by a reduced CPU time invested in solution. Such a model will provide the basis for high resolution studies of the multiple scale interactions between spatially inhomogeneous source patterns in urban and regional environments.     

Quantifying urban heat island intensity in Hong Kong SAR, China

This paper addresses the methodological concerns in quantifying urban heat island (UHI) intensity in Hong Kong SAR, China. Although the urban heat island in Hong Kong has been widely investigated, there is no consensus on the most appropriate fixed point meteorological sites to be used to calculate heat island intensity. This study utilized the Local Climate Zones landscape classification system to classify 17 weather stations from the Hong Kong Observatory’s extensive fixed point meteorological observation network. According to the classification results, the meteorological site located at the Hong Kong Observatory Headquarters is the representative urban weather station in Hong Kong, whereas sites located at Tsak Yue Wu and Ta Kwu Ling are appropriate rural or nonurbanized counterparts. These choices were validated and supported quantitatively through comparison of long-term annual and diurnal UHI intensities with rural stations used in previous studies. Results indicate that the rural stations used in previous studies are not representative, and thus, the past UHI intensities calculated for Hong Kong may have been underestimated.     

The Interstate Air Pollution Surveillance Program Effects Network

A program has been designed to meet a nationwide intelligence-gathering responsibility to obtain general and relative information on current and potential air pollution in areas where interstate transport of pollution may reasonably be expected to exist. This paper describes the field devices utilized in the program. By means of these static “effects packages,” data will be accumulated on: dustfall, particulate impingement, sulfation, corrosion, and tarnishing of metals, and deterioration of textiles, dyes, and rubber. Data accumulated during the “pilot phase” of the program will be discussed.     

曝气生物滤池处理化工污水研究

曝气生物滤池是80年代末在欧美发展起来的一种新型污水处理技术。它采用了一种新型粒状填料,综合了过滤、吸附和生物代谢等多种净化作用,具有占地小、出水质量好、流程简单、对环境影响小等诸多优点。文章介绍了曝气生物滤池生物膜的形成及净化机理,并取某石化公司化工污水处理厂调节池出水进行了实验,主要对水中COD、BOD、SS去除效果进行分析,结果表明:曝气生物滤池具有较强的抗冲击负荷能力,运转方便、设备简单。