Relationships involving particle mass and sulfur content at sites in and around St. Louis, Missouri

Abstract

A number of relationships can be obtained from the measurements made of fine-mode and coarse-mode particle mass and particle sulfur concentrations at ten sites in and around St. Louis in 1975 through 1977. Fine-mode and coarse-mode particle mass occur at about equal concentration levels, but with significant variations with quarter of the year and between urban and rural sites. These variations are associated with those of fine-mode sulfur which as ammonium sulfate is the single largest contributor to fine-mode mass. Ammonium sulfate can constitute up to seven-tenths of the fine-mode mass at non-urban sites during the 3rd quarter of the year. The gradient of the several components of the mass between urban and rural sites vary from just over 1:1 for fine-mode sulfur to over 2:1 for coarse-mode sulfur. The gradients for fine-mode and coarse-mode mass between urban and rural sites ranged near 1.5–1. The variations in fine-mode sulfur appear to be determined by regional rather than local urban influences. The other mass parameters considered show moderate urban influences. The fine-mode mass minus ammonium sulfate shows different variations with season of the year and site than does ammonium sulfate. The other components of both fine-mode and coarse-mode mass are considered and their contributions to the mass estimated.