An Automated Sequential Syringe Sampler for Atmospheric Tracer Studies

Abstract

The design of an improved sampler for the automatic collection of air samples during atmospheric halogenated tracer experiments is described. In this approach, each sample is collected in a small volume (20 to 150 ml) syringe using a rack and pinion drive powered by a precision stepper motor. The sampling rate is controlled via a quartz crystal oscillator and clock to yield averaging periods from 2 to 120 minutes per syringe, and as many as twelve syringe samples can be collected sequentially. Start-up of the sampler is pre-selected using a digital clock and calendar. The sampler is battery-powered, portable and designed for rugged field use. Sample return rates as high as 97% have been achieved in a number of large tracer field programs. Typical results from several of these investigations are also presented.