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The Shiyang River Basin is an inland river basin in the Hexi Corridor, Gansu Province, northwest China. Shiyang is the largest basin in terms of human population density and has the highest exploitation of water resources in the northwest. Serious water shortages constrain social and economic development, and the area has some of the worst ecological and environmental deterioration in China. From historical data and recent observations, we have analysed changes in water systems in the Minqin oasis, at the end of the river basin, and assessed impacts and consequences of a changing climate and intensive human activity. Historically, climate change has been the main cause of changes in the oasis. In the last 50 years, however, a major influence has been intense human activity in the basin. With increasing population (159% in 50 years), the amount of cultivated land has been greatly expanded (by 51%). Many reservoirs have been built by damming rivers and large-scale irrigation has been introduced in the middle reaches of the basin. The introduction of leakage-free canals and more extensive exploitation of underground water have further expanded the irrigated area. Water use by humans has exceeded the carrying capacity of the water resources of the basin, which has led to a dramatic shift in water allocation between the upper and lower reaches and a rapid drop in the water table in the Minqin oasis (by as much as 14 m). The oasis is shrinking, natural vegetation that relies on underground water is disappearing, and desertification is accelerating. An ancient oasis that can be traced back 2000 years is disappearing and this must be a warning sign for future generations. [ABSTRACT FROM AUTHOR]

Premature late-season fruit abscission is a major concern for UK sweet cherry growers, but its causes are not understood. Competition for resources such as photo-assimilates and plant hormones may trigger fruit abscission. We therefore examined the roles of photo-assimilation, sugars and abscisic acid (ABA) in the regulation of late-season fruit abscission. The experimental material consisted of phloem-girdled short shoots (‘spurs’) with two distinct ranges of leaf area to fruit number (LA:FN) ratios. These ratios were achieved by selecting spurs with similar leaf areas, but different fruit numbers. Our previous research showed that fruit rapidly abscise from spurs with a low LA:FN ratio (within 14–21 d after girdling; DAG), while fruit on spurs with a high ratio are typically retained. Photo-assimilation of leaves was measured over 15 DAG. Fruits were collected for the determination of sorbitol, ABA and 1-aminocyclopropane-1-carboxylic acid concentrations 0, 1, 3, 5, 7 and 9 DAG. After girdling, photo-assimilation of leaves from spurs with a low LA:FN ratio was greater than that of leaves from spurs with a high LA:FN ratio. However, fruit on spurs with a low LA:FN ratio potentially received three-fold less photo-assimilate per fruit compared to fruit on spurs with a high LA:FN ratio. Before the symptoms of abscission appeared, sorbitol concentrations in fruit were 30% lower on spurs with low LA:FN compared to fruit on spurs with a high ratio. As the symptoms of abscission developed for fruit on spurs with a low LA:FN ratio, fruit ABA concentrations increased as fruit sorbitol concentrations declined. Experiments to determine if the exogenous application of ABA induced fruit abscission showed a rapid induction of fruit loss. These results support the hypothesis that source limitation, through the supply of photo-assimilates, can cause late-season fruit abscission in sweet cherry. However, the delayed rise detected in fruit ABA concentration appears more consequential than abscission-related. [ABSTRACT FROM AUTHOR]

Despite interpretations of perceived agglomeration diseconomies in metropolitan areas, South African regional development policy remains firmly based on the pursuit of a political ideology in the form of separate development. Initial attempts at decentralisation through incentives and concessions failed to achieve any significant restructuring of the South African space economy and led to a “new” regional development strategy for Southern Africa contained in the Good Hope Plan. This has created a necessity for a complex and integrated system of “multilateral co‐operation” designed to establish consensus amongst the SATBVC states. Fundamental to such co‐operation are the principles of participant autonomy, co‐operative rather than prescriptive action, promotion of private initiative and a rationalisation of industrial development by eliminating competing structures. The implementation of Ciskeian tax reform initiatives tends to indicate shortcomings in the multilateral co‐operation forum, and to raise questions regarding further unilateral actions by TBVC participants. The implications of Ciskei's actions for development in Region D also appear to be serious and require urgent attention. The success of the regional development policy is heavily dependent upon interregional co‐operation and Ciskei's actions have served to highlight the possibility of failure inherent in a policy whose foundations are associated with the spatial manifestation of separate development. [ABSTRACT FROM PUBLISHER]

The various activated sludge models within STOAT, a whole works package, were used to predict the oxygen requirements of a hypothetical activated sludge plant. The predictions which were obtained were then compared with the values calculated from standard equations. The results showed that there were very definite differences both between thepredictions made by the models and betweeni the model predictions and those produced using standard equations. The results also showed that, for carbonaceous oxidation, the COD-based model in STOAT (IAWQ model) was applicable to a wider range of process conditions than the BOD-based model (ASAL model). The IAWQ model was also found to be a more useful tool in optimising a nitrogen removal system. [ABSTRACT FROM AUTHOR]