Sequential Sampling of Rain: Construction and Operation of an Automatic Wet-Only Apparatus

Abstract

An automatic wet only sequential sampler able to divide rain events in fractions <0,1 mm was developed in order to point out the scavenging influence on the rain composition. In this apparatus special pinch solenoid valves have been used to avoid contact between the mechanical parts and the rain sampled. The rain is collected by volume and, since the sampler is connected to a timer able to memorize the exact time of sampling tube changes, it is possible to calculate the rain intensity as well.

The collected rain is then analysed by ion chromatography to obtain the concentrations of inorganic and some organic anions.

Preliminary results for some events collected in the centre of Florence are also reported and the differences in the time series of some components are explained by meteorological considerations.

Key Words:

• Rainwater collector
• sequential sampling
• chemical composition
• precipitation scavenging