NATIONAL TRENDS IN RAINWATER CHEMISTRY

We collected rainwater samples from across the country and analyzed them for anions, cations, and oxygen isotope content in order to investigate regional trends in rainwater chemistry. We examined the various ways in which geography and weather patterns, specifically the Fall 2004 hurricanes along the eastern seaboard, affect the composition of rainwater. We received 70 samples of water from college alumni and relatives of classmates. In addition, we collected samples from several different storms in Northfield, MN. Using an ion chromatograph, we tested for seven anions: fluoride, chloride, bromide, nitrite, nitrate, phosphate and sulfate. Cations tested for included sodium, ammonium, potassium, magnesium, and calcium. Our oxygen isotope analysis confirms that fractionation of rainwater occurs as weather systems move away from their sources. Ion chromatograph analysis suggests regional trends in anion and cation content throughout the United States.