Intercomparison of Wet-Only Collectors and Precipitation Sensors

Abstract

An intercomparison of 11 various types of wet only collectors has shown that large differences in the chemical composition occur, especially for trace metals for which it exceeds those of the main ions. Washing and rinsing experiments have shown that large amounts of trace metals are absorbed or adsorbed in the sampling device before entering the sampling bottle. If all collectors were steered by a single precipitation sensor, the instruments agreed within +/-10 % for the main ions, but not for the trace metals. The investigation of sensors under outside conditions and in a laboratory testing chamber gave comparable results at the onset of precipitation. The behaviour of sensors at the end of rain events was also investigated and large deficiencies have been established.