Precipitation chemistry affected by differences in location of collection sites and storage methods

Abstract

An investigation was carried out to evaluate rigorously the possible differences in measured concentrations of hydrogen, nitrate and sulfate ions in ‘bulk’ precipitation samples that may be caused by variations in location of rain collectors, and duration and temperature of storage. Storage of precipitation samples, up to 1 month, both in the coldroom and in the field resulted in a significant reduction in the concentration of hydrogen ions. Only field storage caused a statistically significant reduction in the concentration of nitrate in the precipitation samples. Levels of sulfate ions were not found to be significantly affected by storage either in the field or in coldrooms. Samples collected from a rain gage located on a building roof were more acidic than those collected in open spaces in forests. Though all samples showed similar seasonal patterns in the concentrations of sulfate and nitrate, the individual values consistently differed from each other.