Influence of suspended particulate matter on salinity measurements

Salinity is a very important parameter in marine science, which is normally measured via the electrical conductivity of sea water. Suspended Particular Matter (SPM) can influence salinity measurements but so far there had been no experimental studies to test this. s paper a new laboratory study about the influence of SPM on conductivity based salinity measurements is presented. Different sensor types were deployed to investigate the influence of the conductivity sensor design on the observed salinity deviations. The role of clay minerals was additionally analysed. Two natural mud samples of different origins were used to set up various SPM concentrations. The results have shown that high suspended sediment concentrations (up to 300 g l−1) can distort salinity measurements up to 30%. On average only 22% of the observed salinity deviation could be explained by the adsorption of ions by clay minerals. The CTD cell geometry had no verifiable effect, in the resolution limits of the instruments. served salinity deviations were caused by a “blinding effect” of the sensor due to the dissolved particles.