Reducing carbon footprint and cooling demand in arid climates using an integrated hybrid ventilation and photovoltaic approach

Environment, Development and Sustainability - A hybrid ventilation system combining both natural and mechanical ventilation has proven very promising in moderating indoor climate, based on its...     

Olfactory and chemical characterization of indoor air. Towards a psychophysical model for air quality

The relationship between the odor strength of total air samples and the odor strengths of the constituents was investigated in three field experiments in an office building and a new preschool. The odor strength was scaled by magnitude estimation according to a master scale principle which results in comparable values for the total and the constituent odors. Between 60 and 120 chemical components were detected by GC/FID in the indoor air samples (N = 66). Most (81%) of the detected components in an air sample were odorous, even though most of them were of the low concentrations. By a method of pattern analysis, chemical as well as odor patterns of indoor air were found to be characteristics of different buildings. From the odor patterns (POG), the “odor print” of the outdoor air associated with the buildings was also recognized in the indoor air. Thus, the “odor print” of an air sample is different from its “chemical print”. A model was found that predicts the overall odor strength of an air sample from the number of FID-detected components most frequently reported to have a strong odor.     

Evaluation and ranking of restoration strategies for radioactively contaminated sites.

An international project, whose aim was the development of a transparent and robust method for evaluating and ranking restoration strategies for radioactively contaminated sites (RESTRAT), was carried out under the Fourth Framework of the Nuclear Fission Safety Programme of the EU. The evaluation and ranking procedure used was based on the principles of justification and optimisation for radiation protection. A multi-attribute utility analysis was applied to allow for the inclusion of radiological health effects, economic costs and social factors. Values of these attributes were converted into utility values by applying linear utility functions and weighting factors, derived from scaling constants and expert judgement. The uncertainties and variabilities associated with these utility functions and weighting factors were dealt with by a probabilistic approach which utilised a Latin Hypercube Sampling technique. Potentially relevant restoration techniques were identified and their characteristics determined through a literature review. The methodology developed by this project has been illustrated by application to representative examples of different categories of contaminated sites; a waste disposal site, a uranium tailing site and a contaminated freshwater river.     

Health and environmental costs of pesticide use in vegetable farming in Nepal

There is a growing concern of pesticide risks to human health, natural environment and ecosystems. Many previous economic valuations have accounted health aspects or environmental components, but rarely combined; thus, overall risk assessment is partially distorted. The study, conducted close to the capital of Nepal, addressed the health effects of pesticides on small-scale farmers and evaluated the monetary risks of pesticide use on human health and environmental resources. We also aim to establish the relationships among valuation methods. The paper adopts cost of illness, defensive expenditure and contingent valuation willingness to pay approach. The study concluded that the methods used for valuing pesticide risks to human and environmental health are theoretically consistent. The exposed individuals are likely to bear significant economic costs of exposures depending on geographical location, pesticide use magnitudes and frequency. Individuals are willing to pay between 53 and 79% more than the existing pesticide price to protect their health and environment. The integrated pest management training is less likely to reduce health costs of pesticide exposure, although it leads to higher investment in safety measures.     

Design,measurement and evaluation of photovoltaic pumping system for rural areas in Oman

In the present paper, the optimum design of a PV system used to operate a water pumping system was determined for Oman. The system design focused on the environmental conditions of Sohar city. The implementation and measurement of the designed system are presented to prove the effectiveness of the proposed system. The results show that the system can provide the required power at peak hours, leading to a substantial reduction in the sizing of the PV system. Consequently, the investment capital costs 2400 USD, and the cost of energy is equal to 0.309 USD/kWh. Furthermore, the results indicate that the system annual yield factor is 2024.66 kWh/kWp and that the capacity factor is 23.05 %, which is encouraging since the latter is typically 21 %. The system capital cost and the cost of energy are worth comparing to a diesel generator. A comparison is made between the proposed system and several others in the literature. The comparison indicated that the system cost of energy is promising.     

Mitigating Greenhouse Gas Emissions from Rice-Wheat Cropping Systems in Asia

The rice-wheat belt comprises nearly 24–27 million ha in South and East Asia. Rice is generally grown in flooded fields whereas the ensuing wheat crop requires well-drained soil conditions. Consequently, both crops differ markedly in nature and intensity of greenhouse gas (GHG) fluxes, namely emission of (1) methane (CH₄) and (2) nitrous oxide (N_2O) as well as the sequestration of (3) carbon dioxide. Wetland rice emits large quantities of CH₄; strategies to CH₄ emissions include proper management of organic inputs, temporary (mid-season) field drainage and direct seeding. As for the wheat crop, the major GHG is N_2O that is emitted in short-term pulses after fertilization, heavy rainfall and irrigation events. However, N_2O is also emitted in larger quantities during fallow periods and during the rice crop as long as episodic irrigation or rainfall result in aerobic-anaerobic cycles. Wetland rice ensures a relatively high content of soil organic matter in the rice-wheat system as compared to permanent upland conditions. In terms of global warming potential, baseline emissions of the rice-wheat system primarily depend on the management practices during the rice crop while emissions from the wheat crop remain less sensitive to different management practices. The antagonism between CH₄ and N_2O emissions is a major impediment for devising effective mitigation strategies in rice-wheat system - measures to reduce the emission of one GHG often intensify the emission of the other GHG.     

Water pollution in Pakistan and its impact on public health--a review

Water pollution is one of the major threats to public health in Pakistan. Drinking water quality is poorly managed and monitored. Pakistan ranks at number 80 among 122 nations regarding drinking water quality. Drinking water sources, both surface and groundwater are contaminated with coliforms, toxic metals and pesticides throughout the country. Various drinking water quality parameters set by WHO are frequently violated. Human activities like improper disposal of municipal and industrial effluents and indiscriminate applications of agrochemicals in agriculture are the main factors contributing to the deterioration of water quality. Microbial and chemical pollutants are the main factors responsible exclusively or in combination for various public health problems. This review discusses a detailed layout of drinking water quality in Pakistan with special emphasis on major pollutants, sources of pollution and the consequent health problems. The data presented in this review are extracted from various studies published in national and international journals. Also reports released by the government and non-governmental organizations are included.     

Water and soil pollution by Spent lubricating oils

This paper shows that spent lubricating oils from automobile engines generate carboxylic acids on environmental exposure. Samples of exposed oils, isolated from polluted river water and shore muds obtained from various locations, showed a direct proportionality between carboxylic acid content and time of exposure. Carboxylic acids were isolated by solvent extraction and studied by infrared spectroscopy.     

Ion current densities produced by energetic electrons in electrostatic precipitator geometries

A new laboratory test system for electron beam ionization in electrostatic precipitator geometries has been constructed to measure ion current density as a function of voltage difference for clean plate (no dust contamination) conditions. The new system incorporates improved electrodes which withstand an applied voltage of ± 55 kV, a factor of 5 increase over the previous test system. A 3 MeV Van de Graaff accelerator produced ionizing electron beams of 1.2 and 2 MeV energy with beam currents of 10.5 and 21 μA in place of corona wire ionization. Ion current densities of up to 130 mA/m² were measured before breakdown between the plates, and no ion current saturation was observed. A comparison of I-V curves and sparkover voltages for various beam energies, currents, and types of collimation is discussed and the need for measurements with good beam geometry is addressed.     

用改进型CAJRIX离子交换技术去除水中镉、铜离子的研究

本文报道用离子交换技术去除镉、铜的新工艺,在传统的CARIX工艺中碳酸钙是便宜的再生添加剂,但再生效率较低,使用较困难.本文报道用镁型化合物作为再生添加剂加入饱和的二氧化碳溶液中,将弱酸性阳离子交换树脂转变为镁型。在不同条件下选用Mg(OH)_2、碱式碳酸镁、白云石等作添加剂。实验结果表明,出水中镉、铜含量可达到废水排放允许标准。