Trace organic compounds in rain. 1. Sampler design and analysis by adsorption/thermal desorption (ATD)

Abstract

The design and sue of a rain sampler with a 0.89-m/sup 2/ collection surface area are described. The sampler is controlled electronically, provides for the in situ filtration of the sample, and carries out the preconcentration of nonpolar organic compounds by means of cartridges of the sorbent Tenax-GC. Analytical results were obtained for 27 compounds by fused silica capillary column gas chromatography with detection by mass spectrometry for four rain events sampled 12 km southwest of Portland, Or, at the Oregon Graduate Center (OGC), and for five rain events sampled in southeast Portland. Mean dissolved rain concentrations for ..cap alpha..-hexachlorocyclohexane (..cap alpha..-HCH), naphthalene, acenaphthylene, fluorene, and phenanthrene were 5.9, 11, 4.7, 3.2, and 24 ng/L, respectively, at OGC. The mean values for the Portland events were 47, 72, 55, 43, and 140 ng/L, respectively. Since dissolved concentrations were measured, the data were also used in conjunction with available Henry's law constants to estimate the concurrent, local atmospheric levels of these compounds at these sites. Many of the H values of interest are available only near T = 298 K. Therefore, the further understanding of the wet deposition of toxic organic compounds will be facilitated by the direct study of wetmore » deposition as well as by the determination of the temperature dependence of the H values of environmentally interesting compounds. 36 references.« less