Floc population characteristics measured with INSSEV during the Elbe estuary intercalibration experiment

Individual floc data obtained with the in situ video camera settling velocity instrument (INSSEV) during the Elbe estuary Intercalibration Exercise, June 1993, are presented in a variety of scattergraph formats and processed to determine individual floc dry mass. The dry mass data are displayed in spectral formats with respect to size, and settling velocity. Similar floc population characteristics to those found in UK estuaries are shown; in particular there is a wide range of effective densities in the smaller floc sizes whereas all the largest flocs have a low effective density. The data are specifically assembled for comparison with results from a settling tube, deployed at similar time and depth. The data indicate that the INSSEV system is able to measure a higher proportion of larger flocs than the settling tube, supporting claims that bottom withdrawal settling tube systems are destructive of the larger, lower density flocs.