Contamination on Zinc and Aluminum Surfaces After Extended Urban Exposures

Abstract

Water soluble contaminants on electromechanical telephone switching equipment exposed for up to 40 years to the New York City environment have been analyzed by a comination of methods. Samples were collected from surfaces by three successive extractions with filter paper squares moistened with distilled water. Elements having atomic number greater than 11 were identified by energy dispersive X-ray analysis. Selected anions were identified with microchemical tests and infrared spectroscopy and determined quantitatively with ion selective electrodes. Nitrate and sulfate concentrations of samples from one location were measured with nitrate and lead ion selective electrodes (the latter for titration of sulfate). Samples from several locations were analyzed with a chloride selective electrode. On zinc surfaces, chloride concentrations averaged 27 μg/cm2 for typical locations, and sulfate and nitrate concentrations averaged 48 and 6 μg/cm2 respectively. On aluminum surfaces, chloride concentrations averaged <2 μg/cm2, and sulfate and nitrate concentrations averaged 25 and 3 μg/cm2, respectively.