Intercomparison of Wet-Only Collectors for Measuring Wet Deposition

Summary

20 precipitation wet only collectors of 11 different designs have been investigated in a field intercomparison. For the bulk ions, deviations between the various types exceeded 20%. For the trace metals, even larger differences occurred. Three main reasons were made responsible:

• 1. Poor sensitivity of precipitation sensors.

• 2. Wetting losses in the funnels, causing a memory effect.

• 3. Interchange between rain water and materials of the collection device.

By rinsing experiments with diluted HNO₃ we found that appreciable amounts of trace metals accumulate at the funnel walls. Under high outside pollution concentrations gases penetrated into the samples with measurable changes in composition. Only rain events were evaluated.