Concentrations of Sulfur Dioxide in Urban Air Space Above North Central Texas, United States

Abstract

Hourly average sulfur dioxide concentrations in February and August 2022 were compiled, graphed, and evaluated for five air monitoring stations in north central Texas. The stations occupy the urban core and periphery of the Dallas-Fort Worth metropolitan area. Concentration time series were evaluated relative to stationary sources of sulfur dioxide, the urban core, and shifting wind patterns. Nine large sources emitting more than 100 tons of sulfur dioxide per year were identified in the study area, as were sixty additional facilities emitting between one and ninety-nine tons per year. The highest emitter, an electric power station, produced 4,921 tons of sulfur dioxide per year in 2021. Overall, sulfur dioxide concentrations were low, but periodically breached design standards downwind of large emitters. Hourly average sulfur dioxide concentrations ranged from a minimum of less than 0.1 parts per billion (ppb) at all monitoring stations to a maximum of 170.5 ppb at a station located approximately 1 km away from a mineral processing facility. However, monitoring stations located 2 km to 3 km away from, and periodically downwind of, other large emitters had much lower concentration spikes. This study (1) shows the importance of stationary sources, as opposed to lengthy transport and extensive regional mixing, on sulfur dioxide concentrations in urban complexes; and (2) a need for source-oriented monitors to effectively document sulfur dioxide concentrations in urban air space.