A field study was established to investigate the chemical composition of atmospheric aerosols in Chicago, IL. One goal of
this study was to determine the influence of precursor trace gases and local meteorology on concentrations of secondary aerosol
ionic species. This paper describes the method details, shows the method is analytically valid, and reports overall as well
as some specific results found during the field study. Two particulate air samples were collected per day onto quartz fiber
filters at the Loyola University Chicago Air Station during the summer months in 2002–2004. In parallel, mixing ratios of
ozone and nitrogen oxides were monitored and weather parameters were recorded. Particulates were extracted from the filter
substrates and the subsequent solutions were analyzed by ion chromatography for anions, including low molecular weight organic
acids, and cations. A washing procedure was implemented to reduce the high background values of the quartz fiber filters.
Method validation showed that the collection method was efficient for all ions with exception of nitrate, whose efficiency
of 70% indicated losses caused by volatilization. The extraction method also proved efficient for both field and laboratory
samples, and the repeatability of the method was high with relative standard deviations less than 10% for all ions. Reproducibility
of the results was determined by comparison of sulfate to sulfur analyzed by total reflection X-ray fluorescence spectrometry
and proved to be high as well. Concentrations differed significantly between the three summer studies due to varying levels
of precursor species as a consequence of distinct temperatures and wind direction profiles. 相似文献
In all tanning technology operations wastes are generated. These reach the environment as residual waters, solid and liquid waste as well as atmospheric emissions and odours.
This study tests an alternative method to the traditional tanning method at an industrial level. The new method is based on tanning without float and by significantly increasing the temperature at the end of the tanning process. The properties of the leathers obtained using the two methods have been compared and the results indicate that those leathers have similar physical, chemical, and organoleptic properties. However, the differences existing from the environmental point of view are significant. It is not necessary to use clean water for this tanning. Moreover, there is a 75% reduction of the residual float, a 91% reduction of the chrome discharged, and a 94% reduction of the chlorides discharged. A financial assessment was carried out to demonstrate that the newly proposed system is 32% more economic than the traditional one. 相似文献
Emerging approaches to water resources development and management typically highlight equity and productivity as two main objectives. In the context of integrated water resources management within a river basin, managers and stakeholders often need a comparative assessment of different options for water augmentation and/or allocation. Pitting such options against predefined objectives, such as equity and productivity, requires an assessment of the effects that available options will have on these objectives. Available documentation indicates that not only does the interpretation of such objectives vary widely, but also the available methods for assessing equity and productivity run into significant limitations in the availability of adequate data. This limitation has largely kept decision makers from gaining a comprehensive overview of equity and productivity scenarios, whether within or across sectors, that could facilitate better‐informed decisions. To address this methodological gap, this article scrutinizes different notions associated with equity and water productivity, and limitations in prevalent assessment methods with the view to develop and demonstrate pragmatic methodologies for assessing equity and productivity in data‐scarce contexts. The discussion and findings are based on a review of relevant literature and empirical and consultative research work in the Olifants River basin in South Africa. The demonstrated methodologies for assessing equity and productivity, besides being useful in data‐scarce contexts, are insightful for initiating several policy measures and also for exploring the relationship between equity and water productivity.相似文献