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The 24-h average coarse (PM10) and fine (PM2.5) fraction of airborne particulate matter (PM) samples were collected for winter, summer and monsoon seasons during November 2008-April 2009 at an busy roadside in Chennai city, India. Results showed that the 24-h average ambient PM10 and PM2.5 concentrations were significantly higher in winter and monsoon seasons than in summer season. The 24-h average PM10 concentration of weekdays was significantly higher (12-30%) than weekends of winter and monsoon seasons. On weekends, the PM2.5 concentration was found to slightly higher (4-15%) in monsoon and summer seasons. The chemical composition of PM10 and PM2.5 masses showed a high concentration in winter followed by monsoon and summer seasons.The U.S.EPA-PMF (positive matrix factorization) version 3 was applied to identify the source contribution of ambient PM10 and PM2.5 concentrations at the study area. Results indicated that marine aerosol (40.4% in PM10 and 21.5% in PM2.5) and secondary PM (22.9% in PM10 and 42.1% in PM2.5) were found to be the major source contributors at the study site followed by the motor vehicles (16% in PM10 and 6% in PM2.5), biomass burning (0.7% in PM10 and 14% in PM2.5), tire and brake wear (4.1% in PM10 and 5.4% in PM2.5), soil (3.4% in PM10 and 4.3% in PM2.5) and other sources (12.7% in PM10 and 6.8% in PM2.5). 相似文献
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Shiva H. Achet Assistant Professor of Geography Environmental Science Bill Fleming 《Journal of Environmental Planning and Management》2006,49(5):675-694
A watershed management framework for mountain areas is based on lessons learned from watershed management experience, social and institutional learning, and the use of a watershed management program evaluation in Nepal. The lessons led to the adoption of a subwatershed-based ecosystem approach based on local participation at the subwatershed level. An integrated watershed management framework (IWMF) consisting of eight steps with three checklists was developed focusing on improvement-oriented adaptive management. The eight steps lead to the preparation of a watershed management plan. In the process three checklists are used. While the first checklist has general questions pertaining to watershed analysis, the second allows participation analysis of stakeholders in terms of their strengths, weaknesses, opportunities and threats and opens up new prospects for further reinforcing or building new user group institutions based on consensus. The final checklist consists of hierarchical watershed management objectives, including goals, results and activities leading to a program planning matrix. The framework was applied to watershed planning in the Chure Region to compare the framework-based planning with conventional planning procedures. A significant difference in quality and substance of the output, with and without the use of the framework, suggests that an integrated framework is a useful tool for an ecosystem-based approach to natural resource management and socio-technical conservation. 相似文献
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Excessive air pollution may adversely affect plant growth and development. The overall objective of this research was to elucidate some microscopic effects of diesel exhaust particles (DEP) on the formation, development, and structure of pollen grains and its proteins in Phaseolus vulgaris L. Bean plants were grown in experimental pots and treated with different concentrations of the water-soluble fraction of DEP. Flowers and young buds were removed, fixed in FAA70 (formalin?:?acetic acid?:?ethanol, 2?:?1?:?17), and subjected to developmental studies. Our results show that DEP cause some abnormalities during pollen development. Pollen grains in normal plants are spherical in equatorial view and triangular in polar view; in DEP-treated plants, they were changed into irregular shapes in equatorial view and asteroidal in polar view. Delay in degeneration of the tapetum layer of the anther, and formation of giant, irregular, and non-fertile pollen grains are other results of DEP treatment. Gel electrophoretic studies revealed that a new protein with a molecular mass of 80?kD was formed in the DEP-treated group. Some pollen proteins may act as allergens, considering the fact that pollen allergy frequency is increased in polluted areas; the possibility arises that DEP could be an effective agent entail formation of detoxifying proteins which, on the other hand, can also act as allergens. 相似文献