Concentrations and Source Modeling of Selected Crustal Elements at a Rural Site Near Bondville Illinois

Abstract

Earth's atmosphere contains a mixture of gases and particles known as aerosols. An aerosol is a suspension of solid or liquid particles in a gas that exhibits stability over some relevant time period. Some aerosols generate significant interest in the field of air pollution because they produce profound environmental effects. These effects motivate scientists to quantify the mass concentrations, physical characteristics and chemical composition of aerosols found in ambient air. Mass concentration is the mass of particulate matter in a unit volume of aerosol (Hinds, 1982). One of the preferred units of mass concentration measurements in atmospheric sampling studies is micrograms per cubic meter (µg/m3) of air. Air is a fluid that can expand or compress in volume, contingent on the temperature and pressure of the air parcel. Therefore, to give meaning to the volume measurement in mass concentration, a standard definition defines the m3 term. This standard definition is termed standard conditions or standard temperature and pressure (stp). Standard temperature and pressure in air pollution research is commonly defined as 25° Celsius or 298.15 Kelvin and 1 atmosphere, 101,325 Pascal or 29.921 inches of mercury measured using a barometric device (Wilson et al., 1983). This stp definition is the one used throughout this report.