As one of six criteria air pollutants monitored by the US Environmental Protection Agency, sulfur dioxide negatively affects human and environmental health. Upon entering the atmosphere, sulfur dioxide is oxidized and dissolved in water as sulfuric acid; consequently sulfate rains out and can act as a tracer for atmospheric processing of sulfur compounds. Precipitation data were taken in Houston and compared to the Attwater Prairie Chicken National Wildlife Refuge in order to compare sulfur sources in atmospheric deposition between urban and rural regions. Houston rain exhibits chemical sign atures that are suggestive of seawater and dust influences on rain chemistry, but leaves uncertainty in attributions to these sources as well as others expected to be present around Houston. This project evaluates the degree to which solute and water isotope data can be used to source sulfate in rainfall both within the major city of Houston and outside of its large suburban area.