Preliminary Study Comparing Precipitation Quality Between Nominal Land Uses in Portland, Oregon

The purpose of this study is to analyze the precipitation quality in various land use categories throughout Portland. Because of its significance in the removal of atmospheric pollutants, wet deposition is an important component to study. In addition to its significant role in cleansing the atmosphere, wet deposition can have a direct impact on the ecosystem due to its potential pollutant load. Various land uses may provide different emission sources, each uniquely affecting the composition of the atmosphere. A literature review found few studies comparing precipitation quality between local land uses within an urban area. Wet deposition studies seem to be fairly limited in the western United States, specifically in the Pacific Northwest. By collecting wet deposition in four different land uses: industrial, commercial, residential, and open space, precipitation quality is compared between each land use using a chosen group of analytes (ammonia, total phosphorus, copper, lead, mercury, zinc, pH, and conductivity). Significant differences were found between a number of land use category pairs for each of the eight analytes, except pH and conductivity. In order to give more insight into the precipitation quality, the results were also analyzed for differences between sites within each land use and differences between storm events. Differences were found between a number of sites, suggesting local effects in precipitation quality throughout Portland. Differences were also found between events, suggesting the importance of meteorological characteristics