Physico-chemical characterization of the water

Caractérisation physico-chimique de l'eau

The variables concerned correspond to measurements made in the field (T°, Specific conductivity 25° and pH) during water sampling as well as alkalinity measurements made in the laboratory. The selected quality code is divided into 4 categories coded from 1 to 4: Code 1: correct Code 2: suspicious Code 3: bad Code 4: missing. Field measurements: They are carried out in 2016 and 2017 by a WTW conductivity and pH meter and from 2018 by an integrated "Smart-Troll" probe from the manufacturer INSITU). In both cases, the calibration and calibration protocols of the probes are carried out according to the manufacturer's instructions and at least once every 6 months for the conductivity probe and before each output for the pH probe. In this context, the data obtained with these two devices are considered reliable (code 1). Alkalinity measurements: They are performed in the laboratory by titrimetry within 1 to 2 months after sampling. The quality criterion was assessed as the average of two potential sources of error assessed as follows: - Uncertainty about the evolution of the mineralization of the sample evaluated by the variability of the conductivity measured in the field and that measured in the laboratory at the time of the ErCond= Abs(CondTerrain-CondLabo)/Cond terrain in %. - Uncertainty about the titration evaluated by the varibility of the results obtained by different interpretation methods with respect to the Gran method. ErTitr= EcType (HCO3)/Mean (HCO3 calculated by 4 graphical methods). The proposed qualification is based on the average of these two errors f (ErCond+ErTitr)/2<=5% : Code 1 If 5%<(ErCond+ErTitr)/2<=10% : Code 2 If (If (ErCond + ErTitr)not defined: Code 4