Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions.

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.     

Repositioning the urban environment question in Zimbabwe: a review of the context,conditions and processes

This analysis is a reappraisal of two perspectives in urban development in Zimbabwe: environmental sustainability and human sustenance. The discussion seeks to reposition the conservation–survival debate by broadening it to the wider urban and national macroeconomic and sociopolitical context. It re‐examines Zimbabwe's environmental problems by examining the challenges posed by urbanisation, industrialisation and informalisation. To these ‘permanent’ strands are added the ‘transient’ phenomena of structural adjustment and indigenisation. The analysis is done within the overall national macroeconomic and sociopolitical environment. The article examines environmental sustainability and human sustenance as the two policy challenges that have to be reconciled in the quest for sustainable urban settlements in Zimbabwe. The analysis stresses that the exercise of striking a balance between the needs of humankind and those of nature has to take cognisance of the complexity of issues and the processes going on elsewhere in the urban and national context.     

Quality Management Systems Certification: Research Note

Although International Quality Standards 9000 certification is one of the most popular quality assurance systems in the world, its contribution to a firm's value is still a controversial issue. This project re-examines this issue by using stock market reactions to the announcements of the award of certification made by a sample of Hong Kong listed companies, as a proxy for its contribution to a firm's value. The results suggest that on average certification increased a firm's value. However, most of this value increase was incorporated into stock prices before formal announcements were published in newspapers. In addition, the contribution of certification to value was greater in smaller firms than in larger ones. This can be attributed to fewer stock traders and professional analysts following smaller firms.     

Finding Pareto Optimal Insurance Contracts

This paper deals with on-line computation—or step-wise learning—of Pareto optimal insurance contracts. Our approach tolerates that the loss distribution might be unknown, intractable, or not well specified. Thus we accommodate fairly inexperienced parties. Losses are here simulated or observed, one at a time, and they cause iterated revisions of the premium. The mechanical and global nature of probability calculus thereby yields to more tentative, myopic procedures, possibly closer to how humans operate or reason in face of risk. Sequential revisions may also reduce the expense of insurers' time and money in seeking sufficient statistics. Emphasized below is the remarkable simplicity and stability of the resulting adaptive procedures. Special attention goes to catastrophic risks, and to subsidized or competitive insurance.     

Fragmentation, Engel's Law, and Learning

This paper outlines the conditions under which trade is beneficial for a developing country's growth. A developing country suffers from two disadvantages: low income and a comparative disadvantage in the production of modern manufactured goods—goods which allow a high rate of human capital accumulation through learning by doing. Low income together with Engel's law imply that developing countries consume and produce very few modern goods in autarky and hence grow slowly. With international fragmentation of production, a developing country may find comparative advantage in the production of some stages of modern goods despite an absence of comparative advantage in the production of modern goods under “100% local content.” More resources can then be allocated to the modern goods sector leading to greater learning externalities and hence growth under free trade than in autarky.     

基于消费者运动的社会营销学研究综述

20世纪美国消费者运动风起云涌。推动了政府的立法活动和营销学研究。本文回顾美国消费者运动的进程，评述基于消费者运动的社会营销学研究，并对中国的消费者权益保护及其社会营销学研究提出建议。     

Using precise data sets on farming and pesticide properties to verify a diffuse pollution hydrological model for predicting pesticide concentration.

Verification of a diffuse pollution model involves comparing results actually observed with those predicted by precise model inputs. Acquisition of precise model inputs is, however, problematic. In particular, when the target catchment is large and substantial estimation uncertainty exists, not only model verification but also prediction is difficult. Therefore, in this study, rice-farming data were collected for all paddy fields from all farmers in a catchment and pesticide adsorption and degradation rates in paddy field soil samples were measured to obtain precise model inputs. The model inputs successfully verified the model's capability to predict pesticide concentrations in river water. Sensitivity analyses of the model inputs elucidated the processes significantly affecting pesticide runoff from rice farms. Pesticide adsorption and degradation rates of the soil did not significantly affect pesticide concentrations, although pesticide discharge to river water accounted for less than 50% of the total quantity of pesticide applied to fields, possibly owing to pesticide adsorption and degradation. The timing of increases in pesticide concentrations in river water was affected mostly by the farming schedule, including the time of pesticide application and irrigation, and secondarily by rainfall events.     

Use of 3D modelling and several ultrasound sensors to assess overflow rate.

A new instrumentation mode has been put in place in order to determine the overflow rate of five complex CSOs of the system in Sélestat (French), which are subject to self monitoring. 3D and 1D models have made it possible to predict the shapes of the water lines and suggest a location for the ultrasound sensors. In order to validate the instrumentation principle, three overhead sensors were placed on a weir. The overflow laws suggested are of the type Q(overflow) = a1h1b1 + a2h2b2 + a3h3b3. Early results of the overflow rate that have been obtained by applying the law are close to 10 % of the flow measured in the physical test bench. On the actual site, the ultrasound sensors were assembled on a rail covering the entire weir in order to be able to change their position in future after models calibration.