Urban growth management in Jeddah

The towns and cities of Saudi Arabia have been subjected to sustained growth pressures since the transformation of the country's economy following the discovery of oil in the Eastern Province of the Kingdom. The rapid growth which has been experienced has created major problems for the central and local government agencies responsible for planning and managing urban growth. The experience of Jeddah, one of the major cities in Saudi Arabia, is described and the problems of planning and managing its growth are analysed. Weaknesses relating to the structure of the planning system are identified, as are major difficulties in relation to the quality and quantity of professional staff. Recent attempts to improve the operation of the planning system are described and evaluated.     

Regional assessment of plant growth problems for colliery spoil reclamation

Possibilities for greater variation in landscaping during the reclamation of derelict colliery spoil heaps and the potential of a regional approach to the survey of revegetation problems are introduced. A survey method for assessing plant growth problems is described which incorporates rapid measurement of physical and chemical constraints to plant growth and which uses bioassay trials as an index of plant growth potential. The use of the survey method on 34 closed and disused sites in the Barnsley and South Yorkshire areas of the National Coal Board is outlined and suggestions for the incorporation of such data in recommendations for the reclamation of individual sites are made.     

The withdrawal of land from mining — A study of the implications for the future

As a result of several decades of growing environmental awareness, pressures to restrict mining activity in areas of high scenic and recreational value are great. The development of planning law, and legislation for National Parks, are outlined as a framework for current mineral policies in this country, which highlight the fact that at present, almost any area in Britain could theoretically be mined, i.e. few areas are actually banned from mineral working. This contrasts with the situation in the USA where considerable acreages, especially in the Western States, are either covered by absolute bans, or are heavily restricted from mining activity.Should some areas of Britain become similarly off-limits to mining, possible implications include increased deficits in the balance of payments, reduced reliability of mineral supplies to industry, adverse social effects on a local scale, and, on the advantageous side, more efficient use of recycled waste and other alternative sources of materials. Taking all these into account, it is concluded that a ban on mining in some areas would be a dangerously short-sighted, inflexible and irreversible step, and a more moderate approach is required, while the need to protect highly valued areas is recognised as being very important.     

Sterilisation and safeguarding of mineral deposits in Britain

This paper gives a detailed account, from a British viewpoint, of the sterilisation of mineral deposits by development and of approaches that can be adopted to safeguard mineral resources in the long term. The ways in which mineral deposits can become sterilised are discussed along with an account of sterilisation trends. Policies on avoidance of sterilisation and safeguarding are traced from their origins through to the present day. Central and local government roles are examined along with responsibilities of those in the mineral industry.Following policy approaches there is consideration of how widely policies have been implemented in practive and how far these approaches to implementation match the aims on safeguarding. Emphasis is placed upon mineral consultation areas and their definition and operation, though landbanks and prior extraction are also considered. Finally, discussion brings out some salient points which form the basis of some concluding recommended courses of action.     

The selenium content of Welsh soils with special reference to bedrock and contamination from sulphide ores

This paper describes a survey of total selenium contents of surface soil samples in Wales. Samples were collected from three areas: over Silurian shales where deficiences in sheep have been reported, in an area severely affected by pollution from lead mining and in an area where black, marine shales outcrop. Selenium levels were low over the Silurian shales but high in the other two areas. Statistical analysis of the data permitted the separating out of a basal range of selenium values low enough to account for the reports of deficiences in sheep. Some selenium values were high enough to suggest the possibility of selenosis in sheep.     

The agricultural impact of opencast coal mining in England and Wales

Opencast coal mining in England and Wales can cause a wide range of environmental problems which are increasingly public issues due to the planned expansion in output and the impact this may have on agriculture and landscape. Opencast mining is reviewed on a county by county basis to identify the variations in the disturbance caused. A detailed review of restoration techniques and the agricultural quality of the restored land is presented, and the role of Planning Authorities is discussed. Significant variations in the impact of opencast operations are identified, especially in relation to the potential for derelict land reclamation and the grade of agricultural land affected. The latter is generally lower grade 3 and below, although in certain areas operations are entering land of higher agricultural and scenic quality. The quality of restoration, while good, still has scope for improvements, such as reducing soil compaction and the subsequent management of the land by the farmer. The impact on agricultural productivity is difficult to assess, but it appears to be only slight in those cases where recent restoration techniques were used and when lower grade agricultural land is taken.     

Extraction,reclamation and after use at gravel quarries near Canterbury,Kent

A study of the extraction, reclamation and after use of flood plain gravel quarries between Bagham and Thannington, south west of Canterbury in Kent, South-east England, was made, based on a review of the literature and field work. The area represents a linear extension of the urban fringe of Canterbury. Gravel production has been the most significant industry in terms of environmental impact over the last thirty years, and the result of such activity has been the creation of an extensive area of lakes and wetland habitats. Present and future gravel production will more than double the existing lakes and wetlands areas. It is suggested that, in terms of land use, this man-made environment is best suited for water-based recreation and that three zones should be recognised for an amenity park, angling and wildlife respectively. Further mineral production between Ashford and Bagham may mean a reappraisal of the proposed water resource use, particularly for wildlife. As a result of this study, attention is drawn to the spatial relationships between recreational demand groups and flood plain location with respect to the urban centre and to each other.     

Glial and neuronal cells in amniotic fluid of anencephalic pregnancies

Cultured amniotic fluid cells from four anencephalic pregnancies were characterized in indirect immunofluorescence (IIF) microscopy using specific antibodies against different types of cytoskeletal intermediate filaments. Most of the cells showed a fine fibrillar cytoplasmic fluorescence with antibodies against glial fibrillary acidic protein (GFA), indicating that amniotic fluid cells in anencephalic pregnancies are of glial origin. The GFA-positive cells were rapidly adhering and proliferating. They remained as the major cell type also in long term cultures, and could easily be recovered from liquid nitrogen without losing their GFA positivity. GFA-positive cells were pleomorphic in appearance, and occurred in several morphologically different shapes. Amniotic fluid from one of the anencephalic cases contained typical neuronal cells, which in IIF were GFA-negative but could specifically be stained with anti-neurofilament antibodies. Most of the GFA-negative cells in all the cases were fibroblasts, identified by their fluorescence only with antibodies against vimentin. Epithelial cells showing positive keratin-fluorescence in IIF, were seen only occasionally.     

溶剂萃取法再生废机油的研究

用溶剂萃取-白土精制法对4种废机油进行了再生研究,萃取过程剂油质量比为3∶1,萃取温度为60℃,减压蒸馏回收溶剂。白土精制过程中白土质量为油质量的10%,精制温度为185℃。精制后4种废机油的密度、凝点、黏度、闪点、酸值等都有不同程度的改善。