Airborne Detection of Acidic Sulfate Aerosol Using an ATR Impactor

Abstract

As a first step in determining how aerosol acidity varies with altitude, studies were conducted using a new instrument called an ATR impactor installed aboard the Battelle Pacific Northwest Laboratory's DC-3 aircraft. This instrument combines collection of the aerosol by inertial impaction with infrared spectroscopic analysis by the highly sensitive ATR technique. Results from several series of flights have revealed the occurrence of acidic sulfate aloft, while simultaneously collected ground-level samples contained only neutral ammonium sulfate. Acidic sulfate was detected in aerosol samples collected on four of the five flights conducted in the Chicago area during the spring of 1981.