Related Experiment Video
Updated: May 25, 2026
10:46
A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Spatial variability and application of ratios between BTEX in two Canadian cities
Lindsay Miller1, Xiaohong Xu, Amanda Wheeler
1Department of Civil and Environmental Engineering, University of Windsor, Windsor, ON, Canada N9B 3P4.
Thescientificworldjournal
|January 12, 2012
Summary
Benzene, toluene, ethylbenzene, and xylenes (BTEX) levels were similar in Windsor and Sarnia, but local industries influenced their ratios. Using multiple BTEX ratios improves photochemical age assessment, especially near industrial sources.
Area of Science:
- Environmental Science
- Atmospheric Chemistry
- Urban Air Quality
Background:
- Volatile organic compounds (VOCs) are significant air pollutants in urban industrial areas.
- Benzene, toluene, ethylbenzene, and xylenes (BTEX) are common VOCs with varying health impacts.
- Understanding BTEX distribution and ratios is crucial for assessing urban air quality and photochemical processes.
Purpose of the Study:
- To compare BTEX concentrations and species relationships in two Canadian urban industrial cities, Windsor and Sarnia.
- To investigate the influence of local industries and land use on BTEX ratios.
- To evaluate the reliability of BTEX ratios for diagnosing photochemical age in industrial urban environments.
Main Methods:
- Conducted spatial monitoring campaigns using passive 3M 3500 organic vapor samplers.
- Collected data across multiple seasons in Windsor (2004-2006) and during fall in Sarnia (2005).
- Analyzed BTEX concentrations and calculated ratios between species, correlating them with land use data.
Main Results:
- BTEX concentration levels and species rank order were similar in both Windsor and Sarnia during fall sampling.
- BTEX species relationships varied spatially in Sarnia, indicating strong local industrial influence.
- Correlation analysis revealed significant impact of land use on BTEX ratios, suggesting potential bias in photochemical age diagnostics from single ratios.
Conclusions:
- While overall BTEX levels were comparable, local industrial emissions significantly affected BTEX species ratios in Sarnia.
- Using multiple BTEX ratios provides more reliable insights into photochemical aging than single ratios, especially in industrially impacted areas.
- Spatial monitoring data revealed deviations from central monitoring stations, highlighting the importance of localized sampling for accurate air quality assessment.
Related Concept Videos
01:52Regression Toward the Mean
Regression toward the mean (“RTM”) is a phenomenon in which extremely high or low values—for example, and individual’s blood pressure at a particular moment—appear closer to a group’s average upon remeasuring. Although this statistical peculiarity is the result of random error and chance, it has been problematic across various medical, scientific, financial and psychological applications. In particular, RTM, if not taken into account, can interfere when researchers try to extrapolate results...
01:25Selected Data About Geographic Locations
Geographic Information Systems (GIS) rely on two core types of data: spatial data and attribute data.Spatial DataSpatial data defines the physical location of features within a coordinate system, typically expressed in terms of latitude and longitude. It provides precise positioning for elements like roads, rivers, or buildings.Attribute DataAttribute data complements spatial data by adding descriptive information about these features. For example, a road's spatial data includes its start and...
00:54Ratio Level of Measurement
The way a set of data is measured is called its level of measurement. Correct statistical procedures depend on a researcher being familiar with levels of measurement. For analysis, data are classified into four levels of measurement—nominal, ordinal, interval, and ratio.
A set of data measured using the ratio scale takes care of the ratio problem and provides complete information. Ratio scale data are like interval scale data, except they have a zero point and ratios can be calculated. For...
A set of data measured using the ratio scale takes care of the ratio problem and provides complete information. Ratio scale data are like interval scale data, except they have a zero point and ratios can be calculated. For...
01:16Bioequivalence Data: Statistical Interpretation
The statistical interpretation of bioequivalence data is a significant aspect of pharmaceutical research. Bioequivalence refers to the absence of any significant difference in the rate and extent to which the active ingredient in pharmaceutical products becomes available at the site of drug action when administered at the same molar dose under similar conditions. This helps determine if different drug products have similar absorption rates, ensuring their interchangeability.Statistical...
01:11Calculating and Interpreting the Linear Correlation Coefficient
The correlation coefficient, r, developed by Karl Pearson in the early 1900s, is numerical and provides a measure of strength and direction of the linear association between the independent variable, x, and the dependent variable, y. Hence, it is also known as the Pearson product-moment correlation coefficient. It can be calculated using the following equation:
01:18Related Rates
When two or more physical quantities are linked by a single relationship, a change in one variable necessarily affects the others. This interdependence forms the basis of related rates analysis, which examines how different quantities change with respect to time. A classic physical example is an expanding balloon, where the size of the balloon changes continuously as air is added.For a hot air balloon, the inflated envelope is commonly idealized as a perfect sphere to simplify mathematical...