ABSTRACT
Monthly ambient air and surface soil samples were taken for analysis in the outskirts of Madrid in an open urban area from November 1998 to October 1999. Thirty-one polychlorinated biphenyl congeners were analysed, selection being done according to their abundance in environmental samples. The present work shows the results obtained when factor analysis (FA) and cluster analysis were applied to concentration data of seventy-one ambient air samples (polyurethane foam plugs and filters). Both chemical parameters (concentrations and total suspended particulate) and two meteorological parameters (temperature and wind velocity) were determined weekly during the sampling period. A bivariate correlation analysis was previously performed to estimate relationships between PCBs and, also between soil and filter medium.
ABSTRACT
Multivariate techniques have been applied to the set of data obtained after one year sampling of volatile organic compounds (VOCs), including volatile aldehydes in the area of Madrid in order to evaluate the possible correspondence among groups of analysed compounds, as far as modelling of different emission sources in relation to location and season. The measurements were carried out at four sites in Madrid, characteristic for urban and suburban areas. Additionally, as reference, a rural area 100 km far from the city was considered. Results of correlation analysis, factor and cluster analysis are presented. Higher correlations were found between variables related with traffic emissions. Factor analysis results showed two main significant variables related to anthropogenic and biogenic emissions respectively. In relation to cluster analysis, samples were grouped according to sampling site and seasonal variations.
Subject(s)
Air Pollutants/analysis , Environmental Monitoring/statistics & numerical data , Organic Chemicals/analysis , Cities , Cluster Analysis , Gas Chromatography-Mass Spectrometry , Seasons , Spain , Vehicle Emissions/analysis , VolatilizationABSTRACT
From November 1995 to October 1996, airborne concentrations of VOCs were measured in the Madrid area to study the organic pollution in general, and the correlation between different pollutants in relation to such parameters as location and season. Mean concentrations for up to 90 compounds were measured at four test sites, including both urban and suburban areas. At the urban sites, maximum concentrations occurred in the autumn and winter, whereas minimum concentrations were reached in summer and spring. Similar changes were obtained for the less contaminated site located in the SE of the city, whereas a different pattern was found at the site in the NW of the city due to meteorological aspects. Mean levels of hydrocarbons in Madrid were quite similar to those found in other European cities. Chemometrical techniques were applied to the set of data in order to assess the influence of such factors as traffic, temperature and seasonal variations on the VOC levels.
ABSTRACT
The focus of this study was to characterize the concentration levels of selected PCBs and compare them to compiled data in order to contribute to the international database. The sampling site is located in the outskirts of Madrid and can be considered an open urban area. 32 samples of air were taken from February 1998 to June 1998 by using a high volume air sampler. Glass fiber filters and polyurethane foam (PUF) were used to collect the paniculate and gas phase material, respectively. PUF plugs were Soxhlet extracted and filters were ultrasonically extracted by using pesticide-grade hexane and dichloromethane, respectively. The cleanup procedure was carried out on a florisil column with hexane and hexane/dichloromethane as elution solvents. GC/MS in a selected ion monitoring mode was used for quantification and 29 selected PCBs congeners were analyzed.
