Study of Rain and Fogs Collected in the Vosges Region (1986–1988)
An automatic opening sequential rainfall detector has been installed at the Donon site to study the physicochemical characteristics of rainfall in a forest area of the Vosges mountains affected by “acid rain”. Sequential sampling line (valves, proximity detectors, sample, distribution arm and physicochemical measurements are controlled by an automatic device connected to a printer. The sampling capacity is around 200 fractions. From July 1986 to October 87, 11 rainfall sequences (corresponding to 20 events) have been sampled per 0.1 mm interval. Rainfall has been classified in relation to the origin of precipitations and the trajectory of the cloud formation in question. It is thus possible to follow the change in physicochemical characteristics (pH, conductivity, ionic contents) of precipitations as a function of atmospheric circulations. Depending on the latter, the change in characteristics can be more or less acute during rainfall; in any event, mean pH values are the lowest for Eastern and North- Eastern circulations as well as for orographic type precipitations. Assessments of wash-out have been undertaken, on the basis of change in the ionic content of the sampled fractions.
Measurements of the chemical composition of fog water have been made, concerning a series of fog events sampled with a system besed on the principle of inertial impaction.
KeywordsInertial Impaction Vosges Mountain Proximity Detector Rainfall Sequence Element Dose
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